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HYDRAULICS EXCAVATORS "988P & C" 03 - 1996 Training center 1 - INTRODUCTION "988" BASIC PRINCIPLES FOR ELECTRONICA
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HYDRAULICS EXCAVATORS "988P & C"
03 - 1996
Training center
1 - INTRODUCTION
"988"
BASIC PRINCIPLES FOR ELECTRONICALLY ASSISTED SYSTEMS
CONTENTS
PAGE
ASSISTANCE FOR STARTING..........................................................................................................1.02.00 ELECTRIC ACCELERATION..............................................................................................................1.04.00 AUTOMATIC RETURN TO IDLE ........................................................................................................1.05.00 ENGINE OVERHEATING SAFETY SYSTEM.....................................................................................1.06.00 “SPEED-SENSING” SYSTEM.............................................................................................................1.07.00 SWING BRAKE RELEASE .................................................................................................................1.08.00 SWING BRAKE ...................................................................................................................................1.09.00 TWO SPEED C EXCAVATORS TRAVEL AUTOMATIC SEQUENCES......................................................................................................................................1.12.00 P EXCAVATORS SPEED RANGE CHANGE .....................................................................................1.14.00
CASE
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1 - 1.00
1 - INTRODUCTION
"988"
BASIC PRINCIPLES FOR ELECTRONICALLY ASSISTED SYSTEMS ASSISTANCE FOR STARTING
switch
Manual pushbutton shutdown
Ignition key
Automatic stop t=2s
Master
If does not start - Safety indicator lamps light up After 30 sec.
Buzzer sounds
- Use push-button to stop
Starts
Servo-motor on the injection pump goes to ECO mode and then comes back to
Engine speed 1200 r.p.m.
Water temp lower than 60° C
Engine speed 1200 r.p.m.
PRE-HEATING LED on control box flashes
Servo-motor
Engine speed 1200 r.p.m.
1 - 2.00
Servo-motor
Temp sensor on engine block
Time with engine speed 1200 r.p.m. less than 3 mn
Water temp higher than 60° C
Select desired engine speed
- The hydraulic filter and air filter indicator lamps go out - Buzzer sounds again
Electronic control housing
Temp sender on engine block
Time with engine speed at 1200 r.p.m. over 3 mn.
PRE-HEATING LED on control box goes out
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Electronic control box
Training Center
CASE
"988"
1 - INTRODUCTION
BASIC PRINCIPLES FOR ELECTRONICALLY ASSISTED SYSTEMS ASSISTANCE FOR STARTING PURPOSE: When the engine is switched on, the system provides: - A pre-opening of the injection pump - Automatic return of injection pump to the high idle position. WORKING PRINCIPLES - When the system is switched on using the ignition key, the buzzer sounds. The buzzer stops automatically after two seconds. - If the engine does not start, the following warning lamps come on: battery charge, engine oil pressure, minimum pilot pressure, air filter and oil filter restriction warning. After 30 seconds, the last two warning lamps go out and the buzzer sounds (the buzzer can be turned off by the push-button on the instrument panel) - If the engine starts, the injection pumps servo-motor is in the “ECO” mode, which then changes to an engine speed equal to 1200 rpm (high idle). - if the engine coolant water temperature is lower than 60°C or if the time that the motor runs at 1200 rpm is less than 5 minutes, the electronic system will not permit changing to the FINE, ECO or MAX modes. This is indicated by the PRE-HEATING indicator which has a flashing indicator lamp (LED).
Location of PRE-HEATING indicator lamp
STOP
PRE HEATING
FINE
ECO
MAXI
1
2
TRAVEL
Location of buzzer stop push-button
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AUTO
LOW
IDLE
IDLE
PRE HEATING
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1 - 3.00
1 - INTRODUCTION
"988"
BASIC PRINCIPLES FOR ELECTRONICALLY ASSISTED SYSTEMS ELECTRIC ACCELERATION (AFTER ASSISTANCE WITH STARTING)
Electronic control box
Control box
Servo-motor
Engine speed depending mode selected
LOW IDLE
950 r.p.m.
AUTO IDLE
1200 r.p.m.
FINE
1600 r.p.m.
ECO
1900 r.p.m.
MAX
2200 r.p.m.
FINE
ECO
MAXI
1
2
TRAVEL
AUTO
LOW
IDLE
IDLE
PRE HEATING
PURPOSE To set the correct engine speed in accordance with the MODE selection made by the operator. It provides the following : • 2 idle modes - LOW IDLE is the low idle speed at 950 rpm. - High idle (1200 rpm) cannot be selected and is only obtained automatically during assistance with starting when selecting AUTO-IDLE function (see page 1.5.00) • -
3 work modes FINE: 1600 rpm for low output work, and for handling ECO: 1900 rpm, economical digging is possible MAX: 2200 rpm, maximum power, hard work
The mode is selected at the control box which informs the electronic control box. This sends a signal to the servo-motor which is directly connected to the injection pump lever. In this way engine speed is obtained in accordance with the selected mode.
1 - 4.00
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CASE
"988"
1 - INTRODUCTION
BASIC PRINCIPLES FOR ELECTRONICALLY ASSISTED SYSTEMS AUTOMATIC RETURN TO IDLE (AUTO-IDLE MODE) - Swing and travel pressure switches not actived - Pressure sensor on LS circuit with P under 40 bar more than 5 sec.
AUTO IDLE on control box
Electronic control box
Pressure sensor on LS circuit with P over 50 bar
Servo motor
Electronic control box
Injection pump
1200 r.p.m.
Servo-motor
Injection pump
- Swing pilot pressure switche
- Travel pilot pressure switche
Engine speed as per mode selected at beginning
PURPOSE Sets engine speed to idle when none of the various controls for excavator functions are activated. This applies whichever mode has been selected (FINE, ECO or MAX) WORKING PRINCIPLES - The LED lights up as soon as the AUTO-IDLE mode is selected to obtain automatic return to idle. - When not operating any of the excavators functions, for a period of five seconds the swing and travel pressure switches must be not activated and the LOAD SENSING information line at a pressure lower than 40 bar. - In that case, the electronic control box activates the injection pump’s servo-motor and the AUTO-IDLE mode is obtained (idles at 1200 rpm) - When one or more of the controls is operated again, the engine returns to the speed of the mode which was previously selected (FINE, ECO or MAX). This is because information is given to the control box in the following manner: For attachment and options functions - When the L-S information pressure sensor detects a pressure greater than 50 bar For the swing function - When the pilot pressure switch receives a pressure information of 6 bar For the travel function - When the pilot pressure switch receives a pressure information of 6 bar or - When the L-S information pressure sensor receives a pressure greater than 50 bar
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1 - 5.00
1 - INTRODUCTION
"988"
BASIC PRINCIPLES FOR ELECTRONICALLY ASSISTED SYSTEMS ENGINE OVERHEATING SAFETY SYSTEM
Push-button to stop
Buzzer sounds
Water Temp over 115° C
Temp sensor on engine block
The LED lights up
Instrument panel
115°
FINE MODE
MAXI or ECO MODES STOP Indicator lamp lights up
Water Temp lower 100° C
Return to selected Mode
Electronic control box
Servo-motor
MODE unchanged
FINE or LOW IDLE MODES
PURPOSE Safeguards the engine as regards temperature WORKING PRINCIPLES - If the engine coolant solution reaches a temperature in excess of 115°C, the sensor on the engine block gives information to the instrument panel - The buzzer sounds (stopped by push-button) - The stop warning lamp located at top left of instrument panel lights up. - The engine temperature gauge needle is in the beginning of the second quadrant. - The engine temperature gauge LED lights up. - If the engine is in ECO or MAX, the information is transmitted to the electronic control box which reduces the engine speed to the FINE mode and the “FINE” LED lights up. - If the engine is in FINE or LOW IDLE, there is no change - As from a temperature threshold of 105°C, all modes can be selected again
1 - 6.00
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CASE
"988"
1 - INTRODUCTION
BASIC PRINCIPLES FOR ELECTRONICALLY ASSISTED SYSTEMS “SPEED-SENSING” SYSTEM
Engine speed
Sensor on engine (flywheel teeth)
Electronic control box P 35
Pump power (p x qv)
Torque regulator valve
Proportional valve
PURPOSE It maintains power balance between the available engine power and the demands of the hydraulic system, regardless of engine speed selected. WORKING PRINCIPLES - A sensor located on the teeth of the engine flywheel, detects engine speed and transmits it to the electronic control box. - If the hydraulic power which has been consumed causes engine speed to fall, electric information coming from the electronic control box acts on a hydraulic proportional valve, fed by pressure from the hydraulic assistance circuit. - Depending on the intensity of the signal received, which depends itself on the engine speed, this valve delivers a pilot pressure which acts on the torque regulator valve of the hydraulic pump, to reduce the flow supplied by the pump so that the hydraulic power consumed is in line with engine speed (depending on mode selected)
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1 - 7.00
1 - INTRODUCTION
"988"
BASIC PRINCIPLES FOR ELECTRONICALLY ASSISTED SYSTEMS UPPERSTRUCTURE SWING BRAKE RELEASE
P 35
If counter- rotating
Control lever
Pressure selector
Pressure switch
Electronic control box
solenoid valve
Brake release
PURPOSE - Enables the upperstructure swing hydraulic motor brake release to take place WORKING PRINCIPLES - When the control lever is tilted, the pilot pressure actuates a pressure selector. The pressure selector closes a pressure switch which informs the electronic control box - This in turn activates a solenoid valve, fed by the hydraulic assistance circuit pressure. This pressure arrives at the hydraulic motor brake and releases the brake. - Since the hydraulic motor is being fed it drives the upperstructure round by means of a reduction gear - When counter rotation takes place without stopping at the control lever neutral point, the pressure selector acts on the other side and informs the pressure switch which in turn informs the electronic control box and enables the brake to remain released.
1 - 8.00
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CASE
"988"
1 - INTRODUCTION
BASIC PRINCIPLES FOR ELECTRONICALLY ASSISTED SYSTEMS UPPERSTRUCTURE SWING BRAKE(Sensor on hydraulic motor working correctly)
Control lever in neutral position
Upper structure swing speed
Sensor on swing motor
n = 0.4 r.p.m.
Sensor works correctly
Solenoid valve at rest
Upperstructure stops
Time delay = 0.2 sec.
Electronic control box
Braking
PURPOSE - Provides an optimum braking time for the upperstructure swing depending on its speed WORKING PRINCIPLES - When the control lever is at neutral position, the upperstructure decelerates - At a speed less than 0.4 rpm, the hydraulic motor sensor informs the electronic control box - At that moment, a 0.2 seconds time delay enables the solenoid valve to remain piloted so that the upperstructure can stop completely before applying the hydraulic motor brake.
