994F Wheel Loader Hydraulic System Caterpillar

The torque converter stall and implement double stall test helps determine if the engine is producing the correct power output. This stall test may be used for many diagnostic procedures.

Show/hide table

Personal injury or death can result from machine movement. When tests and adjustments are made to the transmission or the torque converter, the parking brake must be disengaged. To prevent movement of the machine and personal injury perform the procedure that follows.

Machine Preparation

1. Move the machine to a smooth level location. Move away from working machines and personnel. Lower the attachments to the ground.

2. Allow only one operator on the machine. Keep all personnel away from the machine or in the view of the operator.

3. Engage the parking brake. Move the transmission direction control switch to the NEUTRAL position.

Stall Test

1. Warm the transmission oil to normal operating temperature of approximately 74° to 85°C (165° to 185°F).

2. Raise the boom to the full lift position. Return the control lever to the HOLD position.

3. Fully depress the right side service brake pedal. Hold the brake pedal in the depressed position for the duration of the test.
   Show/hide table

   Illustration 1	g01144767
   (1) STIC control lock. (2) Hydraulic lockout control.

4. Disengage STIC control lock (1) and hydraulic lockout control (2).

   Note: Move STIC lock control (1) to the left in order to disengage. Move hydraulic lockout control (2) downward in order to disengage.

5. Release the parking brake.
   Show/hide table

   NOTICE
   To make sure that the transmission oil does not overheat, do not keep the torque converter in a stall condition for more than 30 seconds. After the torque converter stall test, reduce engine speed to low idle, move the transmission control to neutral and increase the engine speed to approximately 1500 rpm to cool the oil.

6. Place the transmission in the THIRD SPEED position.

7. Move the transmission direction switch to the FORWARD position.

8. Increase the engine speed to high idle.

9. Move the lift control lever to the full RAISE position in order to move the lift cylinders against the stops. Hold the control lever in the full RAISE position.

10. Allow the engine speed to stabilize. Record the engine rpm. Release the lift control lever.

11. Reduce the engine speed to low idle.

12. Shift the transmission to the NEUTRAL position.

13. Place the implement on the ground.

The correct torque converter stall and implement double stall speed in third speed forward is 1305 ± 50 rpm.

Low stall speeds indicate a possible problem with engine performance . The stall speed should be corrected before the performance of the hydraulic system can be properly tested.