Cargador 920 & 930 Sistema Hidraulico

REG00523-04.'.- ·-;~·C.TERPILLAR® December 1979

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If®®~D[fl)~ ~ ~@]D(ill@~D[fiJ~ 920, 930, 930T & 930T Series II Wheel Loader Hydraulic System

920

41 J1-UP M75J1 UP

62K1-UP

930

71 H1-UP 79J1-UP 41K1-UP 73U1-UP

~.-.-

930, 930T & 930T SERIES II

1781-UP

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INTRODUCTION

This pUblication has instructions and procedures for the subject on the front

cover. The information, specifications, and illustrations in this publication

are on the basis of information that was current at the time this issue was

written.

Correct operation, maintenance, test and repair procedures will give this

product a long service life. Before starting a test, repair or rebuild job, the

serviceman must read the respective sections of the Service Manual, and

know all the components he will work on.

Your safety, and the safety of others, is at all times very important. When

you see this symbol C!) or this symbol &.. in the manual, you must

know that caution is needed for the procedure next to it. The symbols are

warnings. To work safely, you must understand the job you do. Read all

instructions to know what is safe and what is not safe. .._"

It is very important to know the weight of parts. Do not lift heavy parts by

hand. Use a hoist. Make sure heavy parts have a good stability on the ground.

A sudden fall can cause an accident. When lifting part of a machine, make

sure the machine has blocks at front and rear. Never let the machine hang on

a hoist, put blocks or stands under the weight.

When using a hoist, follow the recommendation in the manual. Use correct

lift tools as shown in illustrations to get the correct balance of the

component you lift. This makes your work safer at all times.

40400X3

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SYSTEMS OPERATION ",

'~,_.'oJ' Loader Hydraulic System..................................................... 4

Lift Circuit. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . • . . . . . . . . . . . . . . .. 7

Lift Kickout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 7

Main Pressure Relief Valve ....................................•... , ... ..... 5

Tilt Circuit. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 6

Bucket Position Indicator and Bucket Positioner.. .. .. .. ..... .. .. ... .. .. .. .. 6

Tilt Circuit Relief Valves.................................................. 6

TESTING AND ADJUSTING

Loader Hydraulic System 8

Bucket Position Indicator and Positioner 14

Bucket Position Indicator 14

Bucket Positioner 14

Checking Pump Efficiency " 9

Control Lever Effort 15

Lift Kickout 13

Loader System Test Procedures ,.' .. 9

Lift Circui t Drift 10

Lift and Tilt Circuit Speeds.................................. 9

Multi-Purpose Bucket Circuit 11

Tilt Circuit Drift 10

Main Pressure Relief Valve and Tilt Circuit Relief Valves 11 /"-"\

\ i '"fi" Main Pressure Relief Valve 11

Tilt Circuit Relief Valve (Head Ends) 12

Tilt Circuit Relief Valve (Rod Ends) 13

Operational Checks 9

Visual Checks 8

SPECIFICATIONS

NOTE: For Specifications with illustrations, make reference to the SPECIFICATIONS FOR 920 and 930 WHEEL LOADER HYDRAULIC SYSTEM, Form No. REG01271. If the Specifications given in Form REGOl271 are not the same as given in the Systems Operation and the Testing and Adjusting, look at the printing date on the back cover of each book. Use the Specifications given in the book with the latest date.

NOTE: The "C" is an indication of a change from the former issue.

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3

920 & 930 LOADER HYDRAULIC SYSTEM SYSTEMS OPERATION

LOADER HYDRAULIC SYSTEM

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3~ C?1I4 10~11 13~~~14

17 PUMP FL.GW ,__

18 BLOCK~O OIL 0 SUPPLY OIL i3:~1':1

LOADER HYDRAULIC SYSTEM IN HOLD POSITION

1. Filter. 6. Lift circuit make-up 11. Lift circuit port (connects 18. Lift cylinders (two). 2. Lift and tilt control valve valve (rod ends). to head ends of lift 19. Tilt circuit relief valve

body. 7. Lift circuit check valve. cylinders). (rod en~s). 3. Tilt circuit port (connects 8. Lift circuit control valve 12. Tilt circuit check valve. 20. Tilt circuit relief valve

to rod ends of tilt spool. 13. Port (connects to pump). (head ends). cylinders). 9. Tilt circuit control valve 14. Port (blocked). 21. Tilt circuit make-up valve

4. Lift circuit port (connects spool. 15. Lift circuit make-up (head ends). to rod ends of lift 10, Tilt circuit port (connects valve (head ends). 22. Oil supply tank. cylinders) . to head ends of tilt 16. Tilt circuit make-u p 23. Main pressure relief

5. Make-up valve housing. cylinders). valve (rod ends). valve. 17. Tilt cylinders (two). 24. Pump.

The loader hydraulic system consists of a pump, reach the preset lift height the master cylinder a hydraulic oil supply tank, the lift and tilt control actuates the slave cylinder, which automatically valve with attached make-up and relief valves, moves the lift control lever (and the lift spool in control linkage, and the lift and tilt cylinders. the control valve in the hydraulic tank) from the

