JLG 1850SJ Service Manual - Manual (Page 216)

SECTION 5 - BASIC HYDRAULIC INFORMATION & HYDRAULIC SCHEMATICS
5-46 – JLG Lift – 3121619
10. Remove cylinder head assembly (5) from rod (17).
Remove and discard two wear rings (10), seal (4), wiper
seal (3), O-ring (8), backup ring (7), and O-ring (6) from
cylinder head.
CLEANING AND INSPECTION
1. Clean parts thoroughly with approved cleaning solvent.
2. Inspect cylinder rod for scoring, tapering, ovality, or
other damage. If necessary, dress rod with Scotch Brite
or equivalent. Replace rod if necessary.
3. Inspect threaded portion of rod for excessive damage.
Dress threads as necessary.
4. Inspect inner surface of cylinder barrel tube for scoring
or other damage. Check inside diameter for tapering or
ovality. Replace if necessary.
5. Inspect threaded portion of barrel for damage. Dress
threads as necessary.
6. Inspect piston surface for damage, scoring, or distortion.
Dress piston surface or replace piston as necessary.
7. Inspect threaded portion of piston for damage. Dress
threads as necessary.
8. Inspect seal and O-ring grooves in piston for burrs and
sharp edges. Dress surfaces as necessary.
9. Inspect cylinder head inside diameter for scoring or
other damage, and for ovality and tapering. Replace as
necessary.
10. Inspect threaded portion of head for damage. Dress
threads as necessary.
11. Inspect seal and O-ring grooves in head for burrs and
sharp edges. Dress applicable surfaces as necessary.
12. Inspect cylinder head outside diameter for scoring,
damage, ovality, and tapering. Replace as necessary.
13. Inspect oil ports for blockage or presence of dirt or other
foreign material. Repair as necessary.
ASSEMBLY
NOTE: Use proper cylinder seal kit for cylinder assembly. See your
JLG Parts Manual.
Apply a light film of hydraulic oil to all components before
assembly.
IMPROPER SEAL INSTALLATION CAN CAUSE CYLINDER LEAKS AND IMPROPER
CYLINDER OPERATION. ENSURE ‘POLY-PAK’ PISTON SEALS ARE PROPERLY
INSTALLED. REFER TO WIPER SEAL INSTALLATION FOR CORRECT SEAL ORIEN-
TATION.
1. Install seal (4) and wiper seal (3) to inside grooves of cyl-
inder head (5).
2. Install two wear rings (10) in cylinder head.
3. Install O-Ring (6), backup ring (7), and O-ring (8) to out-
side grooves of cylinder head.
4. Slide cylinder head assembly on rod.
5. Install O-ring (11) to inside groove of piston (12).
6. Install wear ring (14) and seal (15) in outside grooves of
piston.
7. Using suitable protection, clamp cylinder rod in a vise or
similar holding fixture as close to piston as possible.
8. Apply medium-high strength (red) thread-locking com-
pound JLG P/N 0100071 or equivalent to rod threads.
9. Thread piston assembly on rod. Do not dislodge or dam-
age O-ring. Torque piston to 30 ft-lb (40 Nm).
Figure 5-82. Piston and Cylinder Head Disassembly