INTRODUCTION
Basic instructions - Chain Wear Tables - Roller Chains
AXIAL-FLOW 5130, AXIAL-FLOW 6130, AXIAL-FLOW 7130
Chain wear
The individual joints in a roller chain articulat e as they en-
ter and leave the sprockets. This articulation results in
wear on the pins and bushings. Material that is worn away
from these surfaces will cause the chain to gradually elon-
gat e. Chains do not stretch. Material is worn from pin and
bushing.
Critical dimensions of the chain are as follows:
•
(1) 2X pitch
•
(2) Wear plus 2X pitch
•
(3) Elongation due to pin and bushing wear
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Elongat ion is normal and may be minimized by proper
lubrication and drive maintenance. The rate of wear is
dependent upon: the relationship between the load and
the amount of bearing area between pin and bushing, the
material and surface condition of the bearing surfaces, the
adequacy of lubrication, and the frequency and degree
of articulation between pins and bushings. The latter is
det ermined by the quantity of sprockets in the drive, their
speeds, the number of teeth and the length of the chain
in pitches.
An accurate wear measurement (1) can be made by us-
ing the above illust ration. Measure as closely as possible
from the center of one pin to the center of another. The
more pitches (pins) cont ained within the measurement in-
crease the accuracy. If the measured value exceeds the
nominal by more than the allowable percentage the chain
should be replaced. The maximum allowable wear elon-
gat ion is approximately 3 % for most industrial applica-
tions, based upon sprocket design. The allowable chain
wear in percent can be calculated using the relationship:
200 / (N), where (N) is the number of teeth in the large
sprocket. This relationship is often useful since the nor-
mal maximum allowable chain wear elongation of 3 % is
valid only up to 67 teeth in the large sprocket. In drives
having xed center distances, chains running in parallel
or where smoother operation is required, wear should be
limited to approximately 1.5 %.
For example, if 12 pitches (12 pins) of a #80 chain were
measured and the result was 313.944 mm (12.360 in) or
greater (using 3 % as the maximum allowable wear), the
chain should be replaced. Anything less than 313.944
mm (12.360 in) would still be acceptable by most indus-
trial standards.
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