Terex T780 - Hydraulic Cylinder Maintenance

Hydraulic Cylinder Maintenance
HYDRAULIC CYLINDER DISASSEMBLY
GENERAL
Refer to pages 5-37 and 5-38 for removal of cylinders from the boom. Do not disassemble
a cylinder unless no other maintenance procedure can correct the problem. All overhaul or
new cylinder installations should be done in a clean, dust-free atmosphere with all ports
plugged until hose connections are made.
BOOM EXTEND CYLINDERS
The outer case is the "moving" member of the cylinder. The hollow shaft is "stationary".
The hollow shaft ports the piston and case end to retract the cylinder while a tube within
the "shaft" ports the piston and head gland to extend the cylinder.
Disassemble the boom extend cylinders by the following procedure:
1.
Using an adjustable spanner wrench, remove head gland of cylinder. As head gland is
loosened, it may be necessary to begin to move rod out of cylinder tube.
2. With head gland fully disengaged, remove as an assembly, piston rod, head gland,
and piston assembly.
3. To remove piston, remove the setscrews which secure the piston retaining ring to
piston rod.
4. Remove piston and gland which allows access to all seal units of cylinder.
BOOM LIFT CYLINDER
Disassemble the boom lift cylinder by the following procedure:
1. Remove the locking socket head capscrew from the draw ring. CAUTION: Failure to
remove the locking capscrew may result in serious thread damage. With an adjustable
spanner wrench, remove the draw ring and head gland. N0TE: One turn off, back 1/3
turn, alternately.
2. Remove the head gland, shaft, and piston from the case.
3. Remove piston and gland by removing setscrews in retaining collar and removing
retaining nut. Remove piston and gland from rod. Access to all seal units is now possible.
HYDRAULIC CYLINDER INSPECTION
Wash the cylinder bore and all the components with solvent and make the following
inspections:
CYLINDER BORE
For signs of scoring and deep scratches. In the event of any defects, reassemble the entire
cylinder and contact your distributor.
CYLINDER SHAFT
501P/N 12261-683 REVISED: January 2015