1-1

SECTION 1 GENERAL

FOLLOW SAFE PROCEDUREUnsafe work practices are dangerous. Understandservice procedure before doing work; Do notattempt shortcuts.

WEAR PROTECTIVE CLOTHINGWear close fitting clothing and safety equipmentappropriate to the job.

WARN OTHERS OF SERVICE WORKUnexpected machine movement can causeserious injury.Before performing any work on the wheel loader,attach a Do Not Operatetag on the right sidecontroller lever.

USE HANDHOLDS AND STEPSFalling is one of the major causes of personal injury.When you get on and off the machine, alwaysmaintain a three point contact with the steps andhandrails and face the machine. Do not use anycontrols as handholds.Never jump on or off the machine. Never mount ordismount a moving machine.Be careful of slippery conditions on platforms,steps, and handrails when leaving the machine.

WARN

DONOTOPERATE

GROUP 1 SAFETY HINTS

1-2

PREPARE FOR EMERGENCIESBe prepared if a fire starts.Keep a first aid kit and fire extinguisher handy.Keep emergency numbers for doctors,ambulance service, hospital, and fire departmentnear your telephone.

PROTECT AGAINST FLYING DEBRISGuard against injury from flying pieces of metal ordebris; Wear goggles or safety glasses.

PROTECT AGAINST NOISEProlonged exposure to loud noise can causeimpairment or loss of hearing.Wear a suitable hearing protective device such asearmuffs or earplugs to protect againstobjectionable or uncomfortable loud noises.

WORK IN CLEAN AREABefore starting a job :

Clean work area and machine.Make sure you have all necessary tools to doyour job.Have the right parts on hand.Read all instructions thoroughly; Do not attemptshortcuts.

1-3

SUPPORT MACHINE PROPERLYAlways lower the attachment or implement to theground before you work on the machine. If youmust work on a lifted machine or attachment,securely support the machine or attachment.Do not support the machine on cinder blocks, hollowtiles, or props that may crumble under continuousload.Do not work under a machine that is supportedsolely by a jack. Follow recommended proceduresin this manual.

SERVICE COOLING SYSTEM SAFELYExplosive release of fluids from pressurizedcooling system can cause serious burns.Shut off engine. Only remove filler cap when coolenough to touch with bare hands.

HANDLE FLUIDS SAFELY-AVOID FIRES Handle fuel with care; It is highly flammable. Donot refuel the machine while smoking or when nearopen flame or sparks. Always stop engine beforerefueling machine.Fill fuel tank outdoors.

PARK MACHINE SAFELYBefore working on the machine:

Park machine on a level surface.Lower bucket to the ground.Turn key switch to OFF to stop engine. Removekey from switch.Move pilot control shutoff lever to locked position.Allow engine to cool.

1-4

Store flammable fluids away from fire hazards. Donot incinerate or puncture pressurized containers.Make sure machine is clean of trash, grease,and debris.Do not store oily rags ; They can ignite and burnspontaneously.

BEWARE OF EXHAUST FUMESPrevent asphyxiation. Engine exhaust fumes cancause sickness or death.If you must operate in a building, be positive thereis adequate ventilation. Either use an exhaust pipeextension to remove the exhaust fumes or opendoors and windows to bring enough outside air intothe area.

REMOVE PAINT BEFORE WELDING ORHEATINGAvoid potentially toxic fumes and dust.Hazardous fumes can be generated when paint isheated by welding, soldering, or using a torch.Do all work outside or in a well ventilated area.Dispose of paint and solvent properly.Remove paint before welding or heating:

If you sand or grind paint, avoid breathing thedust. Wear an approved respirator.If you use solvent or paint stripper, removestripper with soap and water before welding.Remove solvent or paint stripper containers andother flammable material from area. Allowfumes to disperse at least 15 minutes beforewelding or heating.

1-5

SERVICE MACHINE SAFELYTie long hair behind your head. Do not wear anecktie, scarf, loose clothing or necklace when youwork near machine tools or moving parts. If theseitems were to get caught, severe injury couldresult.

Remove rings and other jewelry to preventelectrical shorts and entanglement in moving parts.

STAY CLEAR OF MOVING PARTSEntanglements in moving parts can cause seriousinjury.To prevent accidents, use care when workingaround rotating parts.

ILLUMINATE WORK AREA SAFELYIlluminate your work area adequately but safely.Use a portable safety light for working inside orunder the machine. Make sure the bulb isenclosed by a wire cage. The hot filament of anaccidentally broken bulb can ignite spilled fuel oroil.

1-6

AVOID HIGH PRESSURE FLUIDSEscaping fluid under pressure can penetrate theskin causing serious injury.Avoid the hazard by relieving pressure beforedisconnecting hydraulic or other lines. Tighten allconnections before applying pressure.Search for leaks with a piece of cardboard.Protect hands and body from high pressure fluids.If an accident occurs, see a doctor immediately.Any fluid injected into the skin must be surgicallyremoved within a few hours or gangrene mayresult.

AVOID HEATING NEAR PRESSURIZED FLUIDLINESFlammable spray can be generated by heatingnear pressurized fluid lines, resulting in severeburns to yourself and bystanders. Do not heat bywelding, soldering, or using a torch nearpressurized fluid lines or other flammable materials.Pressurized lines can be accidentally cut whenheat goes beyond the immediate flame area.Install fire resisting guards to protect hoses or othermaterials.

PREVENT BATTERY EXPLOSIONSKeep sparks, lighted matches, and flame awayfrom the top of battery. Battery gas can explode.Never check battery charge by placing a metalobject across the posts. Use a volt-meter orhydrometer.Do not charge a frozen battery; It may explode.Warm battery to 16C(60F).

1-7

USE TOOLS PROPERLYUse tools appropriate to the work. Makeshifttools, parts, and procedures can create safetyhazards.Use power tools only to loosen threaded tools andfasteners.For loosening and tightening hardware, use thecorrect size tools. Avoid bodily injury caused byslipping wrenches.Use only recommended replacement parts.(SeeParts catalogue.)

PREVENT ACID BURNSSulfuric acid in battery electrolyte is poisonous. Itis strong enough to burn skin, eat holes in clothing,and cause blindness if splashed into eyes.Avoid the hazard by:

Filling batteries in a well-ventilated area.Wearing eye protection and rubber gloves.Avoiding breathing fumes when electrolyte isadded.Avoiding spilling of dripping electrolyte.Use proper jump start procedure.

If you spill acid on yourself:Flush your skin with water.Apply baking soda or lime to help neutralizethe acid.Flush your eyes with water for 10-15 minutes. Get medical attention immediately.

If acid is swallowed:Drink large amounts of water or milk.Then drink milk of magnesia, beaten eggs, orvegetable oil.Get medical attention immediately.

1.2.3.

4.5.

1.2.

3.

1.2.

3.

1-8

SERVICE TIRES SAFELYExplosive separation of a tire and rim parts cancause serious injury or death.Do not attempt to mount a tire unless you have theproper equipment and experience to perform the job.Always maintain the correct tire pressure. Do notinflate the tires above the recommended pressure.Never weld or heat a wheel and tire assembly.The heat can cause an increase in air pressureresulting in a tire explosion.Welding can structurally weaken or deform the wheel.When inflating tires, use a clip-on chuck andextension hose long enough to allow you to standto one side and not in front of or over the tireassembly. Use a safety cage if available.Check wheels for low pressure, cuts, bubbles,damaged rims or missing lug bolts and nuts.

USE PROPER LIFTING EQUIPMENTLifting heavy components incorrectly can causesevere injury or machine damage.Follow recommended procedure for removal andinstallation of components in the manual.

DISPOSE OF FLUIDS PROPERLYImproperly disposing of fluids can harm theenvironment and ecology. Before draining anyfluids, find out the proper way to dispose of wastefrom your local environmental agency.Use proper containers when draining fluids. Donot use food or beverage containers that maymislead someone into drinking from them.DO NOT pour oil into the ground, down a drain, orinto a stream, pond, or lake. Observe relevantenvironmental protection regulations whendisposing of oil, fuel, coolant, brake fluid, filters,batteries, and other harmful waste.

1-9

LIVE WITH SAFETYBefore returning machine to customer, make suremachine is functioning properly, especially thesafety systems. Install all guards and shields.

REPLACE SAFETY SIGNSReplace missing or damaged safety signs. Seethe machine operator's manual for correct safetysign placement.

KEEP ROPS INSTALLED PROPERLYMake certain all parts are reinstalled correctly if theroll-over protective structure(ROPS) is loosened orremoved for any reason. Tighten mounting boltsto proper torque.The protection offered by ROPS will be impaired ifROPS is subjected to structural damage, isinvolved in an overturn incident, or is in any wayaltered by welding, bending, drilling, or cutting. Adamaged ROPS should be replaced, not reused.

