JLG 4017PS Service Manual - Manual (Page 73)

3-35 3706PS, 3707PS, 4014PS, 4017PS, 33.7, 37.6, 37.7
Boom
3.16.3 Inspection Guidelines - 4017
1. Park the machine on a firm, level surface, raise the
boom to a horizontal (level) position, place the
transmission control lever in (N) NEUTRAL, engage
the park brake switch.
2. Fully extend the boom until the extend chain is taut.
Shut the engine off.
3. The extend chains will be visible for inspection with
the vehicle in this state.
4. While doing the chain inspection, check all chain
clevis ends for distortion or cracking and sheaves for
bearing wear or grooving from the chain.
5. Inspect the retract chains every 1000 hours of
operation. Refer to the Service Manual for proper
procedure.
6. Inspect the chains for the following conditions:
Edge Wear
Check the chain for wear on the link plate edges
caused by running back and forth over the sheave.
The maximum reduction of material should not
exceed 5%. This can be compared to a normal link
plate height by measuring a portion of chain that
does not run over the sheave.
a. Extend Chains (fourth to third section)
The extend chains between the fourth and third
boom sections measures 18 mm (.713 in) (1). If the
measurement of the worn chain is less than 17 mm
(.677 in) (2), the chain should be replaced.
b. Extend Chains (third to second section)
The extend chains between the third and second
boom sections measures 29,6 mm (1.2 in) (1). If the
measurement of the worn chain is less than
28,6 mm (1.1 in) (2), the chain should be replaced.
Elongation
It is important to measure the chain in the section
that moves over the sheaves because it receives the
most frequent articulation. Measuring the chain near
its clevis terminals could give an inaccurate reading.
The ends of the chains, near the clevis terminal, will
not have flexed as frequently, if at all, as nearer the
middle of the chains.
a. Extend Chains (fourth to third section)
When the original length (3) of 305 mm (12.00 in)
per foot of extend chain between the fourth and third
boom sections has elongated from wear to a length
(4) of 313 mm (12.36 in), the chain should be
discarded and replaced.
Measure across a span of 16 pins at the center of
the extend chain. Measure from pin center to pin
center. Because the retract chain is inside the boom
you will not be able to measure the chain.
The maximum measurement allowed is
313 mm(12.36 in). If the measurement is more than
313 mm (12.36 in), the chain should be replaced.
b. Extend Chains (third to second section)
When the original length (3) of 317 mm (12.5 in) per
foot of extend chain between the third and second
boom sections has elongated from wear to a length
(4) of 325 mm (12.8 in), the chain should be
discarded and replaced.
Measure across a span of 10 pins at the center of
the extend chain. Measure from pin center to pin
center. Because the retract chain is inside the boom
you will not be able to measure the chain.
The maximum measurement allowed is
325 mm(12.8 in). If the measurement is more than
325 mm (12.8 in), the chain should be replaced.
MZ1463
1 2
MY1360
3
4