When you are defining a problem in the power train system, the following procedure should be followed:
- Prepare the machine for service.
- Perform the visual inspection.
- If the problem has not been identified, perform the operational checks that apply to your machine.
- Perform any applicable calibration procedures that apply to your machine.
- Verify that the machine is using current software.
- If the problem is not fully understood, perform the instrument tests.
- When the problem is defined, go to Troubleshooting. Troubleshooting information can be found in this manual or in a separate Troubleshooting manual for this machine. The Troubleshooting lists the probable causes of a known problem. As there may be more than one cause for a problem, the Troubleshooting information may suggest specific inspections or instrument tests be done. The inspections and the tests help identify the most probable cause of a problem. The list cannot give all possible problems and corrections.
During a diagnosis of the power train system, remember that correct oil flow and pressure are necessary for correct operation. The potential output of the power train oil pump increases with an increase in engine speed and decreases when engine speed is decreased. Oil pressure is caused by resistance to the flow of oil.
Locations of the pressure taps and of the components are given in the Systems Operation portion of this manual. The pressure taps are also identified in each Testing and Adjusting procedure.
Note: The monitoring system (if equipped) for your machine accesses many values that are useful in troubleshooting the power train system. When the situation is appropriate, use the monitoring system in order to find a pressure or determine a system problem.
Refer to the following warnings and notices for all inspections and tests of the power train.
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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 power train. |
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Hot hydraulic oil under high pressure can remain in the components of the hydraulic system or the power train system after the engine has been stopped. The uncontrolled release of the hydraulic oil can cause sudden machine movement and can also result in the following conditions:
If hydraulic oil penetrates body tissue, the injury must be treated immediately by a doctor who is familiar with this type of injury. Use a board or a piece of cardboard to check for a hydraulic oil leak. Make sure that all of the attachments have been lowered to the ground and that all trapped pressure has been released from the hydraulic system and the power train system. Also, make sure that the hydraulic oil is cool before the removal of any components or lines. Remove the hydraulic oil filler cap only when the engine is stopped and the filler cap is cool enough to touch with your bare hand. |
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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. |
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Personal injury or death can result from not engaging the parking brake. Transmission engagement alone will not prevent machine from rolling when the engine is stopped. |
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Personal injury can result if the machine moves while testing. If the machine begins to move during test, reduce the engine speed immediately and engage the parking brake. |
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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, "Dealer Service Tool Catalog" for tools and supplies suitable to collect and contain fluids on Cat products. Dispose of all fluids according to local regulations and mandates. |
Before you troubleshoot, complete the following procedure.
- Permit only one operator on the machine. Keep all other personnel away from the machine or in the operator sight.
- Move the machine to a smooth, horizontal location that is away from operating machines and away from personnel.
- Decrease the engine speed.
- Apply the service brakes in order to slow the machine. Apply the transmission modulator control (inching pedal) in order to stop the machine.
- Place the transmission control switch in the NEUTRAL position.
- Engage the parking brake.
- Lower the attachments to the ground.
- Stop the engine.
- Turn the key to the ON position, but do not start the engine.
- Verify that the implement controls are UNLOCKED.
- Move the control levers through the full range of travel several times. Moving the control levers should relieve any pressure that may be present in the implement hydraulic system.
- Loosen the filler cap on the hydraulic tank so that the pressure in the tank is released. The machine may be equipped with a breaker valve. The breaker valve will be located on top of the tank. To release the pressure of the tank, press the button on top of the breaker valve (if equipped).
- Tighten the filler cap on the hydraulic tank.
- Make sure that the pressure in the entire hydraulic system has been released.
Reference: Refer to Troubleshooting for additional guidance for preparing the machine for testing.
- Check all hydraulic oil line connections for damage and for leaks.
- Follow all hydraulic oil lines from the attachment to the valve. Check the lines and connections for damage and for leaks.
- Check the control valves for leaks.
- Check the connections on the pumps and motors (if equipped) for damage and for leaks.
- Follow the pump lines and the motor lines (if equipped) to the tank and to the valves. Check for damage and for leaks on the hydraulic lines and on the hydraulic tank.
- Check the oil level in the tank.
- Remove the filter element. Check for particles in the filter elements. A magnet separates ferrous particles from nonferrous particles.
If you find metal or rubber particles, all components of the hydraulic oil system must be cleaned out. Always replace damaged parts with new parts.
- Check the transmission and differential oil level.
- Check the oil level in the final drives.
- Check the tandem oil level.
- Check all oil lines, all hoses, and all hose connections for leaks and for damage. Look for oil on the ground under the machine.
- Check the electrical wiring for all power train components.
- Check the screens (if equipped) that are in the following locations for foreign material: bevel gear case and transmission. Check the filter element for foreign material. A magnet separates ferrous particles from nonferrous particles.
If you find excessive metal or rubber particles, all components of the power train oil system must be cleaned out. Always replace damaged parts with new parts. The presence of some metal or rubber particles are considered normal during the break-in period.