Doosan D20S-3, D25S-3, D30S-3, D32S-3, D25S-3(B3.3) User Manual

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Specifications Systems Operation Testing & Adjusting

Lift Trucks Power Train D20S-3, D25S-3, D30S-3, D32S-3 D20S-3(B3.3), D25S-3(B3.3), D30S-3(B3.3), D32S-3(B3.3), D33S-3(B3.3) G20S-3, G25S-3, G30S-3 GC20S-3, GC25S-3, GC30S-3 G20E-3, G25E-3, G30E-3, G32E-3 GC20E-3, GC25E-3, GC30E-3, GC32E-3 G20P-3, G25P-3, G30P-3, G32P-3 GC20P-3, GC25P-3, GC30P-3, GC32P-3

SB2102E01 Jan.2004

Important Safety Information

Most accidents involving product operation, maintenance and repair are caused by failure to observe basic safety rules or precautions. An accident can often be avoided by recognizing potentially hazardous situations before an accident occurs. A person must be alert to potential hazards. This person should also ha v e the necessary training, skills and tools to perform these functions properly.

Read and understand all safety precautions and warnings before operating or performing lubrication, maintenance and repair on this product.

Basic safety precautions are listed in the “Safety” section of the Service or Technical Manual. Additional safety precautions are listed in the “Safety” section of the owner/operation/maintenance publication. Speciﬁc safety warnings for all these pub lications are pro vided in the description of operations where hazards exist. W ARNING labels have also been put on the product to provide instructions and to identify speciﬁc hazards. If these hazard warnings are not heeded, bodily injury or death could occur to you or other persons. W arnings in this publication and on the product labels are identiﬁed by the f ollo wing symbol .

WARNING

Improper operation, lubrication, maintenance or repair of this product can be dangerous and could result in injury or death. Do not operate or perform any lubrication, maintenance or repair on this product, until you have read and understood the operation, lubrication, maintenance and repair inf ormation.

Operations that may cause product damage are identiﬁed by NOTICE labels on the product and in this publication.

DAEWOO cannot anticipate every possible circumstance that might involv e a potential hazard. The warnings in this publication and on the product are therefore not all inclusiv e. If a tool, procedure, work method or operating technique not speciﬁcally recommended by DAEWOO is used, you must satisfy yourself that it is safe for you and others. Y ou should also ensure that the product will not be damaged or made unsafe by the operation, lubrication, maintenance or repair procedures you choose.

The information, speciﬁcations, and illustration in this publication are on the basis of information available at the time it was written. The speciﬁcations, torques, pressures, measurements, adjustments, illustrations, and other items can change at any time. These changes can affect the service given to the product. Obtain the complete and most current information before starting any job. DAEWOO dealers have the most current inf ormation available.

Index

Specifications

Drive Axle Mounting Group....................................... 14

Drive Tire Installation ................................................ 12

Drive Wheel Installation ............................................ 13

Final Drives And Wheels...........................................11

Forward / Reverse Clutch Elements ........................... 6

Forward And Reverse Control Group ......................... 5

Tightening Torques .....................................................9

Torque Converter........................................................ 5

Transmission Solenoid ...............................................5

Valve Block Elements .................................................7

Valve Spring in Transmission Bearing Plate ...............8

Systems Operation

General Information .................................................. 15

Transmission and Drive Axle ....................................16

Basic Control Scheme........................................... 34

Drive Axle .............................................................. 21

Hydraulic System .................................................. 24

Torque Converter ..................................................16

Transmission......................................................... 17

Transmission Hydraulic System............................ 25

Testing And Adjusting

Troubleshooting ........................................................ 38

Check List During Operation.................................39

Check List From Operation Noises ....................... 40

Check List From Pressure Tests ........................... 41

Visual Checks .......................................................38

Transmission and Drive Axle Tests And Adjustments

.................................................................................. 44

Adjustment of Crown Wheel.................................. 58

Adjustment of Wheel Bearings.............................. 60

Adjustments on Drive Axle and Transmission ....... 55

Converter Stall Test ............................................... 46

Electric Control System Tests ............................... 50

Inching Pedal Adjustment......................................53

Installation of Pinion .............................................. 57

Maintenance Transmission and Drive Axle ........... 48

Transmission Pressure Tests ................................ 44

Power Train Index

Specifications

Torque Converter

(1) Torque for six bolts that hold torque converter drive plate to the flywheel …………………………………...45 ± 7 N·m (33 ±5 lb·ft)

Forward And Reverse Control Group

(1) Torque for screws (four) that hold clamp to hand

control switch………..3.4 to 3.9 N·m (30 to 35 lb·in)

(2) Torque for bolts (two) that hold clamp to steering

column……………….2.8 to 3.4 N·m (25 to 30 lb·in)

Apply a bead of LOCTITE NO.242 Sealant to inner radius of the clamp, prior to assembly.

Transmission Solenoid

Valve block elements located on top of transmission housing…………………………………9.7 to 10.3 ohms

For additional solenoid and valve group specifications see section “Valve block elements”

Power Train Specifications

Forward / Reverse Clutch Elements

a) Outer clutch Disc

b) Inner clutch Plate

c) Piston return spring

Length under test force……………...29 mm (1.14 in) Test force………………..970.9 ±50 N (218.4 ± 11 lb) Free length after test(nominal) ..…56.6 mm (2.23 in) Outside diameter…………………..…95 mm (3.74 in)

d) Clearance between piston and pressure disc (disc

pack pushed against snap ring, piston fully retracted in gear)………………..1.4 mm (0.0551 in)

1.4 minimum B

Snap ring

Power Train Specifications

Valve Block Elements

(On top of transmission)

Tighten to 50±7 N·m (37±5 Ib·ft)

Tighten to 0.6 N·m (0.44 Ib·ft) min

Tighten to 25±4 N·m (18.5±3 Ib·ft)

Tighten to 50±7 N·m

A) Spring

B) Spring(Inner)

C) Spring(outer)

D,E

(37±5 Ib·ft)

Tighten to 50±7 N·m (37±5 Ib·ft)

Length under test force……..…...22.5 mm (0.89 in) Test force………………,,,….42 ± 3.4 N (9.4±0.8 lb) Free length after test(nominal)...34.65 mm (1.36 in) Outside diameter…………………...13 mm (0.51 in)

Length under test force……….….26.6 mm (1.05 in) Test force……………….….37.8 ± 3.0 N (8.5±0.7 lb) Free length after test(nominal)….48.2 mm (1.90 in) Outside diameter………………….10.8 mm (0.43 in)

Length under test force…………..26.6 mm (1.05 in) Test force………………….75.6 ± 6.0N (17.0±1.3 lb) Free length after test(nominal)….52.6 mm (2.07 in) Outside diameter………………..15.24 mm (0.60 in)

SECTION A-

Tighten to 5±1 N·m (3.7±1 Ib·ft)

Tighten to 5.5±1.5 N·m

(4±1 Ib·ft)

Tighten to 50±5 N·m (37±3.7 Ib·ft)

D) Spring(outer)

Length under test force…………22.22 mm (0.87 in) Test force…………………...29 to 34 N (6.5 to 7.6 lb) Free length after test(nominal)….31.7 mm (1.25 in) Outside diameter………………...11.91 mm (0.47 in)

E) Spring(Inner)

Length under test force………..…20.0 mm (0.79 in) Test force……………...3.34 ± 0.27 N (0.75±0.06 lb) Free length after test(nominal)...55.93 mm (2.20 in) Outside diameter………………..7.75 mm (0.305 in)

Power Train Specifications

Valve Spring in Transmission Bearing Plate

A) Spring

Length under test force…………….30 mm (1.18 in)

Test force…………….......18.1 ± 1.8 N (4.07±0.4 lb)

Free length after test(nominal)...43.25 mm (1.70 in) Outside diameter…………………10.7 mm (0.42 in)

Tighten to 45 N·m (33.2 Ib·ft)

Converter Inlet Valve

2-S

rings

Tighten to 45 N·m (33.2 Ib·ft)

Converter Outlet Valve

Power Train Specifications

Tightening Torques

Bolt 20 N m (14.8 Ib ft)

Bearing Shims

Bearing Plate

Bolt 55 N m (40.6 Ib ft)

Pump Housing

Bolt 32 N m (23.6 Ib ft)

Flexplate Bolt 55 N m

(40.6 Ib ft)

Bearing Shims

See Instructions

Bolt 40 N m (29.5 Ib ft)

Bearing Shims

See Instructions

Housing Bolt 55 N m (4.6 Ib ft)

Plug 50 N m (36.9 Ib ft)

(40.6 Ib ft)

