JLG 450A_AJ Series II Service Manual - Manual (Page 41)

SECTION 2 - GENERAL
3121180 – JLG Lift – 2-5
2.4 CYLINDER DRIFT TEST
Measure maximum acceptable cylinder drift using the fol-
lowing methods.
Platform Drift
Measure platform to ground drift. Lower booms (if
equipped) slightly elevated, upper boom fully extended
with rated load in the platform and power off. Maximum
allowable drift is 2" (5 cm) in 10 minutes. If machine does
not pass this test, proceed with the following:
Cylinder Drift
Drift is to be measured at cylinder rod with a calibrated
dial indicator. Cylinder oil must be at ambient temperature
and temperature stabilized.
Cylinder must have normal platform load applied.
If cylinder passes this test, it is acceptable.
NOTE: This information based on 6 drops per minute cylinder
leakage.
2.5 PINS AND COMPOSITE BEARING
REPAIR GUIDELINES
Filament wound bearings.
1. Pinned joints should be disassembled and
inspected if the following occurs:
a. Excessive sloppiness in joints.
b. Noise originating from joint during operation.
2. Filament wound bearings should be replaced if any
of the following is observed:
a. Frayed or separated fibers on liner surface.
b. Cracked or damaged liner backing.
c. Bearings that have moved or spun in their housing.
d. Debris embedded in liner surface.
3. Pins should be replaced if any of the following is
observed (pin should be properly cleaned prior to
inspection):
a. Detectable wear in bearing area.
b. Flaking, pealing, scoring, or scratches on pin
surface.
c. Rusting of pin in bearing area.
4. Re-assembly of pinned joints using filament wound
bearings.
a. Housing should be blown out to remove all dirt
and debris. Bearings and bearing housings
must be free of all contamination.
b. Clean bearing/pins with a solvent to remove all
grease and oil. Filament wound bearing are a
dry joint and should not be lubricated.
c. Inspect pin to ensure it is free of burrs, nicks,
and scratches which would damage bearing
during installation and operation.
Table 2-2. Cylinder Drift
Cylinder Bore Diameter
Max. Acceptable Drift
in 10 Minutes
inches mm inches mm
3 76.2 0.026 0.66
3.5
89 0.019 0.48
4 101.6 0.015 0.38
5 127 0.009 0.22
6 152.4 0.006 0.15
7 177.8 0.005 0.13