SEGMENT- 1299208 - Caterpillar

Relief Valve (Main) - Test and Adjust (Heavy Lift)
Position the machine on level ground and stop the engine.
Release the pressure in the hydraulic system. Refer to Testing and Adjusting, "Hydraulic System Pressure - Release".
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Pump compartment (typical example) (1) Pressure tap (pressure for drive pump) (2) Pressure tap (pressure for idler pump) (3) Pressure tap (power shift pressure)
Attach a 60000 kPa (8700 psi) pressure gauge to pressure tap (1) .
Start the engine.
Place the machine controls at the following settings: engine speed dial "10" and AEC switch OFF. Refer to Testing and Adjusting, "Engine Performance - Test (Engine Speed)" for engine rpm settings.
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Set heavy lift switch (A) to the ON setting. Make sure that the indicator light is on.
Increase the hydraulic oil temperature to 55° 5°C (131° 9°F).
Raise the boom until the boom cylinder rods are at full extension.
Check the pressure setting of the heavy lift at pressure tap (1) .
Return the joystick for the boom to the NEUTRAL position.
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Typical example (4) Main relief valve (5) Locknut for the heavy lift (6) Adjustment screw for the heavy lift (7) Locknut for the main relief valve (8) Adjustment screw for the main relief valve
The heavy lift relief valve pressure setting should be 36000 500 kPa (5220 73 psi). If the heavy lift relief valve pressure setting is not within the specification, adjust the heavy lift relief valve pressure setting.
Loosen locknut (5) in order to adjust the relief valve for the heavy lift. Adjust the pressure by turning adjustment screw for the heavy lift (6) until the pressure gauge reading at pressure tap (1) is 36000 500 kPa (5220 73 psi).Note: Turning adjustment screw (6) clockwise increases the pressure. Turning adjustment screw (6) counterclockwise decreases the pressure.Note: Always make final pressure adjustments on pressure rise.
Tighten locknut (5) to a torque of 70 10 N m (50 7 lb ft).Note: Confirm the heavy lift pressure by raising the boom until the boom cylinder rods are at full extension.
Set heavy lift switch (A) to the OFF setting. The indicator light should not be illuminated.
Open the bucket until the bucket cylinder rod is at full retraction.
Check the main relief valve pressure setting at pressure tap (1) .
Return the joystick for the bucket to the NEUTRAL position.
The main relief valve pressure setting should be 35000 500 kPa (5075 72 psi). If the main relief valve pressure setting is not within the specification, adjust the main relief valve pressure setting.Note: During adjustment of screw (8), do not allow screw (6) to move.
In order to adjust the main relief valve, loosen locknut (7) and turn adjustment screw (8) until the pressure gauge reading at pressure tap (1) is 35000 500 kPa (5075 72 psi).Note: Turning adjustment screw (8) clockwise increases the pressure. Turning adjustment screw (8) counterclockwise decreases the pressure.Note: Always make final pressure adjustments on pressure rise.
Tighten locknut (7) to a torque of 50 10 N m (37 7 lb