JLG 4013PS Service Manual - Manual (Page 51)

3-19 3508PS, 3509PS, 3512PS, 3513PS, 4008PS, 4009PS, 4012PS, 4013PS, 4017PS, 40.8, 40.9
Boom
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.
Turning or Protruding Pins
Highly loaded chain, operating with inadequate
lubrication can generate abnormal frictional forces
between pin and link plates. When chain is allowed
to operate in this condition, a pin or series of pins,
can begin to twist out of a chain, resulting in failure.
Examine the pin head rivets to determine if the
“VEE” flats are still in correct alignment (5). Chain
with rotated/displaced heads (6) or abnormal pin
protrusion (7) should be replaced immediately.
DO NOT attempt to repair the chain by welding or
driving the pin(s) back into the chain. Once the press
fit integrity between outside plates and pins has
been altered, it cannot be restored.
Any wear pattern on the pin heads or the sides of the
link plates indicates misalignment in the system.
This condition damages the chain as well as
increases frictional loading and should be corrected.
MZ1463
1 2
MZ1464
3
4
MZ1465
5
6
7