3.2 HYDRAULIC_SYSTEM.pdf

8/10/2019 3.2 HYDRAULIC_SYSTEM.pdf

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HYDRAULIC

CASE 325 & 330ARTICULATEDDUMP TRUCKS

HYDRAULIC SYSTEM


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Procedures, technical information and precautions which, if notrespected and/or incorrectly carried out, could cause injury tousers (safety symbol, see also SECTION 2-SAFETYINSTRUCTIONS WORKSHOP MANUAL).

Failure to heed and/or correctly carry out procedures, technicalinformation and precautions given may cause damage to thevehicle.

Procedures, technical information and precautions which, if notrespected and/or incorrectly carried out, could pollute theenvironment.

Very important procedures, technical information and

precautions.

CNH America LLC 2004

700 STATE STREET

RACINE, WI 53404 U.S.A. Printed in U.S.A.


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CASE Technical Training Hydraulic syste

25 & 30 ARTICULATED DUMP TRUCKS 1

CONTENTS

DESCRIPTION ....................................................................................................................3

HYDRAULIC SYSTEM - general layout...............................................................................4

List of check points ..............................................................................................................4

STEERING SYSTEM...........................................................................................................6

OPERATION .......................................................................................................................8

Stand-by ..............................................................................................................................8

Steering to the left................................................................................................................10

Steering to the right .............................................................................................................16

Emergency (main pump not operating-vehicle moving).......................................................20

BODY RAISING SYSTEM ...................................................................................................22

OPERATION .......................................................................................................................24

Body up ...............................................................................................................................24

Body down...........................................................................................................................28

BRAKING SYSTEM.............................................................................................................30

OPERATION .......................................................................................................................32

Accumulator charging circuit................................................................................................32

Pedal braking circuit ............................................................................................................42

Parking braking circuit .........................................................................................................44

STEERING AND BODY RAISING HYDRAULIC CIRCUIT..................................................46

Front chassis scheme (Version without Retarder) ...............................................................46


Front chassis scheme (Version with Retarder) ....................................................................48


Rear chassis scheme ..........................................................................................................50

COMPONENT DESCRIPTIONS..........................................................................................51

DIFFERENTIAL LOCK ELECTRO-DISTRIBUTOR .............................................................51

OIL FILTER INSIDE THE RESERVOIR ..............................................................................52

HYDRAULIC RESERVOIR..................................................................................................53

FLOW-AMPLIFIER..............................................................................................................54


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Hydraulic system CASE Technical Training

25 & 30 TON ARTICULATED DUMP TRUCKS2

BODY RAISING CONTROL DISTRIBUTOR....................................................................... 55

HIGH PRESSURE OIL FILTER........................................................................................... 56

CONNECTION PLATE........................................................................................................ 57

MAIN HYDRAULIC PUMP .................................................................................................. 58

AUXILIARY STEERING PUMP........................................................................................... 59

POWER STEERING ........................................................................................................... 60

HEAT EXCHANGER........................................................................................................... 61

RETARDER CONTROL VALVE.......................................................................................... 62

STEERING CYLINDER....................................................................................................... 63

Left side .............................................................................................................................. 63

BODY RAISING CYLINDER ............................................................................................... 64

REAR CHASSIS CONNECTION GROUP ASSEMBLY ...................................................... 65

BRAKE HYDRAULIC SYSTEM........................................................................................... 66

Front chassis scheme ......................................................................................................... 66

Rear chassis scheme.......................................................................................................... 67

DESCRIPTION OF COMPONENTS ................................................................................... 68

BRAKE PUMP..................................................................................................................... 68

BRAKE FLUID FILTER ....................................................................................................... 69

ACCUMULATORS .............................................................................................................. 70

PARKING BRAKE ELECTRO-DISTRIBUTOR.................................................................... 71

RECHARGE VALVE ........................................................................................................... 72

BRAKE COMMAND VALVE................................................................................................ 73

TESTS AND CHECKS ....................................................................................................... 74

Hydraulic system pressure test points................................................................................. 74

Hydraulic system pressure test point location ..................................................................... 75

CHECK PROCEDURES ..................................................................................................... 76

Hydraulic plant pressure discharge ..................................................................................... 76

Check efficiency of emergency pump control ...................................................................... 76

Parking brake efficiency test ............................................................................................... 76

Hydraulic system pressure test and calibration procedures ................................................ 77


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DESCRIPTION

The system is divided into three main hydraulic groups: steering, body raising and braking. All the groups use the same hydraulic fluid, which is contained in one reservoir.

