JLG 660SJ Service Manual - Manual (Page 69)

SECTION 3 - CHASSIS & TURNTABLE
3121298 – JLG Lift – 3-25
Figure 3-32. Cylinder Kit Disassembly
7. Remove pistons (44) and slipper retainer (45) from cylin-
der block (46).
NOTE: Pistons are not selectively fitted. However, units with high
hourly usage may develop wear patterns. Number pistons
and bores for reassembly if they are to be reused.
8. Remove ball guide (47), hold-down pins (48), and retain-
ing ring (49) from cylinder block.
NOTE: Most repairs do not require block spring removal. Perform
this procedure only if you suspect problems with the block
spring.
RISK OF PERSONAL INJURY: COMPRESSING THE BLOCK SPRING REQUIRES
FORCE OF ABOUT 80 TO 90 LBF (350 TO 400 N). USE A PRESS SUFFICIENT TO
MAINTAIN THIS FORCE WITH REASONABLE EFFORT. ENSURE THE SPRING IS
SECURE BEFORE ATTEMPTING TO REMOVE THE SPIRAL RETAINING RING.
RELEASE THE PRESSURE SLOWLY AFTER THE RETAINING RING IS REMOVED.
9. Turn block over. Using a press, apply pressure on block
spring washer (50) to compress block spring. Compress
spring enough to safely remove spiral retaining ring
(51). While maintaining pressure, unwind spiral retaining
ring (51). Carefully release pressure and remove outer
block spring washer (50), block spring (52), and inner
block spring washer (53) from cylinder block.
Inspection
After disassembly, wash all parts (including end-cap and hous-
ing) thoroughly with clean solvent and allow to air dry. Blow
out oil passages in housing and endcap with compressed air.
Conduct inspection in a clean area and keep all parts free from
contamination. Clean and dry parts again after any rework or
resurfacing.
PISTON
Inspect pistons for damage and discoloration. Discolored pis-
tons may indicate excessive heat; do not reuse.
SLIPPERS
Inspect slipper running surfaces. Replace piston assemblies
with scored or excessively rounded slipper edges. Measure
slipper foot thickness. Replace piston assemblies with exces-
sively worn slippers. Check slipper axial end-play. Replace pis-
ton assemblies with excessive end-play.
44. Piston
45. Slipper Retainer
46. Cylinder Block
47. Ball Guide
48. Holddown Pins 49. Retaining Ring
50. Block Spring Washer
51. Spiral Retaining Ring
52. Block Spring
53. Inner Block Spring Washer
51
50
52
53
46
49
48
47
45
44
Table 3-7. Slipper Foot Thickness & End Play
Measurement L Frame K Frame
Slipper Foot Thickness 2.71 mm (0.11 in.) 4.07 mm (0.16 in.)
Piston/Slipper End Play 0.15 mm (0.006 in.)
Slipper
Maximum End Play
Minimum Slipper Foot Thickness