PISTON ROD PACKING
When assembling the piston rod packing, always
use new seals, "O" rings, back-up rings and dirt
wipers. It IS also recommended that a tool be fab-
r i c a t e d which will aid in installing the packing
on the piston rod.
Examine the inside of the cylinder tube for ex-
cessive wear caused by dirt. foreign material or by
the piston contacting the cylinder wall. Usually the
majority of wear takes place in the center of the tube.
Cylinders can be bored as much as .010 inch(.254mm)
to clean up scratches and score marks. If more ma-
terial must be removed to clean away scratches, the
tube must be replaced because oversize pistons and
packings are not available.
The tool i S a cone which fits snugly on the rod
Examine the welds which hold the cylinder ends
where the piston would normally fit. The cone is
and pipe connecttons in place. Look for cracks and
tapered so that as the packing is slid over it. the
small holes. The best way to check them IS to pres-
lips on the seals are expanded and slide easily on-
surize the cylinder to 2500 psi (175 Kg/cm) and
to the main portion of the rod.
look for leaks.
If the piston rod packing is of the mono seal type,
Check the large opening in the end of the cylin-
follow these instructions:
der and the smaller holes which conduct oil into
and out of the cylinder to see that they are prop-
erly chamfered. Sharp edges in these areas will cut
If the cylinder mounting bushings are worn, re-
move them and press new bushing in place. Be sure
to align grease holes. Bushings on trunion mounted
cylinders (Fig 3) should be tack welded in 3 places
after being pressed into place.
1. Install back-up ring (14) and O-ring (13) on the
PISTON AND PISTON ROD
cylinder cap (15). The back-up ring sits next to
Examine the piston rod to see that it is not bent,
the O-ring opposite the side which receives the
scratched or pitted and the chrome plating IS in good
shape. It may be necessary to press a new bushing
2. Place a thin coat of light grease on the mono
into the piston rod eye - if so make sure to align
the grease hole in the bushing with the one in the
s e a l (16) and slide the seal into the cylinder
cap (15). The lips of the seal must point toward
the oil pressure.
Examine the piston for scratches and wear marks.
Replace the piston if it shows signs of damage.
3. Press a new dirt wiper (20) into the mono seal