950M and 962M Wheel Loaders Power Train, Steering, Braking, Hydraulic, and Machine Systems Transmission Pressures - Test and Adjust Caterpillar

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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: Burns The penetration of body tissue Other personal injury Death 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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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.

Specifications

Introduction

This procedure includes the following tests:

• Transmission Oil Pump Pressure

• Transmission Clutch Solenoid Modulating Valve

• Transmission Clutch Pressure

• Lubrication Oil Pressure

• Torque Converter Outlet Pressure

• Torque Converter Inlet Pressure

This procedure includes the following adjustment procedures:

• Transmission Clutch Pressure

• Transmission Oil Pump Pressure

Required Tools

Illustration 1	g01106077
Tooling (A)

Illustration 2	g01623868
Tooling (B) 198-4240 Digital Pressure Indicator Gp

Reference: Refer to Tool Operating Manual, NEHS0818, "Using the 198-4240 Digital Pressure Indicator Group" for more information on using Tooling (B).

Machine Set Up

1. Park the machine on a smooth, level surface.

2. Place the transmission in the NEUTRAL position.

3. Lower the work tool to ground.

4. Engage the parking brake.

5. Place blocks in front of the wheels and behind the wheels.

6. Install the steering frame lock.
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   Illustration 3	g02735362

7. Perform machine walk-around and check for any leaks or damage. Check transmission oil level and fill to proper level if necessary.

8. Remove the front axle shafts and rear axle shafts except for stall tests.

9. Allow only authorized personnel on the machine. Keep unauthorized personnel off the machine and in clear sight of the operator.

10. Run the engine and warm the machine to operating temperatures. Engine coolant and hydraulic oil should at normal machine testing temperatures.

    Warm the transmission oil to normal operating temperature of approximately 83° ± 7°C (181° ± 12°F).

    Warm the torque converter oil to normal operating temperature of approximately 93° ± 17°C (199° ± 30°F).

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

Location of Pressure Taps

Illustration 4	g03722228
Transmission clutch pressure taps are located on the right-hand side of the machine. (1) Steering load signal pressure tap (2) Torque converter outlet pressure tap (3) Lock up clutch pressure tap (4) Torque converter inlet pressure tap (5) Transmission Pump Pressure (eMRV) (6) Transmission pressure tap for clutch 1 "Forward - Low" (7) Transmission pressure tap for clutch 2 "Forward - High" (8) Transmission pressure tap for clutch 3 "Reverse" (9) Transmission pressure tap for clutch 4 (10) Transmission pressure tap for clutch 5 (11) Transmission pressure tap for clutch 6

Illustration 5	g03724523
(12) Transmission lubrication pressure tap

Transmission Oil Pump Pressure

Illustration 6	g03739996
(17) Electronic Main Relief Valve (eMRV)

The electronic main relief valve (eMRV) is what controls the "pump pressure". The machine uses an electronically controlled (eMRV) which is controlled by the transmission ECM. The pump pressure, which is controlled by the (eMVR), will automatically increase if the transmission software detects that the pressure is too low or that transmission clutch slip may have occurred.

The following test is not affected by these adjustments. The transmission main relief valve compensation does not need to be reset prior to running this test.

Test for the Transmission Oil Pump Pressure

1. Before checking the Transmission Oil pump Pressure, verify the transmission neutral clutch solenoid modulating valve is functioning.

   Reference: Refer to the section "Test for the Transmission Clutch Solenoid Modulating Valve" in this document for the proper procedure.

   Also, verify the pressure difference between the transmission pump and the transmission neutral clutch is within specification.

   Reference: Refer to the section "Test for the Transmission Clutch Pressure" in this document for the proper procedure.

2. Perform the steps in the "Machine Set Up" and then continue to the following steps.

3. Attach tooling (A) or (B) on pressure tap (5).

4. Connect the machine to a laptop computer equipped with the latest version of AVSpare Electronic Technician Cat ET. Establish communication.

5. In Cat ET, navigate to the "Diagnostics" drop-down menu and select "Diagnostics Tests". Expand the "Transmission ECM" section under "Available ECM(s)" and select "Transmission Main Relief Valve Test".

6. Follow the on-screen instructions through Cat ET to complete the pressure test. The test will automatically command the engine to a predefined speed and ask if the measured pressure is within certain limits for several test points.

If the measured pump pressures do not meet specification, temporarily replace the (eMRV) and repeat the test through Cat ET. If the measured pump pressures are still NOT within specification after replacing the (eMRV), the transmission pump may need checked.

Test for the Transmission Clutch Solenoid Modulating Valve

This test will determine whether the solenoid coil is energized and the solenoid plunger is shifting. The energized coil and shifted plunger will permit the flow of oil through the transmission clutch solenoid modulating valve.

Hearing the click of a solenoid to check that the solenoid coil is energized does not ensure that the solenoid plunger has shifted. Using a screwdriver to check that the solenoid coil is energized does not ensure that the solenoid plunger has shifted. The following test will determine if the solenoid plunger is shifting.

