VALVE KIT 1C3799 - Caterpillar

Boom Lowering with the Engine Stopped
To lower the boom, place the control lever into the Boom Down position. If the accumulator still has a charge, the boom will lower.If the boom fails to lower, the accumulator is empty. Use one of the following procedures to lower the boom.Boom Lowering with the Engine Stopped For Machines Not Equipped With a Boom Lowering Control Device
Use the following procedure when it is necessary to lower the boom while the engine is shut down or if the hydraulic system is disabled.
Be sure no one is under or near the front implement before manually lowering the boom.Keep all personnel away from the boom area when lowering the boom with the engine stopped.
Loosen screw (2) of the vent valve a maximum of a 1/2 turn to lower the boom. Never try to activate any valves other than the vent valve.
1. Check to be sure that no one is under or near the front implement. Slowly loosen locknut (1) and then loosen screw (2) [width across flats: 6.35 mm (.25 in)] counterclockwise a maximum of a 1/2 turn. The boom will continually lower until it is seated on the ground.2. Make sure that the front implement has lowered completely onto the ground. Tighten the screw and locknut.3. Contact your Caterpillar dealer and make the necessary repairs. The vent valve must remain in the fully closed position unless boom lowering is done.Boom Lowering with the Engine Stopped For Machines Equipped With a Boom Lowering Control Device
Use the following procedure when it is necessary to lower the boom while the engine is shut down or the hydraulic system is disabled and the excavator is equipped with a boom lowering control device.
Boom load may cause the cylinder oil pressure to reach the relief pressure of the boom lowering control device when the boom is supported by one cylinder. The boom can lower suddenly.Be sure no one is under or near the front implement before manually lowering the boom.Keep all personnel away from the boom drop area when lowering the boom with the engine stopped.
A boom lowering control device (if equipped) is installed on each of the boom cylinders, as shown. The boom lowering control device allows the operator to manually lower the boom with the engine stopped. The boom lowering control device also functions to prevent a sudden drop of the boom in case there is an oil leak in the boom line.1. Loosen the locknut of one boom lowering control device and then slowly loosen the piston screw until it stops. Do the same for the other boom lowering control device. The boom will start to lower slowly.2. After making sure that the front implement has lowered completely onto the ground, securely tighten the piston screw and then tighten the locknut to a torque of 10 1 N m (7 1 lb ft).3. Make any necessary repairs before placing the excavator back into service. For further information, contact your Caterpillar dealer.