The main hydraulic pump provides the flow required by the steering and body raising function

The system distributes the fluid flow between the two functions giving priority to the steering. the event of failure, an emergency pump ensures adequate steering capacity. The main pumalso supplies the pressure required to handle the central and interaxle differential locks

The brake pump supplies the flow required for the braking function. The system has energaccumulators located between the pump and the actuators.

T2251001. Hydraulic fluid reservoir2. Main hydraulic pump3. Emergency steering pump4. Brake hydraulic pump5. Steering system6. Body raising system7. Braking system8. Priority valve (priority on steering)


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HYDRAULIC SYSTEM - General layout

1. Emergency steering pump2. Main pump3. Brake pump4. Orbitrol steering valve

5. Flow-amplifier6. Body raising valve7. Counterbalance valve8. Parking brake valve9. Central/rear differential locking valve10. By-pass valve11. Suction filter12. Accumulators recharge valve13. Brake modulation valve14. Hydraulic oil heat exchanger15. Main pressure filter16. Check valve17. Steering pressure emergency switch18. Test point19. Steering cylinders20. Body raising cylinders21. Hydraulic accumulators22. Check valve23. Accumulators pressure switch24. Stop lights switch25. Parking brake pressure switch26. Brake system filter27. Quick discharge valve28. Retarder valve29. Check valve

List of check points

Steering control hydraulic pressure test pointHydraulic tilt pressure test pointGearbox/rear differential locking control hydraulic pressure test pointCounter-balancing pressure test pointFront hydraulic brake pressure test pointRetarder cylinder test pointRear hydraulic brake pressure test point

Accumulator pressure test pointHydraulic brake pump pressure test point


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T225101


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STEERING SYSTEM

1. Emergency steering pump2. Main pump4. Orbitrol steering valve5. Flow-amplifier

6. Body raising valve9. Central/rear differential locking valve10. By-pass valve11. Suction filter14. Hydraulic oil heat exchanger15. Main pressure filter16. Check valve17. Steering pressure emergency switch (calibration: 90 psi [6 bar] in descent)18. Test point19. Steering cylinders28. Retarder valve29. Check valve

(a) Priority valve (calibration: 230 psi [16 bar])(b) By-pass module(c) Steering valve(d) Enable valve(e) Relay valve(f) Flow valve(g) Calibrated check valve(h) Controlled maximum pressure valve


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a

f

e

d

g

h

c

b

T

T225102


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OPERATION

1 Stand-by

Conditions

Engine running Body at rest

Steering wheel straight

Standby conditions wi ll remain until the steering wheel is turned, regardless of theposition (straight or steered): consequently, this situation is related to thesteering wheel being STATIONARY (not necessarily straight).

Description

The pump [2] fluid flow goes to the flow-amplifier [5].The priority valve (a) of the flow-amplifier [5] sends the flow towards the body raising valve[6]. It needs to do this because the piloting signal that reaches the valve (a) is not sufficientto make the valve move and overcome the spring resistance.Since the body is at rest, the flow is discharged through the by-pass module (b) and returnsto the reservoir.The line connecting port P of the flow-amplifier [5] to port P on the Orbitrol steering valve iskept under pressure by the priority valve (a) to keep the steering circuit loaded andconsequently reduces the response time when steering.


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T225103


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2 Steering to the left

Conditions

Engine running Body at rest

Steering wheel turned to the left

Description

A. The pump [2] fluid flow goes to the flow-amplifier [5].The valve (c) is moved to the right as the steering wheel is turned. This permits the fluidflow to pass through the valve, exit port L of the Orbitrol steering valve [4] and enter port Lof the flow-amplifier [5].

At the same time the pressure passes through the LS ports to reach the flow-amplifier [5].Valve (a) is at this point subjected to two similar pressures on both sides, and therefore thepresence of the spring moves it to the left.This directs the fluid flow towards the steering system, away from the body raising system.


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2) Steering to the le

A

T225104


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B. The input flow from port L of the flow-amplifier [5] moves the valve (d) to the right by meansof the piloting pressure. The piloting on the right side of the valve, in fact, is connected viaport R to port R of the Orbitrol steering valve [4], and from here is discharged to thereservoir via ports T and the HT port of the flow-amplifier [5].