1-10

GROUP 2 SPECIFICATION

1. MAJOR COMPONENT

Bucket Tire Head light Hydraulic tank Muffler Radiator

Boom cylinderMain control valve Main pump Air cleaner Battery

Quick coupler

Link Bucket cylinder Cab Precleaner CounterweightBoom

Front axle Steering cylinder Step Transmission Rear axle Fuel tank

Engine

1-11

2. SPECIFICATIONSWITHOUT CUTTING EDGE TYPE BUCKET1)

Operating weight kg(lb)

m3(yd3)

mm(ft-in)

km/hr(mph)

Specification

11530(25410)1.6(2.1)1.9(2.5)

7125(23' 5")2550( 8' 4")3237(10' 7") 417( 1' 4")

2900( 9' 6")1900( 6' 3")2972( 9' 9")991( 3' 3")

2430( 8' 0")45565.61.42.7

39(24.2)13(42' 8")

5.03(16' 6")30

6.5(4.0)13.5(8.4)27.1(16.8)39(24.2)6.5(4.0)13.5(8.4)27.1(16.8)

UnitDescription

Bucket capacity

Overall lengthOverall widthOverall heightGround clearanceWheelbaseTreadDump clearance at 45Dump reachWidth over tiresDump angleRoll back angle(Carry position)

Cycle time

Maximum travel speedBraking distanceMinimum turning radius(Center of outside tire)Gradability

Travel speed

Forward

Reverse

Degree ()

sec

m(ft-in)

First gearSecond gear

Third gearFourth gearFirst gear

Second gearThird gear

H

AE 1842

J

2903 C

D

G397

95122

K

IF50305712

40

B

km/hr(mph)

Degree ()

Struck Heaped

ABCDEFGHIJK

Lift(With load)Dump(With load)

Lower(Empty)

1-12

BOLT-ON CUTTING EDGE TYPE BUCKET2)

Operating weight kg(lb)

m3(yd3)

mm(ft-in)

km/hr(mph)

Specification

11650(25680)1.7(2.2) 2.0(2.6)

7208(23' 8")2550( 8' 4")3237(10' 7")417( 1' 4")

2900( 9' 6")1900( 6' 3")2911( 9' 7")1015( 3' 4")2430( 8' 0")

45565.61.42.7

39(24.2)13(42' 8")

5.03(16' 6")30

6.5(4.0)13.5(8.4)27.1(16.8)39(24.2)6.5(4.0)13.5(8.4)27.1(16.8)

UnitDescription

Bucket capacity

Overall lengthOverall widthOverall heightGround clearanceWheelbaseTreadDump clearance at 45Dump reachWidth over tiresDump angleRoll back angle(Carry position)

Cycle time

Maximum travel speedBraking distanceMinimum turning radius(Center of outside tire)Gradability

Travel speed

Forward

Reverse

Degree ()

sec

m(ft-in)

First gearSecond gear

Third gearFourth gearFirst gear

Second gearThird gear

km/hr(mph)

Degree ()

H

AE 1842

J

2903 C

D

G397

95122

K

IF

50305734

B

40

Struck Heaped

ABCDEFGHIJK

Lift(With load)Dump(With load)

Lower(Empty)

1-13

3. WEIGHT

Front frame assemblyRear frame assemblyFront fenderRear fenderCounterweightCab assemblyEngine assemblyTransmission

Drive shaft(Engine to transmission)Drive shaft(Front)Drive shaft(Center)Drive shaft(Rear)Front axle(Include differential)Rear axle(Include differential)Tire(4EA)Hydraulic tankFuel tank

Main pump assemblyMain control valve

Boom

Bucket link

Quick coupler assy2.0m3 bucket, with bolt on cutting edge1.9m3 bucket, without cutting edgeBoom cylinder assembly(2EA)Bucket cylinder assembly(2EA)Steering cylinder assembly(2EA)Quick coupler cylinder assembly(1EA)SeatBattery

Item kg lb

9161223

2334

80510004353505.914

11

10575

5601320 10022020 22

63840

210895775

13294365.5

4044

20192696

51

75

1775

2205959 772

133124

22

126812352910 22048544

491407

88463

197317092912078012

8897

1-14

4. SPECIFICATION FOR MAJOR COMPONENTS

ENGINE

MAIN PUMP2)

Item

ModelTypeCooling methodNumber of cylinders and arrangementFiring orderCombustion chamber typeCylinder bore strokePiston displacementCompression ratioRated gross horse power Maximum gross torque at 1600rpmEngine oil quantityDry weightHigh idling speedLow idling speedRated fuel consumption Starting motorAlternator

Battery

Specification

Cummins B5.9-C4-cycle turbocharged diesel engineWater cooling6 cylinders, in-line1-5-3-6-2-4Direct injection type102120mm(4.02"4.72")5880cc(352.8cu in)17.5 : 1

137ps at 2200rpm58kgfm(419lbfft)16.4 (4.3 U.S. gal)400kg(881.8lb)2370 50rpm950 50rpm157.3g/ps.hDelco Remy 37MT(24V)DAC HC60(24V-60AMP) 212V160Ah

Item

TypeCapacityMaximum operating pressureRated oil quantityRated speed

Specification

Fixed displacement tandem gear pump41+37cc/rev220kgf/cm2(3129psi)163/min(43U.S.gpm)2200rpm

1)

1-15

Item Specification

12070684mm10050750mm 6540429mm 502579mm

Bore diaRod diaStrokeBore diaRod diaStroke

Boom cylinderBucket cylinderSteering cylinderQuick coupler cylinder

BRAKE PUMP3)

Item

TypeCapacityMaximum operating pressureRated oil quantity

Specification

MAIN CONTROL VALVE4)Item

TypeOperating methodMain relief valve pressureOverload relief valve pressure

Specification

3 spoolHydraulic pilot assist220kgf/cm2(3129psi)240kgf/cm2(3414psi)

REMOTE CONTROL VALVE5)

Type

Operating

Single operation stroke

Specification

Pressure reducing type3.7kgf/cm2(52.6psi)30kgf/cm2(427psi)77mm(3.0in)

Minimum

Maximum

Lever

Item

CYLINDER6)

Fixed displacement tandem gear pump8cc/rev150kgf/cm2(2130psi)17/min(4.5U.S.gpm)

1-16

Item Specification

Clark 13.2 HR24423Single-stage, single-phaseSemi-automatic power shiftForward fourth gear, reverse third gearElectrical single lever type, kick-down system4-wheel driveFront fixed locationOscillation 13of center pin-loaded20.5-25, 16PR(L3)Four-wheel, wet-disc type, full hydraulicSpring applied, hydraulic released brake on frontaxle

Full hydraulic, articulated40to both right and left angle, respectively

Torque converterModelTypeTypeGear shiftAdjustmentDrive devicesFront

Rear

Tires

Travel

Parking

TypeSteering angle

Transmission

Axle

Wheels

Brakes

Steering

DYNAMIC POWER TRANSMISSION DEVICES7)

1-17

5. TIGHTENING TORQUE OF MAJOR COMPONENT

No.

1

2

34

5

67

891011

12

1314

15

1617

Items

Engine

Others

Engine mounting bolt, nutRadiator mounting bolt, nutMain pump housing mounting boltMain control valve mounting boltSteering unit mounting boltPriority valve mounting boltBrake valve mounting boltFuel tank mounting boltHydraulic oil tank mounting boltTransmission mounting boltFront axle mounting boltRear axle support mounting bolt, nutTire mounting nutDrive shaft joint mounting bolt, nutCounterweight mounting boltOperator's seat mounting boltROPS Cab mounting bolt(4EA)

Size

M202.5M121.75

1/2-13UNCM121.75

3/8-16UNCM 81.25M 81.25M162.0M121.75

M202.5M202.0M242.0M221.5

3/8-24UNFM302.0M 81.25M243.0

kgfm

57.9 8.712.3 2.519.6 2.912.8 33.3 0.82.5 0.52.5 0.5

27.9 4.512.3 2.557.9 8.7

100 15100 1560 26 0.8

199 29.93.4 0.828 2.6

lbfft

419 6389.0 18142 21

92.6 22 23.9 5.818.1 3.618.1 3.6202 3389.0 18419 63723108723108434 15

43.4 5.8143921624.6 5.8203 19

Hydraulicsystem

Power trainsystem

1-18

6. TORQUE CHARTUse following table for unspecified torque.

BOLT AND NUTCoarse thread

Fine thread(2)

1)(1)

Bolt size

M 6 1.0M 8 1.25M10 1.5M12 1.75

M14 2.0M16 2.0M18 2.5M20 2.5M22 2.5

M24 3.0M30 3.5M36 4.0

0.85 ~ 1.252.0 ~ 3.04.0 ~ 6.07.4 ~ 11.2

12.2 ~ 16.618.6 ~ 25.225.8 ~ 35.036.2 ~ 49.048.3 ~ 63.362.5 ~ 84.5124 ~ 168174 ~ 236

lbfft6.15 ~ 9.0414.5 ~ 21.7

28.9 ~ 43.453.5 ~ 79.588.2 ~ 120135 ~ 182187 ~ 253262 ~ 354350 ~ 457452 ~ 611898 ~ 1214

1261 ~ 1703

kgfm1.14 ~ 1.74

2.73 ~ 4.125.5 ~ 8.39.8 ~ 15.8

16.7 ~ 22.525.2 ~ 34.235.1 ~ 47.549.2 ~ 66.665.8 ~ 98.085.0 ~ 115169 ~ 229250 ~ 310

lbfft8.2 ~ 12.6

19.7 ~ 29.839.8 ~ 60

71 ~ 114

121 ~ 167182 ~ 247254 ~ 343356 ~ 482476 ~ 709615 ~ 832

1223 ~ 16551808 ~ 2242

8T 10Tkgfm

Bolt size

M 8 1.0M10 1.25M12 1.25

M14 1.5

M16 1.5M18 1.5M20 1.5M22 1.5

M24 2.0M30 2.0M36 3.0

kgfm 2.17 ~ 3.374.46 ~ 6.667.78 ~ 11.5813.3 ~ 18.119.9 ~ 26.928.6 ~ 43.640.0 ~ 54.052.7 ~ 71.367.9 ~ 91.9137 ~ 185192 ~ 260

lbfft15.7 ~ 24.332.3 ~ 48.276.3 ~ 83.796.2 ~ 130144 ~ 194207 ~ 315289 ~ 390381 ~ 515491 ~ 664990 ~ 1338

1389 ~ 1879

kgfm3.04 ~ 4.445.93 ~ 8.9310.6 ~ 16.017.9 ~ 24.126.6 ~ 36.038.4 ~ 52.053.4 ~ 72.270.7 ~ 95.790.9 ~ 123182 ~ 248262 ~ 354

lbfft22.0 ~ 32.042.9 ~ 64.676.6 ~ 115130 ~ 174193 ~ 260278 ~ 376386 ~ 522512 ~ 692658 ~ 890

1314 ~ 17951893 ~ 2561

8T 10T

1-19

PIPE AND HOSE

FITTING

2)

3)

Thread size

1/4"3/8"1/2"3/4"1"

Width across flat'mm(

1922

27

3641

kgfm

34

5

12

14

lbfft

21.7

28.9 36.286.8101

Thread size

1/4"3/8"1/2"3/4"1"

Width across flat'mm(

1922

27

3641

kgfm

4

5

61315

lbfft

28.936.2 43.494.0 109

1-20

7. RECOMMENDED LUBRICANTSUse only oils listed below or equivalent.Do not mix different brand oil.

Capacity(U.S. gal)Service point Kind of fluid

Ambient temperature C(F)

SAE 30

SAE 10W

SAE 10W-30

SAE 15W-40

DEXRON

SAE 80W-90LSD/API GL-5

ASTM D975 NO. 1

ASTM D975 NO. 2

NLGI NO. 1

NLGI NO. 2

Ethylene glycol base permanent type

Engine oil pan

Torque converterTransmission

Axle

Hydraulic tank

Fuel tank

Fitting(Grease nipple)

Radiator

Engine oil

Hydraulic oil

Diesel fuel

Grease

16.4(4.3)

25(6.6)

Front : 40(10.6)Rear : 40(10.6)

Tank:75(19.8)

System:120(31.7)

200(52.8)

35(9.2)

-20(-4)

As required

-10(14)

0(32)

10(50)

20(68)

30(86)

40(104)

Mixture of antifreezeand water

50 : 50

Oil

Gear oil

ISO VG 32

ISO VG 68

ISO VG 46

1-21

GROUP 3 OPERATIONAL CHECKOUT RECORD SHEET

Owner Date Hours Serial No. Technician

99999

Use this sheet to record operationalcheckout results.Perform the operational check beforeinstalling any test equipment.