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1 - 9.00
1 - INTRODUCTION
"988"
BASIC PRINCIPLES FOR ELECTRONICALLY ASSISTED SYSTEMS UPPERSTRUCTURE SWING BRAKE (sensor on hydraulic motor not working correctly)
Control lever at rest position
Upperstructure swing speed
Sensor on swing motor
Sensor not working correctly
No information
Electro-control valve at rest
5 sec.time delay
Braking
Pressure selector
Electronic control box
Pressure switch
- If the sensor is defective, when the control lever is released the upperstructure swing pilot circuit pressure switch informs the electronic control box which at that time imposes a 5 second time delay before disactivating the solenoid valve to provide braking
1 - 10.00
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CASE
"988"
1 - INTRODUCTION
BASIC PRINCIPLES FOR ELECTRONICALLY ASSISTED SYSTEMS UPPERSTRUCTURE SWING BRAKE (Sensor is good but problems in hydraulic circuit operation)
Control lever at rest position
Upperstructure swing speed
Sensor on swing motor
n greater than 0.4 r.p.m.
Sensor working correctly
If the upper structure does not stop (damaged safety valve, control jammed control valve spool, open force feed valve, etc), the hydraulic motor speed does not decrease Dynamic brake if necessary
Solenoid valve at rest
Pressure switch
Electronic control box
5 sec time delay
- When there is a problem in the hydraulics (defective safety valve or force feed valve, or a control valve spool jammed, even though the control valve is at rest position, the upperstructure continues turning. The sensor which is still being informed, instructs the electronic control box to perform brake release. But the pressure switch is not being activated. This means that braking * takes place after a time delay of 5 seconds (* which can be dynamic braking)
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1 - 11.00
1 - INTRODUCTION
"988"
BASIC PRINCIPLES FOR ELECTRONICALLY ASSISTED SYSTEMS AUTOMATIC TRAVEL SEQUENCES (TWO-SPEED C EXCAVATORS) First speed selected Electronic control box 11
First speed locked
Hydraulic motors in high displacement mode
Solenoid valve at rest
2
TRAVEL
Electronic command box
Solenoid valve at rest
Hydraulic motors in high displacement
First speed fixed
1. lit up 1
Second speed selected 1
2
2. flashes
TRAVEL
Electronic control box Solenoid valve activated
Hydraulic motors in low displacement
Second speed fixed
2
TRAVEL
1
2
2. lit up
TRAVEL
LS info sensor
If P. over 270 bar
If P. lower than 130 bar
Travel pressure switch
1 - 12.00
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CASE
"988"
1 - INTRODUCTION
BASIC PRINCIPLES FOR ELECTRONICALLY ASSISTED SYSTEMS AUTOMATIC TRAVEL SEQUENCES (TWO-SPEED C EXCAVATORS) PURPOSE - The TRAVEL 2 mode enables the high speed position and automatic speed change to be obtained by reading LOAD SENSING information circuit pressures and the travel pilot pressure (activated pressure switch: pressure greater than 6 bar) - The TRAVEL 1 mode enables the machine to be locked in first speed. WORKING PRINCIPLES - To select first speed, press the TRAVEL key so that LED 1 lights up. The control box locks the machine in this speed. The speed change solenoid valve is at rest position, the motors are in high displacement (low speed). - To select second speed, press the TRAVEL key so as to light up LED 2. The electronic control box activates the speed change solenoid valve and the hydraulic travel motors are in low displacement (high speed). WORKING WITH ATTACHMENTS ONLY IN TRAVEL 2 MODE LED 2 is still lit, LED 1 has gone out. The solenoid valve is activated, the motors are in low displacement WORKING WITH ATTACHMENTS AND TRAVEL OR WITH TRAVEL ALONE. In this case, if the LOAD SENSING information is higher than 270 bar, whatever may be the functions being operated, a sensor fitted on this line informs the electronic control box. A pressure switch fitted on the hydraulic travel motors pilot circuit also informs the control box. These two information inputs taken together enable the control box to disactivate the solenoid valve and to obtain the high displacement on the hydraulic travel motor, which gives first speed (LED 2 flashes and LED 1 lights up) If now the LOAD SENSING information circuit pressure falls to a pressure lower than 130 bar, the control box activates the solenoid valve, the motors return to low displacement, and so change to second speed (only LED 2 is lit up)
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1 - 13.00
1 - INTRODUCTION
"988"
BASIC PRINCIPLES FOR ELECTRONICALLY ASSISTED SYSTEMS WHEELED EXCAVATORS SPEED RANGE CHANGE
Speed range selected
11
Electronic control box
2
TRAVEL
Service brake
Electronic commande box
Service brake pressure switch
Relay K52
Alternator Relay K3
w
Solenoid valves Y 1 1 or Y 1 2
11
2
TRAVEL
JOB SITE RANGE 1 lights up
11
2
TRAVEL
ROAD RANGE
2 lights up
Relay K3 is activated as soon as the engine is started, via terminal W (12 V) of the alternator. The service brake pressure switch (40 bars) is in contact with the earth. If the service brake pedal is depressed and the brake feed circuit pressure reaches 40 bars, the pressure switch located on this circuit closes. The electronic control box is in contact with earth via the pressure switch, the diode and the K3 relay. If the TRAVEL (1 or 2) control is depressed to change the speed range, the electronic control box is informed which activates or disactivates relay K14 which acts either on solenoid valve Y11 or Y12, depending on the TRAVEL mode which was selected NOTA TRAVEL 1 TRAVEL 2
1 - 14.00
K14 relay activated K14 relay disactivated
Job site range Road range
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CASE
8 B - HYDRAULICS
"988"
988 HYDRAULICS GENERAL
988 C TECHNICAL SPECIFICATIONS.......................................................8 LOCATION OF HYDRAULIC COMPONENTS ON 988 C ...............................8 988 C SINGLE-SPEED GENERAL HYDRAULIC SYSTEM.............................8 TWO-SPEED 988 C GENERAL HYDRAULIC SYSTEM.................................8 TECHNICAL SPECIFICATIONS OF THE 988 P ...........................................8 LOCATION OF HYDRAULIC COMPONENTS ON THE 988 P ........................8 988 P GENERAL HYDRAULIC SYSTEM....................................................8
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B 2 B 6 B 8 B10 B12 B16 B18
00 00 00 00 00 00 00
8.B - 1.00
8 B - HYDRAULICS
"988 " 988 C HYDRAULICS GENERAL
HYDRAULIC SYSTEM GENERAL INFORMATION Power unit. - Engine: Idle speed LOW IDLE : 900 to 1000 rpm MEDIUM IDLE : 1180 to 1220 rpm Speeds under load No load speed MAX mode: 1980 to 2020 rpm MAX mode: 2180 to 2220 rpm ECO mode: 1680 to 1720 rpm ECO mode: 1880 to 1920 rpm FINE mode: 1380 to 1420 rpm FINE mode: 1580 to 1620 rpm - Constant torque variable displacement pump with load sensing, flow cancellation and pressure maintenance systems on the attachment, travel and options functions - Fixed displacement pump on the upperstructure swing function. Servo. - Low pressure pump Hydraulic tank. - Self-pressurized to reduce pollution coming from the outside. Filtration. - On general return circuit with by-pass and clogging indicators. - On Load-Sensing information line.(LS1 and LS2) - On functional leaks return (without clogging indicator) Control valves: Attachment, travel, options - “Closed centre and closed outlets“ parallel type. Proportional effect and load sensing. - Flow regulator (balance valve) on each receiving component. Swing control valve. - “Open centre and closed outlets“ parallel type. Linear receiving components. - Double action, single rod cylinders with dashpot and flow limiter on certain chambers. Rotary receiving components. - Fixed displacement hydraulic motor on the swing function, fitted with automatic static brake - Fixed displacement on variable displacement hydraulic motors on the travel function fitted with automatic static brakes. Forced feed. - All receiving components are force fed. - Counter pressure valves on the return circuits for the following functions: attachments, travel, swing, options and servo Oil cooling. - On swing and servo pump flows. - Air cooled by the engine fan. Connective components. - A very large number of hoses is used. - Unions are SAE clamps with ISO seals on
ø≥ 20 mm tubes
- Unions with crimped rings with nuts on ø< 20 mm tubes
8.B - 2.00
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"988"
8 B- HYDRAULICS 988 C GENERAL HYDRAULICS
988 C TECHNICAL SPECIFICATIONS -
-
Installed hydraulic power MAX mode: ...............................................................................................................................................65,5 Kw ECO mode: ..................................................................................................................................................50 Kw FINE mode: ...............................................................................................................................................29,4 Kw
89 hp 68 hp 40 hp
Hydraulic pumps (axial piston and gear type with external teeth) • Maximum displacement (variable displacement pump for attachments, travel and options) ............................................2 x 80 cc/rev • Displacement of the variable displacement swing pump.........................................................................................................28 cc/rev • Servo pump displacement.......................................................................................................................................................12 cc/rev •.Maximum flow (variable displacement pump for attachments)..............................................................................................320 l/min •.Maximum flow (variable flow swing pump)..............................................................................................................................56 l/min •.Maximum flow servo pump .....................................................................................................................................................24 l/min • Pressure for attachment, travel and options .............................................................................................................355 to 365 bar • Servo circuit pressure ...................................................................................................................................................> 34 bar LOAD SENSING valve setting (LS): ∆p between M1 and M3 - Static and dynamic...................................................................................................................................................20 to 23 bar - Dynamic ................................................................................................................................................................21 to 23 bar •.Torque regulation valve setting Bucket or dipper cylinder large chamber pressure ...............................................................................................................300 bar Engine speed ..................................................................................................................................................................≥1980 rpm Variable displacement pump flow .........................................................................................................................................124 I/mn
-
Hydraulic filters Bypass pressure setting .....................................................................................................................................................3,5 bar Clogging indicator pressure setting .....................................................................................................................................3,1 bar Degree of filtration ................................................................................................................................................................10 µ
-
Attachments control valve (three spool stackable) • Bore.........................................................................................................................................................................................20 • Low pressure piloted........................................................................................................................................................8 to 22 • Pressure setting (*with spacer on control lever pushrods): - Relief valve.............................................................................................................................................................390 to 420 - boom cylinder small chamber safety valve ............................................................................................................380 to 410 - boom cylinder large chamber safety valve ............................................................................................................380 to 410 - bucket cylinder small chamber safety valve...........................................................................................................380 to 410 - bucket cylinder large chamber safety valve ...........................................................................................................380 to 410 - dipper cylinder small chamber safety valve ...........................................................................................................380 to 410 - dipper cylinder large chamber safety valve ...........................................................................................................380 to 410
bar bar bar bar bar bar bar bar
• Flow regulator setting (balance valve) - Boom cylinder large chambers...............................................................................................................................165 to 185 I/mn - Dipper cylinders large chambers............................................................................................................................140 to 160 I/mn - Bucket cylinders large chamber .............................................................................................................................155 to 175 I/mn - Swing control valve. • Bore .......................................................................................................................................................................................12 • Low pressure piloted.......................................................................................................................................................8 to 22 bar • Main relief valve pressure setting .............................................................................................................................375 to 405 bar • Swing motor secondary relief valve pressure setting................................................................................................345 to 365 bar
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8.B - 3.00
"988"
8 B - HYDRAULICS 988 C HYDRAULICS GENERAL TECHNICAL SPECIFICATIONS (CONTINUED) •
Travel control valve (stackable, two spools). • Bore ..........................................................................................................................................................................................20 • Low pressure piloted .........................................................................................................................................................8 to 22 bar. • Pressure setting: • Right hand or left hand track secondary relief valve (forward or reverse direction) ....................................................385 to 415 bar. • Flow regulator setting (balance valve). • Right or left hand motor, forward or reverse drive (single or two speed ) ..................................................................130 to 150 I/mn.
