Sprocket Wear
It is recommended to replace sprocket
segments at bushing turn time or track
replacement.
On elevated sprocket machines, sprocket
wear is determined by measuring the
distance across three sprocket teeth.
Measure the minimum distance between
the drive side of one tooth and the
opposite drive side of a sprocket tooth
located three teeth away as shown in the
illustration above. It is important to note
that the distance measured should be
between teeth on the same segment. Avoid
measuring between teeth on different
segments as this may yield an incorrect
measurement.
On low sprocket machines use the sprocket
re-use indicator gauge (D7-D9 = 5P8617;
D4-D6 = 5P8616) for Sealed or Sealed and
Lubricated Track. Its function is to indicate
whether there is sufficient wear material
left in the sprocket tooth to provide struc-
tural life to match the expected remaining
bushing life that will be used with it fol-
lowing a bushing turn or replacement.
The gauge is designed to ignore the
sprocket tooth tip conditions and deter-
mines the ratio of the wear in the tooth
root compared to the wear on the tooth
sides, with the wear on the tooth sides
being the determining factor in reusability
for structural purposes.
The gauge should be placed into one or
more teeth with the point at the root aimed
at the center of the sprocket.
If the point of the gauge touches the tooth
root, the sprocket tooth does not have
enough wear material left to (1) support the
back side of the turned bushing that caused
the wear already present on the sprocket or
(2) support the wear life of the replacement
bushing assuming its expected wear life
potential is equal to the wear life obtained
on the bushing that caused the wear
already present on the sprocket.
Conversely, if only the two tooth side tips
touch and the root tip does not touch then
that segment can be expected to provide as
much wear life as already provided by the
bushing sides that ran against it.
The past and projected sprocket life should
be thought of in terms of the bushing
(sides) of life it has or will be expected to
provide, not in terms of actual hours on
the sprocket itself.
Do not reuse sprocket with turned
(or replaced) bushings.
OK to reuse sprocket with turned
(or replaced) bushings.