Problem Solving

This is intended as a reference for locating and correcting problems that may occur in the power train. In the event further investigation is necessary, use of the 7S8875 or 8M2736 Hydraulic Test Box will be helpful. Pressure tap locations and testing and adjusting procedures are defined in the subject TORQUE CONVERTER, TRANSMISSION AND HYDRAULIC CONTROLS.

In all instances, visual checks of the machine should be made first and then operational checks before proceeding to instrumentation tests.

Visual Checks

1. Check the oil level in the transmission.

2. Examine all external oil lines, hoses and connections for leaks and damage. Look on the ground beneath the machine for evidence of leaks and locate their source.

3. Move the range control lever to REVERSE position and all FORWARD positions. The detents should be felt in each position.

4. Drain the transmission lubrication oil filter housing, remove and check the filter element for foreign material. Also, check the magnetic strainer.

a. Bronze-colored particles would indicate a clutch failure.

b. Bright steel particles in the filter indicate a pump failure.

c. Aluminum particles indicate a torque converter failure.

d. Rubber particles indicate a blown seal or ruptured hose.

If metal or rubber particles are found, clean all components in the hydraulic system and recondition the damaged components.

Operational Checks

With the engine running, move the transmission speed selector lever to all positions. The detents should be felt in each position.

Operate the machine in each direction and at all speeds. Listen for unusual noises and determine their source. If improper operation is observed, refer to the OPERATIONAL CHECK LIST for "problems" and "probable causes."

Operational Check List

Transmission

Problem: Does not operate in any speed or slips in all speeds.

PROBABLE CAUSE:

1 Low oil pressure due to:

a. Low oil level.

b. Control linkage broken loose or incorrectly adjusted.

c. Oil pump or oil pump drive failure.

d. Air leaks on inlet side of pump.

e. Leakage within transmission.

f. Pressure modulating relief valve spool incorrectly adjusted or stuck open.

g. Load piston or differential and safety valve spool stuck.

2 Mechanical failure in transmission.

3 Torque converter failure.

4 Bevel pinion and/or bevel gear failure.

Problem: Transmission does not shift.

PROBABLE CAUSE:

1 Low oil level.

2 Low clutch pressures.

3 Incorrect linkage adjustment or worn or broken parts.

Problem: Sluggish shifting.

PROBABLE CAUSE:

1 Low oil pressure.

2 Incorrectly adjusted internal and external control system linkages.

3 Air leaks on inlet side of pump.

4 Load piston or differential and safety valve sticking in pressure control valve.

Problem: Rough shifting.

PROBABLE CAUSE:

1 Incorrectly adjusted control system linkage.

2 Incorrect initial setting of relief valve.

3 Sticking load piston and/or differential and safety valve spool.

4 Weak or broken valve springs.

Problem: Slips in first, second and third forward speeds only.

PROBABLE CAUSE:

No. 2 clutch slipping due to:

1 Low oil pressure resulting from broken or damaged piston ring seals or O-ring seals.

2 Worn discs and plates.

Problem: Slips in second forward and second speed reverse only.

PROBABLE CAUSE:

No. 4 clutch slipping due to:

1 Low oil pressure resulting from broken or damaged piston ring seals or O-ring seals.

2 Worn discs and plates.

Problem: Slips in first speed forward and first speed reverse only.

PROBABLE CAUSE:

No. 5 clutch slipping due to:

1 Low oil pressure resulting from broken or damaged piston ring seals or O-ring seals.

2 Worn discs and plates.

Problem: Slips in third speed forward and third speed reverse only.

PROBABLE CAUSE:

No. 3 clutch slipping due to:

1 Low oil pressure resulting from broken or damaged piston ring seals or O-ring seals.

2 Worn discs and plates.

Problem: Slips in first, second and third speeds reverse only.

PROBABLE CAUSE:

No. 1 clutch slipping due to:

1 Low oil pressure resulting from broken or damaged piston ring seals or O-ring seals.

2 Worn discs and plates.

Problem: Transmission remains in gear when selector lever is in NEUTRAL.

