Digga HP450, Operator'S Manual, Page: 29 / 37

MAINTENANCE AND SERVICE
CYLINDER SEAL REPLACEMENT
The following information is provided to assist you in the event you should need to repair or rebuild a hydraulic
cylinder. When working on hydraulic cylinders, make sure that the work area and tools are clean and free of dirt to
prevent contamination of the hydraulic system and damage to the hydraulic cylinders. Always protect the active
part of the cylinder rod (the chrome section). Nicks or scratches on the surface of the rod could result in cylinder
failure. Clean all parts thoroughly with a cleaning solvent before reassembly.
DISASSEMBLY PROCEDURE
IMPORTANT : Do not contact the active surface of the cylinder rod with the vise. Damage to the rod could result
.
THREADED TYPE GLAND
1. Rotate the gland with a spanner wrench counterclockwise until the gland is free of the cylinder tube.
2. Pull the cylinder rod from the cylinder tube and inspect the piston and the bore of the cylinder tube for
deep scratches or galling. If damaged, the piston AND the cylinder tube must be replaced.
3. Remove the hex nut, piston, flat washer or spacer tube (if so equipped), and gland from the cylinder rod. If
the cylinder rod is rusty, scratched, or bent, it must be replaced.
4. Remove and discard all the old seals.
ASSEMBLY PROCEDURE
IMPORTANT: Replace all seals even if they do not appear to be damaged. Failure to replace all seals may result
in premature cylinder failure.
NOTE:
Seal kits will service most cylinders of similar bore size and rod diameter.
1. Install the cylinder rod seal in the gland first. Be careful not to damage the seal in the process, as it is
somewhat difficult to install.
NOTE:
A special installation tool is available to help with installing the seal. Simply fit the end of the tool over the
seal so that the large prong of the tool is on the outside of the seal, and the two smaller prongs on the inside. The
lip of the seal should be facing towards the tool. Rotate the handles on the tool around to wrap the seal around the
end of the tool.
PM-000068-A DECEMBER 2017
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