The input flow from port L passes through valve (d) and reaches valve (e), where thepiloting pressure overcomes the spring and moves the valve to the left. The piloting on theright side of this valve in fact is connected to the valves piloting circuit (f), which is stilldevoid of pressure.

The shifting of valve (e) has two effects.The first effect is that the flow coming from port L returns to valve (d) passes through itagain and goes to the CL output of the flow-amplifier [5].From here the flow goes to the steering cylinder chambers [19] to determine the movementin the direction indicated. This flow however is only modest when compared to the powersteering effect effectively required. It constitutes in fact only about 1/8 the total rate of flowthat the system is capable of sending to the steering cylinders [19].


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teft

T225105

B 2) Steering to the left


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C. The second effect is that the two sides of valve (f) are now subjected to two pilotingpressures, determined by the pressure reaching port P of the flow-amplifier [5].

The piloting pressure variation on the right-hand side however is slowed down by the orificein the circuit, which means that valve (f) shifts to the right despite the presence of the

spring. The quicker the steering wheel is turned, the quicker this shift will be made.

Most of the flow that reaches port P of the flow-amplifier is then transferred to valve (f) (thisroute features much lower load losses than that passing through the Orbitrol steering valve[4]), and from here it joins the rate of flow coming from the Orbitrol steering valve [4] toreach the CL output of the flow-amplifier [5], passing through valve (e).

This flow constitutes 7/8 of the total rate of flow that the system is capable of sending to thesteering cylinders [19].

Most of the flow that reaches the steering cylinder [19] chambers comes directly from port

P of the flow-amplifier. It therefore acts as fluid flow supplier according to the commandsgiven by the Orbitrol steering valve [4].

The chambers opposite to those involved in the flow are discharged so that the steeringcylinders [19] can be shifted.

The discharge flow enters the flow-amplifier from port CR, through valve (d) and exits to thereservoir through port T.

The spring loaded check valve (g) generates a discharge back-pressure to preventcavitation phenomenon inside the flow-amplifier.

The secondary valves (h) absorb any ramming that could occur on the pipes connectingoutputs CR and CL and the corresponding steering cylinders.

These valves open at the calibration pressure and directly discharge the correspondingpipe.

It should be noted that when the steering wheel is no longer turned, valve (c) will close,valve (d) will also close since the piloting pressures are no longer present, and the samehappens with valve (e) and valve (f). The system keeps the steering cylinders in theposition they have reached, and remains in stand-by.

To straighten up the vehicle, turn the steering wheel in the opposite direction until thewheels are parallel.


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C 2) Steering to the left

T225106


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3 Steering to the right

Conditions

Engine running

Body at rest Steering wheel turned to the right

Description

A. Valve (c) is moved to the left when the steering wheel is turned. This permits the flow topass through the valve, exit port R of the Orbitrol steering valve [4] and enter port R of theflow-amplifier [5].

At the same time the pressure passes through the LS ports to reach the flow-amplifier [5].

Valve (a) is at this point subjected to two similar pressures on both sides, and therefore thepresence of the spring moves it to the left.

This directs the fluid flow towards the steering system, away from the body raising system.


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3) Steering to the rig

A

T225104B


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B. The input flow from port R of the flow-amplifier [5] moves the valve (d) leftwards by effect ofthe piloting pressure. This is because the piloting pressure on the left side of the valve isconnected via port L to port L of the Orbitrol steering valve [4], and from here is dischargedto the reservoir via ports T and the HT port of the flow-amplifier [5].

The cylinders are consequently moved in the opposite direction with respect to steering to

the left.

The function of other flow-amplifier valves [5] remains unchanged with respect to thedescription above.


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ve.

B

T225107


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4 Emergency (main pump not operating-vehicle moving)

Conditions

Vehicle moving (by inertia or towed)

A. Under normal conditions, solenoid valve [10] will continuously circulate the flow generatedby the emergency pump [1].

The purpose of check valve [29] is to prevent the discharge of the main pump [2] flow.

B. In the event of an emergency, the solenoid valve [10] will be activated by the electro-mechanical pressure switch [17] that closes when the pressure generated by the mainpump drops below 90 psi (6 bar).

C.The rate of flow required by the steering is then provided by the emergency pump [1] drivenby the automatic transmission.

