JLG 450A_AJ Series II Service Manual - Manual (Page 104)

SECTION 3 - CHASSIS & TURNTABLE
3-54 – JLG Lift – 3121180
RISK OF PERSONAL INJURY: COMPRESSING 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 SPRING IS SECURE BEFORE ATTEMPTING TO
REMOVE SPIRAL RETAINING RING. RELEASE PRESSURE SLOWLY
AFTER RETAINING RING IS REMOVED.
28. Turn block over. Using a press, apply pressure on block
spring washer (50) to compress block spring enough to
safely remove spiral retaining ring (51). Maintain pres-
sure and 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
housing) 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
pistons may indicate excessive heat. Do not reuse.
SLIPPERS
Inspect running surface of slippers. Replace piston
assemblies with scored or excessively rounded slipper
edges. Measure slipper foot thickness. Replace piston
assemblies with excessively worn slippers. Check slipper
axial end-play. Replace piston assemblies with excessive
end-play.
Minimum slipper foot thickness and maximum axial end-
play are shown in table 3.7.
CYLINDER BLOCK
Measure cylinder block height. Replace blocks worn
beyond minimum height specification. Inspect running
surface of cylinder block. Replace or resurface worn or
scratched blocks. Blocks may be resurfaced if resurfacing
will not reduce block height below minimum specification
shown in Table 3-8, Cylinder Block Measurements.
Table 3-7. Slipper Foot Thickness & End Play
Measurement L Frame K Frame
Slipper Foot Thickness
mm
(in.)
2.71
(0.11)
4.07
(0.16)
Piston/Slipper End Play
0.15
(0.006)
A
Table 3-8. Cylinder Block Measurements
Measurement L25 L30 L35 K38 K45
Minimum Cylinder Block Height
(A) 50.8 (2.00) 50.8 (2.00) 50.8 (2.00) 54.4 (2.14) 54.4 (2.14)
Cylinder Block Surface Flatness
0.002
(0.0000079)
0.002
(0.0000079)
0.002
(0.0000079)
0.002
(0.0000079)
0.002
(0.0000079)