- Linear receiving components. • Boom cylinder (quantity 2) .........................................................................................................................................100 x 70 C1030 - fitted with dashpot on large chamber end and a flow limiter in the separator block (large chamber end). • Bucket cylinder ............................................................................................................................................................100 x70 C130. - fitted with dashpot on largel chamber side. • Dipper cylinder ........................................................................................................................................................110 x 80 C 1320. - fitted with dashpot on the large and small chamber ends and a flow limiter on the feed block (small chamber end). • Offset backhoe cylinder ............................................................................................................................................110 x 80 C480 - fitted with dashpot on small chamber end • Articulated boom cylinder ..........................................................................................................................................110 x 70 C775 - fitted with dashpot on large chamber end • Adjustable boom cylinder ........................................................................................................................................100 x 70 C1625 - fitted with dashpot on small chamber end - Rotary receiving components. • Swing motor/Reduction gear. - Fixed displacement hydraulic motor with axial pistons • Displacement ...........................................................................................................................................................................40 • Theoretical speed ................................................................................................................................................................1505 - Reduction gear fitted with oil-bath multidisc automatic type brake, mechanically braked, with hydraulic brake release. • Reduction ratio.....................................................................................................................................................................1/ 28 • Theoretical speed at output shaft ........................................................................................................................................53,8 • Upperstructure braking torque .........................................................................................................................................XXXXX • Pressure required for brakes to be completely released ........................................................................................................8,6
cc rpm.
rpm. mdaN. bar.
• Swing pinion..........................................................................................................................................................13 teeth, module 10 • Turntable...............................................................................................................................................................79 teeth, module 10
8.B - 4.00
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"988"
8 B- HYDRAULICS 988 C HYDRAULICS GENERAL
TECHNICAL SPECIFICATIONS (CONTINUED) • Single speed travel motor/reduction gear assembly: -Fixed displacement, axial piston hydraulic motor • Displacement.................................................................................................................................................... .................60 cc • Theoretical speed ..........................................................................................................................................................2110 rpm Two speed travel motor/reduction gear assembly: -Variable displacement, axial piston hydraulic motor. • Displacement.............................................................................................................................................................. 60/36 cc • Theoretical speeinfirstspeed..........................................................................................................................................2110 rpm. • Theoretical speed in second speed .............................................................................................................................3505 rpm • Displacement change pressure : - Changing from small to large displacement.......................................................................................... 270 to 275 bar - Changing from Large to small displacement........................................................................................ 130 to 140 bar -Reduction gears fitted with oil-bath multidisc automatic type brake, withmechanical braking and hydraulic brake release. • Reduction ratio ............................................................................................................................................................ 1/75.5 • Theoretical speed at output shaft in first speed...................................................................................................................28 rpm • Theoretical speed at output shaft in second speed............................................................................................................ 46 rpm • Output shaft torque .........................................................................................................................................................2268 mdaN • Pressure required for complete brake release ...................................................................................................................11 bar. ALL FUNCTIONS ARE FORCE FED Force feed pressure: On the attachment, travel, swing and options functions (M3 static) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 to 12 bar On swing function. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 to 17 bar. - Low flow option control valve (stackable, one or two sections). • Bore .....................................................................................................................................................................................12 • Low pressure piloted ....................................................................................................................................................8 to 22 . bar. • Clamshell rotation pressure setting .......................................................................................................................130 to 150 . bar. • Flow regulator setting and authorised flow per section Control valve type
Balance setting
Section 1 flow
1SP12
30 l/min
30 l/min
1SP12
60 l/min
60 l/min
2SP12
60 l/min
60 l/min
Section 2 flow
30 l/min
- Hydraulic hammer option control valve (stackable, one section). • Bore ..................................................................................................................................................................................20. • Low pressure piloted ................................................................................................................................ ................. 8 to 22 • Rated secondary relief valves pressure setting.....................................................................................................190 to 210 • Flow regulator setting (balance valve)..............................................................................................................................130 • Flow adjustment using spool mechanical stop ................................................................................................................130
bar bar I/mn I/mn
NOTE: ALL THESE VALUES SHOULD BE CHECKED WITH THE HYDRAULIC OIL TEMPERATURE AT 50°C. Caution: ALL DISPLACEMENTS, PUMP FLOWS, ENGINE SPEEDS ARE THEORETICAL. To avoid any injury or scalding. DO NOT ALLOW THE TEMPERATURE TO RISE OVER 60°C during these checks.
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8.B - 5.00
"988"
AD
M3
8
6
RC
LS
8 B - HYDRAULICS
7
M27
90
10
22b 26
82
M6
M1
63
81
M4
22a
42 3
M7
43
M17
101 61b 103 102 104
M2
41
61a 61c
8.B - 6.00
62
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"988"
8 B- HYDRAULICS
988 HYDRAULICS GENERAL LOCATION OF HYDRAULIC COMPONENTS: 3 6
-
7 8 10
-
Low flow option control valve (clamshell rotation, articulated boom) High pressure hydraulic pump: 1 variable flow body for attachments, travel and options, 1 fixed flow body for swing. Low pressure hydraulic pump for servo circuit Hose / accumulator on variable flow pump LS information circuit Anti-surge valve on pump LS circuit, with LS1 filter
22a 22b 26 -
Pedal control valve for right hand travel function Pedal control valve for left hand travel function Feed and return circuit manifold for servo circuits
41 42 43
-
Swing control valve Hydraulic swing motor Swing function safety and forced feed flange
61 61a 61b 61c 62 63
-
Solenoid valve block consisting of: Automatic swing braking and brake release solenoid valve Arm rest safety solenoid valve Pressure limiter P35 Hydraulic travel motor displacement change solenoid valve (two-speed excavators) Electrically controlled proportional reduction valve (DRE4)
81 82
-
Attachments control valve P10 counter pressure block
90
-
Hydraulic swivel
101 102 103 104
-
Travel control valve (single-speed excavators) Fixed displacement hydraulic travel motors (single-speed excavators) Travel anti bypass block Variable displacement hydraulic travel motors (two-speed excavators)
M1 M2 M3 M4 M6 M7 M17 M27
-
Attachments/travel and options (if any) pressure test point Swing pressure test point LS circuit pressure test point Servo circuits pressure test point Pressure test point at manual control travel block outlet Swing brake and brake release pressure test point Travel pressure test point on speed limiter Pressure test point at proportional valve outlet point.
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8.B - 7.00
"988"
8 B - HYDRAULICS
2
16
3,1 bar
0,4 bar
B2
P
43
110
+
9
G1
M1
T2
81
40 X
T3 T1
M2 B10
V
82
F2 F4
42
A
M7
4
L
F3 F1
F
B
44
B
G
M1
9
T4 P3
M P4
P1
B21 Θ
1
T
F5
3
V
A2
R1
S
B9
M
P2
11 A1 R2
Ø 2,5
3bar S1
6
B1
T1
A1
28
A1
T
P
80
Zb1
T2
B
B1 A1
Za1
21
A
80
87
LS
67
B2
G1
41 12
P
88 A2 Zb2
3
Ø 0,8 X4
M2
B2
85 B2
29
9 Zb1
B1
B
Za2
Ø 0,8
G2
A2
A
4 2
1
7 X3
B1
T
46
A2
A
A1
86
Za1 P
47 R3
9
64
66
45
9
T
1
63
M 27
Zb3
2 M15
Y4
A
B3
210 B11 P Z2 Z3
8
213
9
84
Z1 P
LS
28
B7 214
C
10
B
A
A
A1 B
101
65a
REAR FRONT
Zb2
AVANT
5
C1
REAR
C
89
A2 ARRIERE
A
B2
B
Za2
ARRIERE
8
FRONT AVANT
X
5
P
61a
F
61
7 6
25
Y2 B1 55
3,39
P0
P10
P11
P2
P6 P4
T5 T7
T8
T0
Y5 B2
26
P9
P1
P8 P5 P3
P7
T9
T3
T2
T1
T4 T6
15 bar
17
T1 P3
23
+ 49
9 T1
R
1 2 REAR
27
F B
FRONT
B8 M
T3
2
REAR
P5 L
1
FRONT
A
215
Za1
REAR ARRIERE
X
LS1
214 1
P
103
Y2
65b X2
R1 : AVANT DROIT R2 : ARRIERE DROIT L1 : AVANT GAUCHE L2 : ARRIERE GAUCHE
M6
Pp1
101c
Pp2 T LS M
M2
P Z2 Z1
F
9
M3
101b
M 17
CASE
F
A
A
9
988 C
B
ARRIERE
B
Y1
22b
MP MF
8.B - 8.00
FRONT AVANT
A1
FRONT
B3
61 c
Zb1
90
24
22a
X1 M4
A2
B3
B1 REAR
2
61b A3
102
AVANT
49
211
F
LS2
1 4 3 2 9
S24 A1
B
83
Za3
3
M3
209
A3
4
101a
Any reproduction of this document, either total or partial, is forbidden without special authorization
Training Center
"988"
8 B- HYDRAULICS
988 HYDRAULICS GENERAL 988 C SINGLE SPEED GENERAL HYDRAULIC CIRCUIT DESCRIPTION: 1 2 3 4 5 6
10 11 21
Tank Hydraulic fluid filler cap with self-pressurising valve and gauze filter Return manifold with filter elements and clogging indicator Magnetic filter LS sensor information selector block with filter on LS travel information. High pressure hydraulic pumps - 1 fixed flow body for the swing circuit - 2 variable flow bodies for the attachments, travel and options - Fixed flow low pressure pump for the servo circuit - Accumulator hose - Pressure test points M1 - Attachments/travel and options (if any) circuit pressure M2 - Swing circuit pressure M3 - Pump LS information circuit pressure M4 - Servo feed circuit pressure M6 - Pressure test point at travel manual control block outlet (not fitted) M7 - Swing braking and brake release pressure test point M15 - Pressure test point for swing pilot (not fitted) M17 - Pressure test point for travel on speed limiter (not fitted) M27 - Pressure test point at proportional valve outlet - Anti-surge valve and filter on LS information line (attachments/options) - Calibrated orifice (ø2.5 mm) on main pump irrigation circuit - Boom and bucket (or clamshell) functions manual control block
22b 23 24 25 26 27 28
-
7 8 9
-
-
Swing pilot pressure switch (6 bar) Travel pressure switch (6 bar) Electronic control box Hydraulic swing motor speed sensor
81 82 83 84 85 86 87 88 89 90
-
Attachments control valve block ( boom, bucket, dipper) P10 pressure limiter Dipper cylinder small chamber flow limiter Dipper cylinder (dashpot on small and large chamber) Backhoe / Clamshell selector block Bucket cylinder (dashpot on small chamber) Boom cylinders feed separator block with flow limiter on cylinder largechambers Boom cylinders (dashpot on large chambers) Pressure selector between LS information circuits for attachments/optionsand travel. Hydraulic swivel
101 101a 101b 101c 102 103 110 -
29
Left hand travel control block Manual travel control block Travel information selector block (AUTO-IDLE function) Pressure release pump (foot control pedal) Pilot circuit manifold Minimum pilot pressure switch Swing pilot pressure information selector block (automatic swing braking and brake release function + AUTO-IDLE function) - Manual control block for dipper and swing function
41 42 43 44 45 46 47
-
Swing control valve block Swing function safety flange/forced feed Hydraulic swing motor with static brake 3 bar valve block Braking valves on swing control valve spool pilot circuits 0.5 bar valve on forced feed circuit (mounted on swing control valve) Accumulator
61 61a 61b 61c
-
Solenoid valve block consisting of: Arm rest safety solenoid valve Automatic swing brake and brake release solenoid valve P35 pressure limiter
63 64