The purpose of check valve [16] is to prevent the discharge of the emergency pump [1] flowwhen solenoid valve [10] is activated.


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4) Emergenc

A

T225108

B

T225109


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BODY RAISING SYSTEM

2. Main pump5. Flow-amplifier6. Body raising valve7. Counterbalance valve

11. Suction filter14. Hydraulic oil heat exchanger15. Main pressure filter16. Check valve17. Steering pressure emergency switch18. Test point20. Body raising cylinders27. Quick discharge valve

(a) Electrohydraulic main control valve(b) Reducing valve(c) By-pass module(d) Discharge valve(e) Controlled maximum pressure valve(f) Controlled maximum pressure valve (calibration: 160 bars)(g) Compensation valve

A Body upB Body down


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e

c

e

b

f

da

g

T225110


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OPERATION

1 Body raising

Conditions

Engine running Body up control


Description

A. The pump [2] fluid flow goes to the flow-amplifier [5].

The priority valve (a) of the flow-amplifier [5] directs most of the flow towards the bodyraising valve [6]. It needs to do this because the piloting signal that reaches the valve is notsufficient to make the valve move and overcome the spring resistance.

The hydraulic piloting of main control valve (a) is enabled through reducing valve (b) byusing the control located in the cab. The main control spool valve (a) moves downwards.

By-pass module (c) and discharge valve (d) are closed by the piloting pressure that comesdirectly from the main control valve (a), line LS, it thus prevents the discharging of thepump flow and permits the pressurising of the circuit.

The flow input from port P through valve (a), reaches output A, on through the counter-balance valve [7] and goes to the body raising cylinder chambers [20] (up flow).

The cylinders will begin to extend, the fluid in the chamber opposite the extension chamberin the third stage is made to discharge through the counter-balance valve [7], which is keptopen by the piloting pressure (that corresponds to the up pressure).

The discharge flow reaches port B of the body raising valve [6], passes through valve (a)and made to discharge through port T.

The maximum pressure valve (f) has the function of limiting the maximum piloting pressurevalue of the the main control valve (a).

The purpose of the controlled maximum pressure secondary valve (e) is to absorb anyramming that could occur on the up pipes between port A and the corresponding bodyraising cylinders.

This valve opens at the calibration pressure and directly discharges the correspondingpipe.

The purpose of the compensation valve (g) is to maintain the body raising speedregardless of the load on the body.


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1) Body u

A

T225111


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B. Under critical conditions (very steep terrain) the bodys center of gravity moves beyond therear contact point between the vehicle and the ground. A body raising torque results, whichcreates an abrupt drop in the raising pressure.

This partially closes the counter-balance valve [7], since the spring prevails over the

reduced piloting pressure. This partial closing generates a counter-pressure on the cylinderdischarge line and consequently slows down the cylinder extension.

After the body raises all the way, the driver releases the control located in the cab, whichreturns to neutral and shifts the main control valve (a) to the center and therefore isolatesthe cylinders [20] from the pump flow and reopens the by-pass valve (c).

If the steering is turned at the same time, this will slow down the raising of the body, sincethe priority valve of the flow-amplifier [5] gives priority to the steering system and reducesthe flow available for body raising. Under limited conditions, all of the main pump flow goesto the steering and the body raising is stopped.


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up

B 1) Body Up

T225112


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2 Body lowering

Conditions

Engine running

Body down control


Description

The pump [2] fluid flow goes to the flow-amplifier [5].

The priority valve (a) of the flow-amplifier [5] directs most of the flow towards the bodyraising valve [6]. It needs to do this because the piloting signal that reaches the valve is notsufficient to make the valve move and overcome the spring resistance.

The hydraulic piloting of the main control valve (a) is enabled through reducing valve (b) by

using the control located in the cab. The main control valve spool (a) moves upwards.

By-pass module (c) and discharge valve (d) are closed by the piloting pressure that comesdirectly from the main control valve (a), line LS, it thus prevents the discharging of thereservoir return flow and permits the pressurising of the circuit.

The flow input from port P through valve (a), reaches output B through the counter-balancevalve [7] and goes to the body raising cylinder chambers [20] (lowering flow).

The cylinders begin to withdraw because the fluid in the chambers opposite the extensionchambers is discharged via two routes.

One part of the discharge flow reaches port A of the body raising valve [6], passes throughvalve (a) and is made to discharge by port T.

