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

HYDRAULIC SYSTEM

UPPER TELESCOPE CYLINDER

Description

The upper boom telescope cylinder Figure 2-43 has a 6 in
(15.2 cm) bore and is internally ported (rod ported).
The retracted length of the telescope cylinder is 347.75 in
(883.3 cm). The cylinder has a stroke of 298.69 in (759 cm)
which gives an extended length of 646.44 in (1642.0 cm)
from the end of the barrel to the center of the cylinder block.
Foreign material is prevented from entering the cylinder
during rod retraction by a wiper ring in the head. O-ring seals
prevent internal and external leakage.
The cylinder weighs 1667 lb (756 kg).

Maintenance

Disassembly
NOTE: Replace all cylinder seals and O-rings with new
ones anytime the cylinder is disassembled.
1. Using a chain wrench, unscrew the cylinder head from
the cylinder barrel.
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.
2. Remove the cylinder rod assembly from the cylinder
barrel and cover the barrel to avoid contamination.
CAUTION
When removing seals and rings, avoid scratching
grooved and gland surfaces.
NOTE: Align old seals in order of removal to facilitate
installation of new seals.
3. Remove the guide lock ring at the top of the piston to
gain access to the setscrew securing the piston to the
cylinder rod.
2-72
CAUTION
Published 9-04-2014, Control # 422-08
RT765E-2 SERVICE MANUAL
4. Remove the setscrew and discard.
5. Unscrew the piston from the rod.
6. Remove the remaining guide lock ring, the hydrolock
seal assembly, and the wear rings from the outside of
the piston.
7. Remove the O-ring and backup rings from the inside of
the piston.
8. Remove the spacer from the rod and the wear ring from
the spacer.
9. Remove the head from the rod.
10. Remove the O-ring and backup ring from the outside of
the cylinder head.
11. Remove the wear rings, buffer seal, backup ring, deep Z
rod seal and wiper ring from the inside of the head.
Inspection
1. Clean all parts with solvent and dry with compressed air.
Inspect all parts for serviceability.
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 with solvent and dry with compressed air parts
that have been stoned and polished.
4. Inspect the barrel for scoring.
Assembly
1. If removed, install the holding valve. Refer to Valves,
page 2-30.
CAUTION
Avoid scratching or damaging the grooved and gland
surfaces or the seals and rings.
NOTE: Lubricate new seals and rings with clean hydraulic
oil. Orient wear ring gaps 180° apart.
2. Install the wiper ring and wear rings in the inside of the
head.