- Electro-hydraulic proportioning valve (DRE4) - LS information pressure sensor
Training Center
65a 65b 66 67
Travel control valves block - Anti-excess flow valve - Hydraulic travel motors automatic brake release valve - Speed limiter Fixed flow hydraulic travel motors (with static brake) Travel anti bypass block Hydraulic oil cooler
Any reproduction of this document, either total or partial, is forbidden without special authorization
8.B - 9.00
"988"
8 B - HYDRAULICS
2
16
3,1 bar
0,4 bar
B2
P
43
110
+
9
L
M1
X
B21 Θ
V
A2
R1
S
B9
M
T3 T1
M2 B10
Ø 2,5
T4 P3
M P1
P4
P2 3bar S1
B1
T1
A1
28
A1
T
P
Zb1
T2
B
B1 A1
Za1
21
A
80
87
LS
67
6 80
M1
9
44
B
G
11 A1 R2
T2
81
40
V
82
F2 F4
42
A
M7
4
F3 F1
F
B
1
T
F5
3
B2
G1
41 12
P
88 A2 Zb2
3
Ø 0,8
B1
B
B2
Za2
85
Ø 0,8
G2
A2
A
4 2
1
7 X3
B1
T
46
X4
Zb1
M2 R3
9
64
66
45
T
1
209
A3
4
Zb3
2 M15
Y4
A
B
83
Za3
3
M3
B3
210 B11 P Z2 Z3
C
Z1 P
LS
8
213
9
B
B7 214
84
10
28
A A1
A æ
B
65a
101
X6
REAR FRONT
5
C1
Zb2 A2
AVANT
C
REAR
89
ARRIERE
A
FRONT
B
Za2
ARRIERE
B2
8
AVANT
X
5 7 6
61a P
25
F
61
3,39
S24
P0
Y5 B2 P9
26
211
P11
P10
P7
P1 M4
A2
17
61 c
P2
P8 P5 P3
T5 T7
T8 T9
T3
T2
T0 T1
15 bar
MP MF
B
F
X4
X5
AVANT
ARRIERE FRONT
Za1
FRONT
R
1 2 REAR
B8 Y1 M
22b
B
A
A A1
T3
2
REAR
P5 L
1
FRONT
A
215
ARRIERE
X
214 1
P
103
Y2
65b X2
R1 : AVANT DROIT R2 : ARRIERE DROIT L1 : AVANT GAUCHE L2 : ARRIERE GAUCHE
9
REAR
LS1
Pp1
101c
Pp2 T LS M
M2
P Z2 Z1
F
M6
9
M3
M 17
988 C 8.B - 10.00
FRONT
90
24
22a
B3
F
A4
Zb1
B
P3
Y6 B4
62
T4 T6
23
27 219
X5
2
T1
+ 49
9
A3
P6 P4
X1
61b
B3
B1 REAR
X4
104
AVANT
A1
T1
F
LS2
1 4 3 2 9
0
Y2 B1 55
101b
101a
CASE
Centre de formation 05 - 07 - 95
86
A1
P
47
9
A2
A
Za1
63
M 27
B2
29
9
Any reproduction of this document, either total or partial, is forbidden without special authorization
Training Center
"988"
8 B- HYDRAULICS 988 C GENERAL HYDRAULICS
988 CTWO-SPEED GENERAL HYDRAULIC CIRCUIT DESCRIPTION: The only difference between this circuit and that of the single speed circuit is: 62 - Solenoid valve for hydraulic travel motors displacement change 104 - Variable displacement hydraulic travel motors
Training Center
Any reproduction of this document, either total or partial, is forbidden without special authorization
8.B - 11.00
8 B - HYDRAULICS
"988" 988 P GENERAL HYDRAULIC SYSTEM
Power Unit. - Engine: Idle speed: LOW IDLE : 900 to 1000 rpm MEDIUM IDLE : 1180 to 1220 rpm No-load speed MAX mode: 2180 to 2220 rpm ECO mode: 1880 to 1920 rpm FINE mode 1580 to 1620 rpm
Speed under load MAX mode 1980 to 2020 rpm ECO mode 1680 to 1720 rpm FINE mode: 1380 to 1420 rpm
- Constant torque power variable displacement pump with load sensing, flow cancellation and pressure maintenance systems on the attachment, travel, stabiliser and options functions - Fixed displacement pump on the upperstructure swing function Servo system - Low pressure pumps 1 body for servo systems 1 body for steering and brake circuits Hydraulic tank. - Self-pressurised for reducing pollution coming from outside. Filtration. - On general return circuit with bypass and clogging indicators - On brake unit feed circuit (with bypass) - On load-sensing information (LS1 and LS2). - On functional leaks return (without clogging indicator) Control valves: attachments, travel, stabilisers, options - Parallel type with “closed centre and outlets”. Proportional effect and load-sensing. - Flow regulators (balance valve) on each receiving component. Swing control valve. - Parallel type with “open centre and closed outlets” Linear receiving component - Single rod, double acting cylinders with dashpot and flow limiter on certain chambers for the attachment function - Double rod, double acting cylinder for steering - Single rod, single acting cylinders for front axle locking (with piloted valve) - Single rod, double acting cylinders for stabilisers and dozer blade function (with piloted valves) Rotary receiving components. - Fixed displacement hydraulic motor on swing function, fitted with automatic static brake Forced feed. - All receiving components are force fed. - Counter-pressure valve on the return circuits for attachment and swing functions. Steering. - By “ORBITROL” type steering box Travel braking. - Fully hydraulic braking on all four wheels - Two separate circuits Hydraulic fluid cooling: - On swing and servo pump flows - Air cooled by engine fan
8.B - 12.00
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Training Center
"988"
8 B- HYDRAULICS 988 P HYDRAULICS GENERAL
TECHNICAL SPECIFICATIONS Installed hydraulic power MAX mode: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65.5 Kw 89 hp ECO mode: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 kW 68 hp FINE mode: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29.4 kw 40 hp - Hydraulic pumps(axial piston type and gear type with external teeth) Maximum displacement (variable displacement pump for attachments, travel and option) . . . . . . . . . . . . . . . . . . . . 2 x 80 Fixed displacement swing pump, displacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 Servo pump displacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Steering and braking pump displacement. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
cc/rev cc/rev cc/rev cc/rev
Maximum flow (variable displacement pump) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 320 Maximum flow (fixed flow swing pump) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56 Servo system pump maximum flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 Steering and braking pump maximum flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
l/min l/min l/min l/min
Flow cancellation pressure for attachments, travel and options functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 355to 365
bar
Servo system circuit pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ≥ 34 bar LOAD SENSING (LS)valve setting: (∆ p between M1 and M3) - Static . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 to 25 - Dynamic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 to 23
bar bar
Torque regulator valve setting Bucket or dipper cylinder large chamber pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 300 Engine speed. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ≥ 1980 Variable displacement pump flow. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ≥ 124
bar rpm l/min
- Hydraulic filters By pass pressure setting. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.5 bar Clogging indicator pressure setting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.1 bar Degree of filtration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 µ - Attachments distributor (stackable, three spool) Bore. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 Low pressure piloted. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 to 22 Pressure setting - Main relief valve395 to 430 bar - Boom cylinder small chamber safety valves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 390 to 420 - Boom cylinder large chamber safety valves. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 380o 410 - Bucket cylinder small chamber safety valve. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 380 to 410 - Bucket cylinder large chamber safety valve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 380 to 410 - Dipper cylinder small chamber safety valve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 380 to 410 - Dipper cylinder large chamber safety valve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 380 to 410 Flow regulator valves setting (balance valves) - Boom cylinders large chambers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165 to 185 - Bucket cylinder large chambers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140 to 160 - Dipper cylinder large chambers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155 to 175
bar
bar bar bar bar bar bar l/min l/min l/min
8.B - 13 00
Training Center
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"988"
8 B - HYDRAULICS 988 P GENERAL HYDRAULICS TECHNICAL SPECIFICATIONS (continued)
- Travel control valve (stackable, two spools) Bore ........................................................................................................................................................................20 Low pressure pilote..................................................................................................................................................8 to 22 bar Pressure settings - Travel secondary relief valve (forward or reverse drive)........................................................................................ 380 to 410 bar - Stabiliser and dozer blades secondary relief valve (lowering) ..............................................................................380 to 410 bar Flow regulator valves setting (balance valves) - Travel motor (forward drive) ....................................................................................................................163 to 173 l/min - 4 stabilisers lowering ......160 to 180 l/min raising.............. 80 to 100 l/min - 2 stabilisers lowering ............ l/min raising.............. 40 to 50 l/min - 2 stabilisers and dozer blade lowering ......160 to 180 l/min raising.............. 60 to 80 l/min Blade only lowering...............60 to 80 l/min raising...............15 to 30 l/min - Swing control valve. Bore......................................................................................................................................................................................12 Low pressure piloted ....................................................................................................................................................8 to 22 bar Pressure settings.: Main relief valve ........................................................................................................................................375 to 405 bar Swing motor secondary relief valve pressure setting..................................................................................345 to 365 bar - Linear receiving components Boom cylinder (quantity 2) ....................................................................................................................................100 x 70 C1030 - Fitted with dashpot on large chamber and small chamber ends and a flow limiter on the separator block (large chamber end) Bucket cylinder (fitted with dashpot on small chamber end) ................................................................................100 x 70 C1030 Dipper cylinder ......................................................................................................................................................110 x 80 C1320 -Fitted with dashpot on large chamber and small chamber end and a flow limiter on the feed block (small chamber end) Offset backhoe cylinder (fitted with dashpot on small chamber end) ..................................................................100 x 80 C 480 Articulated boom cylinder (fitted with dashpot on large chamber) ......................................................................110 x 70 C 775 Adjustable boom cylinder (fitted with dashpot on small chamber) ......................................................................100 x 70 C1625 Stabiliser cylinders (fitted with piloted valves) ......................................................................................................125 x 90 C 520 Dozer blade cylinder (fitted with piloted valves) ..................................................................................................140 x 100 C 233 Steering cylinder .................................................................................................................................................... 90 x 50 C 170 Axle locking cylinder (fitted with piloted valves) ..............................................................................................................70 C 135 - Rotary receiving components Swing motor/reduction gear assembly - Fixed displacement, axial piston hydraulic motor. Displacement ....................................................................................................................................................................40 . . cc Theoretical speed ........................................................................................................................................................1500 trpm - Reduction gear fitted with oil-bath multidisc automatic brake, mechanically braked, with hydraulic brake release Reduction ratio ..................................................................................................................................................................1/28 Theoretical output shaft speed ........................................................................................................................................50 . rpm Upperstructure braking torque ....................................................................................................................................3342mdaN Pressure required for full brake release ........................................................................................................................ 8,6 . bar Swing pinion......................................................................................................................................................13 teeth, module 10 Turntable............................................................................................................................................................79 teeth, module 10 - Hydraulic travel motor: Variable displacement, axial piston hydraulic motor Minimum displacement........................................................................................................................................................ 41 ..cc Maximum displacement ...................................................................................................................................................... 93 ..cc Displacement change pressure ..............................................................................................................................240 to 260..bar.
