Adjustable pitch sprocket

As the sprocket teeth wear, the pitch of the sprocket teeth decreases. As the chain wears, the pitch of the chain increases, this causes the rate of wear to increase. A sprocket after being in use for 1000 hours may have four times the wear as it had after 500 hours use. This invention, a sprocket with simultaneous adjustable pitch of the teeth, will keep the wear rate to the minimum.

DESCRIPTION OF TERMS 
SPROCKET PITCH: The distance between the center of one chain pin to the 
center of the adjacent chain pin. 
SPROCKET TOOTH ROOT DIAMETER: Twice the distance from the bottom of one 
sprocket tooth to the center of the sprocket. 
SPROCKET PITCH DIAMETER: The sprocket tooth root, diameter plus the 
diameter of one chain pin or bushing. (if the chain has bushings). 
SPROCKET OUTSIDE DIAMETER: Twice the distance from the outer point of 
sprocket tooth to center of sprocket. 
SPROCKET TOOTH SHANK: The part of tooth extending towards center of 
sprocket to secure tooth to adaptor disc. 
It is apparent from the foregoing that the present invention provides an 
adjustable pitch sprocket effecting equal pitch adjustment of all sprocket 
teeth simultaneously, with gradual adjustment over a wide range being 
obtainable. Moreover, the tapered shank adjustment bolts assure positive 
and gradual adjustment without danger of being broken. The adjustable 
pitch sprocket may be used in applications where existing sprockets fit 
splined shafts or have expensive hubs, simply by adapting the existing hub 
to the adaptor disc, and may be substituted for existing sprockets without 
the necessity of replacing the existing chain carried by the sprocket.

DETAILED DESCRIPTION 
The sprocket assembly would consist of five different parts: an adaptor 
disc (or plate), shown in FIG. 4, a pitch adjustment disc (or ring), shown 
in FIG. 6, individual adjustable teeth, shown in FIG. 7, tapered shank 
adjustment bolts shown in FIG. 9, and standard bolts, which may be used to 
secure teeth to the adaptor disc. 
The teeth would be secured to the adaptor disc with bolts. The teeth would 
be mounted individually, with bolts through the slotted bolt holes 6 in 
the adaptor disc allowing the teeth to be adjusted from the center of the 
disc outward, thereby increasing the pitch diameter. The adjustment would 
be accomplished with an adjustment disc of the type shown in FIG. 6. The 
adjustment disc would have a number of protruding areas 7 (one or two 
each) equal to the number of teeth. The tooth shorter shank 9 would have 
an inner surface 8 on one side of the adaptor disc bearing against the 
pitch adjustment disc protruding areas 7 (i.e., against the adjustment 
disc cam surface). When rotated, the adjustment disc forces all teeth 
outward simultaneously. This action increases the pitch diameter of all 
teeth and in turn increases the distance (known as the sprocket pitch) 
between all teeth equally. The adjustment disc and the adaptor disc will 
have a series of bolt holes 10, 11 on the same diameter bolt circle. Each 
of these holes for one half of the bolt circle would be offset (as to 
distance apart by 25 percent of the hole size). That is, the bolt holes 
10, 11 along each 180 degree arc, are arcuately offset from one another 
due to the unequal arcuate spacing between the bolt holes through one of 
the discs. When the adjustment bolts shown in FIG. 9 are inserted in the 
mismatched holes 10, 11 and the nuts tightened on the bolts, the 
adjustment disc will be forced to rotate (by 25 percent of the hole 
diameter distance) by the action of the axially extending wedge surface 
provided by the conical cam surface around the shank of the tapered 
adjustment bolt, thereby adjusting all teeth. The holes on the one half of 
the adjustment disc will be exactly 180 degrees from the opposite holes. 
To adjust the sprocket pitch it is necessary to loosen all bolts in all 
teeth, insert. Insert two adjustment bolts in through both pairs of 
opposite holes 10, 11 that are 25 percent mismatched, tighten the nuts on 
the two adjustment bolts until the sprocket is in pitch with the chain, 
and then tighten all tooth shank bolts. If one hole adjustment is not 
sufficient to adjust the pitch, remove the two adjustment bolts and insert 
them in the next adjoining holes 10, 11 which have been brought within 25 
percent of alignment during the previous hole alignment. This procedure 
may be continued until the sprocket is adjusted to the correct pitch to 
match the chain's pitch, or the total adjustment allowed is accomplished. 
The teeth, shown in FIG. 7, would be secured to the adaptor disc, shown in 
FIG. 4, with standard bolts. The teeth would be mounted individually, with 
bolts through the slotted bolt holes, 6 in the adaptor disc, shown in FIG. 
4, allowing the teeth to be adjusted from the center of the disc outward 
(or radially), thereby increasing the pitch diameter. The adjustment would 
be accomplished with an adjustment disc, shown in FIG. 6. The adjustment 
disc would have a number of protruding areas 7 (one or two each) for each 
of the teeth. The shorter shank would have an inner surface 8 on one side 
of the adaptor disc, bearing against the pitch adjustment disc protruding 
area 7. When rotated, the adjustment disc forces all teeth outward 
simultaneously. This action increases the pitch diameter of all teeth and 
in turn increases the distance (known as the sprocket tooth pitch) between 
all teeth equally. The adjustment disc and the adaptor disc will have a 
series of bolt holes, 10 & 11 on the same diameter bolt circle. Each of 
these holes for one half of the bolt circle would be offset, (as to 
distance apart by 25 percent of the hole size). When the adjustment 
bolts, shown in FIG. 9, are inserted in the mismatched holes, 10 & 11 and 
the nuts tightened on the bolts, the adjustment disc will be forced to 
rotate (by 25 percent of the hole diameter distance), thereby adjusting 
all teeth. The holes, 10 on the one half of the adjustment disc will be 
exactly 180 degrees from the opposite holes. To adjust the sprocket pitch 
it is necessary to loosen all bolts in all teeth insert two adjustment 
bolts in opposite holes, 10 & 11 that are 25 percent mismatched, tighten 
the nuts on the two adjustment bolts until the sprocket is in pitch with 
the chain, and then tighten all tooth shank bolts. The outer bolts are 
secured through holes 6 and 12. The inner bolts are secured through holes 
6, 13, and 14. If one hole is not sufficient to adjust pitch, remove the 
two adjustment bolts and insert them in the next adjoining holes, 10 & 11 
which have been brought within 25 percent of alignment from the previous 
hole alignment. This procedure may be continued until the sprocket is 
adjusted to the correct pitch to match the chain pitch, or the total 
adjustment allowed is used up. 
It is apparent from the foregoing that the present invention provides an 
adjustable pitch sprocket effecting equal pitch adjustment of all sprocket 
teeth simultaneously, with gradual adjustment over a wide range being 
obtainable. Moreover, the tapered shank adjustment bolts assure positive 
and gradual adjustment without danger of being broken. The adjustable 
pitch sprocket may be used in applications where existing sprockets fit 
splined shafts or have expensive hubs, simply by adapting the existing hub 
to the adaptor disc, and may be substituted for existing sprockets without 
the necessity of replacing the existing chain carried by the sprocket.