1. Perform the steps in the "Machine Set up" and then continue to the following steps.

2. Attach tooling (A) or (B) on pressure tap (6) through pressure tap (11).

3. Engage the parking brake. Shift the transmission to the NEUTRAL position. Start the engine and operate the engine at low idle.

4. Use the transmission neutralizer override switch in order to disengage the transmission neutralizer.

5. Depress the right service brake pedal and hold the right service brake pedal. Make sure that the machine is in FIRST SPEED. Release the parking brake. Watch the pressure gauge. Shift the transmission from the NEUTRAL position to the FORWARD position.

   The pressure on Number 1 clutch (6) should rise. The pressure on the pressure gauge for the Number 6 clutch (11) should rise. With the transmission in the FORWARD position, shift through the remaining forward speeds and return to the FIRST SPEED position. Use the transmission direction and speed control lever or the transmission upshift switch to change speeds. A pressure rise should be observed in each respective speed. This checks the operation of all the speed clutches.

6. Perform Step 5 for all reverse speeds. A pressure rise should be noted in all reverse speeds.

If a pressure rise is noted, the solenoid and the related electrical circuit are functioning.

If a pressure rise is not noted, use a screwdriver to check that the solenoid coil is energized. If the screwdriver is attracted to the solenoid coil, the attraction will indicate that the solenoid coil is energized. The problem is in the solenoid cartridge. The problem could be a bent solenoid stem, a screen that is dirty or plugged, or a spring that is weak or broken.

If the screwdriver does not indicate that the solenoid coil is energized, the problem is in the electrical circuit.

Reference: For additional information about calibrating the transmission clutch solenoid modulating valves, refer to the Service Manual module Testing and Adjusting, "Calibration and Programming" for the machine that is being serviced.

Reference: For additional information about calibrating the transmission clutch solenoid modulating valves, refer to the Service Manual module Testing and Adjusting, "Fill Time for the Transmission Clutch (Electronic Technician) - Calibrate" for the machine that is being serviced.

Test for Transmission Clutch Pressure

Use the following procedure to check the pressure of the direction clutch oil and the speed clutch oil.

1. Perform the steps in the "Machine Set Up" and then continue to the following steps.

2. Attach tooling (A) or (B) to each clutch pressure tap (6) through (11) and to the pump pressure tap (5).

3. Engage the parking brake. Shift the transmission to the NEUTRAL position. Start the engine and operate the engine at low idle.

4. Use the transmission neutralizer override switch in order to disengage the transmission neutralizer.

5. Depress and hold the right service brake pedal. Make sure that the machine is in FIRST SPEED. Release the parking brake. Watch the pressure gauges. Shift the transmission direction and speed control lever (if equipped) from the NEUTRAL position to the FORWARD position. Make sure that the transmission oil is at normal operating temperature. The pressure on Number 1 clutch (6) should rise. The pressure on Number 6 clutch (11) should rise. Compare the pressure difference between each clutch and the transmission pump (pressure tap 5) to the values listed in Table 1. Compare the gauge pressure for each clutch to the values that are listed in Table 1. Verify that the system meets at least one of these two criteria.

   Note: The transmission clutch control system can alter the desired clutch pressure under certain conditions for all six transmission clutches and the lock up torque converter clutch. Altering the desired clutch pressure can also affect the pressure difference between the clutch and the transmission pump. The system is functioning normally if the system meets at least one of the two criteria that are listed in Table 1 for each clutch.

   Note: If using the "Transmission Clutch Pressure Test" available through Cat^® Electronic Technician (Cat ET), only the difference between the transmission pump and the clutch pressure should be used.

   With the transmission in the FORWARD position, shift through the remaining forward speeds and return to the FIRST SPEED position. Use the transmission direction and speed control lever (if equipped) or the transmission upshift switch (if equipped) to change speeds. Either the gauge pressure or the difference from pump pressure for each energized clutch must be within the values that are listed in Table 1. Use Table 3 in order to determine which clutches should be energized in each gear.

6. Perform Step 5 for all reverse speeds. Use Table 3 in order to determine which clutches should be energized in each gear.

Adjustments for the Transmission Clutch Pressure

If the pressure difference between the transmission pump and one of the clutches is not within the values that are listed in Table 1, then transmission clutch valve may need replaced. After properly shutting down the machine, temporarily replace the valve and retest to see if the pressure is now within specification. If pressures are still out of specification after changing valves, the transmission may have an internal leak.

Reference: For additional information about calibrating the transmission clutch solenoid modulating valves, refer to the Service Manual module Testing and Adjusting, "Fill Time for the Transmission Clutch - Calibrate" for the machine that is being serviced.

Reference: For additional information about electrical system troubleshooting, refer to the Service Manual module Testing and Adjusting, "Troubleshooting Diagnostic Codes" for the machine that is being serviced.

Test for the Lubrication Oil Pressure

Use the following procedure to check the pressure of the transmission lubrication oil.

The pressure tap for the transmission lubrication oil is located on the front of the transmission under the cab. Access the tap from the left-hand side of the machine. Refer to Illustration 5.

1. Perform the steps in the "Machine Set Up" and then continue to the following steps.

2. Attach tooling (A) or (B) on pressure tap (12).

3. Start the engine and operate the engine at high idle with transmission in neutral. Observe the pressure gauge. With the oil at normal operating temperature, the lubrication oil pressure must be within the values in Table 1.

