Improvements in and relating to Chain Gearing.
Year: 1897

page_text: Improvements in and relating to Chain Gearing.
I, JOHN GARDNER, of Marine View, Knott End, Fleetwood, in the County of
Lancaster, Engineer, do hereby declare the nature of this invention to be as
follows:
This invention relates to chain gearing and its object is to so construct the chain
and the chain wheels that they may be used with less friction and loss of power than
has heretofore been the case.
In carrying these improvements into effect I so construct and arrange the wheels
and the chain that a cycloidal or other suitable tooth or part always drives a pin
or its equivalent.
A chain at present commonly employed is one in which solid blocks alternate
with open links. Both the driving and the driven wheels are formed with similar
cycloidal teeth.
According to this invention I form the chain driving wheel as at present with
cycloidal or other teeth and so form the ends of the chain blocks with which they
engage that they act as pins or their equivalents, or I may substitute pins for the
blocks. The other ends of the blocks or those parts of the chain which engage
with the driven teeth are formed with cycloidal or other suitable driving curves.
The teeth of the driven wheel instead of being formed as at present are rounded to
act as pins or are substituted by pins.
Instead of forming the ends of the blocks to engage with the driven teeth I may
form the blocks or the links of the chain with lugs or projections to engage with
the pins or their equivalents upon the driven wheel.
W. E. HEYS & SON,
Agents for the Applicant.
Improvements in and relating to Chain Gearing.
I, JOHN GARDNER, of Marine View, Knott End, Fleetwood, in the County of
Lancaster, Engineer, do hereby declare the nature of this invention, and in what
manner the same is to be performed, to be particularly described and ascertained
in and by the following statement:―
This invention relates to chain gearing and its object is to so construct the chain
and chain wheels that they may be used with less friction and loss of power than
has hitherto been the case.

page_text: In ordinary chain gearing, such as is used in connection with velocipedes, the
block pattern is more commonly employed and it is to gearing with this type of
chain that my invention is more conveniently applicable. As now constructed the
blocks are 8-shaped and are connected with the chain of which they form part by
means of pins or rivets passing through the holes in the blocks and through the
side links. Thus, in effect, the blocks act as, and are equivalent to the pins some-
times used in gearing wheels instead of teeth. In such gearing experience has
shewn that the pins must be on the follower, or in other words that the pins must
be driven, otherwise greater loss of power and wear and tear occur. In the parallel
case of chain driving it is found that the flanks of the teeth of the driven wheel
wear far more rapidi than can be accounted for by the difference in diameter. I
have found that this defect can be overcome by so constructing the chain and
wheels that the driving or leading elements of the gearing are curved and only
the driven or following elements are cylindrical of pin-like. It is to be understood
that by
"curved" when herein used with reference to the form of the side of a
tooth or of the end of a chain block. is to be understood the ordinary involute,
cycloidal or equivalent curvature, used in the formation of toothed gearing!
I will describe my said invention with reference to the accompanying drawings
in which:-
-
Figure 1 illustrates in side elevation, two teeth of an ordinary chain wheel hav-
ing between them a single block of an ordinary block chain.
Figure 2 similarly illustrates a portion of a driven wheel shewing the teeth and
the driving end of the block constructed according to these improvements.
-
Figure 3 repeats Figure 2 except that an ordinary chain block is shewn between
the teeth.
Figure 4, represents on an enlarged scale a full curvature upon one end of a
chain block.
If both the driving and the driven wheels be made with teeth nearly semi-
cylindrical upon one side A, and curved upon the other side B, and if the chain
blocks are made with the following end a semicylindrical, and with the leading
end 6 curved as shewn in Figure 2, the condition of least wear and of least friction
will be filled. In the first place let the direction of motion be as indicated by the
arrow Figure 2, and D be the crank or driving wheel, then the wheel drives and
the chain is the follower and it is found that the driving surface B, is curved and
the following surface a is semicylindrical or pin-like. Now, the direction of rota-
tion being the same and D being the wheel driven by the chain; the curved
surface of the chain block 6 drives and the semicylindrical surface A of the tooth
follows. In both cases the best conditions are satisfied. It will be observed that
in order to obtain the required semicylindrical form of the wheel teeth, it is
necessary to undercut them as indicated at c, and whilst this is not found to prac-
tically weaken the teeth, it is found to produce the advantage that the chain blocks
have a much diminished tendency to mount the teeth by sliding upwards. This
result is obtained by these improvements without in the least degree preventing
the free disengagement of the blocks from the teeth in ordinary running.
In Figure 4, an extended curvature of the end of the chain block is shewn by
dotted lines so as to more clearly indicate its production, but in practice the curva-
ture is limited to the actual form shewn by the full lines.
It will be obvious that in the wheel teeth, although I have shewn in Figure 2
that the contour on one side is curved and on the other side rounded or semi-
cylindrical, this is not necessary. It will suffice if the working face of the tooth
has its appropriate form. Thus in a velocipede the teeth of the crank wheel may
be curved on the going side and any convenient form on the following side, whilst
in the driven wheel the teeth may be rounded or semicylindrical on the following
or driven side and any convenient form on the opposite face. It is however
generally convenient to make the teeth alike in both wheels, that is to say with one
face rounded and the other curved, I am aware that chain blocks have had both
their ends curved for use with chain wheels with the ordinary curved teeth and
'

page_text: that other chain blocks have been formed with projecting teeth gearing with
rollers or balls in the wheels. I therefore desire it to be understood that I do
not claim such devices as being any part of my present invention.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is: :-
1. In a chain for chain gearing, a block engaging the teeth of the wheels having
the driven end semicylindrical and the driving end curved, substantially as
and for the purpose herein before described and as illustrated by Figures 2 and 4
of the accompanying drawings.
2. In chain gearing, wheel teeth having semicylindrical driven sides A c, substan-
tially as and for the purposes herein before described and as illustrated by Figures 2
and 3 of the accompanying drawings.
3. In chain gearing, the combination and arrangement with a chain having
blocks with curved driving ends b of wheel teeth having semicylindrical parts A c
in contact therewith, substantially as and for the purpose hereinbefore described,
and as illustrated by Figures 2 and 4 of the accompanying drawings.
4. Chain gearing constructed and arranged so that a rounded or semicylindrical
part on the wheel or on the chain is always driven by a curved part on the chain
or on the wheel, substantially as hereinbefore described with reference to the
accompanying drawings.
1000