JLG 740A, Service And Maintenance Manual

Page: 87 / 408

SECTION 3 - CHASSIS & TURNTABLE
3121160 – JLG Lift – 3-35
28. Turn the block over. Using a press, apply pressure
on the block spring washer (50) to compress the
block spring. Compress the spring enough to safely
remove the spiral retaining ring (51). While maintain-
ing pressure, unwind the spiral retaining ring (51).
Carefully release the pressure and remove the outer
block spring washer (50), block spring (52), and
inner block spring washer (53) from the cylinder
block.
Inspection
After disassembly, wash all parts (including the end-cap
and housing) thoroughly with clean solvent and allow to
air dry. Blow out oil passages in the 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 the pistons for damage and discoloration. Discol-
ored pistons may indicate excessive heat; do not reuse.
SLIPPERS
Inspect the running surface of the slippers. Replace any
piston assemblies with scored or excessively rounded
slipper edges. Measure the slipper foot thickness.
Replace any piston assemblies with excessively worn slip-
pers. Check the slipper axial end-play. Replace any piston
assemblies with excessive end-play.
Minimum slipper foot thickness and maximum axial end-
play are given in the table below.
CYLINDER BLOCK
Measure the cylinder block height. Replace blocks worn
beyond the minimum height specification. Inspect the run-
ning surface of the cylinder block. Replace or resurface
worn or scratched blocks. Blocks may be resurfaced to
the specifications shown in the drawing, provided resur-
facing will not reduce the block height below the minimum
specification. Table 3-8, Cylinder Block Measurements.
Slipper
Maximum end play
M inimum
slipper fo ot
thick ness
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)