JLG 25AM Service And Maintenance Manual page 45

CYLINDER
ASSEMBLY
Piston
Visually inspect the outside surface for scratches or polishing.
Deep scratches are unacceptable. Polishing indicates uneven
loading and when this occurs, the diameter should be checked
for out-of-roundness. If out-of-roundness exceeds 0.007 in.,
this is unacceptable. Check the condition of the dynamic seals
and bearings looking particularly for metallic particles embed-
ded in the bearing and in the piston seal surface. Remove the
seals and bearings. Damage to the seal grooves, particularly
on the sealing surfaces, is unacceptable. In the event that an
unacceptable condition occurs, the piston should be replaced.
31215808
RETAINING RING
GROOVE
LOCKNUT
TORQUE
TUBE
PISTON
175-200 ft.lbs.
(237-271 Nm)
Figure 2-1. Lift Cylinder Internal Component Assembly Cross-Section
WEAR
RING
PISTON
O-RING
SEAL
BACKUP
O-RING
WHEN ASSEMBLING
CYLINDER
APPLY ANTI-SEIZE
CYLINDER
COMPOUND
HEAD
AROUND THE HEAD
IN THIS AREA ONLY
Tube Assembly
Visually inspect the inside bore for scratches and pits. There
should be no scratches or pits deep enough to catch the fin-
gernail. Scratches that catch the fingernail but are less than 0.5
in. long and primarily in the circumferential direction are
acceptable provided they cannot cut the piston seal. The
roughness of the bore should be between 10 and 20 ì inches
RMS. Significant variation (greater than 8 ì inches difference)
are unacceptable. In the event that an unacceptable condition
occurs, the tube assembly should be repaired or replaced.
SECTION 2 - SERVICE PROCEDURES
CYLINDER
HEAD
RETAINING
RING
RING
ROD
SEAL
ROD
WIPER
CYLINDER
ROD
2-17