Group 34, Uprights
34-5-4 • Cylinder Removal, Shimming, Overhaul, and Replacement SM 765, Nov ’06
8. Disconnect the cylinder rod retaining bolts.
In Hi-Lo upright, Remove the cylinder hoses.
9. Remove the cylinders by raising the inner rail (and
intermediate rail on the triple stage upright) to free
the cylinder rod ends from the tie bar.
10. Remove any shims and note number and location.
11. Lift the cylinders off the base mount.
Use these steps in reverse to replace the cylinders. Torque
the cylinder rod retaining bolts to 20-25 N⋅m (14.8-18.5
ft-lb). Torque the cylinder guide bolt nuts to 30-35 N⋅m
(22.2-25.6 ft-lb). Check Group 40 for hydraulic fitting
tightening procedures.
Cylinder Overhaul
Use these steps to overhaul the primary and lift and sec-
ondary (TSU) cylinders.
N
TE
During overhaul, set rod or cylinder on a
work bench with adequate support for safe
and convenient disassembly. Two sets of 4x4
in (100x100 mm) “V”-notched blocks are
helpful; one set for the cylinder barrel and
one set for the piston rod. The blocks prevent
nicks and scratches from harming the piston
or rod.
Cylinder Disassembly
• To overhaul the primary cylinder, it is not neces-
sary to remove the cylinder from the upright.
Instead, free the rod end of the cylinder as
explained in “Cylinder Removal.”
• To overhaul piston-type cylinders, you should
remove the cylinders from the upright as explained
in “Cylinder Removal.” The cylinders have seals
on the piston, and the rods must be removed for
seal replacement.
1. Clean the rod-end and gland thoroughly to prevent
contamination from falling into the cylinder during
disassembly.
2. With a blunt punch or chisel, bend the lock ring out
of the locking grooves of the gland.
3. Use a spanner wrench to remove the gland. Reuse the
lock ring if undamaged.
4. Carefully lift the rod out of the cylinder and place in
a clean area.
5. Inspect the tube and tube end for damage and cover
the cylinder tube end to prevent contamination.
6. Remove all rings and seals from the piston and the
gland.
7. For piston-type cylinders:
a. Remove the check valve from the piston for
inspection and cleaning by removing the snap
ring from the piston bore.
Check Valve. Arrow shows direction of flow
b. Use a blunt hook to pop the check valve out.
Rod Wiper
Rod Seal
O-Ring
Back-Up Ring
Gland
O-Ring
Tube
Spacer
Retaining Ring
Check Valve
Piston
Cylinder Seal
Snap Ring
Wear Ring
Rod
Pin
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