Housing Bolt 55 N m

U-joint Bolt 70 N m (51.7 Ib ft)

Axle Lube Pump Bolt 12 N m (8.9 Ib ft)

PTO Pump Bolt 30 N m (22.1 Ib ft)

Power Train Specifications

Tightening Torques

Bolt 115 N m (84.9 Ib ft)

Apply Loctite 242 to thread

Bolt 28 N m (20.7 Ib ft)

Apply Loctite 242 to thread

Nut 150 N m (110.7 Ib ft)

Apply Loctite 242 to thread and face

Spacer and Shims

(See Instructions)

Shims

(See Instructions)

Bolt 115 N m (84.9 Ib ft)

Apply Loctite 242 to thread

Bolt 80 8 N m (59.0 5.9 Ib ft)

(Slightly Oiled)

Adjust to

19.6 N m (14.5 Ib ft) drag

(See Instructions)

Grease Bearing

With Molycote BR2

Bolt 285 N m (210.3 Ib ft)

Apply Loctite 242 to thread

Nut 50 N m (36.9 Ib ft)

(See Instructions)

Power Train Specifications

Final Drives And Wheels

GC Model Trucks

1 2

Oil Cooled Disc Brake Type

(1) Apply LOCTITE NO.242 Thread Lock to threads of

spindle bolts. Torque for bolts that hold spindle to drive axle housing……………..115 ± 14 N∙m (85 ± 10 lb∙ft)

(2) Torque for wheel mounting bolts…270 ± 25 N∙m

………………………………………(200 ± 20 lb∙ft)

(3) Wheel bearing adjustment :

(a) Tighten wheel bearing nut to 135 N∙m (100lb∙ft)

while the wheel is turned in both directions.

(b) Loosen the nut completely. Tighten the nut

again to 50 ± 5 N∙m (37 ± 4 lb∙ft).

the wheel bearing nut.

(4) Torque for bolts that hold cover to axle housing

……………………………55 ± 10 N∙m (40 ± 7 lb∙ft)

(5) Apply Loctite No.515 Sealant to the axle flange and

cover on the contact area.

D,G Model Trucks Dual Drive wheels shown

Oil Cooled Disc Brake Type

(1) Apply LOCTITE NO.242 Thread Lock to threads of

spindle bolts. Torque for bolts that hold spindle to drive axle housing………………..115 ± 14 N∙m (85 ± 10 lb∙ft)

(2) Use a crisscross procedure to tighten nuts.

(a) Torque for single drive wheel mounting.

nuts………...........644 ± 34 N∙m (470 ± 25 lb∙ft)

(b) Torque for inner and outer dual drive wheel

mounting nuts…………………….644 ± 34 N∙m

(470 ± 25 lb∙ft)

(3) Torque for bolts that hold adapter assembly to

hub………………...285 ± 13 N∙m (210 ± 10 lb∙ft)

(4) Wheel bearing adjustment :

(a) Tighten wheel bearing nut to 135 N∙m(100 lb∙ft)

while the wheel is turned in both directions

(b) Loosen the nut completely. Tighten the nut

again to 50 ± 5 N∙m (37 ± 4 lb∙ft).

the wheel bearing nut.

(5) Torque for bolts that hold cover to axle housing

………………..…………..55 ± 10 N∙m (40 ± 7 lb∙ft).

(6) Apply Loctite No.515 Sealant to the axle flange or

spacer and cover on the contact area.

Power Train Specifications

Drive Tire Installation

GC20, GC25 Models

GC30, GC32 Models-Narrow Axle

GC30, GC32 Models-Wide Axle

The drive tire must be installed as shown below. Failure to do so will decrease the stability of the truck, and can cause injury to the operator.

WARNING

GC20, GC25 Models

Install the tire so that the edge of the tire is even with the outside edge of the wheel.

GC30, GC32 Models

Narrow Axle :

Install the tire so there is distance (X) between the edge of the tire and the inside edge of the wheel.

Distance(X) is……………38.2 ± 0.8 mm (1.50 ± .03 in)

Wide Axle :

Install the tire so there is distance (Y) between the edge of the tire and the outside edge of the wheel.

Distance(Y) is....................25.0 ± 0.8 mm (.98 ± .03 in)

Power Train Specifications

Drive Wheel Installation

GC Model Trucks

(1) Tighten wheel mounting bolts to a torque of

……………………….270 ± 25 N∙m (200 ± 20 lb∙ft)

D,G Model Trucks

(1) Tighten wheel mounting bolts to a torque of

……………………….644 ± 34 N∙m (470 ± 25 lb∙ft) Use a crisscross procedure to tighten nuts.

Power Train Specifications

Drive Axle Mounting Group

Special shoulder Bolt

Chassis

Standard Bolt

Drive

Axle

Housing

(1) Torque for two nuts that hold the axle to the

chassis……………..…488 ± 27 N∙m (360 ± 20 lb∙ft)

(2) Torque for two nuts that hold the axle to the

chassis………...…..….488 ± 27 N∙m (360 ± 20 lb∙ft)

Power Train Specifications

Systems Operation

General Information

Power Flow (1) Drive axle. (2) U-joint. (3) Transmission. (4) Engine.

The basic components of the power train are engine (4), Transmission (3), U-Joint(2), Drive axle(1) and the final drives and wheels.

Two axle shafts connect the differential to two final drives. The drive wheels are mounted to the final drives.

Power from the engine goes through the flywheel into the torque converter. Power then flows through a transmission (3) and U-joint(2) to yoke of drive axle(1). The transmission has two hydraulically operated clutch packs that are spring released. The transmission has one speed in forward and one speed in reverse.

Power from yoke of drive axle is sent through a spiral bevel gear set to the differential. The differential sends power out through the axles to the final drives and wheels.

Power Train Systems Operation

Transmission and Drive Axle

Torque Converter

Torque converter (1) Turbine. (2) Stator. (3) Impeller. (4) Housing. (5) Stator support. (6) Stator clutch.

There is no direct mechanical connection between engine and the transmission. Power from the engine is transferred through the torque converter, which hydraulically connects the engine to the transmission. Transmission drive train oil is used to turn the turbine and transmission input shaft.

When the lift truck works against a load, the torque converter can multiply the torque from the engine and send a higher torque to the transmission.

The torque converter has four main parts : housing (4), impeller(pump) (3), turbine(1) and stator(2). The housing is connected to the engine flywheel through a flexplate. Impeller (3) and housing (4) are welded together and turn with the engine flywheel at engine speed and in the direction of engine rotation. Turbine (1) turns the transmission input shaft. Stator (2) is installed stationary on stator support (5) by a freewheel clutch that allows one way rotation of the stator.

The hub, which is part of impeller (3), fits into the transission oil pump. The turning impeller (3) rotates the pump to supply oil for the operation of the torque converter and transmission

When the engine is turning, oil flows through the converter to lubricate and cool it. With the transmission in neutral, the impeller, turbine, stator and oil are all turning together in a direct fluid coupling. The turbine/impeller speed ratio is 1/1.

Once a direction is selected the direct fluid coupling no longer exists, the turbine/impeller speed ratio changes (the turbine will be turning slower than the impeller). When this happens the impeller outlet pressure to turbine inlet pressure changes. This causes the oil flow in the torus (fluid path containing the impeller, turbine and stator) to gain momentum.

As impeller (3) turns, it increases the energy state of the oil and directs the oil to the outside diameter of converter housing (4). Oil leaving impeller (3) is directed to turbine (1) where much of the oil? energy is absorbed by turning the turbine. The pressure and flow change in the torus becomes torque and speed at the turbine and transmission input shaft.

Oil follows the turbine blades inward toward the center of the converter. When the turbine/impeller speed ratio is less than .85/1, oil is directed against the concave side of stator (2) with enough force to stop its one way rotation and lock the freewheel clutch.

Most of the energy from the oil that strikes the turbine is used to turn the turbine, but some energy is left over. Torque multiplication comes about because the locked stator (2) directs this left over oil back to impeller (3) in the same direction as the impeller rotation. This energy force of the oil increases the torque on the turbine and transmission input shaft. During operation, this cycle is repeated over and over.

Without the stator, oil leaving the turbine is travelling in a direction that is against impeller rotation. Torque multiplication is only possible because of the stator.

Power Train Systems Operation

Transmission

which is in mesh and drives the output gear, when the forward clutch (8) is closed.

The reverse shaft (9) carries the reverse shaft gear (9A), the reverse clutch (10) and the reverse gear (11) which is in mesh and drives the output gear (12) when the reverse clutch (10) is selected. The quill shaft (14) is splined to the torque converter and therefore rotates with engine speed and direction. A coupling (14A) connects the PTO pump (15) to the quill shaft (14). The axle lubrication (16) pump engages in and is driven by the reverse shaft. It always operates when the engine rotates, but rotating speed varies with torgue converter output.

