Page 48 | Stellar
®
Heavy-Duty Telescopic Crane Owner’s Manual
Problem: Winch “Up”, Main Cylinder “Down”, and Extension Cylinder “Out” are the only functions
that don’t operate.
Solutions:
• Make sure that the anti-two block weight and chain on the end of the boom are straight so
they slide easily along the wire rope cable.
• Make sure that the limit switch is working properly. Disconnect the two wires connected to the
limit switch and tie them together. If all functions operate, replace the limit switch.
• Make sure that the cord for the cord reel is undamaged. Check the continuity of the cord.
Disconnect the cord reel from the crane harness and bypass the harness connection. If the
crane operates properly, replace cord reel.
Problem: Cylinder drifts outward or downward.
Solutions:
• Check to see if there is air in the hydraulic system. Operate all cylinders connected to the
hydraulic system. Start with the extension cylinder, then operate the main boom, winch,
rotation, and ending with the hydraulic stabilizers, if installed. When operating, extend each
cylinder halfway out, retract all the way in, and then extend until the cylinder rod is at the end
of its stroke. Operate cylinders slowly so air is pushed through the system to the reservoir. Repeat
this cycle 2-3 times.
• Make sure the holding valves are operating properly. Note: Before performing any maintenance
on hydraulic components, relieve hydraulic oil pressure from all hydraulic circuits. Remove,
clean, and then inspect each holding valve. When removing a holding valve, always relieve
the pressure inside the cylinder by loosening jam nut of the holding valve and turning set screw
inward/clockwise. Count the number of turns until the set screw is seated. When reinstalling the
holding valve, make sure the valve is reset by turning the set screw the number of turns it took
to relieve the pressure. Finish by tightening the jam nut.
• Check the cylinder rod for scratches. If a scratch is located on the cylinder rod, hydraulic uid
can pass through and cause a loss of pressure. Replace cylinder rod or cylinder.
• Check to see if the piston seals are damaged. If they show signs of damage, install a new
cylinder seal kit.
Courtesy of CraneMarket.com
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