8.B - 14.00
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Training Center
"988"
8 B - HYDRAULICS 988 P GENERAL HYDRAULICS TECHNICAL SPECIFICATIONS (CONTINUED) Two-speed box Reduction ratio in first speed................................................................................................................................................1/6 Reduction ratio in second speed ......................................................................................................................................1/1,8 Speed change control pressure ........................................................................................................................................≥ 34
bar
Steering box -Regulator pressure ..................................................................................................................................................155 to 160 -Safety valves pressure ............................................................................................................................................200 to 220
bar bar
Brake unit: -Engagement Disengagement Engagement pressure ..............................................................................................................................................120 to 135 Disengagement pressure ....................................................................................................................................................160 -Maximum service brake pressure ..................................................................................................................................45 to 60 -Parking brake pressure ................................................................................................................................................120 to 160 -Pressure switch Minimum braking circuit pressure........................................................................................................................................105 Minimum steering circuit pressure ..........................................................................................................................................5 Stoplights ................................................................................................................................................................................5 Parking brake ....................................................................................................................................................................105 ALL FUNCTIONS ARE FORCE FED - Forced feed pressure: On attachments, travel, swing and options functions (M3 static)....................................................................................9 to 12 On swing function ........................................................................................................................................................15 to 17
bar bar bar bar bar bar bar bar
bar bar
- Low flow option control valve (stackable one or two sections) Bore ......................................................................................................................................................................................12 Low pressure piloted ......................................................................................................................................................8 to 22 bar Clamshell rotation pressure setting ............................................................................................................................130 to 150 bar Flow regulator setting(balance valve)and flow per section. Control valve type
Balance setting
Section 1 flow
1SP12
30 l/min
30 l/min
1SP12
60 l/min
60 l/min
2SP12
60 l/min
60 l/min
Section 2 flow
30 l/min
Hydraulic hammer control valve option (stackable, one section) Bore ........................................................................................................................................................................................20 Low pressure piloted ......................................................................................................................................................8 to 22 bar Rated safety valves pressure .................................................................................................................................... 190 to 210 bar Flow regulator setting (balance valve) ..........................................................................................................................50 to 180 l/min flow control using spool mechanical stop ..............................................................................................................................130 l/min NOTE: ALL THESE VALUES MUST BE CHECKED WITH THE HYDRAULIC OIL TEMPERATURE AT 50 °C. Caution: ALL DISPLACEMENTS, PUMP FLOWS, ENGINE SPEEDS ARE THEORETICAL To avoid any injury or scalding DO NOT ALLOW THE TEMPERATURE TO RISE ABOVE 60°C during these checks.
Training Center
Any reproduction of this document, either total or partial, is forbidden without special authorization
8.B - 15.00
"988"
8 B - HYDRAULICS
6
11
113
203
AD
M3
LS
8
110
M12
M27
M11
RC
7
91 105 M1
102 10 103
82 81
M6
104
23
M22
42
M1
43 26 M7
61b
M4
61a
28
109
61e 61c
4
M5
29 32a 61f
M10
M2
M8
61d
22
101 41
8.B - 16.00
112
203
Any reproduction of this document, either total or partial, is forbidden without special authorization
Training Center
"988"
8 B- HYDRAULICS
988 HYDRAULICS GENERAL LOCATION OF HYDRAULIC COMPONENTS 4 6
low flow option valve (swing clamshell, articulated boom) High pressure pumps with one fixed flow body for the swing function and two variable flow bodies for the attachment and travel functions 7 Low pressure pump for steering/brake system - Low pressure pump for servo circuits 8 Hose / accumulator on pump LS information circuit 10 Anti-surge valve and filter on attachments LS circuit 11 filter on steering / braking circuit 22 Travel control pedal 23 Travel direction inverter (INCHING) 26 Servo circuit manifold 28 Steering box (ORBITROL) 29 Brake unit 32a Travel pilot pressure switch (automatic front axle unlocking) 41 Swing control valve block 42 Fixed displacement hydraulic swing motor 43 Hydraulic swing motor safety flange 61 Hydraulic servo block consisting of: 61a Swing brake and brake release solenoid valve (Y5) 61b Selector bloc / L/H armest safety / front axcel lock 61c Solenoid valve (Y2 and Y13) arm rest raising safety system - front axle beam locking and unlocking) 61d 35 bar pressure limiter (P35). 61e Travel speed change solenoid valve (Y11: job-site speed-Y12: road speed) 61f Stabiliser and dozer blade solenoid valve (Y26: raising-Y27: lowering) 81 82 91 101 102 103 104 105 109 110 112 113
Attachment control valve block (boom, bucket, dipper) Counter pressure valve P10 16 passage hydraulic swivel Travel and stabiliser/dozer blade control valve block Hydraulic travel motor (with displacement change) Travel motor forced feed flange Speed limiter and safety block Two-speed box with parking brake Brakes on front axle Brakes on rear axle Stabiliser/dozer blades selector valve Connector block on stabilisers or rear blades small chamber feed line
203
Flow limiter on stabiliser cylinders small chambers
M1 M2 M3 M4: M6: M7: M8: M22: M27:
Attachments/travel or options circuit pressure Swing circuit pressure Pump LS information circuit pressure Servo feed circuit pressure Travel manual control block outlet pressure Swing braking and brake release pressure test point Brake circuit pressure Hydraulic travel motor displacement change circuit pressure Proportional valve outlet pressure test point
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8.B - 17.00
"988"
8 B - HYDRAULICS 2
T
F5
3
0,4 bar
3,1 bar
F3 F1
16 B2
43
120
F
M1
L
F4
B
A
M7
4
12
1 V
R1
A1 R2
B1
T1
A1
P4
87 A1
T
Zb1
P
28
P3
P2
LS
44
67
S1
T4
M
P1
3bar
Ø 2,5
6 80
M1
9
B
G
V
B9
M
S
T3 T1
M2
B10 B21 Θ
T2
42
40
9 X
A2
82
F2
+
P
B
T2
80
A1 B2
36
G1
B1 M3 P
9
10 C
12
X3
8
Ø 0,8
B1
B
B2
Za2
85
A
B
90
X4
A2 Zb2
3
41
7
Ø 0,8
G2
89
4 2
1
B2
21
86 A2
A
9
A1 Zb1
M2
Za1
P
9
45
46
64
R3
T
M15
4
A3 Zb3
A
B
83
Za3
2
84
210
209
B11
P
B3
Z1
Z2 Z3
5
35
66 P
LS
M27
9
1
3
Y4
63
88
A2
A
T 12
B1
Za1
B7 214
213
65a
81
A
A1 B C1
11
C
61a
61 P F12
55
1(6)
P2 P3 P5
P0 B1
55
58
K9
+ 49
P1 P7 P4
61b Y13
64 54
26
F
Y2
P8 P6
T7 T5
T11
T2 T8
T3
A1
T4
T10
T6
22
2,35 P
25
27
12
T
B5
61c
A P 7
P
A2
B B
61d
61e
8
32a
SC 3
106
214
SC 2
52
219
Y27 B5
Y26
33a
MP MF
F
65b
29
B50
P
B
A1
A
A
24
34
49
105
101
P3
A' G
Y
B53
P
LS 63
G'
MA
82
B2 49
63
X
Za2
2
104 Sh
49
61f
94
62
K3
A2
F2 F1
A4
84
P
B51
30a
P1 P
II
91
A2
33b 30c
110
M 22
S
P
66
M8
98
31
A1
P
65
B12
+
F P
A2'
9
237 W ALTER (12V)
A3
103
Zb2
3 B A3'
107
Z
P
G
B
M 18 B1
Zb1
53
T
Za1
5
R
49 63
G
G B'
K14 A5
51
M
P
M6
A4
51
50
6
MB
215 83
53
9
T
P
A4
15
9
B8
106
Y11
53
SC 4 50
C
A
A
Y14
auto 54
B
4 16
105
53
B4
105
A
P
57
manu
108
10
23
F
Y5 B2 211
T
T9
1 M4 17
B3 A3
T1
9
105 S24
T0
B
102
113
I
B52
9h
III
T1
11
A
112
II
30b 9
94
B
I
111
A
III
B
A
A
A
Y16
203 60
60 203
MF MP
202 90b
90c
B
P
32b
L
B
201
14
28 T
988 P
109
R 13
CASE 204
Centre de formation
8.B - 18.00
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205
204
204
205
204
Training Center
"988"
8 B- HYDRAULICS
988 HYDRAULICS GENERAL 1 2
Tank Tank filler cap with self-pressurising valve and gauze filter. 3 Return manifold with filter elements and clogging indicator 4 Magnetic filter on functional leaks returns 5 Information selector block for LS sensor and filter on travel/stabilisers LS circuit 6 High pressure pump (1 fixed flow body for swing function, 2 variable flow bodies for attachments, travel and options) 7 Low pressure pump - 1 body for steering/braking circuit+ 1 for servo system 8 Hose / accumulator on pump LS information circuit 9 Pressure test points M1: attachments/travel or options circuit pressure M2: Swing circuit pressure M3: Pump LS information circuit pressure M4: Servo feed circuit pressure M6: Travel manual control block outlet pressure M7: Swing braking and brake release pressure M8: Brake unit circuit pressure M22: Hydraulic travel motor displacement change circuit pressure M27: Proportional valve outlet pressure 10 Anti surge valve and filter on LS circuit 11 Steering/braking circuit filter 12 Calibrated orifice (ø2.5 mm) on main pump irrigation circuit 21 22 23 24 25 26 27 28 29 30a 30b 30c 31 32a 32b 33a 33b 34