ItemOK

Comments

1. Monitor indicator and gauge checks(Engine OFF)

Hourmeter and gauge check Battery check Monitor indicator circuit check Monitor turn signals and warning indicator check

2. Transmission, axle and engine linkages, neutral startswitch and reverse warning alarm switch checks

Transmission control lever and neutral Neutral start and reverse warning Alarm circuit checks Engine speed control linkage check

3. Monitor indicator and gauge checks(Engine running)

Monitor display and alternator output checks Monitor bypass circuit and seat belt indicator check Monitor primary and secondary level check Transmission oil warm up procedure Transmission temperature gauge check

NOTOK

1-22

4. Brake system and clutch cut off checks

Park brake capacity check Park brake transmission lockout check Service brake pump flow check Service brake capacity check Brake accumulator precharge check Brake system leakage check Service brake pedal check Service and park brake system drag check Clutch cut off check

5. Driving checks

Transmission oil warm up procedure Transmission noise check Speedometer check Transmission kick down system check 1st, 2nd, 3rd and 4th speed clutch pack drag check Transmission pressure, pump flow and leakage check Transmission shift modulation check Torque converter check Engine power check

6. Hydraulic system checks

Hydraulic system warm up procedure Hydraulic pump performance check Pilot control valve boom float check Boom down solenoid valve check Control valve lift check Bucket rollback circuit relief valve check Bucket dump circuit relief

Low pressure check High pressure check

Boom and bucket cylinder drift check Boom down solenoid valve leakage check Pilot controller check Return to dig check Boom height kickout check-if equipped

1-23

7. Steering system checks

Steering valve check Steering system leakage check Priority valve

Low check pressure High check pressure

8. Accessory checks

Operating lights check Work light check Brake light check Cab light check Horn circuit check Windshield washer and wiper check Defroster blower check Heater/Air conditioner blower check Heater functional check Air conditioner functional check Start aid system check

9. Cab components and vandal protection checks

Cab door latch check Cab door hold open latch check Cab door release button check Cab door lock check Cab door window check Cab window latch check Steering column adjustment check Seat and seat belt check Air intake filter door check Engine side panels check Radiator cap access door check Frame locking bar check Boom lock check Service decal check

3-1

SECTION 3 POWER TRAIN SYSTEMGROUP 1 STRUCTURE AND FUNCTION

1. POWER TRAIN COMPONENT OVERVIEW

The power train consists of the following components :

TransmissionFront, upper, center and rear drive shaftsFront and rear axles

Engine power is transmitted to the transmission through the torque converter.

The transmission is a hydraulically engaged four speed forward, three speed reverse countershaft typepower shift transmission. A disk type parking brake is located on the front of the transmission housing.

The transmission outputs through universal joints to three drive shaft assemblies. The front drive shaftis a telescoping shaft which drives the front axle. The front axle is mounted directly to the loader frame.The front axle is equipped with limited slip differential.

The rear axle is mounted on an oscillating pivot. The rear axle is equipped with limited slip differential.

The power transmitted to front axle and rear axle is reduced by the pinion gear and ring gear ofdifferential. It then passes from the differential to the sun gear shaft(Axle shaft) of final drive.The power of the sun gear is reduced by a planetary mechanism and is transmitted through theplanetary hub to the wheel.

Front axle Front drive shaft Center drive shaft Rear drive shaft Rear axle

Transmission Upper drive shaft Engine

3-2

HYDRAULIC SCHEMATIC

To transmissionlube

Oil cooler(Option)

Declutch

From mastercylinder

1-2-3

FR

Chargingpumpassembly

Filter

Convertersafety valve

Clutchregulator

Vent

Oil sump

Removablescreen

Torqueconverter

1)

3 -3

HYDRAULIC CIRCUIT

Modulationvalve FWD

Modulationvalve REV

Torqueconverter Clutch

regulator valve

Hose

Hose Lubrication

Oil sump

Air breather

Suction screen

Pump

Filter

Convertersafetyvalve

B

A

C

D

E

REV

FWD,LO

FWD,H/4

2

1

3

Oil cooler(Option)

B

CA

E

D

1

X

X

X

2

X

X

3

X

4

X

X

1

X

X

X

2

X

X

3

X

1

X

X

2

X

3Forward Reverse Neutral

X : Solenoid activated

2)

Speed

3-4

2. TRANSMISSION

12 3 8

7

10 119

4

5

6

The transmission is a mid-mount torque converter and transmission assembly connected to the engineby means of a drive shaft.The control valve assembly(7) mounted directly on the side of the converter housing(9).The function of the control valve assembly is to direct oil under pressure to the desired directional andspeed clutch. A provision is made to neutralize the transmission when the brakes are applied. This isaccomplished through use of a brake actuated shutoff valve. The speed and direction clutchassemblies are mounted inside the transmission case(10) and are connected to the output shaft of theconverter either by direct gearing or drive shaft. The purpose of the speed or directional clutches is todirect the power flow through the gear train to provide the desired speed range and direction.

STRUCTURE1)

1 Filter2 Charging pump3 Regulating valve4 Impeller

5 Turbine6 Stator(Reaction member)7 Control valve8 Modulator valve

9 Converter housing10 Transmission case11 Rear cover

3 -5

OPERATIONWith the engine running, the converter charging pump(2) draws oil from the transmission sumpthrough the removable oil suction screen and directs it through the oil filter and the pressureregulating valve(3).The pressure regulating valve maintains pressure to the transmission control cover for actuating thedirection and speed clutches. This requires a small portion of the total volume of oil used in thesystem. The remaining volume of oil is directed through the torque converter circuit to the oil coolerand returns to the transmission for positive lubrication. This regulator valve consists of a hardenedvalve spool operating in a closely fitted bore. The valve spool is spring loaded to hold the valve in aclosed position. When a specific pressure is achieved, the valve spool works against the springuntil a port is exposed along the side of the bore. This sequence of events provides the propersystem pressure.

After entering the converter housing the oil is directed through the stator support to the converterblade cavity and exits in the passage between the turbine shaft and converter support. The oil thenflows out of the converter to the oil cooler. After leaving the cooler, the oil is directed to a lubricatingfitting on the transmission and through a series of tubes and passages lubricates the transmissionbearings and clutches. The oil then gravity drains to the transmission sump.

The hydraulic torque converter consists basically of three elements and their related parts tomultiply engine torque. The engine power is transmitted from the engine flywheel to the impellerelement through the impeller cover. This element is the pump portion of the hydraulic torqueconverter and is the primary component which starts the oil flowing to the other components whichresults in torque multiplication. This element can be compared to a centrifugal pump in that it picksup fluid at its center and discharges at its outer diameter.

The torque converter turbine(5) is mounted opposite the impeller(4) and is connected to the outputshaft of the torque converter. This element receives fluid at its outer diameter and discharges at itscenter. Fluid directed by the impeller out into the particular design of blading in the turbine andreaction member(6) is the means by which the hydraulic torque converter multiplies torque. The reaction member of the torque converter is located between and at the center or innerdiameters of the impeller and turbine elements. Its function is to take the fluid which is exhaustingfrom the inner portion of the turbine and change its direction to allow correct entry for recirculationinto the impeller element.

The torque converter will multiply engine torque to its designed maximum multiplication ratio whenthe output shaft is at zero RPM. Therefore, we can say that as the output shaft is decreasing inspeed the torque multiplication is increasing.

The control valve assembly consists of a valve body with selector valve spools. A detent ball andspring in the selector spool provides one position for each speed range. A detent ball and spring inthe direction spool provides three position, one each for forward, neutral and reverse.

With the engine running and the directional control lever in neutral position, oil pressure from theregulating valve is blocked at the control valve, and the transmission is in neutral. Movement of theforward and reverse spool will direct oil, under pressure to either the forward or reverse directionclutch as desired. When either directional clutch is selected the opposite clutch is relieved ofpressure and vents back through the direction selector spool. The same procedure is used in thespeed selector.

2)

3 -6

The direction or speed clutch assembly consists of a drum with internal splines and a bore toreceive a hydraulically actuated piston. The piston is "oil tight" by the use of sealing rings. A steeldisc with external splines is inserted into the drum and rests against the piston. Next, a friction discwith splines at the inner diameter is inserted. Discs are alternated until the required total isachieved. A heavy back-up plate is then inserted and secured with a snap ring. A hub with outerdiameter splines is inserted into the splines of discs with teeth on the inner diameter. The discs andhub are free to increase in speed or rotate in the opposite direction as long as no pressure ispresent in that specific clutch.

