950G Series II Wheel Loader and 962G Series II Wheel Loader Electrohydraulic System Torque Converter Stall and Implement Pump Double Stall - Test Caterpillar

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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.

Note: Machines with both the transmission oil at normal operating temperatures and running good quality Number 2 Diesel Fuel should have engine stall speeds that are within the specified range. Refer to the factory test measurements in order to determine the appropriate specification for the machine that is being serviced. If the machine that is being serviced is outside the range of engine stall speeds, the power train components should be inspected. Use the component test specifications in order to determine the corrective action. These ranges of engine stall speed should not be used to adjust the engine power of the machine. If engine output is suspect, the engine should be tested on a dynamometer.

The torque converter stall test helps determine if the engine is producing the correct power output. The torque converter stall test provides an engine speed for comparison with the torque converter stall engine speed that is measured at the factory. The engine stall speed should be in the range that is shown in Table 2. This stall test is used in many diagnostic procedures.

The service brakes must be applied when the tests are performed. Make sure that the service brakes and the parking brake are fully operational before you perform any tests.

Make sure that the transmission oil is at the normal operating temperature. Refer to Table 3 for the temperature of the machine that is being serviced.

1. Move the machine to a smooth, level surface.

   Reference: For more information about preparing the machine for troubleshooting, refer to the Service Manual module Testing and Adjusting, "Machine Preparation for Troubleshooting".

2. Turn the engine start switch to the OFF position.
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   Illustration 1	g00892580
   Solenoid Valve (Demand Fan)

3. Set the hydraulic fan to the maximum rpm. In order to run the hydraulic fan system at the maximum rpm, the connection to the solenoid valve for the hydraulic fan system must be disconnected.

   Note: The solenoid valve is located on the right side of the engine and below the hydraulic fan pump. Turn the engine start switch to the OFF position. Disconnect the electrical connection from the connection on the solenoid valve.

   Note: Removing the connector from the solenoid valve (demand fan) will create a fault code CID 362. This fault code will be logged and need to be cleared after the testing is completed. The fault code can be cleared through AVSpare Electronic Technician.

4. Ensure that the parking brake is engaged.

5. Start the engine. Warm the transmission oil to normal operating temperature. Refer to Table 3 for the temperature of the machine that is being serviced.

6. The following table gives the speed and direction control for the machines that are listed.
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   Table 1

   Speed Control
   Machine	Speed and Direction Control
   950G Series II	Fourth Speed Forward
   962G Series II(1)	Fourth Speed Forward
   962G Series II(1)	First Speed Forward

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   (1)	The 962G Series II machine has dual horsepower. The machine must be tested in both FOURTH SPEED FORWARD and FIRST SPEED FORWARD.

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   Table 2

   Speeds For The Torque Converter Stall And Implement Double Stall
   Machine	Torque Converter Stall Speeds	Double Stall Speeds
   950G Series II	2110 ± 65 rpm	1620 ± 100 rpm
   962G Series II Fourth Gear(1)	2175 ± 65 rpm	1675 ± 100 rpm
   962G Series II First Gear(1)	2160 ± 65 rpm	1685 ± 100 rpm

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   (1)	The 962G II machine has dual horsepower. The machine must be tested in both FOURTH SPEED FORWARD and FIRST SPEED FORWARD. The difference between the fourth speed forward and the first speed forward must be at least 40 rpm.

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   Table 3

   Temperature For The Torque Converter Stall And Implement Double Stall (1)
   Machine	Temperature
   950G Series II	76 °C (168 °F) to 112 °C (230 °F)
   962G Series II Fourth Gear	76 °C (168 °F) to 112 °C (230 °F)
   962G Series II First Gear	76 °C (168 °F) to 112 °C (230 °F)

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   (1)	The temperature of the torque converter oil is measured at the torque converter outlet.

7. Ensure that the work tool is positioned on the ground.

8. Reduce the engine speed to low idle.

9. Fully depress the right side service brake pedal. Shift the transmission direction and speed control to the position that is referred to in Table 1. Hold the right service brake pedal in the depressed position for the duration of the test. Ensure that the parking brake is applied.

   Note: Do not use the left brake pedal as a service brake.