RAISE position detent to the HOLD position.The lift circuit consists of a check valve, valve

spool and make-up valves. When moved to an The tilt system includes either a bucket position operating position, the valve spool directs pump indicator or a bucket positioner hydraulic circuit. flow to the lift cylinders. The spool has four posi The mechanism in this circuit consists of a master tions: RAISE, HOLD, LOWER and FLOAT. cylinder mounted on the right hydraulic tilt cyl

inder and a slave cylinder on the left side of the The tilt circuit consists of a check valve, valve hydraulic tank to move the tilt control lever link

spool, rod end and head end relief valves and make age. The master cylinder actuates the slave cylup valves. When moved to an operating position, inder, which automatically moves the tilt control the valve spool directs pump flow to the tilt cylin lever (and the tilt spool in the control valve in the ders. The spool has three positions: TILT BACK, hydraulic tank) from the TILT BACK positionHOLD and DUMP. detent to the HOLD position at a preset bucket

digging angle. The lift system includes a hydraulic lift kickout circuit. The mechanism in this circuit consists of Oil flow for the hydraulic system is supplied by a master cylinder mounted on the loader frame the large section of a two section insert vane-type near the hydraulic lift cylinder and a slave cylin hydraulic pump.der on the left side of the hydraulic tank to move the lift control lever linkage. When the lift arms The oil flow through the hydraulic system when

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. the control levers are in HOLD position is as follows:

The pump draws supply oil from the tank. The oil is directed to the lift and tilt control valve in

~ the tank and flows by the tilt and lift valve spools. The valve spools are held in HOLD position by centering springs. The oil leaves the lift and tilt control valve and flows to the tank. On machines equipped with an implement control valve, the oil flows through the implement valve before flo'Ning to the tank.

MAIN PRESSURE RELIEF VALVE (5J9113)

The main pressure relief valve is mounted to the control valve body. The valve limits the pressure that can be imposed on the hydraulic pump. It also protects both the lift and tilt circuits in all operating positions. This valve consists of a springloaded dump valve and a spring-loaded pilot valve.

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.932198 9 10

MAIN PRESSURE RELIEF VALVE

1. Shims. 2. Pilot valve spring. 3. Dump valve spring. 4. Orifice. 5. Dump valve. 6. Dump valve seat. 7. Inlet chamber. 8. Pilot valve. 9. Pilot valve seat. 10. Orifice. 11. Chamber. 12. Dump port.

When the pilot valve (8) is seated, the pressure in chambers (7) and (11) is equal. Dump valve (5) is held seated by spring (11). The pressure at which the dwnp valve opens is determined by the shimadjusted force of spring (2) and force of spring (3). As the system pressure approaches the relief valve setting, the pilot valve is unseated slightly opening orifice (0) to tank. Orifice (10) is larger than orifice (4). Therefore, as the pilot valve moves against the spring force, more area of orifice (10) is exposed. When the exposed area becomes larger than the area of orifice (4), oil can leave chamber (11) faster, than the oil can enter chamber (11). The pressure in chamber (11), at this point, is lower than pressure in chamber (7). When the dif

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ference between these pressures becomes sufficient to overcome the force of spring (3), the dump valve (5) is unseated. Pump flow is directed through port (12) to the tank, preventing any further rise in pressure.

MAIN PRESSURE RELIEF VALVE (3G2315)

The 3G2315 main pressure relief valve is mounted to the control valve body. The valve limits the pressure that can be imposed on the hydraulic pump. It also protects both the lift and tilt circuits in all operating positions except DUMP position. This valve consists of a springloaded dump valve and a spring-loaded pilot valve.

A9831SXl 10

MAIN PRESSURE RELIEF VALVE

1. Adjustment screw. 2. Orifice. 3. Dump v81ve spring. 4. Dump valve. 5. Dump ports. 6. Pilot valve spring. 7. Pilot valve. 8. Chamber. 9. Orifice. 10. Inlet chamber.

When the pilot valve (7) is seated, the pressure in chamber (8) and inlet chamber (10) is equal. Dump valve (4) is held seated hy dump valve spring (3). The pressure at which the dump valve opens is determined by the shim adjusted force of pilot valve spring (6) and force of dump valve spring (3).

As the system pressure approaches the relief valve setting, the pilot valve is unseated slightly opening orifice (2) to tank. Orifice (2) is larger than orifice (9). Therefore, as the pilot valve moves against the spring force, more area of orifice (2) is exposed. When the exposed area becomes larger than the area of orifice (9), oil can leave chamber (8) faster, than the oil can enter it. The pressure in chamber (8), at this point, is lower than pressure in inlet chamber (10). When the difference between these pressures becomes sufficient to overcome the force of spring (3), the dump valve (4) is unseated. Pump flow is directed through ports (5) to the tank, preventing any further rise in pressure.

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920 & 930 LOADER HYDRAULIC SYSTEM SYSTEMS OPERATION

TILT CIRCUIT When the tilt control lever is moved to TILT

BACK position, the tilt control valve spool moves outward. Pump flow is directed to the tilt circuit check valve. The check valve remains seated until pump flow pressure becomes greater than the combined force of the oil pressure in the head ends of the cylinders and the force of the check valve return spring. The check valve prevents reverse oil flow and resulting cylinder drift. The oil unseats the check valve and is directed to the head ends of the tilt cylinders, tilting the bucket back. Oil in the rod ends of the cylinders returns through the control valve to the supply oil in the tank.

