CORRECTIVE ACTION - Continued
With hydraulic oil at a working temperature, elevate boom to a 60 degree angle and suspend a
5 ton (4.54 metric ton) load on a two-part line 1 ft (305 m) off ground. Extend telescoping section
approximately 1/2 of full extension. Shut engine off. Disconnect hose from tube on left side of
boom. Extend cylinder at boom base. Some hydraulic oil should run out, but will stop. Pull boom
extend lever to the retract position and hold. Boom should hold its position.
If boom retracts and no hydraulic oil comes out of tube, counterbalance valve must
If boom retracts and hydraulic oil comes out of tube, boom extend cylinder is bypassing and
Counterbalance Valve Not Seating Properly.
O-ring Around Counterbalance Valve Damaged.
Boom Extend Cylinder Bypassing.
END OF WORK PACKAGE