Dipper - swing function manual control block Travel control pedal Travel direction inverter (INCHING) Travel spool pilot selector block for AUTO-IDLE function Foot pressure release pump Servo circuits manifold Pilot circuit minimum pressure switch Steering box (ORBITROL) Brake unit Accumulator on parking braking circuit Accumulator on front axle braking circuit Accumulator on rear axle braking circuit Braking pressure switch for travel speed change Travel pilot pressure switch (automatic front axle unlocking) Pressure switch (stop lights) Parking brake pressure switch Braking minimum pressure switch Steering minimum pressure switch
Training Center
35 36 41 42 43 44 45 46
61 61a 61b 61c 61d 61e 61f 62 63 64 65a 65b 66 67 81 82 83 84 85 86 87 88 89
Automatic swing brake release swing spool pilot selector block Manual control block for boom - bucket functions Swing control valve block Hydraulic swing motor safety / forced feed flange Fixed flow hydraulic swing motor with static brake 3 bar valve for swing motor forced feed Braking valves on swing control valve pilot circuits Spring type accumulator on swing control valve spool pilot Hydraulic servo block, comprising : Solenoid valve for swing braking and brake release selector block / L/H armest safety / front axte lock Solenoid valve (Y2 and Y13) arm rest raising safety system / front axle locking and unlocking 35 bar pressure limiter (P35) Travel speed change solenoid valve (Y11: job site speed-Y12: road speed) Stabilisers and dozer blade solenoid valve (Y26: raising-Y27: lowering) Working brake solenoid valve (Y15) Electro-hydraulic proportioning valve (DRE4) LS information pressure sender Swing pilot pressure control valve spool for swing brake release and or Auto-Idle function. Travel control valve pilot pressure switch for AutoIdle function. Electronic control box Swing motor speed sensor
101 Travel and stabilisers/dozer blade control valve block 102 Hydraulic travel motor (with displacement change) 103 Travel motor forced feed flange 104 Speed limiter and safety block 105 Two-speed box with parking brake and speed range change cylinder 106 Speed range change safety and indexing block 107 Hydraulic travel motor disengagement block (for speed range change) 108 Calibrated orifice on parking brake circuit 109 Brakes on front axle Steering cylinder 110 Brakes on rear axle 111 Front axle beam locking cylinder 112 Stabiliser/dozer blade selector valve 113 Front stabiliser or rear dozer blade small chambers feed connection block 201 Dozer blade cylinder 202 Calibrated orifice on dozer blade cylinder large chamber 203 Flow limiter on stabiliser cylinder small chambers 204 Stabiliser cylinder 205 Stabiliser cylinder piloted valve
Attachments control valve block (boom, bucket, dipper) P10 pressure limiter block Flow limiter on dipper cylinder small chamber Dipper cylinder (dashpot on small and large chamber) Backhoe-clamshell selector block (option) Bucket cylinder(dashpot on the large chamber) Boom cylinder feed block with flow limiter on cylinder large chambers. Boom cylinders(dashpot on large chambers) Shut-off valve on boom cylinder large chambers (for transport position)
90
Pressure selector on attachments and travel/stabiliser LS circuits 90b& Pressure selector on brake circuits 90c (Working brake and dynamic brake) 91 16 passage hydraulic swivel
Any reproduction of this document, either total or partial, is forbidden without special authorization
8.B - 19.00
"988"
8 B - HYDRAULICS 988 HYDRAULICS GENERAL
8.B - 20.00
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"988"
8 D- HYDRAULICS 988 TANK - FILTERS - COOLER
- THE TANK ...........................................................................................................8D .02 00 - SHUT-OFF VALVE - FILTERS .............................................................................8D .04 00 - THE OIL COOLER - THE THERMOSTATIC SHUT-OFF VALVE ........................8D .06.00
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8D - 1.00
"988"
8 B - HYDRAULICS 988 TANK - FILTERS - COOLER HYDRAULIC TANK The welded tank 1 stores the hydraulic fluid. It is self-pressurised. This self-pressurisation is controlled by a valve set to 0.4 bar. DESCRIPTION: 1 - Tank 2 - Shut-off valve 3 - Breather and filler cap 4 - Filters (quantity 2). 5 - Filter clogging pressure switch (3,1 bar standard and 2 bar if the excavator is fitted with a hydraulic hammer). 6 - Inspection plate 7 - Lifting ring (tank less oil) 8 - Fluid level sight glass. 9 - Tank pressure release cap 10 - Fluid temperature sensor 11 - Filling gauze. PORT LOCATIONS A : Variable flow pump inlet B : Fixed flow pump inlet E : Hydraulic hammer circuit returned. on symbol schematic C : Pilot pump inlet D : Steering/braking pump inlet for P excavators F : Swing and P35 pressure limiter returned G : Attachments/travel general return H : Leaks and magnetic filter return circuit
E
X 3,1 bar
7 6
1
5
4
8
A
B
2
F
16
0,4 bar
9
10
G
4
3
B2
P
5
3 +
B
11
2 1 H C
D
9
10 B21 Θ
8D - 2.00
B A
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Training Center
"988"
8 D- HYDRAULICS 988 TANK - FILTERS - COOLER
HYDRAULIC TANK (continued) LEVEL: Every 10 hours or every day - Park the excavator on flat horizontal ground, extend the dipper, open the bucket and lower the attachment to the ground (on P excavators, raise the stabilisers and the blade) - Stop the engine - Check the tank level. It should be between marks 4 and 5. FILLING - Unscrew the pressure release plug 9, remove breather 3, screw in the funnel delivered with the excavator and top up the hydraulic fluid. - Re-install breather 3 and retighten plug 10. REPLACING THE BREATHER (every 2000 hours) - Stop the engine, lower the attachment to the ground, release pressure in the tank by unscrewing plug 9, remove breather 3. - Fit a new breather - Start the engine, extend all the cylinder rods and check the tank level. SELF-PRESSURISATION FUNCTION The breather is fitted with a valve b which prevents cavitation and a valve which limits pressure in the tank to 0.4 bar. Air necessary for the tank to be pressurised passes via filter C.
0,4 bar c
b
a
- When starting up, if fluid is fed to the cylinder big chambers, the level of oil goes down. Atmospheric pressure opens valve b and air enters the tank via filter c - If the small chambers of the cylinders are fed, the oil level rises. The air cannot escape via the valves. With the temperature the pressure increases in the tank and it is limited to 0.5 bar by valve a. RECOMMENDATION: When the starting the machine for the first time, extend all the attachment cylinder rods, check the minimum hydraulic oil level and bring the maximum of air into the hydraulic fluid tank to ensure correct self-pressurisation function.
FILLER CAP GAUZE 1 - It is located in breather cap 3 - It enables the oil to be filtered when refilling or adding oil (filtration fineness = 10 µ) - To clean or change the gauze, remove the breather and the screws 2. When re-installing check that the two seals 4 are correctly placed.
3
2
4
1
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8D - 3.00
"988"
8 B - HYDRAULICS 988 TANK - FILTERS - COOLER THE HYDRAULIC TANK SHUT-OFF VALVE Located at the bottom of the tank, the shut-off valve enables the tank to be isolated when maintenance operations are taking place on the tank or the hydraulic pumps. CAUTION: Before starting up the excavator, make sure that the shut-off valve is open and that pin A is in its correct housing.
RETURN FILTERS
A
DESCRIPTION 1 - Manifold. 2 - Clogging indicator. 3 - Filter elements 4 - Element by-pass valve REPLACEMENT: The filter elements must be replaced when the indicator lamp on the instrument panel stays on or every 500 hours. - Unscrew the plug to release the pressure in the tank. - Remove the used elements 3 and replace them by new elements
1
A
2
3 4
3
1
8D - 4.00
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2
Training Center
"988"
8 D- HYDRAULICS 988 TANK - FILTERS - COOLER
OTHER FILTERS IN THE HYDRAULIC SYSTEM On the brake system of wheeled excavators This is a filter element (11)which is installed between the gear pump outlet and the brake unit feed.
11
LOCATION It is located under the walkway behind the cab This filter has no clogging indicator and the element must be replaced every 500 hours. The arrow shows the direction of circulation of the oil.
On the hydraulic pumps “LOAD SENSING” information circuits They are in the anti-surge valve (10) and also on the information circuit selector block (5) ”LS2” (see the pumps section ) These filters must be changed every 500 hours
5
LS1
LS2 10
On the functional leaks return circuit (4) It is a cartridge-type filter. It filters the leak return circuit before returning to the reservoir. It is located by the side of the hydraulic tank on the engine side This filter has no clogging indicator and the element must be replaced every 500 hours.
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4
8D - 5.00
"988"
8 B - HYDRAULICS 988 TANK - FILTERS - COOLER HYDRAULIC OIL COOLING CIRCUIT The hydraulic system cooler is fed from the swing return circuit and from the 3 bar pressure limiter (44). The hydraulic oil cooler is attached to the engine water radiator and the cooling air is drawn through the oil cooler by the engine fan. The oil cooler is located at the lower part of the radiator.
WATER
OIL
THE THERMOSTATIC SHUT-OFF VALVE (Optional fitment) Purpose: This valve by-passes the oil cooler when the temperature of oil is under 40oC and directs the oil through the oil cooler at 50oC.