When the control lever is moved to DUMP position, the valve spool is moved into the valve body and the oil flow is reversed. Oil is directed to the rod ends of the tilt cylinders, dumping the bucket. Oil from the head ends of the cylinders returns to the supply oil in the tank.

The tilt circuit make-up valve housing is mounted to the lift and tilt control valve body. The make-up valves will unseat and allow oil from the tank to supplement pump flow when the piston rods extend or retract faster than the pump can supply oil to the cylinders. A make-up valve will also unseat when the tilt circuit is in HOLD position and the tilt cylinder piston rods are moved by an excessive force being exerted on the bucket. In this case, a tilt circuit relief valve will open to relieve oil pressure and a make-up valve will unseat to fill the void of oil in the opposite ends of the cylinders.

Tilt Circuit Relief Valves

When the tilt circuit control valve spool is in HOLD position, the tilt relief valves (rod ends) and (head ends) protect the circuit and machine components by limiting the external force that can be imposed on the bucket. The tilt relief valves have higher settings than the main pressure relief valve. All relief valves are mounted to the tilt circuit make-up valve housing.

The tilt relief valves are spring-loaded dump valves. When oil pressure exceeds the tilt relief valve settings, the springs are compressed and the dump valves open to the dump ports. The oil flows through the dump ports and returns to the tank. The relief valves in the tilt circuit allow excessive external forces on the bucket to move the tilt cylinder pistons, thus preventing damage to the machine components.

Bucket Position Indicator and Bucket Positioner The bucket position indicator (1) is a strip,

mounted on a tube which moves with the hydraulic cylinder rod end, and an angle, mounted on the hydraulic cylinder. As the bucket is moved to TILT BACK position the strip and angle become visually aligned. When they are aligned the bucket

BUCKET POSITION INDICATOR AND POSITIONER ACTUATOR

1. Bucket POSitIon indicators. 2. Bucket positioner master cylinder. 3. Cam, mounted on a tube connected to the rod end of the hydraulic cylinder. 4. Roller.

is at the correct digging angle and the tilt control lever is moved to the HOLD position to stop the bucket in the digging position.

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1. Bucket position indicators. 2. Bucket pOSitioner master cylinder. 4. Roller. 5. Hydraulic tank. 6. Right side hydraulic tilt cylinder. 7. Bucket position slave cylinder. 8. Hydraulic tube (connects master cylinder to slave cylinder). 9. Tube assembly.

On machines equipped with the hydraulic bucket positioner, the bucket positioner automatically moves the tilt control lever from TILT BACK to HOLD position. This action stops the bucket movement at the conect digging position.

With the tilt control lever in TILT BACK position, the tilt cylinder rod extends to a position where cam (3) moves under roller (4) and the roller actuates the piston in the bucket positioner master cylinder (2). The master cylinder hydraulically actuates the bucket positioner slave cylinder (7). The action of the slave cylinder moves the tilt control lever and the spool in the control valve to the HOLD position. The tilt control lever must be held in the TILT BACK position to allow the hydraulic cylinder rod to move the bucket from the preset digging angle to full tilt back.

BUCKET POSITION INDICATOR AND POSITIONER SYSTEM

The location of cam (3) sets the bucket POSl

tioner for the desired bucket digging angle.

LIFT CIRCUIT When the lift control lever is moved to RAISE

position, the lift circuit control valve spool is moved outward. The oil pressure opens the lift circuit check valve and pressure oil is directed to the head ends of the lift cylinders, raising the lift ann. Oil in the rod ends of the lift cylinders returns back through the control valve and to the tank.

When the control lever is moved to LOWER position, the valve spool is moved into the valve body and pressure oil is directed to the rod ends of the lift cylinders. The oil in the head ends of the cylinders returns through the control valve and to the tank.

When the control lever is moved to FLOAT position, the head ends, rod ends, pressure chambers and return chambers within the valve body are open to each other. The lift cylinder pistons can move in either direction depending on the external forces acting on the bucket. As the pistons move, all excess oil returns to the tank and make-up oil is supplied by the pump.

The valve spool is locked in FLOAT position by the float position detent in the spool. The control lever must be manually moved out of FLOAT position.

The lift circuit make-up valve housing is mounted.or'. to the control valve body. The make-up valves will unseat and allow oil from the tank to supplement pump flow when the piston rods extend or retract faster than the pump can supply oil to the cylinders.

Lift Kickout

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LIFT KICKOUT COMPONENTS

1. Hydraulic tank. 2. Loader frame. 3. Hydraulic lift cylinder. 4. Lift kickout master cylinder. 5. Roller. 6. Lift kickout slave cylinder. 7. Hydraulic tube (connects master cylinder to slave cylinder).

The lift kickout automatically returns the lift control lever (and lift spool in the control valve) from RAISE to HOLD position when the bucket reaches a preset height.

When the lift control lever is placed in the RAISE position, the lift hydraulic cylinder rods extend and the lift anns raise. As the lift arms raise past a horizontal attitude the lift hydraulic cylinder (3) begins to pivot toward the loader frame. When the lift anns approach the preset bucket height, the lift cylinder contacts the roller (5) on the lift kickout master cylinder (4). The roller pushes the piston in the master cylinder and the master cylinder hydraulically actuates the lift kickout slave cylinder (6). The action of the slave cylinder moves the lift control lever (and the control valve lift spool) to the HOLD position and the bucket stops at the preset height.