Test of the Torque Converter Outlet Pressure

1. Perform the steps in the "Machine Set Up" and then continue to the following steps.

2. Attach tooling (A) or (B) on pressure tap (2).

3. Start the engine and run the machine at the torque converter stall with the engine at high idle and transmission in neutral. With the oil at normal operating temperature, the torque converter outlet pressure must be within the values in Table 1.

Torque Converter Stall and Implement Pump Double Stall - Test

The following procedure is used in order to test the torque converter stall test.

Note: Insure that the transmission oil is at normal operation temperature. Machines operating under normal conditions 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 speed that is measured at the factory. The engine stall speed should be in the range that is shown.

The torque converter stall test helps determine if the engine is producing the correct power output. This stall test is used in many diagnostic procedures.

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

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

Machine Preparation

1. Position the machine on a smooth horizontal location.

2. Ensure that the parking brake is engaged. Apply service brake during test.

Test Procedure for Torque Convertor Stall

1. Run the engine and warm the machine to operation temperatures. Engine coolant and hydraulic oil should be at normal machine testing temperatures.

   Note: Warm transmission oil and torque converter oil to the temperatures listed in table.

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   Table 4

   Oil at Normal Operating Temperature
   Transmission Oil	Torque Converter Oil
   83° ± 7°C (181° ± 12°F)	93° ± 17°C (199° ± 30°F)

   • Fully apply parking brake and service brake. Select manual shift mode. Shift transmission to FOURTH SPEED, NEUTRAL.

2. Shift the transmission to FOURTH SPEED, FORWARD, and press throttle pedal to 100%.

3. A warning indicating that the machine is in gear with parking brake applied will appear on the display.

4. Once the engine speed stabilizes, record engine speed.

5. Shift the transmission to FOURTH SPEED, NEUTRAL, and release throttle pedal.
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   Table 5

   Stall Speed
   Stall speed for the 950M		Stall speed for the 962M
   Economy Mode Off 1980 +10/ - 20 rpm		Economy Mode Off 2020 +10/- 20 rpm

   If the torque converter stall speed is too high, the engine power output could be too high. (Not likely)

   If the torque converter stall speed is too low, the engine may not be developing full power. There may be a parasitic load on the engine.

Test Procedure for Torque Convertor Double Stall

1. Run the engine and warm the machine to operation temperatures. Engine coolant and hydraulic oil should be at normal machine testing temperatures.

   Note: Warm transmission oil and torque converter oil to the temperatures listed in table.

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   Table 6

   Oil at Normal Operating Temperature
   Transmission Oil	Torque Converter Oil
   83° ± 7°C (181° ± 12°F)	93° ± 17°C (199° ± 30°F)

   • Fully apply parking brake and service brake. Select manual shift mode. Shift transmission to FOURTH SPEED, NEUTRAL.

2. At low idle shift the transmission to FOURTH SPEED, FORWARD.

3. Fully place the bucket in the racked back position.

4. Place engine in HIGH IDLE.

5. Stall tilt fully in the racked back position, and command full lift.

6. Once the engine speed stabilizes, Record the stabilized engine speed that occurs when the lift cylinders are extending.

7. Shift the transmission to FOURTH SPEED, NEUTRAL, and release throttle pedal.
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   Table 7

   Double Stall Speed
   Stall speed for the 950M		Stall speed for the 962M
   Economy Mode Off 1480 +/- 100 rpm		Economy Mode Off 1530 +/- 100 rpm

   If the torque converter double stall speed is too high, the engine power output could be too high. (Not likely)

   If the torque converter double stall speed is too low, the engine may not be developing full power. There may be a parasitic load on the engine.

Test for the Torque Converter Inlet Pressure

1. Perform the steps in the "Machine Set Up" and then continue to the following steps.

2. Attach tooling (A) or (B) on pressure tap (4).

3. Start the engine and operate the engine at high idle with transmission in neutral. Observe the pressure. With the oil at normal operating temperature, the torque converter inlet pressure must be within the values in Table 1.

Torque Converter Lockup Clutch Pressure - 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 moving the machine to perform the test that follows.

Lockup Clutch Engaged (Maximum stabilized pressure)

Note: This test is performed while moving the machine. Ensure test area is safe to operate.

1. Install test equipment to test ports (3) and (5).

2. Enable lockup clutch in second gear.

3. Engage the parking brake.

4. Move the transmission direction control switch to the NEUTRAL position. Start the engine.

5. Apply the service brakes and release the parking brake

6. Release the service brakes

7. Place the transmission in SECOND SPEED forward.

8. Move the transmission direction control switch to the FORWARD position.

9. Increase the engine speed to high idle.

10. Operate the machine at maximum speed and observe the pressure reading on both gauges. Make sure that the left and right service brake pedals are not depressed. If either the left or right service brake pedal is depressed, the lockup clutch will not engage. Either the gauge pressure or the difference from pump pressure at pressure tap (5) and Lock-Up Clutch (3) must be within the values that are listed in Table 1.