Lower Telescope Cylinder; Description; Maintenance - Manitowoc Grove RT765E-2 Service And Maintenance Manual

HYDRAULIC SYSTEM

LOWER TELESCOPE CYLINDER

Description

The boom lower telescope cylinder Figure 2-39 has a 6 in
(152 mm) bore and is internally ported.
The retracted length of the cylinder from the center of the
support block to the center of the cylinder mounting pin is
352.72 in (895.9 cm). The cylinder has a stroke of 298.69 in
(758.7 cm) which gives an extended length of 651.41 in
(1654.6 cm).
Foreign material is prevented from entering the cylinder rod
during retraction by a wiper ring in the head. O-ring seals
prevent internal and external leakage.
The cylinder weighs 2105 lb (955 kg).

Maintenance

Disassembly
NOTE: Replace all seals and O-rings any time the cylinder
is disassembled.
1. Remove the capscrews and washers securing the rod
retaining plate to the barrel.
2. Remove the capscrews and washer that secures the rod
retaining plate to the inner rod end.
Do not use air pressure to remove the rod. Use only a
source of controlled hydraulic oil pressure if the rod is
hard to move. Injury may result from the cylinder rod
unexpectedly exiting the cylinder barrel.
CAUTION
Exercise extreme care when handling or setting down the
cylinder rod. Do not damage the chrome surface.
NOTE: Align the old seals in order of removal to facilitate
installation of new seals.
3. Using a chain wrench, unscrew the cylinder head from
the barrel. Remove the rod from the barrel and cover the
opening in the barrel to keep contaminates out of the
barrel.
CAUTION
When removing seals and rings, avoid scratching
grooved and gland surfaces.
2-68
CAUTION
Published 9-04-2014, Control # 422-08
RT765E-2 SERVICE MANUAL
4. Remove the guide lock ring from the piston to gain
access to the setscrew.
5. Remove the setscrew and unscrew the piston from the
rod.
6. Remove the remaining guide lock ring, the hydrolock
seals, and wear rings from the outside of the piston.
Remove the O-ring and backup rings from the inside of
the piston.
7. Remove the spacer from the rod and the wear rings from
the spacer.
8. Remove the cylinder head from the rod.
9. Remove the wear rings, buffer seal assembly, deep Z
rod seal, and back-up ring from the inside of the head.
10. Remove the O-ring and backup ring from the outside of
the cylinder head.
11. Slide the inner rod out of the outer rod. The seal retainer
will slide out with the inner rod. Remove the guide lock
ring from the inner rod end.
12. Remove the seal retainer from the inner rod.
13. Remove the wear rings and seal from the inside of the
seal retainer.
14. Remove the O-ring and backup ring from the outside of
the seal retainer.
Inspection
1. Clean all parts with solvent and dry with compressed air.
Inspect for damaged or worn parts and replace as
required.
CAUTION
Clean all surfaces and remove all burrs and nicks before
installing new seals and rings. Replace all damaged or
worn parts.
2. Stone out minor blemishes and polish with fine crocus
cloth.
3. Clean all with solvent all parts that have been polished.
4. Inspect the barrel for scoring.
Assembly
NOTE: Lubricate new seals and rings with clean hydraulic
oil. Orient wear ring gaps 180° apart.
CAUTION
Improper seal installation can cause faulty cylinder
operation.