CONE-BEARING 7Y0825 - Caterpillar

Boom Lowering Control Valve
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, causing possible injury or death.To avoid possible injury or death, be sure no one is under or near the work tool before manually lowering the boom.Keep all personnel away from the boom drop area when lowering the boom with the engine stopped.
If the engine is shut down or the hydraulic system is disabled, the operator can still lower the boom. Use the following procedure if the machine is equipped with a boom lowering control valve.
Illustration 1 g01221008
(5) Locknut
(6) Check valve The boom lowering control valve (if equipped) is installed on each of the boom cylinders. The boom lowering control valve allows the operator to manually lower the boom if the engine is stopped. The boom lowering control valve also prevents the sudden descent of the boom if there is an oil leak in the hydraulic line of the boom.
Loosen locknut (5) of the boom lowering check valve.
Slowly turn check valve (6) counterclockwise until the check valve stops. The boom will lower to the ground.
Make sure that the work tool has been completely lowered onto the ground. Tighten check valve (6).
Tighten locknut (5) to a torque of 2.25 0.25 N m (1.66 0.18 lb ft).
Before operating the machine, make any necessary repairs. For additional information, consult your Caterpillar dealer.