   Note: For the 962G II Wheel Loader, the torque converter stall test should be done with the transmission in fourth speed forward. The 962G Wheel Loader is equipped with the dual horsepower. Also, the machine must be tested for the torque converter stall in first speed forward.

   Note: While the parking brake is applied,the following procedure is used in order to engage the power train in the FIRST SPEED FORWARD position. Move the transmission direction and speed control to the NEUTRAL position. Select the FIRST SPEED position on the transmission direction and speed control. Move the transmission and speed control to the FORWARD position. Then move the transmission direction and speed control to the NEUTRAL position, and finally move the transmission direction and speed control back to the FORWARD position.

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   Illustration 2	g00892864
   Instrument Panel (1) Speedometer/Tachometer module. (2) Gauge display. (3) Display for the monitoring system.

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   Illustration 3	g00892866
   Control Panel (4) Switch for the display Module. (5) Digital Tachometer.

10. Press switch (4) for the display module until display shows the rpm setting. The rpm will show on the digital tachometer (5).
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    NOTICE
    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 stall test, reduce the engine speed to low idle. In order to cool the oil, move the transmission control to the NEUTRAL position and run the engine between 1200 rpm and 1500 rpm.

11. Slowly, depress the governor control pedal to full travel. Allow the engine rpm to stabilize. Then, observe tachometer (1) or (5). Record the result. Refer to Table 2 for the correct torque converter stall speed.

    Note: The results of the torque converter stall test must be within specifications before the double stall test can be performed.

    Reference: To check the performance of the AVSpare 3126B, refer to the following service literature: Specifications, SENR9579, "3126B Engines For AVSpare Built Machines" and Systems Operation, Testing and Adjusting, SENR9580, "3126B Engines For AVSpare Built Machines".

    The double stall test is used in order to determine the performance of the implement pump. This stall test is also used in other diagnostic procedures.

12. Shift the transmission direction and speed control to the NEUTRAL position.

    Note: Allow the engine coolant and the transmission oil to cool. Wait at least two minutes between tests in order to allow the transmission oil to cool.

13. Make sure that the transmission oil is at the normal operating temperature. Refer to Table 3 for the temperature of the machine that is being serviced.

14. Fully depress the right side service brake pedal. Shift the transmission direction and speed control to the position that is referred to in Table 1. Hold the right serviced brake pedal in the depressed position for the duration of this test. Ensure that the parking brake is applied.

    Note: For the 962G II Wheel Loader, the torque converter stall test and the double stall should be done with the transmission in fourth speed forward. The 962G Wheel Loader is equipped with the dual horsepower. Also, run the torque converter stall and implement pump double stall test in first speed forward.

    Note: While the parking brake is applied,the following procedure is used in order to engage the power train in the FIRST SPEED FORWARD position. Move the transmission direction and speed control to the NEUTRAL position. Select the FIRST SPEED position on the transmission direction and speed control. Move the transmission and speed control to the FORWARD position. Then move the transmission direction and speed control to the NEUTRAL position, and finally move the transmission direction and speed control back to the FORWARD position.

15. Move the tilt control lever to the full TILT BACK position and hold the lever in this position.

16. Slowly, depress the governor control pedal to full travel.
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    NOTICE
    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 stall test, reduce the engine speed to low idle. In order to cool the oil, move the transmission control to the NEUTRAL position and run the engine between 1200 rpm and 1500 rpm.

17. Allow the engine rpm to stabilize. Then, observe tachometer (1) or (5). Record the result. Refer to Table 2 for the correct double stall speed for the machine that is being serviced.

18. Move the control lever to the HOLD position. Reduce the engine speed to low idle. Shift the transmission direction and speed control to the NEUTRAL position.

Turn the engine start switch to the OFF position. Connect the connector for the solenoid valve in the hydraulic fan system.

Double stall speeds that are too high or too low indicate improper performance of the implement pump system or improper performance of the engine. Measure the pressure of the main relief valve and adjust the valve, if necessary. If the pressure in the specifications for the main relief valve can not be achieved with the main relief valve, the pump must be tested.

Reference: For additional information for adjusting the main relief valve, refer to Testing and Adjusting, "Relief Valve (Main) - Test and Adjust".

Reference: For additional information about determining the condition of the implement pump, refer to Testing and Adjusting, "Pump Performance (Implement) - Test".