SEAL 4Q5139 - Caterpillar

Illustration 3 g02102305
Main relief valve (standard) (A) Adjustment screw (L) Locknut
Illustration 4 g02102306
Main relief valve (heavy lift) (A) Adjustment screw (L) Locknut
Loosen the locknut. Set the main relief pressure to 40000 500 kPa (5802 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.
Mark the original position of the line relief valve for the boom cylinder head end.
Move the joystick for the boom until the boom is at the full BOOM RAISE position (full extension of boom cylinders).
Check the pressure setting of the line relief for the boom cylinder head end.
Loosen the locknut of the boom line relief valve. Turn adjustment screw of the boom line relief valve until the pressure reading is 38000 kPa (5512 psi).
Move the joystick for the boom until the boom is at the full BOOM RAISE position (full extension of boom cylinders).
Check the pressure setting of the line relief for the boom cylinder head end.
Turn the adjustment screw of the boom line relief valve until the pressure reading at pressure tap (1) is 40000 500 kPa (5802 73 psi).Note: Always make final pressure adjustments on the pressure rise.Note: In order to prevent over setting, the adjustment should be stopped immediately after the pressure becomes within specification.
Move the joystick for the stick until the stick is at the full STICK OUT position (full retraction of stick cylinder).
Check the pressure setting of the line relief for the stick cylinder rod end.
Loosen the locknut for the stick line relief valve. Turn adjustment screw of the stick line relief valve counterclockwise until the pressure reading is 38000 kPa (5512 psi).
Move the joystick for the stick until the stick is at the full STICK OUT position (full retraction of stick cylinder).
Check the pressure setting of the line relief for the stick cylinder rod end.
Turn the adjustment screw of the stick line relief valve until the pressure reading at pressure tap (1) is 40000 500 kPa (5802 73 psi).Note: Always make final pressure adjustments on the pressure rise.Note: In order to prevent over setting, the adjustment should be stopped immediately after the pressure becomes within specification.
Reset main relief valve pressure setting to the normal operating condition after the completion of the line relief test and adjust. Refer to Testing and Adjusting, "Relief Valve (Main) - Test and Adjust".Procedure for 374D
The procedure for 390D will be similar to the 374D. Refer to your machine Testing and Adjusting, "Relief Valve (Line) - Test and Adjust" for the correct line relief settings.37 MPa Line Relief Valves
Mark the original position of the line relief valve for the stick cylinder rod end.
Loosen the locknut for line relief valve for the stick cylinder rod end. Turn the adjustment screw clockwise by one quarter turn. Tighten the locknut.
Start the engine.
Place the hydraulic activation control lever in the UNLOCKED position.
Place the machine controls at the following settings:
Engine speed