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920 & 930 LOADER HYDRAULIC SYSTEM TESTING AND ADJUSTING

LOADER HYDRAULIC SYSTEM .~-

It::" WARNING ~}.~

Hydraulic oil, under pressures that can be higher than 3000 psi (20700 kPa) can remain in the hydraulic systems on this machine after the engine and pump have been stopped. Serious injury can be caused if this pressure is not released before any service is done on the hydraulic systems. To prevent possible injury, be sure that the pressure is released before any fitting, hose or component is loosened, tightened, removed or adjusted.

When possible, the bucket must always be flat on the ground before service is started. When it is necessary for the bucket to be raised while tests or adjustments are done, be sure that the lift arms have correct support and the bucket is in the full dump position.

Always move the machine to a location away from the travel of other machines. Be sure that other personnel are not near the machine when the engine is running and tests or adjustments are being made.

\Vhen analyzing the hydraulic system, remember that propel' oil flow and con'ect oil pressure are necessary for proper operation. Oil flow is dependent on the pumjJ output which is a function of engine speed. Oil pressure is a result of restriction to the oil flow.

In all instances, visual checks and measurements should be made first. Then proceed to operational checks and finally to instrumentation checks.

Use the 585123 Hydraulic Testing Group, a stop watch, a magnet, a thermometer and an inch (mm) scale for basic test to measure;

1. Opening pressure of the main pressure relief valve and the tilt circuit relief valves. Low relief valve pressure reduces the lifting and digging capabilities of the machine. Too high opening pressures can reduce hose and component life.

2. Lift and tilt circuit drift rates. Circuit drift resul ts from leakage past cylinder piston seals, control valve O-ring seals, poorly seated check or make-up valves and/or excessive spool-tovalve bore clearances.

3. Lift and tilt circuit cycle times. Excessive circuit cycle times results from leakage, pump wear and/or pump speed.

If basic testing reveals internal circuit leakage, install a 9S2000 Flow Meter and follow the FLOW METER TEE TEST PROCEDURE~II to isolate the probable leakage source.

To adjust components located in the tank, it is necessary to drain the tank and remove the tank side cover.

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The analysis of a malfunction will be easier and the conclusion more certain if the following loader hydraulic system fundamentals are remembered.

The tilt circuit and lift circuit are arranged in a series circuit. (In bucket dump, pressure oil is not available to the lift circuit.) The hydraulic pump and main pressure relief valve are common to both the lift and tilt circuits. Each circuit has a check valve to prevent cylinder drift during valve spool movement. Each circuit also has mal\e-up valves to supplement pump flow. ".~

Relief valves in the tilt circuit, limit the external pressure imposed on the circuit when the tilt control valve is in the HOLD position.

VISUAL CHECKS

A visual inspection of the system with the engine stopped should be the first step when trouble-shooting a problem. With the bucket lowered to the ground and the oil reasonably cool, perform the following inspections:

1. Check the oil level. Slowly loosen the tank filler cap. If oil comes out the bleed hole when the filler cap is loosened, allow tank pressure to bleed off before removing the filler cap.

2. Remove the filter elements and check for presence of foreign material. A magnet wil1 separate ferrous metal material from nonferrous metal and non-metallic sealing material (piston rings, O-ring seals, etc.).

3. Inspect all lines and connections for damage or leaks.

~ OPERATIONAL CHECKS

The operational check of the system is useful in detecting possible internal leakage, faulty valves or a faulty pump. The speed of cylinder operation can be used as a check of the pump and cylinders.

Raise, lower, tilt and tiltback the bucket several times.

1. Observe cylinder extension and retraction for erratic movement.

2. Listen for pump noise.

3. Listen for relief valve action. Relief valves should not open except at full cylinder ex· tension or retraction when bucket is em pty.

4. Observe bucket positioner and lift kickout action.

Lift control lever should lock in RAISE.

Tilt control lever should lock in TILT BACK.

Bucket positioner mechanism should return the tilt control lever from TILT BACK to HOLD at the pre-set position.

Lift kickout should return lift control lever from RAISE to m:rtD at pre-set height.

Test and check adjustment of any area where incorrect operation is evident or suspected. (See appropriate section of LOADER SYSTEM TEST PROCEDURES.)

When or if hydraulic circuit intemal leakage is determined or suspected, perform pressure checks first. If operation is still slow or sluggish install a 9S2000 Flow Meter to isolate the suspected leakage source (See FLOW METER TEE TEST PROCEDURE-II.)

CHECKING PUMP EFFICIENCY

For any pump test, the pump flow, measured in gpm (liter/min) at 100 psi (690 kPa) will be larger than the pump flow at 1000 psi (6900 kPa) at the same rpm.

The difference between the pump flow of two operating pressures is the flow loss.

Method of finding flow loss ...

r·o Pump flow at 100 psi'. . 57.5 gpm (liter/min)* ~~-.+ ~ Pump flow at 1000 psi. -52.0 gpm (liter/min)*

Flow loss . 5.5 gpm (liter/min)*

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Flow loss when expressed as a percent of pump flow is used as a measure of pump performance.

