Introduction

Reference: For Specifications with illustrations, make reference to Specifications For D3C, D4C and D5C Series III Tractor Power Train, SENR5334. If the Specifications in SENR5334 are not the same as in the Systems Operation Testing and Adjusting, look at the printing date on the back cover of each book. Use the Specifications given in the book with the latest date.

Power Train Hydraulic System

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Sudden movement of the machine or release of oil under pressure can cause injury to persons on or near the machine. To prevent possible injury, perform the procedure that follows before testing and adjusting the hydraulic system.

1. Move the machine to a smooth horizontal location. Move away from working machines and personnel and lower implements to the ground.

2. Permit only one operator on the machine. Keep all other personnel either away from the machine or in clear view of the operator.

3. Engage the parking brake.

4. Stop the engine.

5. Put blocks in front of and behind the tracks.

6. Make sure all hydraulic pressure is released before any fitting, hose or component is loosened, tightened, removed or adjusted.

Procedure

When defining a power train hydraulic system problem, the following procedure should be followed. First, perform Visual Checks. If when complete the problem has not been identified, perform operation checks. If the problem is still not fully understood, perform Instrument Tests. This procedure helps identify power train hydraulic system problems. As soon as the problem is defined, go to Troubleshooting. The Troubleshooting section lists the probable causes of a known problem. Since there may be more than one cause for a problem, the Troubleshooting section may suggest specific inspections or instrument tests be done.

These inspections and tests help identify which of the causes is most probable. This list cannot give all possible problems and corrections. The service personnel must find the problem and its source, then make the necessary repairs.

During a diagnosis of the power train hydraulic system, remember that correct oil flow and pressure are necessary for correct operation. The output of the hydraulic pump (oil flow) increases with an increase in engine speed (rpm) and decreases when engine speed (rpm) is decreased. Oil pressure is caused by resistance to the flow of oil.

Use this as a reference for the location and correction of problems in the power train hydraulic system. When more checks are necessary, use the 8T5320 Hydraulic Test Group and the 4C4890/4C4892 Fitting Groups. Locations of the pressure taps and procedures for testing and adjusting are given in the Power Shift Transmission Testing And Adjusting, SENR5336 or Hydraulics Systems Operation Testing and Adjusting, SENR5339.

Visual Checks

A visual inspection of the power train hydraulic system and its components is the first step when a diagnosis of a problem is made.

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Personal injury or death can result from improperly checking for a leak. Always use a board or cardboard when checking for a leak. Escaping fluid under pressure, even a pinhole size leak, can penetrate body tissue, causing serious injury, and possible death. If fluid is injected into your skin, it must be treated immediately by a doctor familiar with this type of injury.

1. Check the power train oil level.

2. Check the oil level in the final drives.

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

4. Check the control linkages for the transmission, steering differential and service brakes for damage and/or adjustment.

5. Check the adjustment of the track.

6. Check the screens and filters for foreign material.

a. Bronze-colored particles give an indication of a clutch failure.

b. Shiny steel particles give the indication of a pump failure.

c. Rubber particles give an indication of a seal failure or hose failure.

d. Aluminum particles give an indication of a torque converter failure.

NOTE: If any of the above particles are found during any visual check, all components of the power train hydraulic system must be cleaned. Do not use any damaged parts. Any damaged parts must be removed and new parts installed.