The remaining part of the discharge flow passes through the quick discharge solenoidvalve [27], which is open during lowering, and is discharged directly to the reservoir in orderto reduce the lowering time.

The purpose of the controlled maximum secondary relief valve (e) is to absorb anyramming that could occur on the lowering tubing between port B and the correspondingbody raising cylinders.

This valve opens at the calibration pressure and directly discharges the correspondingtube.


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2) Body dow

T225113


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BRAKING SYSTEM

3. Brake pump8. Parking brake valve11. Suction filter12. Accumulators recharge valve

13. Brake modulation valve18. Test point21. Hydraulic accumulators22. Check valve23. Accumulators pressure switch (Normally closed switch, opens when the accumulators are

charged, closes as the pressure desends below 1815 psi [125 bar], turns on brake warninglight)

24. Stop lights switch25. Parking brake pressure switch26. Brake system filter

(a) Slide valve(b) Adjustment valve (calibration: 2510 psi [173 bar] up, 1930 psi [133 bar] down)(c) Supply valve(d) Check valve


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ad

b

c

T225114


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OPERATION

1 Accumulator charging circuit

Conditions

Engine running Accumulator charged

Description

A. When the pressure in one of the accumulators [21] reaches the maximum pre-establishedvalue, the relative section of the supply valve (c), subjected to the piloting pressures of asimilar value on both sides, is closed by the spring load.

This sifting of the spool results in the accumulator [21] being isolated from the accumulatorcharging valve [12].

When the second accumulator [21] reaches the same condition, both sections of valve (c)are in the closed position.


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1) Accumulator charging circu

A

T225115


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B. As a result of the action of the piloting pressure from pump [3], coming from port P of theaccumulator charging valve [12], the adjustment valve (b) moves to the right as the springyields.

When the adjustment valve (b) moves, it discharges the piloting pressure on the left-hand

side of the slide valve (a).

C. Since this valve is subjected to the piloting pressure from the pump [3] coming from port Pon the opposite side, it moves to the left and directs the flow towards the discharge throughport O.

The purpose of the check valve (d) is to keep a given piloting pressure in the sectionbetween this valve and valve (c) during the subsequent accumulator charging cycle.


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B

T225116

C

T225117


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Conditions

Engine stationary

Accumulator charged

Description

D. In these conditions, the position of valve (c) does not change while valve (a) movesrightwards due to the action of the spring when the piloting pressure on both sides comesless.

When the engine is started, providing the accumulator is charged, valve (a) is subjected topiloting pressure from the right-hand side and moves leftwards by pushing the spring; thisre-establishes the short circuit to exhaust of the flow through port O, to unload the pump.


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D

T225115B


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Conditions

Engine running

Accumulator discharged

Description

E. When the pressare in at least one of the two accumulators [21] reaches the minimum pre-established value, the relative section of the supply valve (c) opens. The piloting pressurein the section between the check valves (c), overcomes the combined resistance of thespring and the accumulator pressure.

If the second accumulator [21] reaches the same condition, both sections of valve (c) are inthe open position.

F. The drop in pressure in the piloting circuit of valve (b) allows the spring load to shift the

valve to the left. This leads to the creation of a piloting pressure on the left-hand side of thevalve (a), which shifts it to the right.


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E

T225118

F

T225119


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G. Valve (a) is at this point subjected to two similar piloting pressures on its two sides, whichallows the spring load to shift it to the left. The fluid is consequently sent from pump [3]through the accumulator charging valve [12] to recharge the accumulators [21].

In the event of circuit failure (tubes, pump, etc.), the pressure in the accumulators will drop

continuously each time the brake pedal is pressed.

Pressure switch [23] lights up the braking circuit failure warning lamp if the pressure dropsbelow the minimum value of 1815 psi, (125 bar).

Once the braking circuit failure warning lamp comes on, it is only possible to brake safelyfive more times (in accordance with the ISO 3450).


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G

T225120


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2 Pedal braking circuit

The following description supposes that the accumulators are charged. Theconsiderations made also apply in the case of accumulators being charged.

Description

A. Brake pedal released

When the pedal is released the brake modulation valve [13] is moved to the left.The brake cylinder chambers are discharged through port T, and therefore no pressure isexerted on the pads.

B. Brake pedal pressed

When the pedal is pressed the brake modulation valve [13] is moved to the right.The accumulator pressure is sent to the cylinder chambers through input port P and outputBR1/BR2 of the brake modulation valve [13]. The braking pressure is exerted on the pads.