Example of finding percent of flow loss ...

gpm flow lOSS) Percent ( Pump flow @ 100 psi x 100 = of flow

loss

* 55)or ( *57:5 x 100 = 9.5%

If the percent of flow loss is more than 10%, pump performance is not good enough.

*Numbers in examples are for illustration and are not values for any specific pump or pump condition. See SPECIFICATIONS for pump flow of a new pump at 100 psi and 1000 psi.

Test On The Machine

Install a 9S2000 Flow 'Meter. [See subject, PUMP TESTS (CHART B) in FLOW METER TEE TEST PROCEDURE II, FORM NO. REG0080]. Measure pump flow at 100 psi (690 kPa) and at 1000 psi (6900 kPa) with engine at 2000 rpm. Formula I:

gpm @ 100 psi - gpm @ 1000 PSi) Percent ( gpm @ 100 psi x 100 = of flow

loss

Test On The Bench

If the test bench can not be run at 1000 psi (6900 kPa) at a high rpm, do the first part of the test with the pump shaft rotation at 1000 rpm. Measure pump flow at 100 psi (690 kPa) and at 1000 psi (6900 kPa). Then in order to measure the pump flow for the last part of the test, see SPECIFICATIONS for: Pump rpm at 100 psi (690 kPa) with the engine at 2000 rpm.

Formula II:

gpm @ 100 psi - gpm @ 1000 PSi) _ Percent ( gpm @ 100 psi @ pump rpm x 100 - of flow

loss

LOADER SYSTEM TEST PROCEDURES

Lift and Tilt Circuit Speeds

The oil must be of recommended viscosity and at normal operating temperature to obtain accurate test results. The speed tests are made with the engine at high idle.

9

920 & 930 LOADER HYDRAULIC SYSTEM

The speeds in the charts are those of a machine equipped with a general purpose bucket.

System speeds similar to the speeds given, indicate that th e circuits are operating normally. Ho wever, the relief valves sho uld be tested to be certain they are set at the proper ratings.

If only the lift circuit or only the tilt circuit has slow speeds, check the slow circuit for excessive drifting.

APPROX. LIFT CIRCUIT SPEED TESTS TIME IN

SECONDS

'Raise emply bucket from ground level to lift kickout height. 6.0

'Same as above but, with loaded bucket. 6.6

'lower empty bucket from lift kickout height to ground level with control lever In LOWER Position. 3.4

Some as above but, with control lever in FLOAT position. 3.5

CAUTION: Set the lift kickout so the lift cylinder piston rods stop .25 in. (6.4 mm) from end of their strokes.

TILT CIRCUIT SPEED TESTS APPROX. TIME IN

SECONDS

'Move empty bucket from full liltback dump. (Lift arms at maximum heigh!).

to full 1.2

'Some os above bUI, with loaded bucket 104

'Move bucket from level to full tiltbock on the ground).

(bucket .9

'If both the liFt and nit c,rcults have extremely slow speeds, check For pump malFunctioning. Also check the main pressure relief valve For leakage a r low pressure setting.

Lift Circuit Drift

Drift measurements are the maximum permissible during the time interval shown for the oil temperature in the system.

LIFT CYLINDER DRIFT

Oil 100° to 1 20° F 1 200 to 150° F Over 150° F Temperature (37 0 to 48° C) (48 0 to 65° C) (Over 650 CI

Maximum in. mm in. mm in. mm permissible

Drift .38 9.7 .38 9.7 .38 9.7

Time interval Minutes 5 2.7 1.7

TESTING AND ADJUSTING

TEST NO. 1: Raise the front of the machine off the ground by lowering the bucket. Place the lift control lever in HOLD position. Shut off the engine and observe if lift cylinder rods extend.

TEST NO.2: Raise the front of the machine off the ground by lowering the bucket. Shut off en· gine and place the lift control lever in LOWER position. Observe if lift cylinder rods extend.

TEST NO.3: Raise the empty bucket off the ground. Place the lift control lever in HOLD posi- C tion. Shut off engine and observe if the lift cylinder rods retract.

TEST NO.4: Raise the empty bucket off the ground. Shut off engine and place the lift control C lever in RAISE position. 0 bserve if the lift cy1inder rods retract.

TEST RESULTS PROBABLE CAUSE

Drlftin9 occurs only in Tesl 1. Lift circuit moke-up valve No.1 (rod ends) lea king.

Drifting occurs only In Test 1. Lift circuit moke-up volve No.3 Ihead ends) leaking.

Drifting occurs only in Tests 1. Lea kage between pistons No.1 and No.3 and cylinders.

2. Leakage between lift circuil control valve spool ond body.

",.,. Drifting occurs only in Tesls 1. Lift circuit check valve No.2 and No.4 leaking (Ieakoge between

valve and seat and/or sea land bodyl.

NOTE: Remember thot on O-ring seal fo;lure in the circuit can have the some effect os a main componenr failure.

Tilt Circuit Drift


TILT CYLINDER DRIFT

Oil 1 00° to 1 20° F1200 to 150°F Over 150° F Temperature (37° to 480 C) (48° to 65°CI (Over 65° C)

Maximum in. mm in. mm in. mm permissible

Drift .62 15.8 .62 15.8 .62 15.8


TEST NO. L Raise the front of the machine off the ground by partially dumping the bucket. Place the tilt control lever in HOLD position. Shut off engine and observe if the tilt cylinder rods extend.