PROBABLE CAUSE:

1 Control linkage broken, loose or incorrectly adjusted.

2 Directional clutches not releasing.

Problem: Transmission engages, torque converter stalls and engine under load condition. Machine does not move.

PROBABLE CAUSE:

1 Locked transmission.

a. Broken parts.

b. One or more clutches improperly engaged.

2 Broken teeth on bevel pinion or bevel gear.

3 Broken teeth on pinion and/or gears in final drives.

Problem: Overheating of the transmission.

PROBABLE CAUSE:

1 Low oil level.

2 Oil cooler core partially plugged.

3 Excessive clutch drag.

4 Low oil flow as a result of a worn oil pump or extreme leakage in the hydraulic system.

Problem: Unusually noisy pump.

PROBABLE CAUSE:

1 An intermittent loud popping sound which gives the impression that foreign materials are passing through the pump is caused by pump cavitation.

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

Torque Converter

Problem: Torque converter overheating.

PROBABLE CAUSE:

1 Improper operation of machine. Constant overloading.

2 Faulty temperature gauge.

3 Cooling system of machine faulty.

4 Mechanical failure of torque converter.

5 Excessive oil build-up in the torque converter housing around converter due to excessive leakage through torque converter.

6 Insufficient oil supply to the converter caused by:

a. Excessive leakage in the transmission.

b. Faulty pump.

c. Torque converter inlet ratio valve spool sticking or leaking.

d. Clogged oil cooler or lines.

Clutch designation:

Torque Converter, Transmission And Hydraulic Controls

TRANSMISSION HYDRAULIC CONTROLS - SCHEMATIC (FIRST - FORWARD)
1-Torque converter. 2-Load piston. 3-Modulating relief valve. 4-Converter inlet ratio valve spool. 5-Lubrication relief orifice. 6-Pressure control valve body. 7-Combination-differential, safety, flow control, check-valve. 8-Oil cooler. 9-Directional selector valve spool. 10-Oil filter. 11-Lubrication oil line to transmission. 12-Oil pump. 13-Speed selector valve spools. 14-Oil sump. 15-Selector valve body. A-Torque converter inlet pressure tap. B-Torque converter outlet pressure tap. C-Speed clutch pressure tap. D-Directional clutch pressure tap. E-Lubrication pressure tap. F-Pump pressure tap.

PRESSURE TAP LOCATIONS
A-Torque converter inlet pressure tap (P3). B-Torque converter outlet pressure tap. C-Speed clutch pressure tap (P1). D-Directional clutch pressure tap (P2). E-Lubrication pressure tap. F-Pump pressure tap.

PRESSURE CONTROL VALVE
2-Load piston. 3-Modulating relief valve. 6-Pressure control valve body. 16-Spacers.

6. Pressure control valve body. A. Torque converter inlet pressure tap (P3). C. Speed clutch pressure tap (P1). D. Directional clutch pressure tap (P2).

Hydraulic Control Linkage Adjustment

1. Put neutral lock lever (5) in the ENGAGED (lever up) position.

TRANSMISSION HYDRAULIC CONTROL LINKAGE
1-Control handle. 2-Indicator collar. 3-Rack. 4-Housing assembly. 5-Neutral lock lever. 6-Lever. 7-Lever. 8-Speed control rod. 9-Directional control rod.

2. Place transmission directional control lever (6) in the NEUTRAL (N) detent, adjust length of rod (9) as necessary and connect to lever (6).

3. Remove cap from the top of housing assembly (4).

4. Rotate control handle (1) counterclockwise until top of rack (3) is even with the top of housing assembly (4).

5. Place transmission control lever (1) in THIRD SPEED detent and adjust and connect rod (8).

6. Adjust indicator collar (2) to THIRD SPEED position and tighten set screw.

Differential And Bevel Gear

Differential And Bevel Gear Adjustment

NOTE: Adjustment of the standard and torque proportioning differentials are the same.

1. Make the adjustment to the bearing preload of the bevel pinion (1) so 6 to 10 lb. in. (6,9 to 11,5 cm.kg) is needed to turn the pinion shaft.