To engage the clutch, as previously stated, the control valve is placed in the desired position. Thisallows oil under pressure to flow from the control valve, through a passageway, to a chosen clutchshaft. This shaft has a drilled passageway for oil under pressure to enter the shaft. Oil pressuresealing rings are located on the clutch shaft. These rings direct oil under pressure to a desiredclutch. Pressure of the oil forces the piston and discs against the heavy back-up plate. The discs,with teeth on the outer diameter, clamping against discs with teeth on the inner diameter, enablesthe hub and clutch shaft to be locked together and allows them to drive as a unit.

There are bleed balls or bleed orifices, in the clutch piston which allow quick escape for oil when thepressure to the piston is released.

3 -7

3. TRANSMISSIONTYPICAL CROSS SECTION1)

FWD

2ndREV 1st

4th 3rd

3 -8

TRANSMISSION LAYOUT2)

A Torque converterB Charge pump assemblyC Pump drive idler gearD Pump drive gearE Forward clutch

F Reverse clutchG 1st clutchH 2st clutchJ Idler shaft

K 3rd clutchL 4th clutchM Output shaftN Solenoid control valve

D

B

C

A

N

E

F

L

H

KG

M

J

3 -9

OPERATION OF TRANSMISSION

ForwardForward 1stIn 1st forward, foreward clutch and 1st clutch are engaged.Foreward clutch and 1st clutch are actuated by the hydraulic pressure applied to the clutchpiston.

3)(1)

FWD

2ndREV 1st

4th 3rd

Idler

OUTPUT

INPUT

3 -10

Forward 2ndIn 2nd forward, foreward clutch and 2nd clutch are engaged.Foreward clutch and 2nd clutch are actuated by the hydraulic pressure applied to the clutchpiston.

FWD

2ndREV 1st

4th 3rd

Idler

OUTPUT

INPUT

3 -11

Forward 3rdIn 3rd forward, foreward clutch and 3rd clutch are engaged.Foreward clutch and 3rd clutch are actuated by the hydraulic pressure applied to the clutchpiston.

FWD

2ndREV 1st

4th 3rd

Idler

OUTPUT

INPUT

3 -12

Forward 4thIn 4th forward, 4th clutch and 3rd clutch are engaged.4th clutch and 3rd clutch are actuated by the hydraulic pressure applied to the clutch piston.

FWD

2ndREV 1st

4th 3rd

Idler

OUTPUT

INPUT

3 -13

Reverse

Reverse 1stIn 1st reverse, reverse clutch and 1st clutch are engaged.Reverse clutch and 1st clutch are actuated by the hydraulic pressure applied to the clutch piston.

(2)

FWD

2ndREV 1st

4th 3rd

Idler

OUTPUT

INPUT

3 -14

Reverse 2ndIn 2nd reverse, reverse clutch and 2nd clutch are engaged.Reverse clutch and 2nd clutch are actuated by the hydraulic pressure applied to the clutchpiston.

FWD

2ndREV 1st

4th 3rd

Idler

OUTPUT

INPUT

3 -15

Reverse 3rdIn 3rd reverse, reverse clutch and 3rd clutch are engaged.Reverse clutch and 3rd clutch are actuated by the hydraulic pressure applied to the clutch piston.

FWD

2ndREV 1st

4th 3rd

Idler

OUTPUT

INPUT

3 -16

ELECTRIC SOLENOID CONTROL VALVE4)

Direction Solenoids Clutches & speed energized pressurized

Forward 1st V X Y Forward & 1stForward 2nd V X Forward & 2ndForward 3rd V Forward & 3rdForward 4th V Z 4th & 3rdReverse 1st W X Y Reverse & 1stReverse 2nd W X Reverse & 2ndReverse 3rd W Reverse & 3rd

Pilot and clutch pressure check points1P 1st pilot2P 2nd pilot2C 2nd clutch4P(FHP) 4th clutchRP Reverse pilotRC Reverse clutch

Energized

De-energized

RC RP

2P

2C

1P

FHP

VFWD

Z4th

Y1st

WREV

X2nd

Inlet

Pilot pressureVent

Vent

3 -17

4. EGS LEVERSHIFT LEVER OPERATIONEGS lever applications share the principle of selecting direction and gear positions.

Direction is selected by placing the lever in one of three detented positions(Neutral, Forward orReverse).Gear shifts are made by bringing the lever either in the upshift position or in the downshiftposition. These positions are spring returned.

With the EGS, shifts are made relative to the previous position : The EGS remembers the selectedgear position and shifts either to a higher gear or to a lower gear.

The EGS display always shows the selected shift lever position, the selected direction, the gearposition and the gear direction.

This operating principle accounts for the flexibility of the EGS system : It makes possible to controlany(Electric) powershift transmission with the same shift lever, provided the correct software(Aprogram for the EGS computer) is installed.It also facilitates features such as kickdown, automatic powerup in neutral, preset gear selectionafter a direction change, etc..

1)

DownshiftSPRING RETURN

Neutral

ReverseLOCK

ForwardLOCK

Heatsink

Display - LEDS

UpshiftSPRING RETURN

The froward driving direction is selected by pushing the lever away from the driver(This usuallycorresponds with pushing it to the normal driving direction).The reverse driving direction is selected by pulling the lever towards the driver.The neutral can be selected by placing the lever into its central detented position.

An upshift is requested by rotating the shift lever counter clockwise.A downshift is requested by rotating the shift lever clockwise.

3 -18

FUNCTIONAL DESCRIPTION

Automatic powerup in neutralWhen power is first applied to the EGS, neutral is always selected.

This is regardless of the position of the shift lever(It can be in either forward, neutral or reverseposition).In order to start driving, the driver first has to place the shift lever into the neutral(Central detented)position before a specific direction can be selected.

Neutral start protectionEach EGS can have an output signal, which is deactivated whenever the shift lever is in theneutral position.

This signal can be used to control a normal closed relay preventing engine start up whenever theshift lever is not in the neutral detented position.

If during powerup the shiftlever is in forward or in reverse, the neutral start protection will not beactivated(Due to the function automatic powerup in neutral). Only after leaving this functionautomatic powerup in neutral the neutral start protection will be activated.

KickdownThis EGS lever is also available with a shift lever integrated push button, which is used for thekickdown function.

Usually it's used for requesting a downshift from 2nd to 1st gear, which is dropped after a directionchange : F2KickdownF1R2This is called kickdown.

If however the speed is too high, the kickdown request is stored for a certain time. If during thistime the speed has not slowed down sufficiently, the request is dropped.

2)(1)

(2)

(3)

3 -19

DISPLAY FUNCTIONThe EGS has an internal bicolor LED display for displaying the selected shiftlever position, theselected shiftlever direction, the transmission position and the transmission direction.

Application specific details are described in a separate document : EGS functional description.This EGS functional description can be requested for each EGS unit. This description overrulesthe below description wherever applicable.

Displayed informationTypically four types of information about the EGS and the transmission can be of interest to thedriver :Selected shiftlever position and transmission positionSelected shiftlever direction and transmission directionApplication specific informationDiagnostic informationSelected position and directionThe difference between shift lever position and transmission position might not be immediatelyclear, but when one remembers that the EGS can protect the transmission(Example : By notallowing a downshift), it becomes clear that the requested position(The shift lever position) canbe different from the actual engaged position(The position of the transmission).Both shift lever position and transmission position can be divided in two subcategories:Gear position (1st, 2nd, 3rd, 4th)Driving direction (Forward, neutral, reverse)Application specific informationThis can be anything(Whatever the customer wants to see).As an example : On an EGS automatically controlling the lockup clutch, it's interesting to see

whether or not the converter is in lockup. This can be indicated on the EGSdisplay by using the LED 7-yellow.

Diagnostic informationTwo types of diagnostic information are considered :

ON LINE diagnosticsThis information is given during normal driving when something special happens.

In most applications, the LED 8 is used to indicate standstill. This helps to spot problems withthe speed sensor in an early stage before the lack of protection resulting from the failure canproduce damaged to the drivetrain.

Which on line diagnostic functions are provided is detailed in the application specific EGSFunctional description.

OFF LINE diagnosticsThere are three selftest modes built into the EGS. Details about their function and usage aredescribed in clause 5), Selftest functions.

3)

(1)

3 -20

Display layoutThe EGS uses LED's(Light Emmitting Diodes) to give information to the driver.It consists of eight multicolor LED's :Labelled 1 to 8 and can light up in red, green and yellow.

(2)

These numbered LED's are used for displaying both the shift lever selection and the transmissionengagement.

They also used to indicate diagnostic information in the different test modes.

The red LED is labelled N and when this lights up it indicates that the transmission is placed inneutral(This is possible even while the shift lever is not in neutral).The yellow LED is labelled T which stands for troubleshooting. This LED is ON while working inone of the three selftest modes described in clause 5), Selftest function.Display methodBasically the gear position is shown by turning ON the LED that corresponds with the selectedposition. In 1st gear, LED 1 is ON, in 2nd gear, LED 2 is ON etc..

The selected direction is shown with the color of the LED :Red Indicates NeutralGreen Indicates ForwardYellow Indicates ReverseAdditionally LED N(Red) is ON while the transmission is in neutral.The position shown is always the selected shiftlever position. Most of the time, the actualtransmission position will be the same as the shown one, and in that case that's all there is.

However if, because of an active protection or because of some internally generated delay, thereis a discrepancy between transmission position and shift lever position, a 2nd LED will indicate thetransmission position(Color indicates direction).To let the driver know the difference between both indications, the transmission LED blinks whilethe shift lever LED stays ON all the time.

While this may seem a bit confusing at first, it's very easy to understand the shown information inreality.

Example :

(3)

Driving in 4th gear forward at high speed.

When the driver is making a downshift, but due to atoo high speed the EGS will protect the transmissionand will not allow the requested downshift. Thus thetransmission will stay in 4th gear forward, while theshiftlever is in 3rd gear forward.