14A

(1) TC Housing. (2) TM Bearing Plate. (3) TM Housing. (4) Torque Converter. (5) Input Shaft. (5A)Input Shaft Gear. (6) Oil Pump. (7) Forward Gear. (8) Forward Clutch. (9) Reverse Shaft. (9A) Reverse Shaft Gear. (10) Reverse Clutch. (11) Reverse gear. (12) Output gear. (13) U-joint. (14) Quill Shaft. (14A) Coupling. (15) PTO Pump. (16) Axle Lubrication Pump.

The Transmission consists of 3 sections:

a) TC housing (1) which contains torque converter (4)

and the oil pump (6) and its housing. Tangs on the TC neck engage in and drive the pump.

b) Bearing plate (2) which contains the rear bearings

of input, reverse shaft and output gear and the oil supply channels. The oil channels are sealed by the front TC housing wall.

c) Transmission housing (3) containing input shaft (5),

forward clutch (8), forward gear (7), reverse shaft (9), reverse clutch (10), reverse gear (11), output gear (12) and parking brake. The input shaft engages in and is driven by the TC turbine hub spline and rotates in same direction as the engine. It carries an input shaft gear (5A) which is in mesh and drives the reverse shaft gear (9A), the forward clutch (8) and the forward gear (7),

Power Train Systems Operation

Transmission Power Flow Forward :

With the transmission control in forward, which will pressurize the forward clutch (8), power will flow from the engine through the torque converter to drive the oil pump (6) and the input shaft (5), also the quill shaft (14). Since the forward clutch (8) locks the forward gear (7) to the input shaft, the power flows through the forward clutch (8), the forward gear (7) to output gear (12) which is in mesh with the forward gear. The u-joint (13) which is splined to the output gear will transmit power to the axle.

Power Train Systems Operation

Transmission Power Flow Reverse :

With the transmission controls in reverse, which will pressurize the reverse clutch (10), power will flow from the engine through the torque converter to drive the oil pump (6) and the input shaft (5) also the quill shaft (14). Since the reverse clutch (10) is closed, power will flow through input shaft gear (5A) which is in mesh and drives reverse shaft gear (9A) and reverse shaft (9). The reverse gear (11) which is locked to the reverse shaft by the reverse clutch (10) is in mesh and drives the output gear (12). The U-joint, which is splined to the output gear will transmit power to the axle.

Power Train Systems Operation

Transmission Lubrication Schematic :

Oil for lubrication of the clutch shaft bearings and cooling the clutch discs and plates comes from the outlet passage of oil cooler. Lubrication oil is also splashed inside the transmission case. Lubrication oil is especially important for cooling the clutches.

High temperatures can be caused during repeated shifting of the lift truck.

Oil Cooler

TC Relieve Valve

Power Train Systems Operation

Drive Axle

(1) Axle Housing. (2) Carrier (3) Brake Housing Left/Right. (4) Pinion. (5) Crown wheel/differential. (6) Drive Shaft Left/right. (7) Ring Gear/Hub. left/right. (8) Pneumatic Tire Wheel Flange Left/right. (9) Multi-disc brake left/right. (10) Spindle. (11) Axle Mounting Pads. (12) Mast Mounting Hooks.

The Axle Consists of 4 main sections

a) The carrier housing (2), pinion (4) and crownwheel

with differential assembly (5).

b) The axle housing with left and right drive shaft (6),

mounting pads (11) and mast mounting hooks (12).

5,5A,5B,5C

c,d) Hub section left and right with ring gear (7), wheel

flange (8), spindle (10) and multi-disc brake (9).

Wheel flange (8) used with pneumatic tire trucks only.

Power Train Systems Operation

Axle power flow

Power is transmitted by the transmission output shaft to the pinion (4) which meshes with and drives the crownwheel (5), which is mounted to the differential.

The differential is part of the drive axle. It is a single reduction unit with a differential drive gear fastened on the differential case.

The differential is used to send the power from the transmission to the wheels. When one wheel turns slower than the other, the differential lets the inside wheel stop or turn slower in relation to the outside wheel.

Differential case (5A) has four differential pinion gears (5B) on the differential pinion shaft. The pinion gears are engaged with two side gears (5C). The side gears are splined to the axle shafts.

When the lift truck moves in a forward direction and there is the same traction under each wheel, torgue in each axle and pinion gears (5B) are balanced. Both left and right axles roatate the same. During a turn, the force(traction) that is on the drive wheels is different. These different forces are also felt on opposite sides of the differential and cause pinion gears (5) to turn. The rotation of pinion gears (5) stops or slows the inside wheel and lets the outside wheel go faster. This moves the machine through a turn under full power. The differential gets lubrication from oil thrown about inside the housing.

Power Train Systems Operation

Axle Lubrication Schematic

The axle is lubricated by means of the transmissionmounted lubricant pump (2) which gets oil from the axle suction port (1) and supplies it to the hub section pressure parts (3) to lubricate and cool hub drive and multi-disc brakes. Oil returns to the sump through the drive shaft bearings and axle housing.

3 1

PUMP

Power Train Systems Operation

Hydraulic System

(1) Transmission Oil Sump. (2) Oil Pump. (3) Primary Filter. (4) Main Valve. (5) Orifice. (6) Inching Valve. (7) Modulating Valve. (7A) Load Piston. (7B) Modulating Valve Orifice. (8) Selector Valve. (9) Solenoid Valve Forward. (10) Solenoid Valve Reverse. (11) Forward Clutch. (12) Reverse Clutch. (13) Relief Valve. (14) Torque Converter. (15) Relief Valve. (16) Converter Bypass. (17) Oil Cooler. (18) Torque Converter Supply Bypass.

Power Train Systems Operation

The basic components of the hydraulic system for operating the transmission are transmission oil sump (1), oil pump (2), primary oil filter (3), valve block, containing main valve (4), orifice (5), inching valve (6), modulating valve (7), selection valve (8), forward and reverse solenoid valves (9,10), forward clutch (11), reverse clutch (12), torque converter (14) with relief valves (13,15), bypass (16) and oil cooler (17).

The pump is located in the torque converter housing, and valve block is located on top of transmission, the filter is located on the right hand of the transmission housing.

Transmission Hydraulic System

The transmission hydraulic system is explained in three sections. The first section is the oil pump, filter, torque converter and oil cooler systems. The second section is the transmission lubrication system. The third section is the transmission hydraulic control system which controls the lift truck direction control.

Pump, Filter, Torque Converter And Oil Cooler Systems

The oil for the operation and lubrication of the transmission is made available by pump (2). The pump is located in the torque converter housing and is driven by Tangs on the torque converter neck.

Oil sump (1), for the transmission, is in the bottom of the transmission case. Oil from reservoir flows through the strainer and internal channels to the suction side of positive displacement pump .

Oil from pump (2) flows to primary oil filter (3). If there is a restriction in the oil filter or if the oil is cold and thick, a bypass valve in the filter will open. The difference in pressure at which the bypass valve will open is 124 ± 7 kPa (18 ± 1 psi). From the primary oil filter, the oil flows on to main relief valve (4). In the spool of main relief valve there is a bypass (18). The purpose of this bypass is to supply lubrication and coolant oil to the torque converter at low speeds and especially during hot oil conditions. Converter relief valve (13) protects the torque converter from oil pressure higher than 670 kPa (97 psi), such as during cold oil start-ups. At this pressure, the oil is released back to the reservoir. Converter inlet passage has converter bypass orifice (16). The purpose of this orifice is to prevent too much of a pressure load on the torque converter by allowing some of the oil to bypass the converter. In converter outlet passage, there is cooler bypass valve (15). Cooler bypass valve (15) will release oil back to the reservoir if the oil pressure reaches 400 kPa (58 psi). This can happen if the oil cooler has a restriction or if the oil is cold and thick.

Power Train Systems Operation

Neutral Position

Transmission Hydraulic System-Neutral

(1) Transmission Oil Sump.

(2) Oil Pump.

(3) Primary Filter.

(4) Main Valve.

(5) Orifice.

(6) Inching Valve.

(7) Modulating Valve.

(7A) Load Piston.

(7B) Modulating Valve Orifice.

(8) Selector Valve.

(9) Solenoid Valve Forward.

(10) Solenoid Valve Reverse.

(11) Forward Clutch.

(12) Reverse Clutch.

(13) Relief Valve.

(14) Torque Converter.

(15) Relief Valve.

