JLG 740A, Service And Maintenance Manual

Page: 88 / 408

SECTION 3 - CHASSIS & TURNTABLE
3-36 – JLG Lift – 3121160
BALL GUIDE AND SLIPPER RETAINER
Inspect the ball guide and slipper retainer for damage,
discoloration, or excessive wear. A discolored ball guide
or slipper retainer indicates excessive heat. Do not reuse.
VALVE PLATE
The condition of the valve plate is critical to the efficiency
of the motor. Inspect the valve plate surfaces carefully for
excessive wear, grooves, or scratches. Replace or resur-
face grooved or scratched valve plates. Measure the valve
plate thickness and replace if worn beyond the minimum
specification. Valve plates may be resurfaced to the speci-
fications shown in the drawing, provided resurfacing will
not reduce the thickness below the minimum specifica-
tion.
SWASHPLATE AND JOURNAL BEARINGS
Inspect the running face, servo ball-joint, and swashplate
journal surfaces for damage or excessive wear. Some
material transfer may appear on these surfaces and is
acceptable providing the surface condition meets specifi-
cations shown. Measure the swashplate thickness from
the journals to the running face. Replace swashplate if
damaged or worn beyond minimum specification.
Replace swashplate if the difference in thickness from one
side to the other exceeds specification.
Inspect the journal bearings for damage or excessive
wear. Replace journal bearings if scratched, warped, or
excessively worn. The polymer wear layer must be
smooth and intact.
SHAFT BEARINGS
Inspect bearings for excessive wear or contamination.
Rotate the bearings while feeling for uneven movement.
Bearings should spin smoothly and freely. Replace bear-
ings that appear worn or do not rotate smoothly.
SHAFT
Inspect the motor shaft. Look for damage or excessive
wear on the output and block splines. Inspect the bearing
surfaces and sealing surface. Replace shafts with dam-
aged or excessively worn splines, bearing surfaces, or
sealing surfaces.
Slipper retainer
Ball guide
3.83 mm [0.151 in] min.
0.025 mm
[0.001 in]
0.0076 mm
[0.00030 in]
convex max
LV
25.8 mm
[1.015 in]
24.6 mm
[0.969 in]
KV
Thickness equality
side to side:
0.05 mm [0.002 in]
0.0025 mm
[0.0001 in]