LED 4 - Green

LED 3 - Green &LED 4 - Blinking green

N T

1 2 3 4 5 6 7 8

F N R

3 -21

CONNECTOR PIN DESIGNATIONSBelow table lists the function of each EGS connector pin for the transmission :

4)

1

2

34

5

67

891011

12

1314

15

16

Battery plusBattery groundNeutral start signalCV Solenoid 1CV Solenoid 2CV Forward solenoidCV Reverse solenoidNull

Speed 5km/hrSpeed sensor input HOTSpeed sensor input GNDTravel speed signalCV High / Low solenoidDeclutch

Extension kick downShield ground(Internally connected to wire 2)

Pin Comment

CV stands for control valve.

3 -22

SELFTEST FUNCTIONSThe EGS has special circuitry to help verifying its operation.

Three selftest modes are built into the EGS control programs :Input testSpeed sensor test + LamptestOutput test

The EGS furthermore has the ability to check for possible problems while driving(On linediagnostics).As described in clause(2), Display layout at page 3-18, the T LED is used for identifying differenttroubleshooting modes. This is done in combination with the status of the N LED.

Operation of the N and T LED'sOverview

5)

(1)

In normal situations(Driving, no problems)When error is detectedIn selftest mode

Situation LED

T LED is always OFFT LED is ON or BLINKINGT LED is always ON

Normal operationInternal faultInput testOutput testSpeed sensor test

On when transmission neutralONBlinking SLOWLYBlinking FASTOFF

OFFBlinking SLOWLYONONON

Detailed operation

Situation N LED T LED

Selftest operationSelftest modes can only be started while powering up the EGS.Invocation of a certain mode is done by moving the shift lever to a specific position while switchingon the power of the EGS.Leaving the selftest mode is done by switching OFF the power of the EGS.Selftest mode invocationBelow table lists what conditions must be satisfied during powerup to get into a specific selftestmode :

(2)

Input testSpeed sensor testOutput test

FWD & UPREV & UPFWD & DOWN

Selftest mode To enter mode

3 -23

Input testWhen EGS shiftlever is held in the forward up position while power is applied, input test modeis activated.In this mode, driving is not possible, since all EGS outputs remain OFF until the testmode is left.

This test is used to verify operation of the shiftlever and its inputs.

The LED's(Gear position indicators) on the EGS top cover are used to display test information :

NeutralUPDOWN

FWDFWD & UPFWD & DOWN

REVREV & UPREV & DOWN

Wire 14 = GROUNDWire 15 = GROUND

REDREDRED

GREENGREENGREEN

YELLOWYELLOWYELLOW

REDGREEN

453

453

453

1 (Together with above LED)1 (Together with above LED)

Shift lever position LED Color LED Number

If wire 14 and wire 15 are grounded simultaneously LED 1 lights up yellow.

Speed sensor testWhen EGS is held in the reverse up position while power is applied, speed sensor test mode isactivated.

In this mode, driving is possible.

The test begins with a lamp test and then displays the speed sensor information.

Speed displayThe LED corresponding with below table burns to indicate converter turbine speed :

00 - 249

250 - 499500 - 749750 - 999

1000 -12491250 - 14991500 - 17491750 -1999Above 2000

1 BLINKS1 ON2 ON3 ON4 ON5 ON6 ON7 ON8 ON8 BLINKS

Turbine rpm LED Number(Green)

3 -24

Output testWhen EGS is held in the forward down position while power is applied, output test mode isactivated.

In this mode, driving is not possible, since all EGS outputs remain OFF until the testmode is left.

LED's 1 - 8 light up sequentially during output test :First LED 1 is switched on shortly, then LED 2 etc..

When LED 8 is switched off, LED 1 is again switched on and so on.

The color of the LED indicates its status :

GREENYELLOWRED

Output OKOutput NOT connected or shorted to battery plusOutput shorted to ground(or to another output)

Color Status

The LED numbers correspond to output wires as follows :

1

2

34

5

67

8

67

4

5

91383

LED Number Output wire

To find the function of the corresponding output wires - See EGS functional description

3 -25

Remove screw(33).Remove screw(38).Remove screw(34).Remove screw(25). Remove plate(26) and seal(27).Slide the PCB's(42, 43) out of the housing, with rear cover connected(31, 35).Remove plastic cover(40). Replace EP-ROM(39).Notice the correct position of the mark on the EP-ROM (See D).Reassemble the EGS.Notice the correct slots for the different ports. See on the right figure.

A : Slots for cover(40)B : Slots for PCB(42)C : Slots for PCB(43)

(1)(2)(3)(4)(5)(6)(7)(8)(9)

REPLACING OF EP-ROM6)

2526

27 31

33

35

34

38

40

42

43

39

D

A

B

C

3 -26

5. AXLEOPERATION

The power from the engine passes through torque converter, transmission and drive shafts, and isthen sent to the front and rear axles.Inside the axles, the power passes from the bevel pinion to the bevel gear and is sent at rightangles. At the same time, the speed is reduced and passes through the both differentials to theaxle shafts. The power of the axle shafts is further reduced by planetary-gear-type final drives andis sent to the wheels.

Front axle

1)

1 Final drive 2 Differential 3 Axle

Rear axle(2)

(1)

1

2

3

1 Final drive 2 Differential 3 Axle

1

2

3

3-27

SECTION OF FRONT AXLE DIFFERENTIAL2)

1 Bevel pinion2 Bevel gear

3 Sun gears4 Shaft

5 Side gear(Differential)

A A

4

15

2

3

3 -28

1 Bevel pinion2 Bevel gear

3 Sun gear4 Shaft

5 Side gear(Differential)

SECTION OF REAR AXLE DIFFERENTIAL3)

A A

4

15

2

3

3 -29

DIFFERENTIAL

DescriptionWhen the machine makes a turn, theoutside wheel must rotate faster than theinside wheel. A differential is a devicewhich continuously transmits power to theright and left wheels while allowing themto turn a different speeds, during a turn.The power from the drive shaft passesthrough bevel pinion(1) and is transmittedto the bevel gear(2). The bevel gearchanges the direction of the motive forceby 90, and at the same time reduces thespeed.It then transmits the motive force throughthe differential(3) to the axle gear shaft(4).

4)

Pinion gearSide gear Side gear

Axle gear shaft

CarrierPinion gear

SwingPinion gear

Side gear Side gear

Carrier

Pinion gear Ring gear

When turningWhen turning, the rotating speed of theleft and right wheels is different, so thepinion gear and side gear inside thedifferential assembly rotate in accordancewith the difference between the rotatingspeed of the left and right wheels.The power of the carrier is thentransmitted to the axle gear shafts.

When driving straight forwardWhen the machine is being driven straightforward and the right and left wheels arerotating at the same speed, so the piniongear inside the differential assembly do notrotate. The motive force of the carrier issend through the pinion gear and the sidegear, therefore the power is equallytransmitted to the left and right axle gearshaft.

(1)

(2)

(3)

1

23

4

3 -30

TORQUE PROPORTIONING DIFFERENTIALFunctionBecause of the nature of their work, 4-wheel-drive loaders have to work inplaces where the road surface is bad.In such places, if the tires slip, the abilityto work as a loader is reduced, and alsothe life of the tire is reduced.The torque proportioning differential isinstalled to overcome this problem.In structure it resembles the differential ofan automobile, but the differential piniongear has an odd number of teeth.Because of the difference in theresistance from the road surface, theposition of meshing of the pinion gearand side gear changes, and this changesthe traction of the left and right tires.

5)(1)

FL FRa b

Spider rotatingdirection

Left side gear Pinion Right side gear

Engagingpoint

Engagingpoint

OperationWhen travelling straight(Equalresistance from road surface to left andright tires)Under this condition, the distancesinvolving the engaging points betweenright and left side gears and pinion-a andb-are equal and the pinion is balanced asFLa=FRb. Thus, FL=FR, and theright and left side gears are driven withthe same force.

(2)

3 -31

When travelling on soft ground(Resistance from road surface to left andright tires is different)If the road resistance to the left wheel issmaller, the left side gear tends to rotateforward, and this rotation changes theengaging points between the side gearsand pinion. As a result, the distancesinvolving the engaging points becomesa>b. The pinion now is balanced as FLa=FRb, where FL>FR. The rightside gear is driven with a greater forcethan the left side gear. The torque canbe increased by up to about 30% foreither side gear.The pinion therefore does not run idleand driving power is transmitted to bothside gears until the difference betweenroad resistance to the right and leftwheels reaches about 30%.

FLFR

a b

Spider rotatingdirection

Left side gearPinion

Right side gear

Small roadresistance

Large roadresistance

Engagingpoint Engagingpoint

3 -32

FINAL DRIVE(Front & rear)6)

1 Axle shaft2 Planetary gear

3 Ring gear 4 Sun gear

To gain a large drive force, the final drive uses a planetary gear system to reduce the speed andsend drive force to the tires.

The power transmitted from the differential through axle shaft(1) to sun gear(4) is transmitted toplanetary gear(2). The planetary gear rotates around the inside of a fixed ring gear(3) and in thisway transmits rotation at a reduced speed to the planetary carrier.This power is then sent to the wheels which are installed to the planetary carriers.

2

4

1

3

(1)

(2)

3 -33

6. TIRE AND WHEEL

1 Wheel rim2 Tire

3 O-ring4 Lock ring

5 Side ring6 Valve assembly

2

5

4

6

3

1

The tire acts to absorb the shock from the ground surface to the machine, and at the same timethey must rotate in contact with the ground to gain the power which drives the machine.

Various types of tires are available to suit the purpose. Therefore it is very important to select thecorrect tires for the type of work and bucket capacity.

1)

2)

3-34

GROUP 2 OPERATIONAL CHECKS AND TROUBLESHOOTING

1. POWER TRAIN OPERATIONAL CHECKSThis procedure is designed so that the mechanic can make a quick check of the system using aminimum amount of diagnostic equipment. If you need additional information, read Structure andfunction, Group 1.

A location will be required which is level and has adequate space to complete the checks.

The engine and all other major components must be at operating temperature for some checks.Locate system check in the left column and read completely, following the sequence from left to right.Read each check completely before performing.

At the end of each check, if no problem is found(OK), that check is complete or an additional check isneeded. If problem is indicated(NOT OK), you will be given repair required and group location.If verification is needed, you will be given next best source of information :

Chapter 2 : TroubleshootingGroup 3 : Tests and adjustments

3-35

Transmission oil must be at operating temperature for these checks.

