STRAINER 3178272 - Caterpillar

Table 4
Relief Valve Pressure Change With One Turn Of Adjustment Screw
Main relief valve 14400 kPa (2100 psi)
Line relief valves 19800 kPa (2871 psi) Note: Pressure values in Table 4 are approximate values. Use a pressure gauge for adjustment.
Start the engine.
Select a work tool to meet the following conditions.
Two-way flow from one pump
Variable relief valve pressure set at the default specifications of 40,000 kPa.Refer to Testing and Adjusting, "Work Tool - Select" for the Tool Control System.
Place the hydraulic activation control lever in the UNLOCKED position.
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.
Increase the hydraulic oil temperature to 55° 5°C (131° 9°F).
Move the joystick for the stick until the stick is at the full STICK OUT position (full retraction of the stick cylinder).
Check the main relief valve pressure setting at pressure tap (1) or pressure tap (2). The main relief valve pressure setting should be 35000 500 kPa (5076 73 psi).
Illustration 5 g03627277
Main relief valve (standard)
(A) Adjustment screw
(L) Locknut
Illustration 6 g03627279
Main relief valve (heavy lift)
(A) Adjustment screw
(L) Locknut
Loosen the locknut. Set the main relief pressure to 37000 500 kPa (5366 73 psi). Tighten the locknut. Note: Turn the adjustment screw clockwise in order to increase the pressure. Turn the adjustment screw counterclockwise in order to decrease the pressure.Note: Always make final pressure adjustments on pressure rise.
Verify the temporary main relief pressure setting with a second function. Move the joystick for the boom until the boom is at full BOOM RAISE position (full extension of the boom cylinder). The main relief pressure should be 37000 500 kPa (5366 73 psi).
Illustration 7 g03635676
Line relief valve for extension of the attachment control valves (typical example)
Mark the original position of the line relief for the attachment control valve extend.
Illustration 8 g02292583
Control Inputs