JLG DVSP Series Service Manual - Manual (Page 95)

SECTION 5 - MAST COMPONENTS
3121136 – JLG Lift – 5-7
5.4 HYDRAULIC LIFT CYLINDER -
REMOVAL, INSPECTION AND REBUILD
HYDRAULIC CYLINDERS ARE DESIGNED TO HOLD HYDRAULIC
FLUID UNDER HIGH PRESSURE. ENSURE ALL APPROPRIATE MEA-
SURES ARE TAKEN TO RELIEVE RESIDUAL PRESSURE IN THE CYL-
INDER BEFORE DISCONNECTING LINES.
Lift Cylinder Removal
Removal of the hydraulic lift cylinder without removing the
mast from the machine requires laying the machine on it’s
back (hood side) with the platform end on top.
1. Remove the following components from the
machine before laying machine on it’s back:
• Rear Covers (See Section 4)
• Batteries (See Section 4)
• Drive Motor Cover (See Section 3)
2. Seal the vented cap on the hydraulic fluid reservoir
by removing the cap, covering the hole with a few
layers of plastic wrap or equivalent. Then install and
tighten the cap over the plastic wrap to prevent leak-
age of hydraulic oil from the reservoir while machine
is in a layed back position.
3. Use a forklift truck or overhead crane and carefully
lay the machine on it’s back, place a support under
the mast end, keeping mast close to level. (See Fig-
ure 5-3.)
4. At the base end, remove and cap the extend and
return hydraulic lines.
5. Remove the mini covers from the tops of the mast
sections.
6. Manually extend the mast assembly until the top of
mast section-2 is extended approximately one (1)
foot (31cm), to allow access to the sheave wheel-
anchor block at the top of mast section-2 and the lift
cylinder.
1. Be Careful of Control Components in this Area
2. Support Mast Here - Keep Mast Approximately Level
Figure 5-3. Machine Positioned for Cylinder
Removal.
1
2
Hydraulic Extend and Return Lines
1. Cylinder Return Line 3. Cylinder Valve Block
2. Cylinder Extend Line 4. Drive Motor Assemblies
Extending Mast Sections
1. Mast Section-2 2. 1 ft. (31cm) Extended
1
2
4
3
1
2