BOOM HOIST CYLINDERS MAINTENANCE - CONTINUED
Hydraulic oil, under pressure, can remain within cylinder after disconnecting hydraulic hoses. To avoid
severe personal injury, slowly loosen counterbalance valve and allow pressure to escape before removing
Use a vise with soft jaws to secure cylinder in a horizontal position for disassembly.
Relieve pressure in cylinder by slowly removing
counterbalance valve (1). Drain residual oil through
valve holes into a suitable container.
Remove back-up rings (2 and 3), two back-up rings
(4) and three O-rings (5 thru 7) from each counterbal-
ance valve (1). Discard back-up rings and O-rings.
Do not scratch or damage the wear surface
of rod, piston or gland. Follow this precau-
tion to prevent failure of the cylinder.
Pull rod (8) out approximately 5 in. (12.7 cm) for
removal of gland (9).
Place a container under gland (9) to catch oil con-
tained in cylinder.
Use a spanner wrench to unscrew gland (9) from cyl-
inder tube (10). Pull gland (9) out of cylinder far
enough to unseat O-ring (11). Allow oil to drain into
Use care when removing rod and piston assembly to prevent wear ring damage. Keep rod in line with cylin-
der tube to prevent binding.
Remove rod (8) and piston assembly from cylinder tube (10).
Place rod and piston assembly on suitable supports to prevent damage.
Remove two wear rings (12).