For dents, deep scratches, or damaged chrome plating. File any sharp edges on ends of
shaft to protect the seals upon reassembly. Always protect the shaft finish when clamping
in a vice or when welding against weld splatter.
PISTON RINGS
For cracks or other damage. Particularly check the interlocking ends that they are not
missing or broken.
PISTON SEALS
For signs of severe damage. Do not remove unless replacement is necessary.
PISTON & HEAD GLAND
It is not normally necessary to replace the piston, piston rings, or head gland.
HYDRAULIC CYLINDER REASSEMBLY
GENERAL
As cylinder components are reassembled, be certain all rings, seals, spacers and
setscrews required in one step are in place before proceeding to the next step. See Group
39 of the Parts Book for a complete listing of cylinder parts.
A teflon ring must be installed before the piston ring or wear ring is installed since the teflon
ring must first be "walked" into the piston ring groove and then onto its own groove. Warm
the teflon ring until reasonably flexible and oil the piston ring or wear ring to aid in the
installation.
MOST PISTON RING BREAKAGE IS DUE TO CARELESS OR HASTY ASSEMBLY
AT THIS POINT.
BOOM LIFT CYLINDERS
With the piston, piston rod, head gland, retaining ring and rod eye reassemble as a unit,
slide the piston into the cylinder bore. Next, insert and seat the head gland. It may be
necessary to drive the gland into place using a wood block and hammer. In this event,
cover the rod with rags or a rubber tube to prevent damage from a glancing hammer blow.
The retaining ring is then spun in and tightened to secure the head gland. Install socket
capscrews. the retaining ring should be secured with Loctite Grade 242. Coat both grooves
around the thread ring as well as the bolt heads with a "silastic" type silicon sealant to keep
moisture out.
NOTE: When installing the piston ring nut on the piston rod, torque to 2500 ft. lbs.
and then secure with setscrew lock. Use Loctite Grade 242 on ring nut and setscrews.
BOOM EXTEND CYLINDERS
With the piston, piston rod, head gland, and retaining ring assembled as a unit, slide the
piston into the cylinder bore. Next, insert the head gland. It may be necessary to tap the
T300-1_T500-1_T780
Service / Parts
502 P/N 12261-683
REVISED: January 2015
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