Troubleshooting

Problem Checklist

Transmission Problem List

1. Transmission does not operate in any speed or does not engage (slips) in all speeds.

2. Transmission does not make a shift.

3. Slow shifts.

4. Transmission engages very suddenly (rough shifting).

5. Transmission operates in FORWARD speeds only.

6. Transmission operates in REVERSE speeds only.

7. Transmission does not operate in First speed FORWARD or REVERSE.

8. Transmission does not operate in Second speed FORWARD or REVERSE.

9. Transmission does not operate in Third speed FORWARD or REVERSE.

10. Transmission does not disengage (release) when the selection lever is in NEUTRAL.

11. Transmission engages but the machine does not move.

12. Transmission gets hot.

13. Pump noise not normal.

14. Transmission engages, torque converter stalls, engine under load condition. Machine does not move.

Torque Converter Problem List

1. Torque converter gets hot.

2. High converter inlet pressure.

3. Low inlet pressure.

4. Noises in torque converter that sound like metal in contact.

Steering and Brakes Problem list

1. Machine not turning in one direction.

2. Machine not turning in either direction.

3. Machine moves in either direction when both steering clutches are engaged.

4. Slow steering.

5. Service brakes not engaging.

6. Service brakes not releasing.

Problem 1: Does not operate in any speed or does not engage (slips) in all speeds.

Probable Cause:

1. Low oil pressure caused by:

a. Low oil level.

b. Control linkage loose or adjustment not correct.

c. Failure of the oil pump or the pump drive.

d. Air leaks on the inlet side of pump.

e. Leakage inside the transmission.

f. Load piston or differential valve operation not correct.

g. Load piston not moving correctly.

2. Mechanical failure in transmission.

3. Failure of torque converter.

4. Transfer gear, bevel pinion and/or bevel gear failure.

5. Failure in steering clutches.

6. Failure in final drives.

Problem 2: Transmission does not make a shift.

Probable Cause:

1. Control linkage loose or adjustment not correct.

2. Low oil level.

3. Low clutch pressure.

Problem 3: Slow shifts.

Probable Cause:

1. Low oil pressure.

2. Adjustment of control linkage not correct.

3. Air leaks on inlet side of pump.

4. Load piston or differential valve not moving in pressure control valve.

Problem 4: Transmission engages very suddenly (rough shifting).

Probable Cause:

1. Adjustment of control linkage not correct.

2. Initial pressure setting of relief valve not correct.

3. Load piston or differential valve not moving correctly.

4. Valve springs that are weak or have damage.

Problem 5: Transmission operates in FORWARD speeds only.

Probable Cause:

1. Control linkage loose or adjustment not correct.

2. No. 1 clutch not engaged (slips) because of:

a. Low oil pressure or leakage.

b. Discs and plates have too much wear.

c. Clutch has parts that are broken.

Problem 6: Transmission operates in REVERSE speeds only.

Probable Cause:

1. Control linkage loose or adjustment not correct.

2. No. 2 clutch not engaged (slips) because of:

a. Low oil pressure or oil leakage.

b. Discs and plates have too much wear.

c. Direction clutch has parts that are broken.

Problem 7: Transmission does not operate in First Speed FORWARD or REVERSE.

Probable Cause:

1. No. 5 clutch not engaged (slips) because of:

a. Low oil pressure or leakage.

b. Discs and plates have too much wear.

c. Clutch has parts that are broken.

Problem 8: Transmission does not operate in Second Speed FORWARD or REVERSE.

Probable Cause:

1. No. 4 clutch not engaged (slips) because of:

a. Low oil pressure or leakage.

b. Discs and plates have too much wear.

c. Clutch has parts that are broken.

Problem 9: Transmission does not operate in Third Speed FORWARD or REVERSE.

Probable Cause:

1. No. 3 clutch not engaged (slips) because of:

a. Low oil pressure or leakage.

b. Discs and plates have too much wear.

c. Clutch has parts that are broken.

Problem 10: Transmission does not disengage (release) when the selection lever is in NEUTRAL.

Probable cause:

1. Control linkage loose or adjustment not correct.

2. Direction clutch is engaged, and does not release.

Problem 11: Transmission engages but the machine does not move.

Probable Cause:

1. Failure in final drives.

2. Failure in steering clutches.

3. Failure in bevel gear and pinion.

4. Failure of drive shaft.

5. Failure of transfer gears.

6. Gears in the transmission not moving because of:

a. Too many clutches are engaged.

b. Mechanical failure in transmission.

c. Mechanical failure in torque converter.

Problem 12: Transmission gets hot.