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920 & !:UU LOADt:H HY[fH-AUlIL ~y~ I t::IVl

<TEST NO.2: Raise the front of the machine off the ground by partially dumping the bucket. Shut off engine and place the tilt control lever in DUMP position. Observe if the tilt cylinder rods extend.

TEST NO.3: Start the engine. Raise bucket off the ground (empty with bucket bottom parallel

C to ground). Place the tilt control lever in HOLD position. Shut off the engine and observe if tilt cylinder rods retract.

TEST NO.4: Start the engine. Raise bucket off the ground (empty with bucket bottom parallel

C to ground). Shut off engine and place the tilt control lever in TILT BACK position. Observe if tilt cylinder rods retract.


Drifting occurs only in Test 1. TM circuit relief valve No.1 (rod ends) damaged ar

leaking.

2. Tilt circuit make-up valve Irad endslleoking.

Drifting occurs only in Test 1. Tilt circuit relief valve No.3 (head ends) damaged or

leaking.

2. Tilt circuit make-up vqlve (head ends) leaking.

3. Bucket pasilioner hydraulic circuli lea king. 'M;.'d"

Drifting occurs only in Tests 1. Leakage between pistons No.1 and No.3 and cyl inders.

2. Leakage between tilt Circuit valve spool and body.

Drifling occurs anly in Tests l. Tilt circuit check volve No.2 and No.4 leaking lIeakage between

valve and seal and/or seat and body.).

NOTE: Remember that on O-ring seal failure in the circuit can have the some effect as a major component failure.

c Multi-Purpose Bucket Circuit


1. Raise the bucket off the ground.

2. Extend the tilt cylinders fully.

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3. Extend Multi-Purpose bucket cylinders to position bowl approximately 1 in. (25.4 mm) above cutting edge. Stop the engine and observe if the bucket cylinder rods extend.

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MULTI·PURPOSE BUCKET CYLINDER DRIFT

Oil Temperature

100° to 120° F(37° to 48° CI

~ 20° to 150° F (48° t1:l 65° C)

Over 150° F (Over 65° C)

Maximum permissible

Drift

in.

.31

mm

7.9

in.

.31

mm

7.9

in.

.31

mm

7.9



Drifting occurs in 1. Leakage between pistons and cyl-Step N1:I. 3 inders.

2. Leakage between circuit valve spool and body.

3. Leakage In circuit check valve. (Leakage between valve and seat and/or seat and body).

MAIN PRESSURE RELIEF VALVE AND TILT CIRCUIT RELIEF VALVES

Tools required to test relief valve: 5S5123 Hydraulic Testing Group.

The pressure at which the relief valves open should be checked occasionally and, if necessary, reset to insure correct operating pressure. The tank or control valve need not be disturbed to check the pressure setting.

If the pressures are not within the settings given, it will be necessary to disassemble the hydraulic tank to obtain access to the pressure adjusting shims. Adding shims will decrease the pressure; removing shims will increase the pressure.

A, WARNING

Use only high pressure testing equipment; pressure can exceed 2800 psi (19280 kPa).

Before installing test equipment, place the bucket flat on the ground. With the engine shut ofT, move the lift and tilt control levers to all positions to relieve pressure in the hydraulic lines. Return the control levers to the HOLD position.

Main Pressure Relief Valve

Remove the pressure tap plug (1) and install the oil pressure test gauge. The test equipment to use from the 585123 Hydraulic Testing Group is: 788714 Gauge (0 to 4000 psi), 584648 Hose Assembly and the fittings necessary to connect the test gauge in the head end pressure tap.

Remove the floor plates. Install test equipment in the lift circuit line (head ends) .

I I

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920 & 930 LOADER HYDRAULIC SYSTEM TESTING AND ADJUSTING

LIFT CYLINDER HEAD END PRESSURE TAP (Located under the loader framel

1. Pressure tap plug.

Start the engine and raise the bucket until the lift cylinders are at the end of their strokes. With engine speed at high idle, hold the lift control lever in the RAISE position. The pressure reading on the gauge should be within 2500 ± 2512Si (17250 ± 170 kPa).

2 "'l. 3

T96145-A

5J9113 MAIN RELIEF VALVE

2. SF 1974 Shims. 3. Plug, shim and spring retainer.

Torque for plug (3) is 60 ± 2 lb. ft. (80 ± 3 N·m).

PRESSURE CHANGE BY REMOVAL OR ADDITION OF ONE 8F1974 SHIM

VALVE NO. SHIM THICKNESS CHANGE IN psi

5J9113 .005 In. (0.13 mm) 35 psi (240 kPa)

PRESSURE CHANGE FOR 3G2315 VALVE

One turn of adjustment screw. 840 psi (5805 kPa}

3G2315 MAIN RELIEF VALVE

Tilt Circuit Relief Valve (Head Ends)

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TILT CYLINDER HEAD END PRESSURE TAP .... ,..it!

4. Pressure tap plug:

Remove the head end pressure tap plug (4) and install the oil pressure test gauge. Test equipment to use from the 5S5123 Hydraulic Testing Group:

I

LOWERING THE LIFT ARMS

5. Bucket (back against blocks). 6. Blocks.

7S8714 Gauge (0 to 4000 psi) (0 to 27500 kPa), 5S4648 Hose Assembly and the fittings necessary to connect the test gauge in the head end pressure tap.

