Tools Needed     | Qty     |
6V-3079 Pressure Hose Assembly     | 2     |
6V-4143 Coupler Assembly     | 4     |
8T-0856 Pressure Gauge ( 0 to 6000 kPa (0 to 870 psi))     |
1     |
8T-0857 Pressure Gauge ( 0 to 10000 kPa (0 to 1450 psi))     |
1     |
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Hydraulic oil pressure can remain in the hydraulic oil system on this machine after the engine and pump have been stopped. Serious injury can be caused if this pressure is not released before any service is done on the hydraulic systems. To prevent possible injury, refer to the procedure in Testing and Adjusting Manual, "Release of Pressure in the Hydraulic System". When possible, the bucket must always be lowered to the ground before service is started. When it is necessary for the boom to be in the raised position while tests or adjustments are done, be sure that the boom, stick and bucket have correct support. Be sure the swing parking brakes and the travel parking brakes are on and the brake release lines are disconnected and plugged. 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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Note: Always warm the hydraulic oil to a minimum temperature of 50°C (122°F) before starting the testing and adjusting procedure.
Note: Any change to the low pilot system pressure also changes the high pilot system pressure. Always set the low pilot system pressure before setting the high pilot system pressure.
Low Pressure Pilot Relief Valve
Preparation
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Illustration 1 | g00434558 |
Pilot Manifold (1) Low pilot pressure tap |
Connect a 5515 kPa (800 psi) pressure gauge to low pilot pressure tap (1) on the pilot manifold.
- Connect the 6V-4143 Coupler Assemblies to the 6V-3079 Pressure Hose Assemblies .
- Connect a hose assembly to pressure tap (1) and a 8T-0856 Pressure Gauge .
- Start the engine.
- Warm the oil to a minimum temperature of 50 °C (122 °F). Refer to the Testing and Adjusting, "General Information" for the proper procedure for warming the hydraulic oil.
- Set the throttle switch to position 3. Read the pressure gauge that is connected to pressure tap (1). The pressure should be 4500 ± 200 kPa (630 ± 29 psi).
- To adjust the pilot pressure for the low pressure pilot circuit, loosen the locknut (3) on the relief valve (2). Turn the adjustment screw (4) until the pressure gauge indicates 4500 ± 200 kPa (630 ± 29 psi). Tighten locknut (3) .
Note: Always make pressure adjustments on the pressure rise.
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Illustration 2 | g00434666 |
Pilot Manifold (2) Low pressure pilot relief valve |
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Illustration 3 | g00434667 |
Pilot Relief Valve (3) Locknut (4) Adjustment screw |
- With the engine at throttle position 1, verify that the low idle setting is at 725 ± 20 rpm. The low pilot system pressure should be no less than 3100 kPa (450 psi). If the low pilot system pressure is less than 3100 kPa (450 psi), refer to Testing and Adjusting, "Hydraulic System Troubleshooting".
High Pressure Pilot Relief Valve
Preparation
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Illustration 4 | g00434668 |
Pilot Manifold (5) High pressure pilot relief valve (6) High pilot pressure tap |
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Illustration 5 | g00434794 |
Pilot Hydraulic Oil Filter (7) High pilot pressure tap |
- Connect the 6V-4143 Coupler Assemblies to the 6V-3079 Pressure Hose Assemblies .
- Connect a hose assembly to pressure tap (6) or to pressure tap (7) and a 8T-0857 Pressure Gauge .
- Start the engine.
- Warm the oil to a minimum temperature of 50 °C (122 °F). Refer to the Testing and Adjusting, "General Information" for the proper procedure for warming the hydraulic oil.
- Set the throttle switch to position 10.
- Monitor the engine speed and verify that the high idle setting is at 1810 ± 20 rpm. Read the pressure gauge that is connected to pressure tap (6) or pressure tap (7). The pressure should be 7000 ± 200 kPa (1015 ± 29 psi).
- To adjust the pilot pressure for the high pressure pilot circuit, loosen the locknut (3) on the relief valve (5). Turn the adjustment screw (4) until the pressure gauge indicates 7000 ± 200 kPa (1015 ± 29 psi). Tighten locknut (3) .
Note: Always make pressure adjustments on the pressure rise.