(16) Converter Bypass.

(17) Oil Cooler.

(18) Torque Converter Supply Bypass.

When the transmission is in NEUTRAL position with the engine running, oil is pulled from reservoir and the strainer assembly (1) to pump (2). From there, pump oil flows through the primary filter (3) to main relief valve (4). Oil will also flow through orifice (18) to lubricate the torque converter during hot, low speed conditions.

When the pump pressure reaches 895 kPa (130 psi), relief valve spool (4A) will move to the left side and most of the pressure oil flows to the torque converter.

Spool will move left and right to maintain 895 kPa (130 psi). Oil can also bypass the torque converter through converter bypass orifice (16). The purpose of orifice (16) is to prevent too much of a pressure load being put on the torque converter.

Oil flows from the torque converter through a passage to oil cooler (17). Oil then flows back to transmission to cool and lubricate the clutches and shaft bearings.

In NEUTRAL position, the remaining pressure oil flows from main relief valve (4) to inching valve (6). Without inching (inching pedal up and valve in), oil flows around and through the center of spool (6A) to the bottom of the spool. The oil, at the bottom, pushes the spool to the position shown. Oil flows around the lands of the spool and through a passage to modulating valve (7).

In NEUTRAL position, forward solenoid (9) and reverse solenoid (10) are OFF. Pump oil flow is blocked at the solenoids. Oil cannot flow through oil passage to the forward or reverse selector spool. Pump oil pressure is felt at slugs. This forces forward selector spool to the right and reverse selector spool to the left. With the spools in this position, forward clutch (11) and reverse clutch (12) are open to drain. Most of the oil still flows through the lube circuit.

Power Train Systems Operation

Forward Direction

Transmission Hydraulic System-Forward

(1) Transmission Oil Sump.

(2) Oil Pump.

(3) Primary Filter.

(4) Main Valve.

(5) Orifice.

(6) Inching Valve.

(7) Modulating Valve.

(7A) Load Piston.

(7B) Modulating Valve Orifice.

(8) Selector Valve.

(9) Solenoid Valve Forward.

(10) Solenoid Valve Reverse.

(11) Forward Clutch.

(12) Reverse Clutch.

(13) Relief Valve.

(14) Torque Converter.

(15) Relief Valve.

(16) Converter Bypass.

(17) Oil Cooler.

(18) Torque Converter Supply Bypass.

When the transmission is in FORWARD, the oil flow from the reservoir, through the pump, primary filter, torque converter and oil cooler circuits will be the same as explained in NEUTRAL position.

Oil will flow from the main relief valve to inching valve (6). Without inching (inching pedal up and valve in), oil flows around and through the center of reducing spool (6A) to the bottom of the spool. The oil, at the bottom, pushes the spool up to the position shown. Oil flows around the lands of the spool and through a passage to modulating valve group (7).

In FORWARD, forward solenoid (9) is ON, so pump oil is sent to the forward selector spool through oil passage. Forward selector spool (8A) moves to the right, causing reverse selector spool (8B) to move to the right also.

With the reverse spool in this position, reverse clutch (12) is open to drain, Forward selector spool (8A) opens forward clutch (11) to pump oil. This also opens reverse selector spool (8B) to drain through oil passage. Forward clutch (11) will fill with pump oil. Once filled, oil pressure begins to build up. Pump oil goes through orifice (7B) and moves load piston (7A) to the left as pump pressure increases. Oil pressure increases as the load piston moves further to the left. The pressure increases to the control pressure of 895 kPa (130 psi). Forward clutch (11) will now be fully engaged. Modulating valve assembly (7) will now shuttle between pump oil and drain to maintain clutch pressure. Clutch fill time takes 0.4 seconds and pressure increase takes 0.7 seconds. This approximate 1.1 second clutch fill and pressure rise time, gives a cushion engagement of forward clutch (11).

Power Train Systems Operation

Reverse Direction

Transmission Hydraulic System-Reverse

(1) Transmission Oil Sump.

(2) Oil Pump.

(3) Primary Filter.

(4) Main Valve.

(5) Orifice.

(6) Inching Valve.

(7) Modulating Valve.

(7A) Load Piston.

(7B) Modulating Valve Orifice.

(8) Selector Valve.

(9) Solenoid Valve Forward.

(10) Solenoid Valve Reverse.

(11) Forward Clutch.

(12) Reverse Clutch.

(13) Relief Valve.

(14) Torque Converter.

(15) Relief Valve.

(16) Converter Bypass.

(17) Oil Cooler.

(18) Torque Converter Supply Bypass.

When the transmission is in REVERSE, the oil flow from the reservoir, through the pump, primary filter, torque converter and oil cooler circuits will be the same as explained in NEUTRAL position.

In REVERSE, reverse solenoid (10) is ON, so the pump oil is sent to the reverse selector spool through an oil passage. Reverse selector spool (8B) moves to the left, causing forward selector spool (8A) to move to the left also.

With the forward selector spool in this position, forward clutch (11) is open to drain. Reverse selector spool (8B) opens reverse clutch (12) to pump oil. This also opens forward selector spool (8A) to drain through passages. Reverse clutch (12) will fill with pump oil. Once filled, oil pressure begins to build up. Pump oil goes through orifice (7A) and moves load piston (7A) to the left as pump pressure increases. Oil pressure increases as the load piston moves further to the left. The pressure increases to the control pressure of 895 kPa (130 psi). Reverse clutch (12) will now be fully engaged. Modulating valve assembly (7) will now shuttle between pump oil and drain to maintain clutch pressure. Clutch fill time takes 0.4 seconds and pressure increase takes 0.7 seconds. This approximate 1.1 second clutch fill and pressure rise time, gives a cushion engagement of reverse clutch (12).

Power Train Systems Operation

Forward Direction During Inching

Transmission Hydraulic System-Forward Inching

(1) Transmission Oil Sump.

(2) Oil Pump.

(3) Primary Filter.

(4) Main Valve.

(5) Orifice.

(6) Inching Valve.

(7) Modulating Valve.

(7A) Load Piston.

(7B) Modulating Valve Orifice.

(8) Selector Valve.

(9) Solenoid Valve Forward.

(10) Solenoid Valve Reverse.

(11) Forward Clutch.

(12) Reverse Clutch.

(13) Relief Valve.

(14) Torque Converter.

(15) Relief Valve.

(16) Converter Bypass.

(17) Oil Cooler.

(18) Torque Converter Supply Bypass.

When the transmission is in FORWARD (or REVERSE) during INCHING, the oil flow from the reservoir, through the pump, filter, torque converter and oil cooler circuits will be the same as explained in NEUTRAL position.

Oil will flow from the main relief valve through a passage, to inching valve (6). Inching valve (6) lets the operator control the oil pressure to forward clutch (11) between 280 and 0 kPa (40 and 0 psi), which permits a partial engagement of the clutch. Through the use of the inching valve, the lift truck can move slowly while the engine is at higher speeds. This lets the operator move the lift truck slowly up to a load while the mast is raised rapidly.

When the operator pushes the inching pedal part of the way down, inching plunger (6B) moves out of the inching valve. This takes away some of the spring force between plunger (6B) and reducing spool (6A). It also removes the balance condition between the pump pressure, at the bottom of spool (6A), and the spring force. Reducing spool (6A) moves to the right, which causes a restriction for the pump oil flow. The pressure drops from 895 kPa (130 psi) to 280 kPa (40 psi). The pressure can drop further depending on the position of plunger (6A). Pressure reduces as plunger (6A) is moved out (as the inching pedal is pushed down).

This reduced pressure flows to selector valve group (8). The oil will flow through the valve as explained in forward direction. The reduced (inching) pressure will flow through a passage to partially engage forward clutch (11). This reduced pressure permits slippage of the forward clutch plates and discs. Therefore, the truck will have an operator controlled movement. The amount of oil pressure to clutch (11) depends on the position of inching plunger (6A). As the plunger is pulled out completely (inching pedal all the way down) clutch pressure will drop to 0 kPa (0 psi). The forward clutch will be disengaged at approximately 65.5 kPa (9.5 psi).