2. Install the differential with the bevel gear (5) into the carrier housing (6) and install adjusting nuts (4 and 7).

DIFFERENTIAL AND BEVEL GEAR (Standard Differential Illustrated)
1. Bevel pinion shaft. 2. Shims. 3. Bolts that hold differential carrier to axle housing. 4. Differential bearing adjusting nut. 5. Bevel gear. 6. Differential carrier housing. 7. Differential bearing adjusting nut. 8. Bolts that hold bevel gear to differential housing.

3. Install bevel pinion shaft assembly with shims (2) temporarily into carrier housing (6).

4. Align the heels of the teeth of the bevel gear (5) and the bevel pinion shaft (1) by turning nuts (4 and 7) and removing or adding shims (2). Turn nut (7) to put approximately the correct amount of free movement (backlash) between the bevel gear (5) and bevel pinion shaft (1). See Step 6.

5. Remove bevel pinion shaft assembly (1) and shims (2).

6. Make the adjustment to the preload for the bearing of the carrier assembly (6) until 30 to 50 lb. in. (34,6 to 57,7 cm.kg) is needed to turn the differential assembly. Make this adjustment by turning adjusting nut (4).

7. Again install bevel pinion shaft assembly and correct amount of shims (2). See Step 4.

8. Turn nut (4) and (7) the same amount, but in opposite directions, to get free movement (backlash) of .008 to .013 in. (0,20 to 0,33 mm) between the pinion shaft gear (1) and bevel gear (5). Turning each nut (4) and (7) the same amount does not change the bearing preload but does change the backlash.

9. Check tooth contact setting and make adjustment as needed. See subject BEVEL PINION LOCATION for adjustment for tooth contact setting.

Bevel Pinion Location

If the same pinion shaft is reinstalled in the same differential, use the same shims between the pinion shaft bearing cage and the differential carrier housing that were removed. The pinion can be located by observing the tooth contact setting made by the pinion shaft gear teeth on the bevel gear teeth. This can be done in the following manner.

Use sufficient shims between the pinion shaft bearing cage and the differential carrier to align the heel ends of the bevel gear and pinion shaft gear teeth. This will place the pinion in nearly the correct relationship with the bevel gear.

Adjust the bevel gear backlash as described in the subject DIFFERENTIAL AND BEVEL GEAR ADJUSTMENT. This should give a very close adjustment.

ALIGNING THE BEVEL GEAR AND PINION

To further check the adjustment, chalk the bevel gear teeth (discolor). Rotate the pinion shaft and bevel gear to produce a tooth contact setting on the bevel gear teeth. Correct tooth contact starts near the toe and extends approximately 30 per cent of the length of a bevel gear tooth.

CORRECT TOOTH CONTACT

If tooth contact is more on one side of a tooth or is near the heel of a tooth, the location of the pinion shaft must be readjusted. Add or remove shims to relocate the pinion shaft. Readjust the bevel gear backlash. Produce another tooth contact setting. It may be necessary to make several pinion and bevel gear adjustments to obtain both correct tooth contact and backlash.

Final Drive And Wheels

Wheel Bearing Adjustment

FINAL DRIVE AND WHEEL
1-Brake disc. 2-Wheel retaining nuts. 3-Nut. 4-Bearings.

1. On machines equipped with front wheel brakes, open bleeder valves in the brake head assembly and pry the brake linings away from brake discs (1). Leave the bleeder valves open.

2. Using the tooling shown, very slowly rotate wheel while tightening retaining nut (3). The readings on the following length Torque Wrenches should be:

For any other length torque wrench [lb. in. (cm.kg)] the proper torque reading can be determined by the following formula:

C = torque wrench reading

A = length of the torque wrench

T = torque required on bearings [72-108 lb. in. (83,0-124,5 cm.kg)]

B = distance from the center of the axle housing to the wheel nuts

NOTE: Always align the torque wrench on wheel nut (2) so that it points directly at the center of the axle housing.

3. Very slowly rotate the wheel through a full revolution after achieving proper torque to check the torque reading.

4. Bleed the brakes and tighten the bleeder valves.

TOOL SET-UP