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A

T225121

B

T225122


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3 Parking braking circuit

The following description supposes that the accumulators are charged. Theconsiderations made also apply in the case of accumulators being charged.

The vehicle will remain locked if pressure in the parking brake circuit comes lessfor any reason.Refer to the Use and Maintenance Handbook for the releasing procedure.

Description

A. Brake control disengaged (vehicle moving)

When the control is enabled, input 1/P of the park brake valve [8] is opened by solenoid valve(a), while output 2/T is closed by solenoid valve (b).The cylinders are subjected to the pressure from accumulator [21], and consequently the springsare compressed, the pads released and the vehicle can be moved.

B. Brake control engaged (vehicle stationary)

When the control is enabled, input 1/P of the park brake valve [8] is closed by solenoid valve (a),while output 2/T is discharged by solenoid valve (b).

The cylinders are not subjected to pressure, and consequently the springs act on the pads andbrake the vehicle.


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3) Parking braking circu

BA

a

a

b

b

T225124B


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STEERING AND CAB BODY RAISING HYDRAULIC CIRCUIT

Front chassis scheme (Version wi thout Retarder)

Legend (figure on the next page)

A. Differential lock electro-distributorB. Oil filterC. Hydraulic oil reservoirD. Flow-amplifierE. Body raising main control valveF. Body raising pressure test portG. High pressure oil filterH. Connector plateI. Main hydraulic pumpJ. Auxiliary steering pumpK. Hydraulic steering orbital valve

L. Heat exchanger


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Front chassis scheme (Version without retarder)

2211601


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Front chassis scheme (Version with Retarder)

Legend (figure on the next page)

A. Differential lock electro-distributorB. Oil filterC. Hydraulic oil reservoirD. Flow-amplifierE. Body raising main control valveF. Body raising pressure test portG. High pressure oil filterH. Connector plateI. Main hydraulic pumpJ. Auxiliary steering pumpK. Hydraulic steering orbital valve

L. Heat exchangerM. Retarder control valve


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Front chassis scheme (Version wi th retarder)

2211602


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Rear chassis scheme

2081603

N. Steering cylinderO. Tipper cylinderP. Front chassis piping connector group


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COMPONENT DESCRIPTIONS

A. DIFFERENTIAL LOCK ELECTRO-DISTRIBUTOR

2211604

A Version with retarder

B Version without retarder

1. Pressure control intake connecting pipe2. Feed pipe3. Oil return line to the reservoir4. Pipe connecting rear chassis connection plate5. Retarder valve p outlet feed pipe6. Front differential lock control pipe


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B. OIL FILTER INSIDE THE RESERVOIR

1731605

1. Oil delivery piping2. Oil filler cap3. Filter4. Hydraulic oil reservoir


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C. HYDRAULIC RESERVOIR

1731606

1. Filler cap2. Oil level indicators3. Inspection cover


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D. FLOW-AMPLIFIER

20816051. Delivery from check valve2. Delivery to body raising control valve (P)3. Power steering blow-by4. RH steering control to slave cylinders5. Power steering return (T)6. LH Power steering (L)7. Return to the reservoir8. RH Power steering (R)9. Delivery to hydraulic steering10. LH steering control to slave cylinders


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E. BODY RAISING CONTROL DISTRIBUTOR VALVE

2081606

1. Body raising command lever2. Delivery from flow-amplifier (EF)3. Tipper rise command4. Return to reservoir and heat exchanger5. Tipper lower command6. Connection to pressure control test port7. By-pass pipe


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G. HIGH PRESSURE OIL FILTER

2211607

1. Main pump connector pipe2. Emergency steering pump connector pipe3. Flow-amplifier (HP) connector pipe4. Differential locks electro valve pressure connector pipe5. Emergency pump pressure switch


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CONNECTION PLATE

1. Lowercommand from main control valve (B)2. Left steering command3. Right steering command4. Parking brake command5. Rear brake command6. Differential lock command7. Rise command from main control valve (A)8. Delivery to quick discharge valve

2081608


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I. MAIN HYDRAULIC PUMP

2081609

1. Intake pipe from the reservoir2. Delivery pipe to high pressure filter


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J. AUXILIARY STEERING PUMP

2211610

1. Return pipe from emergency pump discharge valve2. Oil intake from the reservoir pipe3. Delivery pipe to emergency pump discharge valve


