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APPENDIX: INSPECTING CHAIN WEAR
MEASURING WEAR ON THE CHAIN
Note:
Inspect the chain regularly for wear, rust, and corrosion.
1
Visual checks
Examine the chain visually for nicks, gouges, weld splatter, corrosion, or distorted
links and slacken chain. Check bearing surfaces between links for wear.
Replace a chain with excessively pitted, corroded, nicked, gouged, twisted, or
worn links with a factory approved chain.
2
Measuring the link thickness (d)
Measure the dimension (d) at several points of the chain and calculate the
dimension (dm).
dm = (d1 + d2) /2 ≤ 0.9 * dn
dn = Nominal
t = Pitch
Criteria:
Chain size
d * t
4x11
5x14
7x20
9x27
11.3x31
d
n
4
5
7
9
11.3
d
m
max
[mm]
(in)
3.6
(0.142)
4.5
(0.177)
6.3
(0.248)
8.1
(0.319)
10.17
(0.4)
Note:
Use only a "knife-edge" caliper or a tool sold by the CPC (Crane Part Center) tool center to eliminate the
possibility of a false reading by not measuring the full pitch length.
3
Measuring the elongation* (P)
Measure (P), the pitch over 11 links, at different regions of the chain.
Criteria:
Chain size
d * t
4x11
5x14
7x20
9x27
11.3x31
d
n
4
5
7
9
11.3
P max
[mm]
(in)
123.42
(4.859)
157.08
(6.184)
224.4
(8.835)
302.94
(11.927)
347.82
(13.694)
*NOTE: A 2 % elongation as per ISO 7592.
