 | |
| Illustration 1 | g00876763 |
Schematic for the Transmission Hydraulic System (1) Transmission hydraulic control relief valve (2) Torque converter (3) Torque converter outlet relief valve (4) Transmission oil filter (5) Clutch solenoid modulating valve for the Number 1 clutch (6) Clutch solenoid modulating valve for the Number 4 clutch (7) Clutch solenoid modulating valve for the Number 2 clutch (8) Clutch solenoid modulating valve for the Number 5 clutch (9) Clutch solenoid modulating valve for the Number 3 clutch (10) Clutch solenoid modulating valve for the Number 6 clutch (11) Transmission oil pump (12) Torque converter inlet relief valve (13) Suction screen and magnet (14) Oil sump (15) Transmission lubrication (16) Oil cooler (A) Pump pressure tap (B) P3 Torque converter inlet pressure tap (C) Torque converter outlet pressure tap (D) Sampling valve for the transmission oil (E) Pressure tap for the Number 1 clutch (F) Pressure tap for the Number 4 clutch (G) Pressure tap for the Number 2 clutch (H) Pressure tap for the Number 5 clutch (J) Pressure tap for the Number 3 clutch (K) Pressure tap for the Number 6 clutch (L) Transmission lubrication pressure tap | |
 |
Personal injury or death can result from sudden machine movement. Sudden movement of the machine can cause injury to persons on or near the machine. To prevent injury or death, make sure that the area around the machine is clear of personnel and obstructions before operating the machine. |
 |
|
Personal injury can result from hydraulic oil pressure and hot oil. Hydraulic oil pressure can remain in the hydraulic system after the engine has been stopped. Serious injury can be caused if this pressure is not released before any service is done on the hydraulic system. Make sure all of the attachments have been lowered, oil is cool before removing any components or lines. Remove the oil filler cap only when the engine is stopped, and the filler cap is cool enough to touch with your bare hand. |
|
|
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. Always use a board or cardboard when checking for a leak. |
|
| NOTICE |
|---|
Care must be taken to ensure that fluids are contained during performance of inspection, maintenance, testing, adjusting and repair of the product. Be prepared to collect the fluid with suitable containers before opening any compartment or disassembling any component containing fluids. Refer to Special Publication, NENG2500, "Caterpillar Dealer Service Tool Catalog" for tools and supplies suitable to collect and contain fluids on Caterpillar products. Dispose of all fluids according to local regulations and mandates. |
Operational Checks
Operate the machine in each direction and in all speeds. Note the noises that are not normal and find the sources of the noises. If the machine is not operating correctly, refer to the "Troubleshooting Problem List" below.
Make sure that you check for any service codes that have been generated before troubleshooting a problem.
ReferenceFor more information on checking for service codes with the Caterpillar Monitoring System, refer to the Service Manual module Troubleshooting, "Using Caterpillar Monitoring System to Determine Diagnostic Codes" for the machine that is being serviced.
ReferenceFor more information on checking for service codes with the Caterpillar Electronic Technician, refer to the Service Manual module Troubleshooting, "Using Caterpillar Electronic Technician to Determine Diagnostic Codes" for the machine that is being serviced.
Troubleshooting Problem List
- Torque converter pressure is high.
- Torque converter pressure is low.
- The torque converter overheats.
Troubleshooting
Note: In the following section, when components are referenced with a number, refer to the schematic in Illustration 1.
Probable Causes of Problems in the Torque Converter
Problem
Torque converter pressure is high.
Probable causes
- There is a restriction inside the torque converter.
- There is a restriction in an oil passage or in the oil cooler.
- The inlet relief valve (12) for the converter is stuck in the closed position.
Problem
Torque converter pressure is low.
Probable causes
- The inlet relief valve (12) in the converter is stuck in the open position.
- Adjustment of torque converter outlet relief valve (3) is not correct.
- The valve spool in torque converter outlet relief valve (3) does not move.
- Pump flow or oil pressure is low. This may be caused by any of the following conditions:
- Low oil level
- A restriction in the oil flow circuit or a dirty oil strainer
- Oil pump failure.
- Air leaks on the inlet side of the pump.
- Leakage inside the transmission (worn seals around the clutch piston)
Problem
The torque converter overheats.
Probable causes
- The machine is being used for the wrong application. There is too much torque converter slip, which is caused by too much load.
- Incorrect transmission gear is being used for the load that is on the machine. Shift to a lower gear.
- The oil level in the transfer gear case is incorrectly high or low.
- The coolant level in the engine radiator is low.
- The oil cooler or oil lines are restricted.
- Oil flow through the torque converter is too low. This may be caused by any of the following conditions:
- The inlet relief valve (12) in the converter is bypassing too much oil flow.
- Pump flow or oil pressure is low. Refer to the Problem: Torque converter pressure is low.