Item Description Service action

Start engine. Apply servicebrakes and release parking brake.Move EGS lever to 3rd speed.Move EGS lever to forward "F"position.Increase engine speed to high idlefor 30 seconds.Move EGS lever to neutral "N"position and run for 15 seconds.Repeat procedure until transmission temperature gaugearrow points to bar above dial.

Run engine at approximately1600rpm.Drive unit with transmission ineach forward and reverse speed.LISTEN : Transmission must notmake excessive noise in anyrange.Engine rpm must not "lug down"as unit is shifted between gears.

Release parking brake and shift to2nd forward.Drive machine at approximately5km/h and press EGS lever switchonce.

LOOK/FEEL : Transmission mustshift to and remain in 1st gear.Press EGS lever switch once.LOOK/FEEL : Transmission mustshift back to 2nd gear.Shift to(3rd or 4th) gear and pressEGS lever switch once.LOOK/FEEL : Transmission mustnot shift down.

OKCheck completed.

OKCheck completed.NOT OKGo to transmission makesexcessive noise group 3.

OKCheck completed.NOT OKCheck connector at baseof control valve.IF OKGo to transmissioncontroller circuit in group1.

Transmission oil warm-up procedure

Transmission noisecheckEngine running.

Transmiss ion"k ickdown" checkEngine running.

TRANS

3-36

Item Description Service action

Park unit on level surface.Apply service brakes.Move EGS lever to neutral.Move EGS lever to 1st.Release parking brake andservice brakes.Run engine at low idle.LOOK : Unit must not move ineither direction.NOTE : If unit moves forward,either the forward pack or the 4thspeed pack is dragging.

Run engine at low idle.Release parking brake.Shift transmission to reverse, thenforward, and then to 1st, 2nd, and3rd speeds.Wait 5 seconds after each shiftand observe transmissionpressure indicator light.LOOK : Indicator light must notcome on.

NOTE : If light comes on in onegear only, leakage is indicated onthat gear.If light comes on in all gears, lowpump flow or pressure isindicated.

OKCheck completed.NOT OKIf unit moves, repairtransmission.

OKCheck completed.NOT OKDo transmission leakagetest, system pressure test,or pump flow test in group3.

Forward, reverse and4th speed clutch packdrag checkTransmission must

be warmed up for this check.

Engine running.

Transmission pressure,pump flow, and leakagecheckEngine running.

3-37

Item Description Service action

Run engine at approximately1600rpm.Put transmission in 1st forward,shift several times from forward toreverse and reverse to forward.Repeat check in 2nd gear.LOOK : Unit must slow down andchange direction smoothly.

Start engine. Apply servicebrakes and release parking brake.Move EGS lever to 3rd speed.Move EGS lever to forward "F"position.Increase engine speed to highidle.LOOK : Torque converter stallrpm must be within the followingrange.Stall rpm : 2300 ~ 2440rpmMove EGS lever to neutral "N"position and run for 15 seconds.

OKCheck completed.NOT OKGo to unit shifts too fast,chapter 2 in this group.

OKCheck completed.NOT OKIf stall rpm are too low ortoo high, problem may beengine power or torqueconverter.

IF OKReplace transmissiontorque converter.

Transmission shiftmodulation checkEngine running.

Torque converter check

3-38

2. TROUBLESHOOTING

Problem Cause Remedy

Low oil level.

Wrong oil grade.Restricted transmission pumpsuction screen.

Leak in transmission controlvalve or gasket.Low transmission pump flowdue to worn pump.Weak or broken pressureregulating valve spring.

Add oil.Change oil.Remove and clean screen.

Remove valve and inspect gaskets.

Do transmission pump flow test.

Do transmission system pressure test.

Transmission slippage

TRANSMISSIONDiagnose malfunction charts are arranged from most probable and simplest to verify, to leastlikely, more difficult to verify. Remember the following steps when troubleshooting a problem :

Step 1. Operational check out procedure(See group 3 in section 1.)Step 2. Operational checks(In this group.)Step 3. TroubleshootingStep 4. Tests and/or adjustments(See group 3.)

1)

3-39

Problem Cause Remedy

Low oil level.

Applied park brake.

No power to transmissioncontroller.

Malfunctioning parking brakesolenoid valve.

Restricted modulation orifice.

Excessive leakage in transmission element.

Worn clutch disks.Low or no transmission pressure.Service brake will not release.

Failed torque converter.

Broken shafts or gears.

Broken drive shafts.

Broken ring or pinion gear.

Malfunctioning transmissioncontrol solenoid valve.Stuck spool in transmissioncontrol valve.

Stuck modulation valve.

Malfunctioning transmissionspeed sensor.

Add oil.Check parking brake fuse.Check continuity to parking brake switch.Check transmission controller fuse.

Remove and inspect parking brake solenoidvalve.Check for power to solenoid valve.Remove orifice and check for contaminationand/or plugging.(Do not remove valve housing for this purpose.)Do transmission element leakage test usingsystem pressure.Repair transmission.See transmission pressure is low in this group.

Do brake pedal operational check.Do service and park system drag checks.Do torque converter stall test.If engine pulldown in normal, torque converter isgood.Drain transmission to determine if large pieces ofmetal contamination are present.Inspect drive shafts and universal joints forexternal damage. Repair.

If drive shaft rotate with transmission in gear butmachine does not move, a differential failure isindicated. Repair.

Check solenoid valve.

Remove and inspect transmission control valvespools.Remove end cover to inspect modulation spool.Replace if necessary.Check speed sensor.

Machine will not move

Machine does not engage in low gear

3-40

Problem Cause Remedy

Low oil level.

Failed transmission pressureswitch.

Plugged suction strainer.

Stuck transmission pressureregulating valve or brokenspring.Failed control valve gasket.

Stuck modulation valve.

Failed transmission pump.Failed transmission controlvalve gasket.

Leakage in clutch piston or sealring.

Low oil level(Aeration of oil).Low transmission pressure.Restricted transmission pumpsuction screen.

Low transmission pump flow.Excessive transmission element leakage.Stuck modulation valve.

Restricted modulation orifice.

Malfunctioning two stage piston.Restricted oil passagesbetween control valve andtransmission elements.

Check transmission oil level and refill ifnecessary.Verify transmission system pressure. Dotransmission system pressure test.Transmission pump may be noisy if transmissionsuction screen is clogged. Drain transmission.Remove and clean suction screen.Also, check condition of transmission filter.Remove transmission pressure regulating valve.Inspect for damage(See transmission controlvalve).Inspect transmission control valve for externalleakage. Remove control valve.Inspect or replace gasket.Remove end cover to inspect modulation spooland check torque on cap screws retaining controlvalve to transmission.

Do pump flow test.Inspect transmission control valve for externalleakage. Remove control valve.Inspect or replace gasket.Disassemble and repair.

Add oil.Do transmission system pressure test.Remove and clean screen.

Do transmission pump flow test.Do transmission element leakage test usingsystem pressure.Remove end cover to inspect modulation spool.Replace if necessary.Remove orifice and inspect for contamination and/or plugging.Remove and inspect two stage piston.Remove control valve and inspect oil passage.

Transmission pressureis low(All gears)

Transmission systempressure is low (One ortwo gears)

Transmission shiftsdirection too low

3-41

Problem Cause Remedy

Wrong transmission controller.

System pressure too high.Stuck modulation valve.

Malfunctioning two stage piston.Stuck or missing check valves.Missing O-ring from end ofmodulation orifice.Broken piston return spring.

Warped disks and plates intransmission.

High oil level.

Low oil level.

Wrong oil grade.Park brake dragging.Pinched, restricted or leakinglube lines.Machine operated in too highgear range.Malfunction in temperaturegauge or sender.

Restricted air flow through oilcooler or radiator.Failed oil cooler bypassvalve(In thermal bypass valve).Failed thermal bypass valve.

Internally restricted oil cooler.Leakage in transmissionhydraulic system.Malfunction in converter reliefvalve.

Low transmission pump output.

Check if transmission controller has beenchangedDo transmission system pressure test.Remove and inspect modulation valve.Replace if necessary. Also remove end cover toinspect modulation spool and control valvehousing.Replace if necessary.Remove and inspect two stage piston.Inspect transmission control valve.Remove orifice and inspect port for O-ring.

Disassemble and inspect clutch.

Check transmission.

Transmission overfilled or hydraulic pump sealleaking.Add oil.Change oil.Check for heat in park brake area.Check cooler lines.

Operate machine in correct gear range.

Install temperature sensor the verify temperature.Do tachometer/temperature reader installationprocedure.Do radiator air flow test.

Disassemble and inspect.

Remove thermal bypass valve and check to see ifmachine still overheats. Do transmission oilcooler thermal bypass valve test.Do oil cooler restriction test.

Do transmission system pressure, elementleakage, and shift modulation test.Do converter out pressure test.

Do transmission pump flow test.

Transmission directionshifts too fast

Machine "creeps" in neutral

Transmission hydraulicsystem overheats

3-42

Problem Cause Remedy

Too low engine low idle.Worn parts or damaged intransmission.

Warped drive line betweenengine and torque converter.Low or no lube.

Incorrect type of oil.High oil level.

Low oil level.

Air leak on suction side ofpump.

Plugged breather.

Aerated oil.Low engine speed.Failed universal joints ontransmission drive shaft ordifferential drive shafts.

Engine high idle speed set toolow.

Incorrect transmission oil.

Aerated oil.Low transmission pressure.Warped transmission clutch.Torn transmission control valvegasket.Brake drag.Failed torque converter.Low engine power.

Aerated oil.

Stuck open converter reliefvalve.

Leakage in torque converterseal.

Torque converter not transferring power(Bent fins,broken starter).

Check engine low idle speed.Remove transmission suction screen. Inspectfor metal particles.Repair as necessary.Inspect drive line.

Do converter-out and lube pressure test. Dotransmission pump flow test.

Change oil.Transmission overfilled or hydraulic pump sealleaking.Add oil.Check oil pickup tube on side of transmission.