Start the engine. Raise the bucket so lift arms are horizontal. Tilt bucket (5) back against blocks (6) to build up pressure in the rod ends of the tilt cylinders. Return the tilt control lever to HOLD position.

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With the engine speed at high idle, lower the With engine speed at high idle, place the lift lift arms. Observe the pressure reading on the control lever in RAISE position and observe the gauge as the tilt cylinder rods are pushed into pressure reading on the gauge as the tilt rods are their cylinders. The reading should be within pulled from the cylinders. The pressure reading 2800 ± 25 psi (19280 ± 170 kPa). should be within 2800 ± 25 psi (19280 ± 170 kPa).

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5J9106 RELIEF VALvE

7. 5J9100 Shims. 8. Plug. shim and spring retainer. Tighten to 100 ± 5 lb. ft. (135 ± 7 N·m).

PRESSURE CHANGE TO 5J9106VALVE BY REMOVAL OR ADDITION OF ONE SHIM

SHIM NO. SHIM THICKNESS . CHANGE IN psi

5J9100 .005 in. (0.13 mm I 29 psi (200 kPa}

5J9101 '""", ..

.010 in. (0.25 mm) 58 psi (400 kPa)

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Tilt Circuit Relief Valve (Rod Ends)

Remove the rod end pressure tap plug (9) and install the 788714 Gauge.

TILT CYLINDER ROD END PRESSURE TAP

(Located under the tilt cylinderl. 9. Rod end pressure tap plug.

Start the engine and position the lift ann horizontal to the ground. Fully dump the bucket (tilt levers contact stops on the lift anns) and place the tilt control lever in HOLD position.

If it is necessary to correct the rod end relief pressure, either increase or decrease the shim thickness in the 5J9106 Relief Valve in the rod end circuit. The other 5J9106 Relief Valve is in the head end circuit. See the chart in topic TILT CIRCUIT RELIEF VALVE (HEAD ENDS) for the change in relief pressure with either the addition or removal of shims.

9 10 x 169?

RAISING LIFT ARM

5. Bucket (in full dump position with tilt levers against stops on lift arms). 9. Tilt cylinder rod end pressure tap. 10. Lift arm in horizontal position.

LIFT KICKOUT

The lift kickout system should stop the bucket lift before the lift cylinder rods fully extend.

The initial lift kickout adjustment is made on the slave cylinder with the bucket on the ground and the engine stopped.

LIFT KICKOUT SYSTEM SLAVE CYLINDER (Operator's seat has been removed)

1. Control laver. 2. Lift kickout sieve cylinder. 3. Bolt. 4. Locknut. A. Initial dimension .09 in. (2.29 mml. Minimum dimension .02 in. (0.51 mm).

5

13


1. Remove the seat cushion and place the hand lift control in the RAISE detent position.

2. Adjust the length of bolt (3) to obtain an initial dimension (A) of .09 in. (2.29 mm) between the head of the bolt and control lever (1 ).

3. Start the engine and raise the bucket until the lift cylinder rod is .25 in. (6.35 mm) less than full lift.

4. Stop the engine. Move the hand lift control into the RAISE detent position. Extend the length of bolt (3) until it moves control lever (1) out of the RAISE detent. Tighten locknut (4).

5. Start the engine and cycle the lift system. When the hand lift control is in the RAISE detent position the minimum dimension between the head of bolt (3) and control lever (1) is .02 in. (0.51 mm).

BUCKET POSITION INDICATOR AND POSITIONER Bucket Position Indicator

The bucket position indicator has two verticle positioned strips, one mounted on the tilt cylinder and the other actuated by the movement of the tilt cylinder rod.

The adjustment is made with the bucket on the ground and positioned at the desired digging angle. Align the adjustable strip (l) with strip (2) on the tilt cylinder.

If the 920 Wheel Loader is not equipped with a hydraulic bucket positioner, it is necessary to make an adjustment in the tiltback control linkage.


1. Adjustable strip. 2. Strip on the tilt cylinder. 3. Bucket positioner hydraulic master cylinder. 4. Cam. 5. Roller.

TESTING AND ADJUSTING.

Place the control lever in the TILT BACK position. Raise the operator's seat and turn the TILT BACK position lever stop bolt out enough to

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prevent the linkage from going into the TILT (BACK detent.

Bucket Positioner

The bucket positioner will automatically move the hand tilt control from the TILT BACK detent position to HOLD when the bucket moves to the preset digging angle.

The initial bucket positioner adjustments are made with the bucket on the ground and positioned at the desired digging angle with the engine stopped.

1. Loosen cam (4) and move it out from under roller (5).

2. Remove the seat cushion and place the hand tilt control in the TILT BACK detent position. "....

3. Adjust the length of bolt (8) to obtain an initial dimension of .09 in. (2.29 mm) between the head of the bolt and lever (6).

NOTE: Make certain the bolt is fully retracted in the slave cylinder when this adjustment is made.

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BUCKET POSITIONER SYSTEM SLAVE CYLINDER (Operator's seat has baen removed)

6. Lever. 7. Slave cylinder. 8. Bolt. 9. Locknut. A. Initial dimension .09 in. (2.29 mml. Minimum dimension .02 in. (0.51 mm).