Power Train Systems Operation

Basic Control Schematic

The control schematic is shown below. The system consists of 2 valve bores:

1. Modulating valve

2. Forward and reverse selector valves

DR DR

SOLENOID

FWD CLUTCH

RE CLUTCH

SOLENOID

PUMP

Power Train Systems Operation

Modulating valve function

The modulating valve consists of 5 basic elements:

1. Orifice

2. Springs

3. Load piston

4. Modulating valve

5. Reaction slug The function of the modulating valve is to control clutch pressure during a shift. It allows the clutch pressure to raise gently to the maximum transmission pressure in order to provide a smooth clutch engagement and a good shift feel for the vehicle operator. There are two forces acting on the modulation valve:

Force 1 = Pressure (load piston) / Area 1 Force 2 = Pressure (clutch) / Area 2

In order for the modulating valve to stay in a balance position Force 1 must be equal to Force 2. If for example Force 2 is too large (clutch pressure is too large) then the valve will be forced to the left, shutting off supply and opening the clutch and slug

SPRING

DR DR

FLOW TO SELECTOR SPOOLS

LOAD PISTON

ORIFICE REACTION SLUG

Figure 1

PUMP

pressure to drain, and reducing Force 2. If Force 1 is too large then the valve would be forced to the right, opening the clutch circuit to supply, and increasing the value of Force 2 so it balances Force 1. By regulating clutch pressures between supply and drain, valve forces are balanced.

MODULATING VALVE

Power Train Systems Operation

Modulating valve movement during clutch fill

When a new direction is selected by the operator, the selector spools open up a circuit to the new clutch piston. System pressure drops as the new clutch piston is stroking. This drop in supply pressure causes a force imbalance on the modulating valve / reaction slug pressure becomes smaller. Since Force 1 is still the same, Force 1 forces the modulating valve to the right until the end of the modulating valve opens the load piston cavity to drain.

The load piston oil dumps to drain and the load piston immediately moves to the right (shown in fig.2). This action is called "load piston reset". It happens very quickly in comparison to the time needed for the clutch piston to fully stroke. Therefore the modulating valve and load piston are ready to start controlling the clutch pressure in a smooth upward manner once the clutch piston finishes stroking.

Figure 2

Modulation of clutch to top pressure

As long as reaction slug pressure is greater than load piston pressure, oil will flow across the orifice from Area 2 to Area 1. As oil flows to the load piston the springs will continue to compress, allowing the load piston to move to the left. As the load piston moves to the left the spring force increases and load piston pressure increases.

As press (LP) increases the modulating valve will cause a corresponding increase in clutch pressure in order to keep the forces balanced. In simple terms as the load piston strokes to the left the clutch pressure rises to maximum system pressure.

This controlled rise in clutch pressure takes about 0.7 sec. and is shown in fig.4. It occurs immediately after the clutch piston completely strokes (end of clutch fill).

Figure 3

MODULATION

Figure 4

Power Train Systems Operation

Selector spools

The selector spool circuits are arranged in such a way that once a gear (forward or reverse) is selected the opposite solenoid supply is shut off and drained. This is done to prevent any electrical or malfunction of the other solenoid from giving a sudden and unexpected shift. In addition the two selector spools are arranged so they cannot select both forward and reverse at the same time because they mechanically interfere with each other.

The selector spools have two areas:

1. Slug area

2. Spool area

The slug cavity is exposed to system pressure all the time. If the solenoid allows system oil to flow to the end of the spool and pressurize the spool area then the spool will move toward the slug because the spool area is larger than the slug area and the force will be higher. When the solenoid is closed, pressure to the spool is reduced. This allows the pressure at the slug to move the spool away from the slug.

In fig.5 the selector spools are shown with forward gear selected. Notice that the reverse solenoid supply is drained through the forward spool

Figure 5

Power Train Systems Operation

Testing And Adjusting

Troubleshooting

Troubleshooting can be difficult. A list of possible problems and corrections is on the pages that follow.

This list of problems and probable causes will only give an indication of where a problem can be and what repairs are needed. Normally, more or other repair work is needed beyond the recommendations on the list. Remember that a problem is not necessarily caused only by one part, but by the relation of one part with other parts. This list cannot give all possible problems and probable causes. The serviceman must find the problem and its source, then make the necessary repairs.

Always make visual checks first. Check the operation of the machine and then check with instruments.

WARNING

To prevent personal injury, when testing and adjusting the power train, move the machine to an area clear of obstructions. There must be adequate ventilation for the exhaust. When drive wheels are off the ground for testing, keep away from wheels that are in rotation.

Operate the machine in each direction. Make note of all noises that are not normal and find their source. If the operation is not correct, make reference to the troubleshooting chart for "problems" and "probable causes".

Visual Checks

1. Check the oil level in the transmission and axle with

the engine running and with the Transmission in NEUTRAL.

2. Check all oil lines, hoses and connections for leaks and damage. Look for oil on the ground under the machine.

3. Actuate the controls for the forward direction and then for the reverse direction. The actuation must give the same positive action to the hydraulic control circuit for clutch engagement in both directions.

4. Remove and check the filter element for loose particles. Check the strainer behind the transmission oil plug for foreign material.

a. Particles of friction material give an indication of

a clutch failure.

b. Metallic (metal) particles in the filter give an

indication of wear or mechanical failure in the transmission and/or axle.

c. Rubber particles give an indication of seal or

hose failure.

If metal or rubber particles are found, all components of the transmission hydraulic system must be flushed. Make a replacement of all parts that show damage.

NOTICE

Before these checks are started, fill the transmission and axle with oil to the correct level. See the Operation & Maintenance Manual for the procedure to check transmission and axle oil level.

Activate the controls for the FORWARD direction and then for the REVERSE direction. The modulation will be seen on pressure gauge in the clutch pressure tap when the shift is made at low idle. The pressure will increase to 895 kPa (130 psi) when completely filled.

Operate the machine in each direction. Make note of noises that are not normal and find their source. If the operation is not correct, make reference to the check List During Operation for "problems" and "probable causes".

Power Train Testing and Adjusting

Check List During Operation

Problem: Engine starts with directional control switch in FORWARD or REVERSE.

Probable cause:

1. Directional control switch is defective

Problem: Transmission shifts with parking brake engaged.

Probable cause:

1. Parking brake switch is defective.

Problem: Transmission will not stay in gear when shifted.

Probable cause:

1. Parking brake switch mounting is loose.

Problem: Transmission does not operate in either direction or does not shift.

Probable cause:

1. Problems in the electrical circuit (directional con-

trol)

a. Open circuit between ignition switch and direc-

tional control switch.

b. Defective directional control switch.

c. Defective wiring harness between directional

control switch and transmission.

d. Shorted wiring harness for the solenoids.

2. Low oil pressure or no oil pressure caused by:

a. Iow oil, no oil or thick oil.

b. Inching control valve linkage loose, broken or

adjustment is not correct.

c. Inching valve reducing spool stuck open.

d. Failure of the oil pump or a defect in the oil

pump.

e. Main relief valve stuck open.

f. Restriction in the oil flow circuit such as dirty oil

screen.

g. Leakage inside the transmission.

Worn or broken metal seal rings on input or reverse shaft. Worn or broken seals around clutch piston. Modulating valve assemblies stuck Because of contaminated oil

3. External oil lines are not connected correctly.

4. Mechanical failure in the transmission.

Problem:Transmission operates only in FORWARD.

Probable cause:

1. Forward clutch is locked up.

2. Reverse solenoid valve does not actuate.

3. Reverse clutch components have damage.

a. Leakage caused by worn or broken metal sea-

ling rings.

b. Leakage caused by worn or broken clutch piston.

c. Failure of shaft seal ring.

Problem: Transmission operates only in REVERSE.

Probable cause:

1. Reverse clutch is locked up.

2. Forward solenoid valve does not actuate.

3. Forward clutch components have damage.

a. Leakage caused by worn or broken metal

sealing rings

b. Leakage caused by worn or broken seal around

clutch piston.

c. Failure of shaft seal ring.

Problem: Transmission gets hot.

Probable cause:

1. Restriction in cooling circuit.

2. Oil level too high or too low.

3. Core of the oil cooler not completely open.

4. Low pump pressure - worn or damaged pump.

5. Converter one-way clutch worn and slipping.

6. Air mixed in the oil. Air leaks on the intake side of

the pump.

Power Train Testing and Adjusting

7. Low oil flow through converter. Converter relief

valve stuck open (converter bypass orifice plugged)

8. Incorrect use of vehicle. Loads are too heavy for the lift truck.

9. Too much inching operation (slipping the clutch plates and discs).

10. Too much stalling of torque converter.

11. Cooler relief valve stuck open, full oil flow does

not go through oil cooler.

Problem: Clutch engagement is slow or loss of power during engagement.

Probable cause:

1. Low oil pressure

2. Air mixed in the oil.

a. Air leaks on suction side of pump.

b. Low oil level also causes aeration.

3. Inching valve linkage adjustment is not correct.

4. Modulating valve assembly leaks or partially stuck.

Problem: Clutch engagement makes a rough shift.

Probable cause:

1. Modulating valve assembly, load piston and/or

reducing valve stuck.