Inspect breather on top of transmission.Replace.

Add oil.Check engine speed.Check universal joints.

Check high idle adjustment.

Change oil.Add oil.Do transmission system pressure test.Do transmission clutch drag checks.Inspect gasket.

Do brake drag check.Do torque converter stall speed test.Do engine power test.

Put clear hose on thermal bypass outlet port.Run machine to check for bubbles in oil.Do converter-out pressure test.

Do converter-out pressure test.

Replace torque converter.

Excessive transmissionnoise(Under load or noload)

Foaming oil

Oil ejected from dipstick

Machine vibrates

Machine lacks powerand acceleration

Torque converter stallRPM too high

3-43

Problem Cause Remedy

Low engine power.Mechanical malfunction.

Low oil level.

Cold oil.Leak in reverse pack.

Cold oil.No time delay in monitor.Restriction in modulation orifice.

Stuck modulation valve.Low transmission pressurecircuit.

Leak in transmission pressurecircuit.

Failed transmission pump.Clogged filter.

Do engine power test.Remove and inspect torque converter.

Add oil.Warm oil to specification.Do transmission pressure, pump flow, andleakage check.

Warm oil to specification.Do monitor check.

Remove orifice and inspect for restriction and/orplugging.Remove and inspect.Do transmission system pressure test.

Do converter out pressure test.

Do transmission pump flow test.Inspect filter. Replace.

Torque converter stallRPM too low

Transmission pressurelight comes ON whenshifting from forward toreverse(All other gearsOK)

Transmission pressurelight comes ON for eachshift

3-44

External leakage.

Low oil level in differential.

Incorrect type of oil.Dragging brakes.Failed pinion bearing.

Incorrect gear mesh patternbetween ring and pinion gear. Failed differential pinion gearsand/or cross shafts.

Failed axle bearing.Mechanical failure in axleplanetary.

Excessive end play in axle.Worn outer bearing and/or cup.

Overfilled differential.

Low differential oil.Overfilled differential.Brake drag.

Inspect axle and differential for leaks.

Check oil. Remove drain plug and inspect formetal particles in differential case.Disassemble and determine cause.Change oilDo brake check.Remove and inspect pinion.Check to ensure pinion housing was indexed.Remove pinion gear housing and inspect ring andpinion gear.Remove differential housing drain plug andinspect for metal particles. Disassemble andinspect.Do axle bearing adjustment check.Remove differential. Inspect, repair.

Do axle bearing adjustment check.Disassemble and inspect outer axle bearing, cup,spacer, and seal. Replace, if necessary.Check differential oil return system for excessiveinternal restriction.

Add oil.See differential overfills with oil in this group.See brakes drag in this group.

Differential low on oil

Excessive differentialand/or axle noise

Oil seeping from outeraxle seal

Axle overheats

DIFFERENTIAL / AXLE

Problem Cause Remedy

2)

Yokes not in line on driveshafts.Worn front drive line supportbearing.Bent drive shaft.Loose yoke retaining nuts(Driveshafts wobble at high speed).Rear axle oscillating support.Lack of lubrication.

Inspect. Align drive shaft yokes.

Inspect, repair.

Inspect all drive shafts. Replace.Inspect. Replace.

Inspect, repair.Lubricate with proper grade of grease.

Excessive drive linevibration or noise

DRIVE LINE

Problem Cause Remedy

3)

3-45

GROUP 3 TESTS AND ADJUSTMENTS

The setting pressure of the clutch cut-offpressure switch should be suited with thespecification. The rated pressure is 25 kgf/cm2.For the detailed method for pressure adjusting,refer to page 4-22.

Brake valve

Clutch cut off pressure switch

1. CLUTCH CUT-OFF PRESSURE SWITCH TEST

3 -46

2. TRANSMISSION PUMP PRESSURE AND FLOW TESTINGTEST PORT1)

A

D

L

B

E

N

K

M

G

H

J

C

F

Description

Regulated clutch pressure snapconnector(Pressure switch)Modulated forward clutch pressureReverse clutch pressure2nd clutch pressure3rd clutch pressure1st clutch pressureConverter outlet temperatureConverter outlet pressureConverter inlet pressurePort for lube oil from coolerPort for converter out oil to coolerLube in pressure check pointForward high(4th) clutch pressure

Port

A

BCDEFGHJKLMN

3-47

TESTINGBefore testing is carried out, ensure that the oil is at the correct level and at normal operatingtemperature 80~ 95C(180~200F).TORQUE CONVERTER STALL TESTMark the engine crankshaft pulley with chalk or reflective tape and check the maximum no-loadspeed of the engine using a stroboscopic tachometer.

Raise the loader arms and set the machine against fixed obstruction. Apply firmly the footbrake.Select forward 3th and, with the throttle fully open, check engine speed which should be as shownin technical data. Torque converter stall speed is 227070rpm.Do not apply the clutch cut off switch during this test as the clutch disconnect will beactivated and a false reading will result.

Repeat the above test whilst simultaneously operating the loader arm raise service to blow off themain relief valve.Engine speed should be as shown in technical data.

If engine speeds are appreciably below the stated figures, the engine is losing power and should beserviced or overhauled. Where the engine speed does not change significantly from the governedspeed, check the transmission for clutch slippage or internal leakage. Above phenomenon is alsoindicated an incorrect torque converter.

CLUTCH LEAKAGE TESTConnect a flowmeter between the transmission and oil cooler. With the parking brake firmlyapplied, test at 1800rpm transmission input direction spool in forward or reverse and range spool in1st, 2nd or 3rd. Converter out flow should not exceed 2.5GPM(9.5lpm) less than charging pumpflow or a max difference of 1GPM(3.8lpm) between any two speeds. Record the flow rate. Repeatthe test for each clutch pair.

CLUTCH PRESSURE TESTConnect a pressure gauge to the clutch pressure tapping point A. Run the engine at idling speed,engage clutches in sequence(As in previous test) and note the gauge readings which should be asshown in technical data. Clutch pressure should be in 17~20bar(240~280psi). Clutch pressure should not vary by more than 0.34bar(5psi) from one another. Any clutch showinga greater variation should be disassembled for servicing.Never use service brake while making clutch pressure checks.Units having brake actuated declutching in forward and/or reverse will not give a truereading.Always use parking brake when making clutch pressure checks.

2)

3)

4)

5)

3 -48

PUMP FLOW TESTStop the engine and remove transmission filter. Assemble flow test tool by locating adapter Kthrough center bore of body L and securing with adapter.Screw body onto filter spigot on transmission and connect a flow meter N as shown.Start the engine and run at 2000rpm. The flow meter will show the pump flow which should be asshown in technical data. A low reading indicates a worn pump or blocked suction strainer.

SpecificationsOil temperature 80~ 95C(180~200F)Pump flow(Minimum) 17.5GPMLow transmission pump flow can be caused by :Low oil level.Cold transmission oil.Plugged suction screen.Air leak in pump suction tube.Pump mounting cap screws loosen.Worn transmission pump.

6)

K

LM

N

3-94

2. CONTROL VALVESTRUCTURE1)

1 Elbow2 Tube assy3 Elbow4 Valve plug5 Shift spool6 Spring7 Shift spool8 Plug9 Valve spool10 Spring11 Plug & O-ring12 Spring13 Shift spool14 Spool stop15 Roll pin & plug stop

12

8495

6107

11

121314

15

1617 20

21

22

2324

2526

27

2829

30

31

343332

31

45

44

43

42

4041

38

39

37

336

35

19

18

31 Solenoid coil32 O-ring33 O-ring34 O-ring35 Control valve housing36 Spool stop37 Ground wire harness38 Screw39 Receptacle & wire assy40 Lock washer41 Nut42 Grommet43 Dust cover44 Dust cover seal45 Mounting stud

16 Spring17 Shift spool18 Pipe plug19 Gasket20 Plug21 Spool stop22 Spool23 Spring24 Valve body25 Pipe plug26 Lock washer27 Screw28 Lock washer29 Screw30 Shuttle valve solenoid

3-95

DISASSEMBLY AND ASSEMBLYThe numerical sequence shown on theillustration is intended as a guide todisassembling.For assembly the sequence should bereversed.

When disassemblyDepress spool 22 to remove stop 21.Renew oil seals when spools 5 and 13are removed.Depress spool 9 to remove stop 36.When assemblyDepress spool 9 to fit stop 36.Take care not to cut lips of oil sealswhen refitting spools 5 and 13.Depress spool 22 to fit stop 21.Refer to tightening sequence as shownin the figure.Torque settings

2)

(1)

(2)

4 3

7

5

2

9

11

6

8

1

10

12

Item

27, 29

Nm

31-33

kgfm

3.2-3.4

lbfft

23-25

4-1

1. OUTLINEThe brakes are operated by a pressure compensated, closed center hydraulic system.Flow is supplied by a fixed displacement, gear type brake pump.

BRAKE SYSTEMThe fixed displacement brake pump supplies flow to service brake circuit and park brake circuits. Itflows to four accumulator. The accumulator has a gas precharge and an inlet check valve tomaintain a pressurized volume of oil for reserve brake applications.

Oil through the accumulator flows to the brake valves. The brake valve is a closed center design,dual circuit operated by a pedal.

The front and rear brakes will operate simultaneously with only one brake pedal depressed.

The differential contains annular brake piston and double sided disk.

Brake pump flow also goes to the parking brake solenoid valve.

The brake system contains the following components:Brake pumpParking brake solenoid valveBrake valveAccumulatorsPressure switches

SECTION 4 BRAKE SYSTEMGROUP 1 STRUCTURE AND FUNCTION

4-2

FULL POWER HYDRAULIC BRAKESYSTEMADVANTAGES - The full power hydraulicbrake system has several advantages overtraditional brake actuation systems. Thesesystems are capable of supplying fluid to arange of very small and large volumeservice brakes with actuation that is fasterthan air brake systems. Figure representsa time comparison between a typicalair/hydraulic and full power hydraulic brakeactuation system.

