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| Illustration 1 | g00728811 |
Location of Test Points and Ports on Transmission (1) Inlet from oil cooler (2) Outlet to oil cooler (3) Test point (converter outlet temperature and pressure) (4) Test point (converter inlet pressure) (5) Test point (regulated pressure for all clutches) (6) Test point (forward high clutch pressure) (7) Test point (reverse clutch pressure) | |
Problems with the transmission may be caused by mechanical faults, electrical faults or hydraulic faults. The mechanical components and the electrical components must be in good condition and the components must operate properly. In addition, the correct operation of the transmission hydraulic system is critical. The transmission oil circulates through the system for operation, for lubrication, and for cooling.
To ensure the correct operation of the torque converter and the clutches in the transmission, the oil must be supplied in the correct quantity. Also, the oil must be regulated at the required temperature and the required pressures.
The operating temperatures and the operating pressures can be checked in order to help you identify problems when you are troubleshooting the system.
The regulated pressure in the system and the operating pressures of the clutches can be checked with a pressure gauge at test point (5) .
Test points (6) and (7) are provided if a problem is evident with a particular direction clutch.
Test the transmission pressures according to the following procedures:
Pressure Tests
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Make reference to the WARNINGS on the first several pages of the Testing And Adjusting section. |
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| Required Tools | ||
| Qty | Part Number | Description |
| 1 | 9U-7400 | Multitach Tool Group |
| 1 | 8T-0855 | Pressure Gauge (0 to 4,000 kPa (0 to 580 psi)) |
| 1 | 8C-7575 | Adapter |
| 1 | 5P-4675 | Adapter |
| 1 | 6V-3966 | Fitting |
| 1 | 6V-4143 | Coupler |
| 1 | 177-7861 | Hose As |
| 1 | 6V-4142 | Fitting |
| 1 | 6V-4144 | Coupler |
Install the 9U-7400 Multitach Tool Group on the engine in order to enable an accurate measurement of the engine speed (rpm). Refer to Special Instruction, NEHS0605 for further information on the use of this equipment.
Oil level check
Pressure tests must be made with the oil in the transmission at the correct level and at the normal operating temperature. Use the following procedure to check the oil level:
- Operate the machine until the oil in the transmission is at 87.5° ± 5.5°C (190° ± 10°F).
- Operate the engine at low idle.
- Remove the filler cap and the dipstick from the transmission and check the level mark.
- If necessary, add oil. Install the filler cap and the dipstick.
Torque Converter Outlet Pressure
- The torque converter outlet pressure can be tested at test point (3). Remove the plug from the test point. Install the 8T-0855 Pressure Gauge (0 to 4,000 kPa (0 to 580 psi)) with the following fittings:
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| Illustration 2 | g00743704 |
View of Test Point for Torque Converter Outlet (3) Test Point (converter outlet pressure) | |
- Start the engine and operate the engine at 2000 rpm.
- The pressure should be a minimum of 172 kPa (25 psi) and a maximum of 483 kPa (70 psi) when the engine is operating at 2000 rpm.
- Remove the fittings and install the plug that was removed from the test point.
Torque Converter Inlet Pressure
- The torque converter inlet pressure can be tested at test point (4). Remove the plug from the test point. Install the 8T-0855 Pressure Gauge (0 to 4,000 kPa (0 to 580 psi)) with the following fittings:
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| Illustration 3 | g00743550 |
View of Test Point for Torque Converter Inlet (4) Test Point (converter inlet pressure) | |
- Start the engine and operate the engine at 2000 rpm.
- The pressure should be a minimum of 172 kPa (25 psi) and a maximum of 483 kPa (70 psi) when the engine is operating at 2000 rpm.
- Remove the fittings and install the plug that was removed from the test point.
Regulated Pressure and Clutch Operating Pressures
- Park the machine in position against a solid, stationary object such as a loading dock.
- Remove the cap from test point (5) for regulated pressure. Install the 8T-0855 Pressure Gauge (0 to 4,000 kPa (0 to 580 psi)) with the following fittings:
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| Illustration 4 | g00743551 |
View of Test Point for All Clutch Pressures (5) Test Point (regulated pressure for all clutches) | |
- Start the engine and operate the engine at low idle.
- The pressure reading should be 1380 ± 140 kPa (200 ± 20 psi).
- Check that the switch for transmission neutralizer on the instrument panel is in the OFF position.
- Disengage the parking brake.
- Apply the service brake in order to hold the machine stationary. Select each transmission speed in sequence for forward direction and reverse direction. Note each of the readings on the pressure gauge. All clutch pressures must be equal within 35 kPa (5 psi) of the pressure reading in Step 4.
- Engage the parking brake and stop the engine. Remove the test equipment and install the cap that was removed from the test point.
- If a particular problem with the forward high clutch is indicated by the operational checks, install the test equipment at test point (6) for the clutch. Move the transmission control to the appropriate direction and check the pressure. The pressure reading for the forward high clutch should be 1350 ± 170 kPa (195 ± 25 psi).
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| Illustration 5 | g00743552 |
View of Test Point for Forward High Clutch Pressure (6) Test Point (forward high clutch pressure) | |
- If a particular problem with the reverse clutch is indicated by the operational checks, install the test equipment at test point (7) for the clutch. Move the transmission control to the appropriate direction and check the pressure. The pressure reading for the reverse clutch should be 1350 ± 170 kPa (195 ± 25 psi).
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| Illustration 6 | g00743553 |
View of Test Point for Reverse Clutch Pressure (7) Test Point (reverse clutch pressure) | |