14


1. Remove the seat cushion and place the hand lift control in the RAISE detent position.

2. Adjust the length of bolt (3) to obtain an initial dimension (A) of .09 in. (2.29 mm) between the head of the bolt and control lever (1 ).

3. Start the engine and raise the bucket until the lift cylinder rod is .25 in. (6.35 mm) less than full lift.

4. Stop the engine. Move the hand lift control into the RAISE detent position. Extend the length of bolt (3) until it moves control lever (l) out of the RAISE detent. Tighten locknut (4).

5. Start the engine and cycle the lift system. When the hand lift control is in the RAISE detent position the minimum dimension between the head of bolt (3) and control lever (1) is .02 in. (0.51 mm).

BUCKET POSITION INDICATOR AND POSITIONER Bucket Position Indicator

The bucket position indicator has two verticle positioned strips, one mounted on the tilt cylinder and the other actuated by the movement of the tilt cylinder rod.

The adjustment is made with the bucket on the ground and positioned at the desired digging angle. Align the adjustable strip (l) with strip (2) on the tilt cylinder.

If the 920 Wheel Loader is not equipped with a hydraulic bucket positioner, it is necessary to make an adjustment in the tiltback control linkage.


1. Adjustable strip. 2. Strip on the tilt cylinder. 3. Bucket positioner hydraulic master cylinder. 4. Cam. 5. Roller.

TESTING AND ADJUSTING,

Place the control lever in the TILT BACK position. Raise the operator's seat and turn the TILT BACK position lever stop bolt out enough to prevent the linkage BACK detent.

from going into the TILT I,'~':'"~' ;:\

Bucket Positioner

The bucket positioner will automatically move the hand tilt control from the TILT BACK detent position to HOLD when the bucket moves to the preset digging angle.

The initial bucket positioner adjustments are made with the bucket on the ground and positioned at the desired digging angle with the engine stopped.

1. Loosen cam (4) and move it out from under roller (5).

2. Remove the seat cushion and place the hand tilt control in the TILT BACK detent positi~. ~

3. Adjust the length of bolt (8) to obtain an initial dimension of .09 in. (2.29 mm) between the head of the bolt and lever (6).

NOTE: Make certain the bolt is fully retracted in the slave cylinder when this adjustment is made.

BUCKET POSITIONER SYSTEM SLAVE CYLINDER (Operator's seat has been removed}

6. Lever. 7. Slave cylinder. 6. Bolt. 9. Locknut. A. Initial dimension .09 in. (2.29 mm). Minimum dimension .02 in. (0.51 mml.

14

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l :J BUCKET POSITIONER CAM ADJUSTMENT

4. Cam, 5. Roller. B. Cam·to·roller contact maximum dimension .24 in. (6.1 mml. C. Direction to move cam to reduce bucket digging angle. D. Direction to move cam (toward bucket) to increase digging angle.

4. Move cam (4) under roller (5) un til the cam-to-roller contact is less than .24 in. (6.1 mm) from the highest edge of the cam. Tighten the cam in this location.

5. Extend bolt (8) until it moves lever (6) and the hand tilt control from the TILT BACK detent to HOLD. Tighten locknut (9).

6. Start the engine and cycle the tilt system. When th"e hand tilt control is in the TILT BACK detent position, the minimum dimension between the head of bolt (8) and lever (9) is .02 in. (0.51 mm).

CONTROL LEVER EFFORT

To check the effort needed to pull the lift and tilt control levers out of the RAISE and TILT BACK detent positions, a spring scale is needed.

1. Put the lift and tilt control levers in the RAISE and TILT BACK positions.

2, Disconnect the linkage from the levers at the hydraulic tank.

3. Put a spring scale in the linkage hole in the levers. The effort needed to pull the levers out of the RAISE and TILT BACK detent positions is 36 ± 8 lb. (170 ± 36 N).

4. If it is necessary to change the effort needed to pull the levers back to the HOLD positions, add 6J6516 Shims to the de tents in the control valve to increase or remove shims from the detents to decrease the effort.

15

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NAMENO.

CYLINDER RELIEF VALVES1.

CONTROL VALVE FOR LIFT AND TILT2.

RELIEF VALVE FOR MAIN PRESSURE

'0 MAKE-UP VALVES FOR Ll FT AND TI L T

3.

ATTACHMENT CONTROL VALVE5.

TILT CYLINDERS

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6.

MULTIPURPOSE CYLINDERS

.0 LiFT CYLINDERS

STEERING CONTROL VALVE9.

STFERING CYLINDERS

". COOLER (ATTACHMENT)

10.

12. , HyDRAULIC PUMP

13. I FILTER

HAND METERING PUMP1'.

OIL SCREEN15.

1<,. I DIVEHTt::::H VALVE

17. I SUPPLEMENTAL STEERING PUMP

lB. lOlL SCREEN

PRESSURE TAPS

A

B

C

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iMPLEMENT TEE TEST

ROO END PRESSURE IN TILT CIRCUIT

HEAD END PRESSURE IN TILT CIRCUIT

SYSTEM PRESSURE

STEERING TEE TEST

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• 45369X2

Documents

Cargador 920 & 930 Sistema Hidraulico