Problem: Vehicle operates in one direction and creeps in that direction in NEUTRAL. Engine stalls when shifted to the other direction.

Probable cause:

1. Failure of clutch in the direction the lift truck moves.

Clutch discs or plates are warped (damaged) or held together because of too much heat.

2. Failure of the modulating valve assembly in the direction the lift truck moves. The valve assembly stuck in the engaged position possibly caused by metal burrs (particles) or oil contamination.

Check List From Operation Noises

Problem: Noise in NEUTRAL only.

Probable cause:

1. Worn one-way clutch in torque converter.

2. Low oil level (pump cavitation).

3. Worn bearing next to pump.

Problem: Pump noise not normal

Probable cause:

1. A loud sound at short time periods gives an

indication that foreign material is in the transmission hydraulic system.

2. A constant loud noise is an indication of pump failure.

Problem: Noise in the Transmission that is not normal.

Probable cause:

1. Transmission components have wear or damage.

a. Damaged gears.

b. Worn teeth or clutch plates and/or clutch discs.

c. Slipping clutch plates and disc noise.

d. Other component parts have wear or damage.

e. Failure of the thrust washers.

2. Modulating valve assembly makes noise.

Problem: Constant noise in the Drive axle.

Probable cause:

1. Lubricant not to the specific level.

2. Wrong type of lubricant.

3. Wheel bearings out of adjustment or have a defect.

4. Bevel gears not in adjustment for correct tooth

contact.

5. Teeth of bevel gear have damage or wear.

Power Train Testing and Adjusting

6. Too much or too little gear backlash.

7. Loose or worn pinion bearings.

8. Loose or worn shaft bearings.

9. Loose or worn differential bearings.

Problem: Noise at different intervals.

Probable cause:

1. Bolts on drive gear not tightened correctly.

2. Drive gear has a defect (warped).

3. Loose or broken differential bearings.

4. Bevel gear bearing failure.

Problem: Noise on turns only Probable cause:

1. Differential pinion gears too tight on the spider or

the pinion shaft.

2. Side gears tight in differential case.

3. Differential pinion or side gears have a defect.

4. Thrust washers worn or have damage.

5. Too much clearance (backlash) between side gears

and pinion.

6. Worn axle shaft assembly gear.

7. Hub gear worn.

8. Wheel bearings worn or out of adjustment.

Problem: Leakage of lubricant.

Probable cause:

1. Loss through hub seals.

a. Lubricant above specification level.

b. Wrong kind of lubricant.

c. Restriction of axle housing breather.

d. Hub oil seal installed wrong or has damage.

Power Train Testing and Adjusting

2. Loss at bevel input pinion shaft.

a. Lubricant above specification level.

b. Wrong kind of lubricant.

c. Restriction of axle housing breather.

d. Pinion oil seal worn or not installed correctly.

Problem: Drive wheels do not turn.

Probable cause:

1. Broken axle shaft.

a. Loose wheel bearings.

b. Axle shaft too short.

2. Side gear or differential pinion broken.

3. Differential pinion shaft or spider broken.

Check List From Pressure Tests

Problem: Low pressure to FORWARD and REVERSE clutches.

Probable cause:

1. Inching valve linkage adjustment is not correct.

2. Inching valve reducing spool stuck open.

3. Clutch piston seals cause leakages.

4. Main relief valve setting too low caused by a

defective relief valve spring.

5. Low oil pressure. See Probable Cause for Low Oil Pressure.

6. External oil lines are not connected correctly.

7. Modulating valve assembly stuck.

Problem: Clutch pressure and pump pressure are high.

Probable cause:

1. Main relief valve is stuck.

2. A restriction in the hydraulic circuit.

3. Main relief valve not adjusted properly.

Problem: Pressure to one clutch is low.

Probable cause:

1. Clutch piston seal alignment is not correct, oil leaks

through.

2. Seal rings on shaft or clutch piston seals are broken or worn.

3. Modulating valve assembly stuck.

Problem: Low pump pressure.

Probable cause:

1. Low oil level.

2. Main relief valve movement is restricted.

3. Transmission oil pump is worn.

4. Inner oil leakage.

5. Main relief valve not adjusted properly.

Problem: Low lubrication pressure or no lubrication pressure.

Probable cause:

1. Low oil pressure or no oil pressure caused by:

a. Failure of the oil pump or a defect in the oil

pump.

b. Restriction in the oil flow circuit such as a dirty

oil screen.

c. Inching valve reducing spool stuck open.

d. Leakage inside of transmission caused by com-

ponent defects.

2. Oil cooler has restriction to oil flow.

Problem: High lubrication pressure.

Probable cause:

1. Restricted external oil lines or internal passages.

2. External oil lines are not connected correctly.

Problem: High converter charge pressure.

Probable cause:

1. A plugged converter bypass orifice.

2. A restriction inside the converter assembly.

3. A plugged oil flow passage.

Problem: Low converter charge pressure.

Probable cause:

1. Converter relief valve stuck open.

2. Main relief valve movement is restricted.

Problem: Low converter outlet pressure or cooler inlet pressure.

Probable cause:

1. Low oil pressure.

2. Cooler relief valve stuck open.

Problem: High converter outlet pressure or cooler inlet pressure.

Probable cause:

1. Restriction in oil cooler lines or a plugged oil

cooler.

Problem: Low stall speed.

Probable cause:

1. Engine performance is not correct.

2. The one-way clutch of the torque converter does not

hold.

Problem: High stall speed in both directions.

Probable cause:

1. Low oil level.

2. Air in the oil.

3. Clutches slip (clutch plates slide in relation to one

another).

4. Torque converter failure.

Power Train Testing and Adjusting

Problem: High stall speed in one direction.

Probable cause:

1. There is a leak in the clutch circuit.

2. There is a failure in that clutch assembly (clutch

slipping).

Problem: Selector spool problems.

1. Transmission stays in neutral, no shift.

Probable cause:

1. Spools mechanically stuck

a. Contamination

b. Case or body not flat

c. Bore / spool worn

2. Solenoids not working

a. O-rings leaking (cut)

b. O-rings missing

Problem: Modulation spool problems.

1. Slow or no modulation of both clutches

(If only 1 clutch does not modulate correctly then the problem is either with the selector spool or it is a problem in the transmission).

Probable cause:

1. orifice plugged with debris

2. Modulation valve stuck

3. Modulation valve not correctly assembled.

4. Load piston problem

a. Stuck in bore

b. Excessive valve / bore clearance

c. Missing springs

5. Porosity in body in the area of load piston cavity

2. Modulation time is too quick

Probable cause:

c. Ports not machined properly

d. Contamination in solenoid

e. Electrical problem

3. orifice plugged

a. With debris

b. Bad part

4. Modulation valve stuck in "off" position

5. Modulation valve not correctly assembled.

2. Transmission will not shift into or out of 1 gear

Probable cause:

1. Spools mechanically stuck(same as above)

2. Solenoids not working(same as above)

3. Valve not correctly assembled(same as above)

4. Holes not drilled into case properly

1. The upstream orifice (in the oil supply) is not

installed. (The orifice is located in the valve block)

2. The load piston is only moving a small amount

before it sticks. Check the spool to see if it freely

fits in the bore. This check must be made while the

aluminum body is still bolted down to the

transmission.

3. The plastic orifice is not installed or the hole in the

plastic housing is too large.

4. The modulating valve is stuck in an open position.

Check to see if the valve moves freely while the

aluminum body is still bolted down.

5. The springs are not installed or the pin has jammed

the load piston

5. Excessive leakage internally in body

a. Porosity in body

b. Selector bore too large

c. Spool too small

d. Slug/spool fit not right.

Power Train Testing and Adjusting

Transmission and Drive Axle Tests And Adjustments

Transmission Pressure Tests

Tools Needed

Pressure Gauge Group 1

WARNING

To prevent personal injury, when the transmission is tested, move the truck to a clear area, that is level. Keep all other personnel away from the lift truck. Use lifting equipment or a save method to lift the front of the lift truck until the drive wheels are off the floor. Put wood blocks or jack stands of the correct capacity under it to hold it in this position while pressure tests are performed.

When the transmission tests are made, the transmission oil must be at the correct level. The pressure given in the chart are taken with the transmission oil temperature at 49 to 71°C (120 to 160°F). If the oil temperatue is lower than 49°C (120°F) the oil pressure will be higher than that shown. If the oil temperature is higher than 71°C (160°F), the pressure will be lower than that shown.

Raise the front of the lift truck off the floor. Put wood blocks or jack stands of the correct capacity under it to hold it in this position while pressure tests are performed.