44
8D - 6.00
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8F - HYDRAULICS
"988 "
HYDRAULIC PUMPS 988
CONTENTS
PAGE
- WORKING PRINCIPLES - DESCRIPTION OF THE SYSTEM .....................................................................................8F.02.00 - STOPPING THE ENGINE .....................................................................................................8F.04.00 - STARTING THE ENGINE .......................................................................................................8F.05 00 - LOAD SENSING SYSTEM.....................................................................................................8F.07.00 - TORQUE REGULATION.........................................................................................................8F.09.00 - FLOW CANCELLATION AND PRESSURE HOLDING ................................................8F.12.00 ENGINE/PUMPS COUPLINGS ................................................................................8F.14.00 LOCATION OF PORTS AND ADJUSTMENT POINTS.............................................8F.15.00 ASSISTANCE AND STEERING/ BRAKING PUMPS................................................8F.16.00 MAIN PUMP ASSEMBLY..........................................................................................8F.18.00 - VARIABLE DISPLACEMENT PUMP BODIES .......................................................8F.19.00 - THE SERVO-CONTROL AND THE VARIOUS REGULATOR VALVES .................8F.20.00 - THE SWING PUMP ................................................................................................8F.22.00 THE ANTI SURGE VALVE IN THE “LOAD SENSING” INFORMATION CIRCUIT ...8F.23.00 THE PROPORTIONAL VALVE ................................................................................8F.24.00 SYMBOLIC SCHEMATIC OF HYDRAULIC POWER UNIT ......................................8F.25.00
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8F.1.00
8F - HYDRAULICS
"988 " HYDRAULIC PUMPS 988
WORKING PRINCIPLES SYSTEM USING LOAD SENSING VALVE, TORQUE REGULATOR, FLOW CUT OFF AND PRESSURE LIMITING: A-”LOAD SENSING” Purpose of “Load Sensing” valve: - It adjusts the pump flow to correspond to the driver’s requirements. - It is not sensitive to the different loads. - It cancels the flow when the control valve spools are in the rest position, or when maximum pressure is reached at the attachments or travel functions. Advantage: - It prevents unnecessary hydraulic fluids circulation and therefore reduces the amount of power lost in heat. Basic principle: . Flow passing through a given section depends on: a) the diameter and the shape of the passage. b) the power loss for this section. - The “LOAD SENSING” system maintains a constant power loss - Flow therefore depends only on the passage section corresponding to the control valve position. B-TORQUE REGULATION. Torque regulation is widely used by manufacturers of excavators. It consists of limiting the resistant torque of the pump. Current designs enable this torque to be kept constant for all pressure values. Purpose: To make the best possible use of the available power. Advantages: . An engine of a lower power can be fitted. . Torque can be regulated between two separate functions. Basic Principles: - The resistant torque of the pump is proportional to the displacement and the pressure. We therefore have to arrive at the product of those values and to keep it constant. - For this we use a lever to which a force is applied proportional to the pressure, at a distance with an axis proportional to the displacement. A spring opposes this force. - The lever forms part of a valve which feeds the pump control cylinder. C-FLOW CUT OFF AND PRESSURE LIMITING. Purpose: - It limits the pressure in the attachment, travel and options circuits. - It cancels the flow at maximum working pressure, while still maintaining that pressure at its maximum value. Advantages: It enables maximum pressure to be used with only a low power consumption. It reduces the power lost in heat. Basic Principles: - At maximum working pressure a valve opens, the LS valve pilots. This pressure then arrives at the various sections of the variable flow pump displacement control cylinder. - The pump barrel is tilted to the minimum and supplies a flow which is only equal to the value of the system functional leaks.
8F.2.00
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8F - HYDRAULICS
"988 " HYDRAULIC PUMPS 988
20
23
26
21
24
25
22
LS
27
P35 28
1
19
M1 6
2
18
P10 9
14
15
16
17
13 V
5 7
12 11 C
D
Variable displacement pump body Pistons Swashplate Shaft Displacement control cylinder small chamber Displacement control cylinder large chamber Cylinder return spring Pilot piston Lever Torque regulation valve Push rod Return spring Electro-hydraulic proportioning valve (DRE4) P10 pressure limiter
15 16 17 18 19 20 21 22 23
-
24 25 26 27 28
-
4
3
8
A B
10
SYSTEM DESCRIPTION 1 2 3 4 5 6 7 8 9 10 11 12 13 14
-
Non-return valve Pushrod Return spring Closed centre control valve Cylinder ”LOAD SENSING” valve Pushrod LS valve adjustment spring Shuttle ball:pressure selector between attachment and travel Flow cut off (LS) valve Control lever Pilot pump P35 pressure limiter Tank
NOTE: When the available hydraulic power is exceeded, the torque regulator valve takes over from the “LS” valve and the flow from the variable flow pump depends on the pressure in the high pressure circuits (attachments/travel and swing) At maximum pressure, flow cut off is obtained while still maintaining this pressure in the circuits being fed
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8F.3.00
8F - HYDRAULICS
"988 " HYDRAULIC PUMPS 988
OPERATING PRINCIPLE 20 21 22
LS P35
6
P10 7
V
12 10 PHASE ONE With the engine stopped Valves LS20 and torque regulator 10 are at the rest position, under the action of springs 22 and 12. The large chamber 6 of the pump displacement control cylinder is in the return to tank position passing via the torque regulator valve 10 and LS valve 20 The pump barrel is maintained at maximum tilt, under the action of return spring 7
8F.4.00
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Training Center
8F - HYDRAULICS
"988 " HYDRAULIC PUMPS 988 WORKING PRINCIPLE
20 }
22 }
LS
}
21 } }
}
P35 }
}
}
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6 }
}
P10 }
} }
V
5
➟
10
PHASE 2 Starting the engine Variable displacement pump 1 begins to supply flow Since the control valve has the centre closed at rest position, the pressure at the pump outlet increases. This pressure arrives at the springless side of LS valve 20. A pressure differential (∆p) in excess of 20 bar is necessary in order to overcome the force of spring 22 and to move spool 21. As soon as this pressure differential ∆ p is reached, spool 21 moves and directs the pump outlet pressure (passing via torque regulator valve 10) into the displacement control cylinder large chamber 6. The pump outlet pressure is always in the small chamber 5 other cylinder. The difference in section means that the displacement control cylinder moves to bring pump swashplate 1 to a displacement produces the minimum flow necessary to cover the functional leaks. The flow is very low, the power consumed is very low.
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8F.5.00
8F - HYDRAULICS
"988 " HYDRAULIC PUMPS 988
WORKING PRINCIPLE 20 }
21 }
}
22
LS }
}
P35 }
}
6 }
}
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P10 }
14 V
5
PHASE 3 Engine running, all controls at neutral position The pump outlet pressure stabilizes The sum of the hydraulic forces and the force of spring 22 bring the LS valve spool 21 into a position of equilibrium. Details of forces applied to the LS spool
Spring side
Side without spring Pump outlet circuit pressure
P10 pressure (14) + spring pressure
= =
∆p For the system to work correctly, the ∆ p should be about 20 bar
8F.6.00
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8F - HYDRAULICS
"988 " HYDRAULIC PUMPS 988 WORKING PRINCIPLE
➟
23
20
22
} }
LS
}
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P35
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16
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18
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5 7
PHASE 4 Modifying the flow in relation to the demand (LOAD SENSING) Engine running, one function is starting to be controlled Spool 16 of control valve 18 is moved slightly so as to feed cylinder 19 The circuit pressure in the last chamber of cylinder 19 passes via the internal passage of the control valves spool and presses the selector spool against its seat. This pressure arrives at the side with spring of LS valve 20 and its force is added to that of spring 22 force. The outlet pressure of the pump is not sufficient to oppose these forces so spool 22 of LS valve comes back to the rest position. When it moves, spool 22 puts large chamber 6 of the displacement control cylinder into the return to tank position (passing via the torque regulator valve). The pump outlet pressure is still in the spool chamber 5 of the displacement control cylinder. Under the action of this pressure, added to the force of return spring 7, the cylinder controls the tilting angle of the variable flow pump barrel. The barrel increases its flow. Details of forces applied to the LS valve spool Side with spring
>
Pressure of the sealing component circuit + Spring force
Side without spring
>
Pump outlet circuit pressure
To resume If ∆p
< à 20 bar, the control cylinder large chamber returns to tank, the pump flow increases
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8F.7.00
8F - HYDRAULICS
"988 " HYDRAULIC PUMPS 988
➟
20
➟
WORKING PRINCIPLE
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25
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P35
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19
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15
16
18
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6
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➟
V
PHASE 5 Modification of flow in relation to demand (LOAD SENSING) Control valve spool 16 is now being piloted by the control lever 25 The flow supplied by the variable flow pump passes via the non-return valve 15 and through the gradual movement notches in spool 16 to feed the large chamber of cylinder 19 By passing through spool 16, this flow creates a pressure drop which reduces the pressure upstream in control valve 18 greater than the downstream pressure. We therefore have, inthe LS valve (20), a higher pressure on the side without spring than on the side with spring. This makes spool 21 of the LS valve move again into a position of equilibrium. In this position of the LS valve, the return to the tank of pump displacement control cylinder 6 large chamber is partially obstructed. As a result an equilibrium of forces acting on the large and small chamber of the displacement control cylinder is arrived at. This stabilizes the variable flow pump barrel tilting angle. The flow obtained is constant and is proportional to the control pressure of control valve spool 16 Pump flow (and therefore the speed of movement of the load)depends on the tilting angle of the control lever (as required by the driver) To resume If ∆p = 20 bar , the forces of the large and small chambers of the control cylinder are equal , the pump flow becomes constant (a function ofthe control pressure of the control valve spool)
8F.8.00
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8F - HYDRAULICS
"988 " HYDRAULIC PUMPS 988
➟
WORKING PRINCIPLE
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P10 11
V
➟
➟
10
8
PHASE 6 Torque regulation Increasing load on cylinder 19 depending upon available hydraulic power The load gives a greater pressure in cylinder feed circuit 19 The outlet pressure from the pump is also greater Via the internal passage of control cylinder 7, this pressure is applied to piston 8, which creates a torque on lever 9 greater than that of the spring. Lever 9 tilts, thus moving spool 11 of torque regulator valve 10. In moving, spool 11 opens the feed to the displacements control cylinder large chamber by the pressure output from the pump. The difference in the forces applied to the large and small chambers of the control cylinder forces the swashplate to reduce its tilting angle and as a result the flow decreases.
