NIPPLE 7S8888 - Caterpillar

Machines with a Drift Reduction Valve
If the engine is stopped or the hydraulic system is disabled, the operator can still lower the boom. Use the following procedure if the machine is equipped with a Drift Reduction 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.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 g00289939
Bodily injury can occur from unexpected contact with open cab doors on machines equipped with a fixed cab riser.To avoid injury, close the cab door before climbing onto the rear of the machine.
Open the access door on the left side of the machine. Secure the access door.
Illustration 2 g00103395
This photograph is only for illustrative purposes. The photograph may not reflect the drift reduction valves on your machine. Location (1) is the location of the drift reduction valve for machines that are equipped with a VA boom. Location (2) is the location of the drift reduction valve for machines that are not equipped with a VA boom.
Remove the cap.
Loosen the locknut.
Record the initial position of the screw. Slowly turn the screw until the boom begins to lower. Do not turn the screw more than 90 degrees.
Completely lower the front implement to the ground. Return the screw to the initial position that was recorded in Step 4.
Tighten the locknut. Install the cap.
Close the access door.
After completion of the manual boom lowering, make any necessary repairs before