WARNING

Before any pressure tap plugs or connections are removed, the engine must be stopped with the transmission controls in NEUTRAL. This will release hydraulic pressure in the transmission.

For more identification of transmission problems, the pressures that follow can be checked.

a. Pump pressure in neutral.

b. Forward clutch pressure in forward.

c. Reverse clutch pressure in reverse.

d. Converter charge pressure in neutral.

e. Converter outlet or cooler inlet pressure in neutral.

f. Lubrication pressure in neutral.

Most problems in the hydraulic circuit can normally be found when the pump pressure is checked. If more information is necessary, gauges can be installed at each pressure tap location. Locations of the pressure taps and procedures for testing are given as follows. If any of the pressures are not correct, refer to Troubleshooting For Problems and Probable Causes.

1. Be sure the transmission control adjustments are correct before tests are made. See Inching Pedal Adjustment in Testing And Adjusting.

2. Install a tachometer to the engine to show engine speed during the test.

3. Put a thermistor probe in place of the dipstick in the transmission oil reservoir.

4. Remove each of the following pressure tap plugs in the order shown and install the 0 to 2050 kPa (0 to 300 psi) pressure gauge. After the pressure check is done, remove the gauge and install the plug again.

5. Check pump pressure with the transmission in neutral at pressure tap (6) on the valve body first. If it is not correct, then check pump pressure at pressure tap (1) on the bearing plate.

a. If the pressure is low at pressure tap (6), but

correct at pressure tap (1), there could be an oil line restriction or a defective inching valve.

NOTE: Pump pressure should be checked at pressure tap (6) first because pressure tap (6) is easier to get to than pump pressure tap (1) on the bearing plate. If pump pressure is correct at pressure tap (6), it will be correct at pressure tap (1) also.

b. If the pressure is low at both locations, see

Problem: Low pump pressure in Troubleshooting.

NOTE: Pump pressure is adjusted by adding or removing shims in the D700296 Plug. The plug is located in the main relief valve on the valve body.

6. Check clutch pressure as follows:

a. Check forward clutch pressure at pressure tap

(4) with the transmission in forward. If the pressure is not correct, see Problem: Low forward clutch pressure in Troubleshooting.

b. Check reverse clutch pressure at pressure tap

(5) with the transmission in reverse. If the pressure is not correct, see Problem: Low reverse clutch pressure in Troubleshooting.

Power Train Testing and Adjusting

Pressure Tap Locations – Transmission Control Group

Converter Charge Pressure Tap 3

Main Pressure Tap 6

Forward Pressure Tap 4

Reverse Pressure Tap 5

Converter Outlet Pressure Tap 2

Temperature Sensor

To Cooler

From Cooler Lubrication Pressure Tap 7

Power Train Testing and Adjusting

7. Check lubrication pressure at pressure tap (7) with

the transmission in neutral.

a. If lubrication pressure is low, see Problem: Low

lubrication pressure in Troubleshooting.

b. If lubrication pressure is high, see Problem:

High lubrication pressure in Troubleshooting.

8. Check converter charge (inlet) pressure at pressure tap (3) with the transmission in neutral.

a. If converter charge pressure is low, see

Problem: Low converter charge pressure in Troubleshooting.

b. If converter charge pressure is high, see

Problem: High converter charge pressure in Troubleshooting.

9. Check converter outlet or cooler inlet pressure at pressure tap (2) with the transmission in neutral.

a. If the pressure is low, see Problem: Low

converter outlet or cooler inlet pressure in Troubleshooting.

b. If the pressure is high, see Problem: High

converter outlet or cooler inlet pressure in Troubleshooting.

NOTE: Do not activate the inching pedal when pressure checks are made. Check for the pressures as shown in Transmission Pressure Chart in the order that follows:

Converter Chage

Converter Outlet

or Cooler Inlet

Converter Chage - -

Converter Outlet

or Cooler Inlet

Transmission Pressure Chart

Low idle 2000 rpm

Shift position - Neutral

Main Line

Clutch

Lubrication

Shift position – Forward or Reverse

Main Line - -

Clutch

Lubrication - -

830 to 1030 kPa

(120 to 150psi)

0 kPa (0 psi)

14 to 70 kPa

(2 to 10 psi)

70 to 140 kPa

(10 to 20 psi)

25 to 55 kPa

(4 to 8 psi)

725 to 860 kPa (105 to 125 psi)

895 to 1100kPa

(130 to 160psi)

0 kPa (0 psi)

240 to 345 kPa

(35 to 50 psi)

590 to 795 kPa

(85 to 115 psi)

250 to 400 kPa

(36 to 58 psi)

725 to 965 kPa (105 to 140 psi)

Converter Stall Test

NOTE: Make sure that the transmission oil is at the

correct temperature for operation before tests are made.

The converter stall test is a test to check engine power. It can also be used to locate a problem in the transmission or torque converter when the condition of the engine is known. An engine, which does not have correct performance, will give an indication of a stall speed that is not correct. If the engine performance is correct and the stall speed is not correct, the problem in the converter or transmission can be found with this test.

NOTE: To check the engine performance, see the respective engine module. This test checks the maximum RPM that the engine, at full throttle, can turn the converter with the turbine held stationary. To hold the converter turbine, engage the brakes with the transmission in FORWARD or REVERSE.

The drive wheels must not turn during the stall test. Put a heavy load on the forks. Also put the truck in position against a solid object that will not move (such as a loading dock). When the tests are made, the wheel brakes must be engaged with the left foot. The accelerator pedal can be operated with the right foot.

WARNING

Make tests in a clear level area only. There must be one operator. Keep all other personnel away from the lift truck. Check the operation of the brakes before the tests are made.

Check the high idle setting before the stall test is made. Set the high idle to the specification, as given in the respective engine module.

NOTE: Make sure that the transmission oil is at the correct temperature for operation before tests are made.

1. Connect a tachometer to the engine. Start the engine. Engage the wheel brakes with the left foot.

2. Put the transmission control lever in FORWARD and push the accelerator pedal down completely with the right foot. Read the RPM on the tachometer, then release the accelerator pedal.

Power Train Testing and Adjusting

NOTICE

To make sure that the transmission oil does not get hot, do not hold the transmission in a stall condition for more than ten seconds. After the transmission is stalled, put the controls in NEUTRAL and run the engine at 1200 to 1500 RPM to cool the oil.

3. Repeat the procedure above for the REVERSE

direction.

4. The stall speeds for the different trucks are listed in the charts that follow:

LIFT TRUCK STALL SPEED

RPM±100

Engine

DB33A 1778 1678 2450±50

B3.3 1830 1730 2450±50

Hercules

2.7 LP

Hercules

2.7 Gas

Hercules

2.7 Dual

MMC

G424 LP

MMC

G424 Gas

MMC

G424 Dual

G430 LP

Without Power Brakes Applied

1633 1533 2500±100

1520±75 1420±75 2500±100

1830 1730 2700±50

1890 1790 2700±50

1740±75 1640±75 2700±50

1750 1650 2600 ± 50

RPM±100

With Power

Brakes Applied

Engine

Max.RPM

Stall speeds that are low are an indication that the engine performance is not correct or the one-way cutch of the torque converter does not hold in reverse direction. If the one-way clutch has a defect, the stall speed will probably be more than 800 rpm low.

The stall speed must be the same in FORWARD and REVERSE. If the stall speed is high in FORWARD and REVERSE, check the following:

a. Check for air in the oil.

b. Check the torque converter and the clutch

pressures according to transmission Pressure Tests in Testing And Adjusting.

c. If clutch pressure is correct, make an inspection of

the clutch assembly for that direction for possible damage to clutch components.

Power Train Testing and Adjusting

Maintenance

Transmission and Drive Axle

Transmission

ATTENTION : When changing oil, replace filter and clean suction strainer.

Change Filter

Grease Parking Brake Lever

Oil Filler And Dipstick

Pin And Nut Of Parking Brake

Oil Drain Plug

Suction Strainer

And

Power Train Testing and Adjusting

Drive Axle

Brake Cooling Port

ATTENTION : Clean suction strainer when replacing oil.

Oil Drain Plug Port

Pump Suction Port Brake Cooling Port

Combined Oil Filler and Dipstick

Power Train Testing and Adjusting

Electric Control System Tests

Tools Needed

Digital Multimeter 1

NOTE : Refer to Schematic.

Checks on the transmission directional control electrical circuit can be done with a Digital Multimeter. All voltage checks are made at the wiring harness connectors with the ignition switch ON, DO NOT start the engine. All continuity checks are done with the ignition switch OFF.