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8F.9.00
8F - HYDRAULICS
"988 " HYDRAULIC PUMPS 988
WORKING PRINCIPLE
➟
20
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LS
21
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➟ 3
8
18
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11
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9
12
➟
D
10
PHASE 7 Torque regulation (continued) a)The load on cylinder 19 is identical to that of the proceeding phase The tilting angle of the barrel reduces, which in turn reduces the flow from the pump The flow passing via spool 16 of control valve 18 is lowered, therefore the delta p is lower than the adjustment value of LS valve 20. This makes spool 21 of LS valve 20 move again into the at rest position. Torque regulator valve 10 partially obstructs the return to tank of large chamber 6 of the pump displacement control cylinder. As a result the forces acting on the large and small chambers of the displacement control cylinder are equal. This stabilizes the tilting angle of swashplate 3 of the variable flow pump 1. At the same time piston 8 slides on lever 9, closer to the axes of the lever. The torque on the lever decreases, lever spring 9 is stronger. This allows, as a result of the action of return spring 12, torque regulator valve 10 spool 11 to move into a position of equilibrium. The flow and torque which are obtained are constant. NOTE: When pump 1 is at maximum torque, the torque regulator valve spool 11 is in equilibrium.
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8F - HYDRAULICS
"988 " HYDRAULIC PUMPS 988
➟
20
}
➟
} } }
LS
21
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O
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P35
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19 1 6 }
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P10 }
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13 }
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V
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➟ 3
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D
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PHASE 8 Torque regulation (continued) b)same configuration but using fixed flow pump body 13 In this case the pressure at fixed flow pump outlet 13 arrives in chamber D of the torque regulation valve 10. The force applied on the annular section is added tothe force applied by pilot piston 8. The sum of theseforces makes spool 11 move backwards. The variable flow pump outlet pressure enters thelarge chamber 6 of the displacement control cylinder and reduces the tilting angle of the pumpbarrel. This reduces the variable flow pump flow in relation to the swing circuit pressure. The torque consumed by variable flow pump 1 plus that of the fixed flow pump 13 gives us the maximum available torque. NOTE: When pump 1 is at maximum torque, the torque regulator valve spool 11 is in equilibrium.
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"988 " HYDRAULIC PUMPS 988
WORKING PRINCIPLE
➟ 21
➟
}
24
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LS
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}
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O
P35
}
}
19 6 }
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P10
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18
} V
B
PHASE 9 Flow cut off and pressure limiting Spool 16 of control valve 18 is held in the piloted position with a load on the cylinder which is even greater The pressure in the cylinder 19 feed circuit is a t the maximum and the load is immobile. This pressure opens the flow cut off valve LS 24 A small flow passes via the calibrated oriface of this valve The pump outlet flow has a tendency to pass via the internal passage of control valve spool 16. The delta p is greater than adjustment value of valve LS. As a result of the flow cut off valve 24 being opened, the pressure on the LS valve side with spring falls. The pressure on the side without spring is now greater, so the LS valve spool pilots. Oriface b of the torque regulator valve, in communication with the large chamber 6 of the displacement control cylinder, is partially pluged and the pressure in the large chamer 6 is equal to the pressure at the pump outlet.
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8F - HYDRAULICS
"988 " HYDRAULIC PUMPS 988 WORKING PRINCIPLE
➟
}
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PHASE 10 Flow cu off and pressure limiting (continued) The hydraulic force in chamber 6 is greater than the hydraulic and mechanical forces in small chamber 5. The barrel tilts toward the minimum. Pilot piston 8 slides on lever 9 and becomes closer to the lever axis. The spring on lever 9 pushes it back. When the load on pushrod 11 of torque regulator valve 10 is greater than that of spring 12, pushrod 11 returns to the rest position. At that moment the pump outlet pressure arrives directly in the large chamber 6 of the displacement control cylinder. The large and the small chamber of the control cylinder are subjected to the same pressure. As a result of the difference in section, the force in large chamber 6 is greater than the sum of the hydraulic and mechanical forces in small chamber 5. This brings the pump barrel back to the minimum tilting, covering only functional leaks and the flow which passes via the flow cut off valve 24, which is open. The pressure in the feed circuit is at the maximum, but since the flow is very small, the power consumed is low.
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"988 " HYDRAULIC PUMPS 988
UNIT/ENGINE COUPLING It transmits motion between the engine flywheel and the hydraulic pumps assembly. It consists of a flexible flange 1 bolted to the engine flywheel and a splined sleeve 2 mounted on the pumps unit drive shaft
2
1
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8F - HYDRAULICS
"988 " HYDRAULIC PUMPS 988 Location of ports and of adjustment points Ports - S Variable displacement pump body inlets - S1 Fixed displacement pump body inlet - S2 Pilot pump inlet - A Swing pump outlet - A1 Attachments, travel and options pump body outlet - A2 Attachment travel and options pump body outlet - A3 Pilot and irrigation pump outlet
A
X3
5
4
X4 6
S1 A1
T12
On wheeled machines, there is a second pump body to feed the brakes and steering. A2 Legislation in certain countries (Germany, Switzerland, and Italy) requires that the brake circuit S and the steering circuits should be separate. In this case there are two separate gear pump R2 bodies which feed the circuits - R2 Irrigation for variable flow pumps - X4 LOAD SENSING valve information circuit inlet - X3 Swing circuit pressure inlet on torque regulator valve -T12 Anti-surge valve leaks return circuit
7
Adjustment points - 4 Torque regulator valve adjustment - 5 Flow cut off and pressure holding valve adjustment - 6 LOAD SENSING valve adjustment - 7 Variable displacement pump bodies maximum displacement adjustment
4
X3
5
X4
6
4
X4
6
A1 5
A A
A1
A2
S2 S1
A3
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S
A3
S2
S1
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R2
S
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"988 " HYDRAULIC PUMPS 988
Hydraulic servo pumps (P & C excavators) and steering/braking pumps (P excavator) They are attached to the swing pump They are of the gear type with external teeth and they feed : C excavators and P excavator 1st body - the servo circuit - the piston pump housing irrigation circuit P excavators : the 2nd body feeds : - the steering and braking circuit
C excavators A
C excavators
S
Identification of ports S - Inlet A - Output C - Pump direction of rotation Description 1 - Pinion with shaft 2 - Lip seal 3 - Front flange 4 - Centring studs 5 - Seals 6 - Housingr 7 - Rear flange 8 - Rear block 9 - Pinion 10 - Assembly bolt 11 - Front block
1
2
3
4
5
6
7
8 9 11 10
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"988 "
8F - HYDRAULICS HYDRAULIC PUMPS 988
Hydraulic servo pumps (P & C excavators) and steering/braking pumps (P excavators) P excavators
S1
S2
Identification of ports S1 - Servo circuit inlet A1 - Output to solenoid valve block S2 - Steering / braking circuit inlet A2 - Output to brake unit C - Pump direction of rotation Description The design is identical for both pump bodies and each body is the same as the description shown on the previous page. The pinion with shaft of the first body drives the minion in the second body via splined sleeve 12.
A1
A2
12
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"988 " HYDRAULIC PUMPS 988
MAIN TECHNICAL DETAILS OF PISTON PUMPS Description 1 2 3 4 5 6 7
Housing Servo controle LOAD SENSING, torque regulator, flow cut off valve block Drive shaft Variable displacement pumps second body drive pinion Fixed displacement pump body drive pinion Shaft sealing (flange + lip seal) (This description also concerns the photos on the following page)
6
3
7
4
2
5
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1
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"988 " HYDRAULIC PUMPS 988 PISTON PUMPS MAIN TECHNICAL DETAILS 6
4
5
1
3
7
THE VARIABLE DISPLACEMENT DRIVING PUMP BODY Description 1 Splined shaft 2 Lip seal contact surface 3 Nut 4 Taper roller bearings 5 Variable displacement pump second body drive pinion 6 Pistons with rings (quantity 7) 7 Guide piston 8 Barrel
1
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2
5
6
7
8
VARIABLE DISPLACEMENT DRIVEN PUMP BODY It is the same as the previous pump except there is no splined shaft
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8F.19.00
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"988 " HYDRAULIC PUMPS 988
TECHNICAL DETAILS OF PISTON PUMPS The servo control and the various valve blocks 2 Description 1 Torque regulator valve 2 LOAD SENSING valve 3 Flow cut off valve 4 Servo control cylinder small chamber 5 Return spring 6 Servo control cylinder 7 Hydromechanical torque regulator pilot piston 8 Servo control cylinder large chamber 9 Hydromechanical torque regulator lever arm 10 Torque regulator control rod 11 Sealing sleeve between the valve block and the pump housing 12 Barrel drive arm
3
1
4
11 5 10
6
9 1
10
3 7
12
8 2
5
9
8
6
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6
7
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2
12
8F - HYDRAULICS
"988 " HYDRAULIC PUMPS 988 VARIOUS VALVE BLOCKS (continued) LOAD SENSING VALVE A A
B D
C
TORQUE REGULATOR VALVE B
FLOW CUT OFF VALVE C NOTE LS valve stability is insured by restrictor D (A)
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"988 " HYDRAULIC PUMPS 988
MAIN TECHNICAL DETAILS OF PISTON PUMPS Fixed displacement pump body Description 1 Pump shaft 2 Housing 3 Straight roller bearing 4 Thrust plate 5 Pad holding plate 6 Ball joint 7 Belleville washers 8 Pistons with pads 9 Barrel 10 Distribution plate 11 Pilot pump drive splines T12 Anti-surge valve leak return orifice
11
2
6
5
4
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3
4
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6
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9
1
3
8
9
10
10
3
11
T12
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"988 " HYDRAULIC PUMPS 988 The anti-surge valve in the LOAD SENSING information circuit This is located under the hydraulic tank on the left hand side of the upper structure F It is fitted on the LOAD-SENSING information circuit of the low flow pumps Its purpose is to stabilize the LOAD-SENSING valve. Description 1 Body 2 Spool 3 Cap 4 Pushrod 5 Spring 6 O ring 7 Fill support 8 Cap (access to filter) 9 Filter retention spring 10 Filter 11 Non-return valve cap 12 Non-return valve spring 13 Non-return valve 14 Sealing plug 15 Bull
A
D
M3
F
Port locations A : Pressure inlet from attachment LS circuits, or options B : LOAD SENSING valve F : Leak return to the pump(R1) Working Principles a) - Feed: the higher pressure from the LS circuits arrives at A, and passes via filter 9. It pushes non-return valve 13, to inform the pump regulator block LOAD SENSING valve (spring end). When the pressure reaches 25 bars, pushrod 2 pilots and blocks passage C. b) - LOAD SENSING valve stabilization: If a surge phenomenon appears on LS information circuit, the pressure falls at A. The non-return valve 9 is held against its seat, isolating the LS valve from the pump. The pump is no longer subject to pressure variations. Hose D absorbs pressure peaks for greater stability in the LS valve. Pressure test point M3 is located at the end of this hose.
Spécifications The anti-surge valve filter must be changed every 500 hours
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B
3
LS VALVE
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