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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 following test will verify whether the pressure of the power train oil that is delivered from the priority valve is within the specified limits. This test will check the pressure when the priority valve is in PRIORITY MODE (high pressure).
The priority valve pressure should be set with the following conditions: engine at LOW IDLE, parking brake off and power train oil at operating temperature.
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.
- Extend the counterweight fully. Engage the parking brake. Turn the engine OFF.
- Place the counterweight lock lever in the LOCK position.
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| Illustration 3 | g01283132 |
- Place the counterweight control lock in the LOCK position.
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| Illustration 4 | g01286574 |
- Locate the remote pressure taps.
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| Illustration 5 | g01286581 |
The pressure tap for the priority valve is located behind the access door on the right fender of the machine. | |
- Attach tooling (A or B) to pressure tap (P2) .
The priority valve will regulate the oil at high pressure in the following conditions:
- Engine speed is less than 1300 rpm and the parking brake is off. (The priority valve will remain at high pressure until the engine rpm reaches 1350 rpm.)
- A transmission shift is in progress.
- The power train oil temperature is less than 40 °C (104 °F). (The priority valve will remain at high pressure until the power train oil temperature reaches 45 °C (113 °F).)
- A transmission clutch fill calibration is in progress.
- Engine speed is less than 1300 rpm and the parking brake is off. (The priority valve will remain at high pressure until the engine rpm reaches 1350 rpm.)
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| Illustration 6 | g01286683 |
The power train oil filter is not pictured. (P2) Pressure Tap for the Priority Valve (M) Pressure Tap for the Torque Converter Inlet (N) Pressure Tap for the Torque Converter Outlet | |
- Start the engine. Warm the power train oil to a temperature of 80° ± 10°C (176° ± 18°F).
- Make sure that the transmission is in NEUTRAL.
- Operate the engine at LOW IDLE (800 rpm).
- Disengage the parking brake.
- Check the pressure at tooling (A or B). The pressure at tooling (A or B) should be 2760 ± 105 kPa (400 ± 15 psi) (high pressure).
Note: When the parking brake is engaged the pressure at tooling (A or B) will always be low pressure.
ReferenceSee Specifications, Systems Operation/Testing and Adjusting, "Pressure Charts" in this module for additional pressure values.
- If the pressure at tooling (A or B) is not within the specified limits, perform the following adjustment procedure.
Adjustment Procedure
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| Illustration 7 | g00618395 |
(3) Priority valve (4) Inlet relief valve (torque converter) (28) Adjustment screw for the torque converter inlet (29) Adjustment screw for the priority valve | |
- Loosen the locknut that is on adjustment screw (29). Maintain the position of the adjustment screw.
Note: One turn of the adjustment screw changes the pressure setting by 135 kPa (20 psi).
- Turn adjustment screw (29) by the desired amount.
- Do not allow the adjustment screw to rotate when the locknut is tightened.
- Tighten the locknut to a torque of 25 ± 4 N·m (18 ± 3 lb ft).