IT14G Integrated Toolcarrier and 914G Wheel Loader Power Train Caterpillar

Performance Tests

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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.

The hydrostatic pump contains a charge pump. The speed sensing valve in the hydrostatic pump uses the oil from the charge pump in order to create signal oil pressure. The speed sensing valve is controlled by applying the accelerator pedal, which increases the signal oil pressure. The signal oil pressure provides oil to the inching valve, to the implements, and to the motors. The signal oil pressure signals the motors to upstroke or the signal oil pressure signals the motor to destroke.

The charge pump has a relief valve. If the relief valve pressure setting is too low, the performance of the machine will decrease. If the relief valve pressure setting is too high, the life of the hoses and the components will decrease. Performance problems can also result if the relief valve pressure setting is too high.

Problem

The hydrostatic pumps make noise. The machine does not move smoothly and there are air bubbles in the oil.

Possible Cause

1. The hydraulic oil level is low.

2. The viscosity of the hydraulic oil is incorrect.

3. There is an air leak on the suction side of the pump.

Problem

The output of the hydrostatic drive pump is low.

Possible Cause

1. The oil level is low.

2. The viscosity of the hydraulic oil is incorrect.

3. The speed sensing valve to the hydrostatic pump is not set to the correct specifications.

4. The POR valve is not set to correct specifications.

5. The crossover relief valves are not set to correct specifications.

6. The charge relief valve to the hydrostatic pump is not set to the correct specifications.

7. There is a malfunction in the valve for the speed/direction control.

8. The hydrostatic pump has too much wear.

9. The inching operation is actuating improperly. The signal oil pressure from the pump is opened to the hydraulic oil tank. For (S/N: 9WM1-1298, 1WN1-898), the linkage to the inching valve on the master cylinder is not within the specification. For (S/N: 9WM1299-UP, 1WN899-UP), the brake valve is not within the specification.

10. The creeper valve is incorrectly adjusted or incorrectly positioned.

Problem

The machine will not move.

Possible Cause

1. The hydraulic tank is low on oil.

2. An electrical system problem may exist. Check the electronic technician for any fault codes.

3. Check the drive coupling for the hystat pump. If the implement and steering systems function, the drive coupling is not damaged.

4. The system is over the normal voltage. The voltage of the system is above 32 volts. The system turns off all directional solenoids if this occurs.

5. The system voltage is below 21 Volts. If the voltage is below 21 Volts, the ECM will maintain any directional solenoid in ON position. If a new solenoid is turned on, all directional solenoids will be turned off.

6. The creeper control is incorrectly adjusted.

7. The microswitch for the parking brake failed or the microswitch is misadjusted.

8. The inching valve is open to the hydraulic tank.

9. The directional orifice is plugged.

Problem

The machine will not start to move until the engine speed is very high.

Possible Cause

1. The charge relief valve to the hydrostatic pump is not set to the correct specifications.

2. The adjustment for the speed sensing valve is not set to the correct specifications.

3. The inching operation is actuating improperly. The signal oil pressure from the pump is opened to the hydraulic oil tank. For (S/N: 9WM1-1298, 1WN1-898), the linkage to the inching valve on the master cylinder is not within the specification. For (S/N: 9WM1299-UP, 1WN899-UP), the brake valve is not within the specification.

Problem

The machine has low performance or low rimpull.

Possible Cause

1. The engine's high idle is not set to the correct specifications.

2. Engine power is low.

3. The viscosity of the hydraulic oil is incorrect.

4. The specification for the motor displacement of both motors is not set correctly.

5. The adjustments of the POR valves is not set to the correct specifications.

6. The adjustments of the crossover relief valves is not set to the correct specifications.

7. There are fluctuations in the drive pressure that is caused by the interaction between the POR valve and the crossover relief valve.

8. The inching operation is actuating improperly. The signal oil pressure from the pump is opened to the hydraulic oil tank. For (S/N: 9WM1-1298, 1WN1-898), the linkage to the inching valve on the master cylinder is not within the specification. For (S/N: 9WM1299-UP, 1WN899-UP), the brake valve is not within the specification.

Problem

The machine does not attain the maximum speed, when the speed select switch is in the FAST mode.

Possible Cause

1. The parking brake is misadjusted.

2. There is an electrical problem in the circuit for the speed selector.

3. The adjustment for the minimum displacement on the motors is not set to the correct specifications.

4. There is excessive resistance in the final drives.

5. The inching operation is actuating improperly. The signal oil pressure from the pump is opened to the hydraulic oil tank. For (S/N: 9WM1-1298, 1WN1-898), the linkage to the inching valve on the master cylinder is not within the specification. For (S/N: 9WM1299-UP, 1WN899-UP), the brake valve is not within the specification.

6. There is an incorrect signal from the overspeed valve.

7. The motor displacement control is faulty.

8. Low machine voltage. The alternator strap has a poor ground.

9. The speed sensor is faulty or the speed sensor has an incorrect gap.

Problem

The maximum speed of the machine does not change when the speed selector switch is moved from the SLOW mode to the FAST mode.

Possible Cause

1. There is a problem with the electrical circuit in the speed selector.

2. The creeper control lever (if equipped) is misadjusted in the detent position.

3. The creeper speed control is faulty.

Problem

Loss of Hystat braking

Possible Cause

1. The shutoff valve for the hydrostatic system is open to the hydraulic tank. (S/N: 9WM1299-UP, 1WN899-UP)

2. The inching valve is incorrectly adjusted for (S/N: 9WM1-1298, 1WN1-898).

3. The orifice of the speed sensing valve was not installed.

Problem

The machine cannot achieve maximum runout speed in the slow speed.

Possible Cause

1. The creeper speed control is incorrectly adjusted or positioned.

2. The adjustment screw for the stop of the motor is incorrectly adjusted.

3. The motor displacement control is faulty.

4. The pin with the throttling slots for the motor is damaged or the pin is incorrectly assembled.

Problem

The performance of the machine is off in one direction only.

Possible Cause

1. The pump null setting is incorrectly adjusted.

2. The sleeve of the hydrostatic pump is worn.