 |
Hydraulic oil pressure can remain in the hydraulic system on this machine after the engine and pump have been stopped. Serious injury can result if this pressure is not released before any service is done on the hydraulic systems. In order to prevent possible injury, release the hydraulic system pressure before working on any fitting, hose, or hydraulic component. Lower all attachments to the ground before service is started. If the hydraulic system must be serviced, tested, or adjusted with the attachment in the raised position, the attachments and lift cylinders must be supported properly. Always move the machine to a location away from the travel of other machines. Be sure that other personnel are not near the machine when the engine is running and tests or adjustments are being made. |
 |
| NOTICE |
|---|
Care must be taken to ensure that fluids are contained during performance of inspection, maintenance, testing, adjusting, and repair of the machine. Be prepared to collect the fluid with suitable containers before opening any compartment or disassembling any component containing fluids. Dispose of all fluids according to local regulations and mandates. |
Introduction
The main relief valve for the transmission maintains the maximum pressure of the oil that is delivered to the transmission clutches by the transmission modulating valves. Also, the main relief valve protects the transmission hydraulic system from any high pressure spikes.
The following test procedure will verify whether the pressure setting is within the specified limit. The adjustment procedure provides the information that is needed to adjust the main relief valve to the specified limit.
Required Tools
 | |
| Illustration 1 | g01161467 |
Tooling (A) | |
| Required Tools | ||||
|---|---|---|---|---|
| Tooling | Item | Part Number |
Description | Qty |
| A | A1 | 8T-0855 | Pressure Gauge 0 to 4000 kPa (0 to 580 psi) |
1 |
| A2 | 6V-3989 | Fitting | 1 | |
| A3 | 6V-4143 | Coupler | 2 | |
| A4 | 177-7861 | Hose As 0 to 6000 kPa (0 to 870 psi) |
1 | |
Test Procedure (Transmission Main Relief Valve)
- Move the machine to a smooth horizontal location.
- Lower all of the implements.
- Install tooling (A) on pressure tap (P) .
 | |
| Illustration 2 | g01168283 |
(E) Pressure Tap for the Transmission Main Relief Valve (L) Pressure Tap for the Transmission lubrication | |
- Start the engine. Warm the hydraulic oil to a minimum temperature of 80° ± 5°C (176° ± 9°F).
- Operate the engine at HIGH IDLE (2110 rpm). Make sure that the steering control lever is in the NEUTRAL position. Disengage the parking brake.
- Check the pressure at tooling (A). The pressure at tooling (A) should be 3035 ± 140 kPa (440 ± 20 psi).
- Operate the engine at LOW IDLE (800 rpm). Make sure that the steering control lever is in the NEUTRAL position. Engage the parking brake.
- Check the pressure at tooling (A). The pressure at tooling (A) should be 2860 ± 210 kPa (415 ± 30 psi).
Reference: Refer to Testing and Adjusting, "Pressure Charts" in this module for additional pressure values.
- If the pressure at tooling (A) is within the specified limit, the test is complete. If the pressure at tooling (A) is not within the specified limit, perform the procedure in "Adjustment Procedure for the Main Relief Valve".
Adjustment Procedure for the Main Relief Valve
- Perform the steps in "Test Procedure (Transmission Main Relief Valve)".
- Remove 21 bolts (1) from back cover (2). Remove back cover (2) .
 | |
| Illustration 3 | g01161472 |
(1) Bolts (2) Back Cover | |
- Loosen locknut (26). Maintain the position of adjustment screw (27) .
 | |
| Illustration 4 | g01168323 |
(21) Transmission Main Relief Valve | |
 | |
| Illustration 5 | g01168325 |
(21) Transmission Main Relief Valve (26) Locknut (27) Adjustment Screw | |
- Start the engine. Run the engine at low idle (800 rpm). Rotate adjustment screw (27) in order to adjust the pressure setting. Adjust the main relief valve in order to obtain a pressure of 2860 ± 210 kPa (415 ± 30 psi).
- Do not allow adjustment screw (27) to rotate when the locknut is tightened.
- Tighten the locknut to a torque of 18 ± 4 N·m (159.0 ± 35.0 lb in).
- Use 21 bolts (1) in order to attach back cover (2) .