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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. |
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| NOTICE |
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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 transmission relief valve maintains the maximum pressure of the oil that is delivered to the transmission clutches by the transmission modulating valves. Also, the transmission 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 limits. The adjustment procedure provides the information that is needed to adjust the transmission relief valve to the specified value. The pressure setting of the transmission relief valve should be set with the engine at LOW IDLE.
Required Tools
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| Illustration 1 | g01089423 |
Tooling (A) | |
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| Illustration 2 | g01089425 |
Tooling (B) ( 6V-7830 Pressure Gauge (Tetragauge)) | |
| Required Tools | ||||
|---|---|---|---|---|
| Tooling | Item | Part Number |
Description | Qty |
| A | A1 | 8T-0855 | Pressure Gauge 4000 kPa (580 psi) |
1 |
| A2 | 6V-3989 | Fitting | 1 | |
| A3 | 6V-4143 | Coupler | 2 | |
| A4 | 177-7861 | Hose As 41370 kPa (6000 psi) |
1 | |
| B | B1 | 8T-0862 | Pressure Gauge 500 kPa (72 psi) |
1 |
| B2 | 8T-0860 | Pressure Gauge 40000 kPa (5800 psi) |
1 | |
| B3 | 8T-0855 | Pressure Gauge 4000 kPa (580 psi) |
1 | |
| B4 | 6V-3081 | Hose As 41500 kPa (6020 psi) |
1 | |
| B5 | 4S-6399 | Connector | 1 | |
| B6 | 6V-4144 | Coupler | 1 | |
Test Procedure
- Move the machine to a smooth horizontal location.
- Fully retract the counterweight.
- Locate pressure tap (1) ("P") on the machine. Pressure tap (1) ("P") is located above the five pressure taps for the transmission at the rear of the machine.
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| Illustration 3 | g01249931 |
(1) Pressure Tap ("P") (2) Cover (3) Bolts and Washers (4) Pressure Taps (Transmission Modulating Valves) | |
- Attach tooling (A or B) to pressure tap (1) ("P").
- Start the engine. Warm the power train oil to a temperature of 84° ± 8°C (183° ± 14°F).
- Operate the engine at LOW IDLE (700 rpm). Make sure that the steering control lever is in the NEUTRAL position.
- Check the pressure at tooling (A or B). The pressure at tooling (A or B) should be 2760 ± 140 kPa (400 ± 20 psi).
ReferenceSee Specifications, Systems Operation/Testing and Adjusting, "Pressure Charts" in this module.
- If the pressure at tooling (A or B) is not within the specified limits, perform the following adjustment procedure.
Adjustment Procedure
- The transmission relief valve is located behind cover (2), above pressure taps (4) for the transmission modulating valves.
| | |
| Illustration 4 | g01249931 |
(1) Pressure Tap ("P") (2) Cover (3) Bolts (4) Pressure Taps (Transmission Modulating Valves) | |
- Loosen and remove bolts (3) .
- Remove cover (2) .
- Loosen locknut (7) on relief valve (5). Maintain the position of adjustment screw (8) .
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| Illustration 5 | g01089801 |
(5) Relief Valve (6) Transmission Hydraulic Control | |
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| Illustration 6 | g01222630 |
(5) Relief Valve (7) Locknut (8) Adjustment Screw | |
- Turn adjustment screw (8) clockwise in order to increase the pressure at tooling (A or B). Turn adjustment screw (8) counterclockwise in order to decrease the pressure at tooling (A or B) .
Note: One turn of the adjustment screw changes the relief valve setting by 235 kPa (34 psi).
- Tighten locknut (7) to a torque of 18 ± 4 N·m (13 ± 3 lb ft).
- Perform the test procedure again.
- If the pressure is within the specified limits the adjustment procedure is complete.
- Install cover (2) with bolts (3) .