950F Series II Wheel Loader Power Train Caterpillar

The torque converter stall test is designed to test the engine, the torque converter, the drive train and the brake system as a unit. The torque converter output is stalled while the engine is operated at full throttle. The speed of the engine at torque converter stall indicates whether the engine and the transmission are operating correctly under full load.

If the engine speed is lower than the normal given speed or if the engine speed is higher than the normal given speed, this indicates that there is a problem in the engine or in the transmission. If testing shows correct engine performance but the torque converter stall speed is not correct, the problem is in the torque converter or in the transmission.

Reference: To check the performance of the Caterpillar 3126 Engine, refer to the following service literature: Specifications, SENR3582-06, "Basic Engine Components 3114, 3116 & 3126 Engines", Systems Operation, Testing and Adjusting, SENR3583-04, "Basic Engine Components 3114, 3116 & 3126 Engines" and Service Manual Supplement, SENR4615-01, "3114, 3116 & 3126 Engines For Caterpillar Built Machines".

The service brakes must be applied when tests are performed. Make sure that the service brakes are fully operational before you perform any tests. Make sure that the transmission oil is at the normal operating temperature of 82 to 93°C (180 to 200°F) when tests are performed.

The drive wheels must not turn during the torque converter stall test. Place the machine against a solid, stationary object such as a loading dock. Engage the parking brake.

The transmission auto/manual switch must be in the OFF position in order to prevent any unexpected shifts during the stall test.

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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.

Illustration 1	g00743093
Caterpillar Monitoring System (1) Tachometer (2) Display window for digital tachometer

1. Place the transmission neutralizer override switch in the OFF position by depressing the top of the switch.

2. Apply the service brakes and start the engine.

   Note: To ensure that the transmission oil does not overheat, do not keep the torque converter in a full stall condition for more than 30 seconds. After the torque converter is stalled, shift the transmission direction and speed control lever to the NEUTRAL position. Operate the engine at 1200 rpm to 1500 rpm in order to cool the oil.

3. Disengage the parking brake. Shift the transmission direction and speed control lever to the FOURTH SPEED FORWARD position. Fully depress the accelerator pedal. Allow the engine rpm to stabilize. Then, observe tachometers (1) and (2) .

The correct stall speed for the 950F Series II Wheel Loader is 2120 ± 65 rpm.

Stall speeds that are low indicate incorrect engine performance. Stall speeds that are high indicate incorrect transmission performance or incorrect performance of the torque converter. If you must repeat the test, keep the transmission in neutral and wait for two minutes between tests.

Reference: For additional information about the Caterpillar Monitoring System, refer to Service Manual, SENR1394, "Caterpillar Monitoring System".

Reference: For additional information about the Caterpillar Monitoring System, refer to the Service Manual module Systems Operation, "Monitoring System (Power Train Functions)" for the machine that is being serviced.

Reference: For additional information about troubleshooting the transmission and the torque converter, refer to the Service Manual module Testing and Adjusting, "Power Train Troubleshooting" for the machine that is being serviced.