KIT-LINING 3869394 - Caterpillar

Boom load may cause cylinder oil pressure to reach relief pressure of the boom lowering control device when the boom is supported by one cylinder. Boom can lower suddenly.Be sure no one is under or near the implements before manually lowering the boom.Keep all personnel away from the boom drop area when lowering the boom with the engine stopped.
Illustration 1 g00949436
(1) Boom lowering control valve
(2) Locknut
(3) Set screw Note: The boom lowering control valve is at the base of the boom cylinder. The boom lowering control device allows the operator to manually lower the boom if the engine is stopped. The boom lowering control device also prevents a sudden drop of the boom if there is an oil leak in the hydraulic line of the boom.
Loosen locknut (2).
Slowly, turn set screw (3) counterclockwise until the boom begins to lower onto the ground. Note: Once the boom begins to lower, stop turning set screw (3).
After the boom has lowered completely onto the ground, turn set screw (3) back to the original position.
Tighten locknut (2).
Make any necessary repairs before placing the excavator back into service. Note: Consult your Caterpillar dealer for further information.