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M. RETARDER CONTROL VALVE

2211613

1. Diff lock solenoid valve connection2. Connection to pressure measuring port3. Retarder actuator4. Connection to the reservoir


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N. STEERING CYLINDER

Left side (Right side symmetrical)

2081614

1. Steering pipe from front chassis connection2. Left steering pipe cylinder connection3. Right steering pipe cylinder connection4. Rod side cylinder connector pipe5. Cylinder connector pipe


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O. BODY RAISING CYLINDER

2081615

1. Tipper lower command pipe2. Tipper rise command pipe


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REAR CHASSIS CONNECTION GROUP ASSEMBLY

1891615

1. Tipper raising command2. Right tipper cylinder raising command3. Left tipper cylinder raising command4. Right tipper cylinder lower command5. Left tipper cylinder lower command6. Left steering command7. Right steering command8. Body lower command9. Parking brake command10. Rear brake command11. Differential lock command12. Brake pressure test port


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BRAKE HYDRAULIC SYSTEM

Front chassis scheme

A. Brake pump 2211616AB. Brake fluid filterC. AccumulatorsD. Parking brake electro distributorE. Recharge valveF. Brake control valve


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Rear chassis scheme

2211616B


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DESCRIPTION OF COMPONENTS

A. BRAKE PUMP

2081618

1. Reservoir scavenger pipe2. Delivery pipe to brake filter


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C. ACCUMULATORS

1. Accumulator S2 - recharge valve A1 outlet connection2211620

2. Not used3. Accumulator S3 - recharge valve A2 outlet connection4. Pedal valve P outlet - accumulator S3 connection5. Accumulator s1 - recharge valve A2 outlet connection6. Parking brake valve P outlet - accumulator s1 connection


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D. PARKING BRAKE ELECTRO-DISTRIBUTOR

2081621B

1. Delivery pipe from accumulators2. Return pipe to reservoir3. Parking brake command pipe4. Parking brake pressure switch


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E. RECHARGE VALVE

2211622

1. Delivery pipe from high pressure brake filter2. Accumulator S2 feed pipe (rear brakes)3. Accumulator S3 feed pipe (front brakes)4. Accumulator S1 feed pipe (parking brake)5. Oil return pipe to reservoir (main circuit)6. Oil discharge pipe to reservoir (pilot circuit)7. Brake pedal P attachment feed pipe


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BRAKE COMMAND VALVE

2211623

1. Accumulator S3 feed pipe2. Accumulator S2 feed pipe3. Front axle bake command pipe4. Rear axles brake command pipe5. Rear brake return pipe to reservoir6. Front brake return pipe to reservoir


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TESTS AND CHECKS

Hydraulic system pressure test points

Location Pressure Test value psi (bars)

A Body raising 2320 75 (160 5)

B Steering control 2685 75 (185 5)C Front/rear longitudinal differential lock control 110 7 (7.5 0.5)

D Counterbalancing valve 1450 75 (100 5)

E Rear brakes 1870 30 (129 2)

F Retarder cylinder 75 3 (5.0 0.2)

G Front brake cylinder 2000 30 (138 2)

H Accumulators 2250 220 (155 15)

I Brake pump 2610 75 (180 5)


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Hydraulic system pressure test point location

2211630


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CHECK PROCEDURES

Hydraulic plant pressure discharge

The pipes that could contain pressurised fluid with the engine off are betweenthe accumulator recharge valve and:

- The accumulators themselves;- The pedal valve;- The parking brake valve.

Proceed as follows:

Switch the engine off.

Operate the service brake control until the brake lights no longer come on.

Work the foot brake control at least five more times.

Work the parking brake repeatedly until the parking brake warning lamp stays on.

Then work the parking brake at least another ten times.

The system does not have any other parts under pressure.

Check efficiency of emergency pump control

Proceed as follows:

Switch the engine off, move the selector lever to Neutral and engage the parking brake.

With the engine off, move the start-up switch to the run position;

Bring the gear selector to the Forward position.

At this point the buzzer should come on to indicate the emergency steering pump control has cut

in.

Parking brake efficiency test

Proceed as follows:

Position the vehicle on a flat surface that is wide enough to allow small movements.

Switch the engine off, move the selector lever to Neutral and engage the parking brake;the parking brake warning lamp should light up.