A beginning check of the direction control system should be performed before testing the individual components and wiring harness. When the direction solenoids are energized they become magnetized. By holding a metal screwdriver next to the solenoids it can be determined whether they are energized or not.

Turn the ignition switch ON, DO NOT start the engine. Release the parking brake. Place the direction control switch in forward and check the forward solenoid for magnetism. Do the same for the reverse direction.

z If the solenoids didn’t energize begin testing the

control system with step 1.

z If the solenoids did energize, go to step 10.

Power To Directional Control Switch Check

1. Put the directional control lever in neutral. Remove

the cover from the front side of the steering support assembly.

2. Disconnect harness connector (2) from directional control switch connector(1).

Directional Control Switch Connector

(1) Directional Control Switch Connector.

(2) Harness Connector.

3. Engage the parking brake and turn the ignition

switch ON, DO NOT start the engine. Put the multimeter on the 20 volt range.

Power To Directional Control Switch Check

(2) Harness Connector.

4. Put the (-) probe on a good ground. Put the (+) probe on socket 1 of harness connector (2).

a. If the indication is battery volts, do Step 5.

b. If the indication is 0 volts, check the

Forward/Reverse fuse (No.3) located in the fuse box and check the connecting wires for continuity.

Power Train Testing and Adjusting

Directional Control Switch Check

5. Turn the ignition switch OFF and put the

multimeter on the 200 ohm range.

6. Check continuity between pins 4 and 7 of connector (1) with the switch in neutral. forward and then reverse positions. There should be continuity in neutral and no continuity in forward and reverse.

a. If the above checks are correct, do Step 7.

b. If any of the above checks are not correct, replace

the directional control switch.

Directional Control Switch Continuity Check (1) Directional control switch connector.

7. Check continuity between pins 1 and 2 of connector (1) in forward and then neutral position. There should be continuity in forward and no continuity in neutral. While the continuity is checked in forward position, move the lever back and forth (but stay in forward position) to see if the resistance goes up or down. The resistance should be constant.

a. If the above checks are correct, do step 8.

b. If the above checks are not correct, replace the

directional control switch.

8. Check continuity between pins 1 and 3 of connector (1) in reverse and then neutral positions. There should be continuity in reverse and no continuity in neutral. While the continuity is checked in reverse position, move the lever back and forth (but stay in reverse position) to see if the resistance goes up or down. The resistance should be constant.

a. If the above checks are correct, do Step 9.

b. If any of the above checks are not correct, replace

the directional control switch.

Power Train Testing and Adjusting

Transmission Directional Control Schematic

(1) Directional Switch Connector. (2) Connector- Instrument Harness (3) Main Connector-Instrument Harness

(4) Main Connector-Engine Harness

Power Train Testing and Adjusting

Transmission Control Harness Check

Transmission Control Harness. (3) Harness. (5) Connector

9. Disconnect the connector (5) of Engine harness from the connector of transmission harness. Check continuity of socket 12, 13 of engine harness (3) from one end to the other. Repair or replace the wiring harness if there is no continuity.

Transmission Solenoids Visual Check

10. A visual check can be done to see if the solenoid

plungers are moving. Remove the modulating valve assemblies from the transmission

11. Turn the ignition switch ON, DO NOT start the engine. Release the parking brake.

12. Put the directional control switch in neutral.

z Both solenoid plungers should be flush with the

solenoid.

13. Put the directional control switch in forward and then reverse.

z The plunger of the solenoid that is activated should

move in approximately 3.18mm(.125 in).

14. If the solenoid plungers do not move as explained in Steps 12 and 13, replace the defective solenoid.

15. If the solenoid plungers are good, the modulating valves could be stuck or there is mechanical failure in the transmission.

Inching Pedal Adjustment

To check the inching valve adjustment and operation, do the procedure that follows :

WARNING

When this procedure is used, the lift truck must be in an area clear of obstructions. There must be one operator with all other personnel away from the lift truck. Check the operation of the brakes before the test is made.

1. With the engine at idle speed, put the transmission in FORWARD.

nching Operation Test

(1) Inching pedal.

2. Slowly push down on inching pedal (1) until the movement of the brake pedal causes the brake discs to make contact (small drag) with the brake plates.

3. Increase the engine speed to high idle. The truck must not move.

If the operation of the inching valve is not correct, do the procedure that follows.

1. Adjust and bleed the wheel brakes as shown in the

Vehicle Systems module.

Power Train Testing and Adjusting

WARNING

To prevent personal injury, when the inching pedal is adjusted, move the truck to a clear area that is level. Keep all other personnel away from the lift truck. Use lifting equipment or a safe method to lift the front of the lift truck until the drive wheels are off the floor. Put wood blocks or jack stands of the correct capacity under it to hold it in this position while the inching pedal is adjusted.

2. Raise the front of the lift truck off the floor. Put wood

blocks or jack stands of the correct capacity under it while the inching pedal is adjusted.

Inching Pedal Adjustment (1) Inching pedal. (2) Lug. (3) Bolt. (4) Nut.

3. Start the engine and put the transmission FORWARD.

4. With the drive wheels turning, depress inching pedal (1) until the drive wheels stop.

5. Now depress the brake pedal until disc contact is felt.

6. Loosen nut (4) and adjust bolt (3) to contact lug (2) that rotates the brake control cross shaft. Tighten nut (4).

7. Check the inching valve operation again.

Power Train Testing and Adjusting

Adjustments on Drive axle and Transmission

Axle, Pinion, crown gear

1. Measure the depth from center of diff. carrier to the

seat of pinion bearing cup. (Dimension A)

4. Calaulate the shimpack thickness according to the following formula.

Shimpack thickness = A-(127+B+C) Example) if A=160.50, B=32.00, C=+0.05 Then, shimpack thickness

=160.50-(127+32.00+0.55) = 1.45mm

󰼿 * To minimize the measuring error, measure

three places at least and average them.

5. Shims of calculated thickness laid into bearing seat.

2. Measure the width of pinion bearing.(Dimension B)

6. Install bearing cup.

3. Check the etched value on the pinion face.

(Dimension c) *unit : mm

Power Train Testing and Adjusting

7. Install crown gear, differential assy and lightly

torque bridge bilts.

8. Install bearing nuts for correct bridge position and lightly torque them to achieve bearing preload.

9. Tap on differential on both sides to achieve correct bearing cone position, rotate differential (3-5 times).

10. Check drag 19.6 N.m (14.5 lb.ft) on rotating

differential.

11. When drag is correct, mark position of nuts both on nuts and bridge.

12. After marking of position remove differential assy.

Power Train Testing and Adjusting

Installation of Pinion

1. Install cup of rear pinion bearing

4. Tap bearing cone to correct position(Rotate pinion

3-5 times)

2. Install spacer and shims on pinion (basic thickness

1.5mm (0.059 in)).

3. Install bearing cone.

5. Assemble yoke and nut and tighten flange nut to

180 ±15 N∙m (133±11 lb ∙ft)

6. Measure the rolling torque. The value of rolling torque should be 1.5~2.0 N∙m (1.1~1.5 lb∙ft)

7. If the rolling torque exceeds 2 N∙m, add one shim and if it is lower than 1.5 N∙m, subtract one shim

8. When the adjustment is correct, disassemble the

nut and the yoke. Assemble the oil seal and yoke again and then tighten the nut to 180 ±15 N·m (133±11 lb·ft)

Power Train Testing and Adjusting

Adjustment of Crown Wheel

1. Torque crown wheel bolts to 80 N·m (59 lb·ft).

3. Tap on both sides of the differential to achieve

correct position of bearing cups.

2. Install differential assy., to previously mounted position (rotate both nuts simultaneously to maintain bearing preload).

4. Check backlash between pinion and crown gear in 3 different positions. Backlash shall be 0.15-0.25mm (0.006-0.010 in)

5. Check contact face by rotating pinion in both

directions, hold back crown wheel.

Power Train Testing and Adjusting

6. Check contact area position and correct in

accordance with specification if neccessary.

7. Position not correct

9. Position not correct.

10. After correct adjustment of contact area secure

differential nut with cotter pin.

8. Correct position.

Power Train Testing and Adjusting

Adjustment of Wheel Bearings

1. Assemble outer hub bearing without lockwasher.

4. Remove wheel nut for lockwasher installation.

2. Tighten wheel nut to 135 ± 14 N·m (100±10 lb·ft).

3. Tap on and rotate hub 3-5 times to achieve correct

bearing position

5. Install lockwasher and nut.

6. Tighten nut to 50 ±5 N·m (37±3 lb·ft).

Power Train Testing and Adjusting

Doosan D20S-3, D25S-3, D30S-3, D32S-3, D25S-3(B3.3) User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual