JLG DVSP Series Service Manual - Manual (Page 97)

SECTION 5 - MAST COMPONENTS
3121136 – JLG Lift – 5-9
11. At the bottom of mast section-1, remove the cylinder
mount bolts, and mount reinforcement plates.
12. Slide the cylinder and mount assembly out of the
bottom of mast section-1 and -2 and place on a suit-
able work surface.
Cylinder Disassembly
(See Figure 5-4.)
1. Before disassembling the cylinder, clean away all
dirt and foreign substances from openings, particu-
larly the head area.
NOTE: Always protect the chrome surface of the cylinder
rod during assembly and disassembly. Any damage
to this surface will require replacement of the rod.
2. Extend the rod until the piston bottoms out against
the cylinder head.
3. Compress the head retraining ring enough to allow
the cylinder head to be removed.
4. Carefully slide the head/rod/piston assembly out of
the cylinder tube. A gentle tap on the head assembly
may be required to remove the head from the cylin-
der tube.
5. Place the head/rod/piston assembly on a surface
that will not damage the chrome.
6. Remove the piston locknut and separate the piston
from the rod.
7. Slide the head off the rod from the piston end.
NOTE: When removing the old seals use only blunt tools, be
sure there are no sharp edges that may damage the
seal grooves during removal. Scratching the groove
may cause by-pass.
8. Remove and discard all old seals.
Lift Cylinder Component Inspection
Cylinder Rod
There should be no scratches or pits deep enough to catch
the fingernail. Pits that go to the base metal are unaccept-
able. Scratches that catch the fingernail but are not to the
base metal, less than 0.5 inch long and primarily in the cir-
cumferential direction are acceptable provided they cannot
cut the rod seal. Chrome should be present over the entire
surface of the rod and the lack thereof is unacceptable. In
the event that an unacceptable condition occurs, the rod
should be repaired or replaced.
Cylinder Head
Visually inspect the inside bore for scratches or polishing.
Deep scratches are unacceptable. Polishing indicates
uneven loading and when this occurs, the bore should be
checked for out-of-roundness. If out-of-roundness exceed
0.007", this is unacceptable. Check the condition of the
dynamic seals (wiper, rod seals) looking particularly for
metallic particles embedded in the seal surface. It is normal
to cut the static seal on the retaining ring groove upon disas-
sembly. Remove the rod seal, static o-ring and backup and
Lift Cylinder Mount Installation
1. Cylinder/Mount Assembly 3. Washers
2. Reinforcement Plate 4. Mount Mounting Screws (a)
Notes: (a) Apply Loctite #242 to threads at final assembly.
Cylinder Installation
1. Lift Cylinder and Cylinder Mount Assembly
2. Mount Shims (Mark Shim Packs for Reinstallation)
2
1
3
4
1
2