Full power systems can supply significantlyhigher brake pressures with relatively lowreactive pedal forces. The reactive pedalforce felt by the operator will be proportionalto the brake line pressure being generated.This is referred to as brake pressuremodulation.Another key design feature of full powersystems is the ability to control maximumbrake line pressure. In addition, becausethese systems operate with hydraulic oil,filtration can be utilized to provide longcomponent life and low maintenanceoperation.

Because these systems are closed center,by using a properly sized accumulator,emergency power-off braking that isidentical to power-on braking can beachieved. These systems can be eitherdedicated, where the brake system pumpsupplies only the demands of the brakesystem or non-dedicated, where the pumpsupplies the demands of the brake systemas well as some secondary down streamhydraulic devise.Another important note is that all sealswithin these system must be compatiblewith the fluid medium being used.

Response timeFull power brake actuation VSAir/Hydraulic brake actuation

Brak

e to

rque

(lb

in)

1000

900

800

700

600

500

400

300

200

100

Time(Seconds)

Brake torque(Full power)

Brake torque(Air/hydraulic)

Brake pressure(Full power)

Brake pressure(Air/hydraulic)

0 1 2 3 4

4-3

2. HYDRAULIC CIRCUIT

P T

A B

FRONT REAR

BR1 BR2 M2

DS1

S2DS2S1

S3

T

P

N

1821

17

8167

22

16

19

20

23

24

25

1

26 27

P2

P1 T

U3MPa

MCVReturn line

Steering system

Return line

RCV

ABC

13

33

Coupler cylinder

1 Pump assy7 Brake valve8 Check valve13 Pilot supply unit16 Accumulator17 Accumulator

18 Solenoid valve19 Pressure switch20 Pressure switch21 Pressure switch22 Pressure switch23 Line filter

24 Air breather25 Hydraulic tank26 Return filter27 Bypass valve33 Axle

A 1st pumpB 2nd pumpC Brake pump

4-4

SERVICE BRAKE RELEASED

When the pedal of brake valve(7) is released, the operating force is eliminated by the force of thespring, and the spool is returned.When the spool removes up, the exhaust port is opened and the hydraulic oil in the piston of axlesreturn to the tank(25).Therefore, the service brake is kept released.

P T

A B

FRONT REAR

BR1 BR2 M2

DS1

S2DS2S1

S3

T

P

N

1821

17

8167

22

16

19

20

23

24

25

1

26 27

P2

P1 T

U3MPa

MCVReturn line

Steering system

Return line

RCV

ABC

13

33

Coupler cylinder

1)

A 1st pumpB 2nd pumpC Brake pump

4-5

SERVICE BRAKE OPERATED

When the pedal of brake valve(7) is depressed, the operating force overcomes the force of thespring, and is transmitted to the spool. When the spool moves down, the inlet port is opened, andat the same time the hydraulic oil controlled the pressure level by the other spool in the brake valveenters the piston in the front and rear axles. Therefore, the service brake is applied.

P T

A B

FRONT REAR

BR1 BR2 M2

DS1

S2DS2S1

S3

T

P

N

1821

17

8167

22

16

19

20

23

24

25

1

26 27

P2

P1 T

U3MPa

MCVReturn line

Steering system

Return line

RCV

ABC

13

33

Coupler cylinder

2)

A 1st pumpB 2nd pumpC Brake pump

4-6

PARKING BRAKE RELEASED

When the parking brake switch is pushed, the solenoid valve(18) is energized and the hydraulic oilenters the front axle. It overcomes the force of the spring and pushes the piston. This releasesthe brake.Therefore, the hydraulic oil pressure is applied to the parking brake piston in front axle through thesolenoid valve(18) and the parking brake is kept released.

P T

A B

FRONT REAR

BR1 BR2 M2

DS1

S2DS2S1

S3

T

P

N

18

21

17

8167

22

16

19

20

23

24

25

1

26 27

P2

P1 T

U3MPa

MCVReturn line

Steering system

Return line

RCV

ABC

13

33

Coupler cylinder

3)

A 1st pumpB 2nd pumpC Brake pump

4-7

PARKING BRAKE OPERATED

When the parking brake switch is pushed once more, the solenoid valve(18) is deenergized and thevalve open the exhaust port.At the same time, the hydraulic oil return to the tank through the solenoid valve(18). When thepiston is returned by the force of the spring, the parking brake is applied.

P T

A B

FRONT REAR

BR1 BR2 M2

DS1

S2DS2S1

S3

T

P

N

18

21

17

8167

22

16

19

20

23

24

25

1

26 27

P2

P1 T

U3MPa

MCVReturn line

Steering system

Return line

RCV

ABC

13

33

Coupler cylinder

4)

A 1st pumpB 2nd pumpC Brake pump

4-8

3. BRAKE PUMPSTRUCTURE1)

19 Spacer plate20 O-ring21 Back up seal22 Seal element23 Bushing24 Bushing

25 Driven gear26 Drive gear27 Rear body28 O-ring29 Splined coupling30 Cap screw

31 Cover32 Spring washer33 Bolt35 Dowel pin36 O-ring

Brake pump used for the brake of this machine is pressure loaded type gear pump. This gear pumphave a maximum delivery pressure of 150kgf/cm2(2130psi).The pressure loaded type gear pump is designed so that the clearance between the gear and the sideplate can be automatically adjusted according to the delivery pressure. Therefore, the oil leakage fromthe side plate is less than that in the case of the fixed side plate type under a high discharge pressure.Consequently, no significant reduction of the pump delivery occurs, even when the pump is operatedunder pressure.

29

36

28

2122

23

25

27

20

19

3526

24

2422

2120

31

32

33

23

30

4-9

PRINCIPLE OF OPERATION

Mechanism for delivering oilThe drawing at right shows theoperational principle of an external gearpump in which two gears are rotating inmesh.The oil entering through the suction port istrapped in the space between two gearteeth, and is delivered to the dischargeport as the gear rotates.Except for the oil at the bottom of the gearteeth, the oil trapped between the gearteeth, is prevented from returning to thesuction side with the gears in mesh.Since the gears are constantly deliveringoil, the oil delivered to the discharge portis forced out of the port.The amount of discharge increases withthe speed of rotation of the gear.If there is no resistance in the oil passageinto which the discharged oil flows, the oilmerely flows through the passage,producing no increase in pressure.If however, the oil passage is blocked withsomething like a hydraulic cylinder, therewill be no other place for the oil to flow, sothe oil pressure will rise. But the pressurewhich rises in this way will never gohigher, once the hydraulic cylinder pistonstarts moving because of the oil pressure.As described earlier, the pump producesthe oil flow, but not the oil pressure. Wecan therefore conclude that pressure is aconsequence of load.In other words, the pressure depends ona counterpart.

Suction Discharge

(1)2)

4-10

Internal oil leakageOil leaks from a place under higherpressure to a place under lower pressure,provided that a gap or a clearance existsin between.In the gear pump, small clearances areprovided between the gear and the caseand between the gear and the side plateto allow the oil to leak out and to serve asa lubricant so that the pump will beprotected from seizure and binding.The drawing at right shows how theleaked oil flows in the pump. As such,there is always oil leakage in the pumpfrom the discharge side(Under higherpressure) to the suction side. Thedelivery of the pump is reduced by anamount equal to the pump discharge.In addition, the delivery of the pump willalso decrease as the amount of oilleakage increases because of expandedradial clearance resulting from the wear ofpump parts, the lower oil viscosityresulting from increases in the oiltemperature, and the initial use of lowviscosity oil.

Suction

Discharg

e

(2)

4-11

Forces acting on the gearThe gear, whose outer surface issubjected to oil pressure, receives forcesjointing towards its center.Due to the action of the delivery pressure,the oil pressure in higher on the deliveryside of the pump, and due to suctionpressure, is lower on the suction side. Inthe intermediate section, the pressure willgradually lower as the position movesfrom the delivery side to the suction side.This phenomenon is shown in thedrawing at right.In addition, the gears in mesh will receiveinteracting forces.These forces pushing the gears towardthe suction side are received by thebearings. Since the gears are pressedtoward the suction side by these forces,the radial clearance becomes smaller onthe suction side in the case. In somepumps, the clearance may become zero,thus allowing the gear teeth and the caseto come into light contact.For this reason, an excessive increase inthe delivery pressure must be avoided,since it will produce a large force whichwill act on the gears, placing an overloadon the bearings, and resulting in ashortened service life of the bearing orinterference of the gear with the case.

Suctionside

Dischargeside

Pressure distribution

Driven gear

Drive gear

(3)

4-12

"Trapping" phenomenon of the oilWhen a gear pump is rotating with thegears in mesh as shown in the drawing atright, in some instances two sets of gearteeth are in mesh while in other instancesonly one set of the gear teeth is in mesh.When two sets of the teeth are in meshsimultaneously, the oil in the spacebetween the meshed gear teeth will betrapped inside-the front and rear exits willbe completely shut.This is called the "trapping" phenomenonof oil.The space in which the oil is trappedmoves from the suction side to thedelivery side as the gears rotate. Thevolume of the space gradually decreasesfrom the start of trapping until the spacereaches the center section, and thengradually increases after leaving thecenter section until the end of trapping.Since the oil itself is non-shrinkable, areduction of the volume of space willgreatly increase the oil pressure, unlesssome plosion in made to relieve oilpressure. The high pressure oil willcause the pump to make noise andvibrate.To prevent this, relief notches areprovided on the side plates to release theoil to the delivery side.As shown in the drawing at right, the reliefnotches are provided in such a way thatthe oil can be relieved from the tappingspace to the delivery side when thevolume of the space is reduced.Relief notches are also provided on thesuction side to prevent the formation of avacuum in the space by allowing the oil toenter the space from the suction sidewhen the space is reduced.

Delivery side

Suction side

Trapping starts

The spacereaches theminimum

Trapping ends

Fixed side plate type

Pressure loaded type

Side plate

Relief notch

Bushing

(4)

4-13

4. BRAKE VALVESTRUCTURE

802614

82

36213765 41

18

41

1.25

32

42

86274

285

55649

1

12

29

12

87

1.22

30

1.23

3159