With the engine off and ignition switch in run position, disengage the parking brake: the

parking brake warning lamp should go out. Operate the service brake control until the brake lights go out.

Repeatedly engage and disengage the parking brake until the warning lamp remains onwhen the control is disengaged.

Start the engine and wait for the parking brake warning lamp to go out.

Select manual, insert the first speed, let the vehicle move forward VERY SLOWLY, thenengage the parking brake: the warning lamp should light up and the vehicle should stopimmediately (the gearbox automatically goes into Neutral).


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Hydraulic system pressure test and calibration procedures

The pressure test points are M16X2 minimess ports located in the posit ionshown above.The pressure specifications are shown in the respective table.Use a pressure gauge with a sui table full-scale for testing.

Al l procedures must be carried out wi th the vehic le on flat ground, the parkinbrake applied and the transmission in neutral.

A. Maximum pressure in steering circuit

Take the system temperature to 122 F (50C) (measured in the reservoir). Steer the wheels leftwards until the two steering cylinders reach the ends of their respectiv

strokes. With the cylinders at end of stroke position, hold the wheels steered and accelerate th

engine to maximum rpm. Check that the pressure in the cylinder actuating circuit in these conditions corresponds t

specifications, 2685 75 psi (185 5 bar).

The maximum pressure adjuster (arrow) is located on the flow-amplifier.

You are advised not to change the original setting.

T225100B


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B. Maximum body raising pressure

Take the system temperature to 122 F (50C) (measured in the reservoir). Raise and lower the body four or five times to stabilise the measured pressure values. Raise the body completely and accelerate the engine to maximum rpm when the last

cylinder element has reached the end of stroke. Check that the pressure in the cylinder actuating circuit in these conditions corresponds to

specifications, 2320 75 psi (160 5 bar).Turn the specific adjuster to obtain the specified value if required.

The maximum pressure adjuster (arrow) is located on the main distributor.Proceed as follows:

To increase pressure turn clockwise To reduce pressure turn anticlockwise

T225151


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C. Differential lock pressure calibration

Take the system temperature to 122 F (50C) (measured in the reservoir). Idle the engine. Check that the actuating pressure in these conditions corresponds to specification

110 7 psi (7.5 0.5 bar)..Turn the specific adjuster to obtain the specified value if required.

The maximum pressure adjuster (arrow) is located on the control valve.Proceed as follows:


T225152


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D. Counterbalance valve (SUN valve) test

Take the system temperature to 122 F (50C) (measured in the reservoir). Raise and lower the body four or five times to stabilise the measured pressure values. Raise the body with the engine at maximum rpm.

Check that the pressure in the cylinder return line in these conditions corresponds tospecifications, 1450 75 psi (100 5 bar), while the third stage is extending.Turn the specific adjuster to obtain the specified value if required.

The maximum pressure adjuster is located on the valve.Proceed as follows:



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Rear brake actuating pressure testG Front brake actuating pressure test

Make sure that the emergency warning light is off. Take the system temperature to 122 F (50C) (measured in the reservoir). Idle the engine.

Hold the brake pedal pressed. Check that the actuating pressure in these conditions corresponds to specification

1870 30 psi (129 2 bar).

The original settings cannot be changed. Differences may be caused banomalies of components and/or the circuit.

E. Retarder lock pressure calibration

Take the system temperature to 122 F (50C) (measured in the reservoir). Idle the engine. Check that the actuating pressure in these conditions corresponds to specification

75 3 psi (5.0 0.2 bar).Turn the specific adjuster to obtain the specified value if required.

The maximum pressure adjuster (arrow) is located on the control valve.Proceed as follows:


T225154


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H. Accumulator recharging pressure test

Make sure that the emergency warning light is off. Take the system temperature to 122 F (50C) (measured in the reservoir). Idle the engine.

Hold the brake pedal pressed. Check that the recharging pressure in these conditions corresponds to specifications,

2250 220 psi (155 15 bar).

Turn the specific adjuster to obtain the specified value if required.

The pressure adjuster is located on the recharging valve.

The inlet pipe from the hydraulic oil reservoir must be removed for this procedurewith possible leakage of oil.Observe the precautions for releasing residual pressure from the circuit andhanding hydraulic fluids.

Proceed as follows:

Remove the inlet port from the reservoir (1). To increase pressure turn clockwise To reduce pressure turn anticlockwise

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