JLG 450A_AJ Series II Service Manual - Manual (Page 261)

SECTION 5 - HYDRAULICS
3121290 – JLG Lift – 5-21
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.
1. Use seal tool to install new seal in cylinder head groove.
Figure 5-38. Rod Seal Installation
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.
2. Use a soft mallet to tap new wiper seal into applicable
cylinder head gland groove. Install new wear ring into
applicable cylinder head gland groove.
3. Install wear ring in cylinder head.
4. Place new O-ring and back-up seal in outside diameter
grooves of cylinder head.
Figure 5-39. Cylinder Head Seal Installation
5. Install washer ring on rod. Carefully install cylinder head
assembly head on rod. Do not damaged or dislodge
wiper and rod seals. Push head to rod end.
6. Place a new O-ring and back-up rings in inner piston
diameter groove.
Figure 5-40. Piston Seal Installation
7. Using suitable protection, clamp cylinder rod in a vise or
similar holding fixture as close to piston as possible.
8. Carefully thread piston on cylinder rod hand tight. Do
not damage or dislodge O-ring and back-up rings.
NOTE: Tapered bushing, piston, and mating end of rod must be
free of oil.
9. Thread piston onto rod until it aligns with spacer end
and install tapered bushing.