Probable Cause:

1. Low oil level.

2. High oil level.

3. Core of oil cooler not completely open.

4. Low oil flow as a result of pump wear.

5. Long periods of operation with converter at or near stall speed.

6. Too much resistance between the plates and discs of the clutches when not engaged.

Problem 13: Pump noise not normal.

Probable Cause:

1. Loud sounds at short intervals, that give an indication that particles are flowing through the pump, are caused by pump cavitation.

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

3. Air at the inlet side of pump (aeration).

Problem 14: Transmission engages, torque converter stalls, engine under load condition. Machine does not move.

Probable Cause:

1. Seizure in the transmission.

a. Damaged parts.

b. One or more clutches not correctly engaged.

2. Failure of the bevel pinion, bevel gear or transfer gears.

3. Failure of the pinion and/or gears in final drives.

Torque Converter

Problem 1: Torque converter gets hot.

Probable Cause:

1. Bad temperature gauge.

2. Mechanical failure in torque converter.

3. Core or oil cooler not completely open.

4. Long periods of operation with converter at or near stall speed.

5. Too much oil leakage in torque converter.

6. Too much restriction in oil cooler lines.

7. Not enough oil to torque converter because of:

a. Oil pump failure.

b. Too much leakage in the hydraulic system.

c. Ratio valve not operating correctly.

d. Low oil level.

Problem 2: High converter inlet pressure.

Probable Cause:

1. Converter ratio valve not operating correctly.

2. Restrictions in oil cooler.

3. Restrictions in outlet line to oil cooler.

Problem 3: Low inlet pressure.

Probable Cause:

1. Bad transmission oil pump.

2. Converter ratio valve.

a. Dirt or foreign material not letting valve close.

3. Seal leakage in torque converter.

Problem 4: Noises in torque converter that sound like metal in contact.

Probable Cause:

1. Bearings that have too much wear or damage.

2. Loose turbine, impeller or stator blades.

3. Too much side load on output shaft.

Steering And Brakes

Problem 1: Machine not turning in one direction.

Probable Cause:

1. Steering and brake control linkages are damaged or the adjustment is not correct.

2. Too much leakage in steering clutch control valve or oil lines.

3. Steering clutches not releasing.

a. Steering clutch piston not moving freely.

b. Discs or plates are warped.

4. Seals of steering clutch cylinders have damage.

Problem 2: Machine not turning in either direction.

Probable Cause:

1. Low oil pressure to steering clutch control valve.

2. Leaks in steering clutch control valve or oil lines.

3. Adjustment of control linkages for the steering clutches and service brakes not correct.

4. Steering clutch or clutches not releasing.

a. Steering clutch piston not moving freely.

b. Discs or plates are warped.

5. Splines on the steering clutch drum or brake drum have damage.

6. Wear or broken springs in control valve.

7. Too much leakage in transmission.

8. Adjustment of the modulation relief valve not correct, or valve does not close.

Problem 3: Machine moves in either direction when both steering clutches are engaged.

Probable Cause:

1. Adjustments of the control linkages for the steering clutches and service brakes not correct.

2. Steering clutch discs or plates have wear or damage.

3. Steering clutch springs that are weak or have damage.

4. Studs that hold the steering clutch springs are broken.

5. Worn grooves on inner and outer steering clutch drums which cause plates to "hang up".

6. Service brake adjustment is not correct.

Problem 4: Slow steering.

Probable Cause:

1. Control linkages for the steering clutches and service brakes loose, or adjustment not correct.

2. Service brake linings have wear or damage.

3. Low oil pressure to steering clutch control valve.

4. Splines on steering clutch hubs have damage.

5. Leaks in steering clutch control valve and/or cylinder.

6. Steering clutches do not fully release.

a. Steering clutch piston not moving freely.

b. Discs or plates are warped.

Problem 5: Service brakes not engaging.

Probable Cause:

1. Operation of service brake pedal linkage or adjustment of linkage is not correct.

2. Service brake bands have wear or damage.

3. Splines on brake drum flange have wear or are damaged.

Problem 6: Service brakes not releasing.

Probable Cause:

1. Service brake adjustment is not correct.

2. Parking brake not releasing correctly.