HYDRAULIC SYSTEM
RT765E-2 SERVICE MANUAL
2-72
Published 9-04-2014, Control # 422-08
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.
2.
Remove the cylinder rod assembly from the cylinder
barrel and cover the barrel to avoid contamination.
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.
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.
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
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.
CAUTION
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.
CAUTION
When removing seals and rings, avoid scratching
grooved and gland surfaces.
CAUTION
Clean all surfaces and remove all burrs and nicks before
installing new seals and rings. Replace all damaged or
worn parts.
CAUTION
Avoid scratching or damaging the grooved and gland
surfaces or the seals and rings.
Reference Only
