An Improved Chain-adjuster for Cycles.
Year: 1898

page_text: An Improved Chain-adjuster for Cycles.
1, STEPHEN FLETCHER WILES, of North Square, North Street, Guildford, in
the County of Surrey, Cycle Manufacturer, do hereby declare the nature of this
invention to be as follows:
The present invention has reference to an improved chain-adjuster or method of
adjusting the tension of the driving chain of cycles.
According to my invention the forked end of the usual stay is recessed and in the
said recess are fitted two discs through each of which is bored or pierced a circular
hole eccentrically, and the hole in the larger of the two is made large enough to
just permit the smaller disc to lie within it. The top surface of the smaller disc
when in position in the larger one is very nearly flush therewith, and the two
fit flush in the recessed end of the stay.
There are also two small holes provided in the outer or larger one of the two
eccentric discs in order to permit of a tool being inserted therein to turn the outer
disc around the inner one. By this means, the outer disc being turned around the
inner one, which latter is fast on the back wheel spindle, a rectilinear adjustment
of the tension of the chain is effected.
I am aware that one eccentric disc has already been employed to effect this
adjustment, but hitherto such has afforded only a curvilinear adjustment.
The employment of two discs pierced eccentrically with a round hole and fitting
into each other and into a recess specially provided in the forked end of the
proper stay, forms the essence of my invention, and a perfectly rectilinear adjust-
ment is effected by the combination by simply rotating the outer one around the
inner one, which latter as above stated is fast to the spindle of the back wheel of
the cycle.
Dated the 22nd day of March 1898.
PHILLIPS & LEIGH,
Agents for the Applicant.
An Improved Chain-adjuster for Cycles.
I, STEPHEN FLETCHER WILES, of North Square, North Street, Guildford, in
the County of Surrey, Cycle Manufacturer, 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:.
The present invention has reference to an improved chain-adjuster or method of
adjusting the tension of the driving chain of cycles; the object of the invention being
to obtain a perfectly rectilinear adjustment and one wherein the loosening strain

page_text: is not in a direct line in the reverse direction to the tightening strain as usual
but wherein the loosening strain is at right angles to the tightening strain, and there-
1ore the former becomes practically nit; an obvious advantage as there is no strain
in the reverse direction to that by which the tension of the chain is effected and
consequently a ughtening-up nut or other like device is not necessary to maintain
the said tension, and hence my chain adjusting device may be absolutely locked
in any position and there being no contrary strain tending to loosen it, it is
absolutely reliable and safe.
I will now proceed to describe my invention in detail reference being had to the
accompanying sheet of drawings which illustrate by way of example the applica-
tion or my invention to a rear driving "safety" bicycle, in which;
:-
Figure 1 represents, in side elevation, the junction of the rear end of the bottom
tube or stay with the lower end of one of the back stays, shewing the recessed end
of the said bottom tube or stay.
Figures 2 and 3 represent front and side elevation respectively of the larger
of the two eccentrically pierced adjustment discs.
Figures 4 and 5 represent side and front elevation respectively of the smaller
of the two eccentrically pierced adjustment discs.
Figure 6 is a rear end elevation of the junction of the bottom tube or stay
with one of the back stays, shewing the two adjustment discs fitted in position
in the recessed end of the bottom tube.
Figure 7 is a side elevation of Figure 6.
Figure 8 represents in side elevation the junction of the rear end of the bottom
tube or stay with the lower end of one of the back stays, shewing a slight
modification in the recessed end of the said bottom stay or tube.
Figure 9 is a side elevation of the junction of the bottom tube or stay with one
of the back stays, shewing the modification of adjustment discs fitted in operative
position in the recessed end of the said bottom-stay or tube.
Figure 10 is a side elevation of the smaller modified form of adjustment uisc,
shewn detached.
According to my invention the forked end of the usual stay, that is to say,
at the present time the rear extremity of the bottom tube a which is flattened for
the purpose, is recessed; the recess 6 being circular as shewn, but outside this
recess the substance may take any form desired. In the said recess are fitted two
discs c and d shewn detached in Figures 2, 3, 4 and 5 through each of which is
bored, pierced or otherwise formed a circular hole e and f respectively eccentric
to the centre of the disc. These holes are made right through the discs and the
hole e in the larger one c of the two is made large enough to just permit the smaller
disc d to lie within it as shewn in Figures 6, 7 and 9. The top surface of the
smaller disc d when in position in the larger one c it will be seen is very nearly
flush with that of the latter, and the two together fit flush in the recessed end b
of the bottom tube or stay a.
There are or may be also small holes provided in the outer or larger one c
of the two eccentric discs in order to permit of a tool, with two prongs or studs
for instance, being inserted therein by which to turn the outer disc c around the
inner one d when effecting the adjustment of the tension of the driving chain.
These holes are not shewn in the drawings, but a square boss g to fit a spanner or
other device may be employed instead.
The smaller adjustment disc d is mounted fast on the spindle of the back
road wheel; the said spindle being threaded through the eccentric hole f.
A stud such as h working in a slot such as i may be employed as an additional
guide for the smaller disc d in its motion and to limit the stroke or traverse of
the outer disc around the inner one d, but this stud and slot are not essential
and it is quite immaterial whether the stud h be on the disc d and the slot
in the recess b as shewn in Figures 1, 4, 5, 6, 7, or the said stud be in the recess b
and the slot in the disc d as shewn in Figures 8, 9 and 10.
To effect the desired adjustment the outer or larger disc c is rotated by means

page_text: of a tool if necessary fitting the boss or projection g or other equivalent device as
above explained or by hand by means of the milled edge k, this rotary motion
producing a rectilinear backward or forward motion of the spindle of the back
road wheel by reason of the narrower or broader part of the outer disc c, as the
case may be, being thereby insinuated between the inner periphery of the recess b
and the outer periphery of the inner disc d which latter is fast upon the spindle
of the back road wheel as above stated and consequently draws the said spindle
with it in a perfectly straight line thus tightening or loosening the driving chain
as desired.
The amount of friction between the two discs c and d may be regulated for
example, by making the stud h to screw into the disc d when the latter contains
the said stud or into the bottom of the recess b, as the case may be.
I am aware that a single eccentric disc operating as a cam has already been
employed to effect the adjustment of the tension of cycle chains, but hitherto
is not
such has afforded only a curvilinear adjustment but this method
reliable
is
the slackening strain
as
exerted
constantly
38
upon it
well as the tightening strain, whereas by my method the slackening strain
is entirely eliminated by reason of it acting at right angles. I therefore lay
no claim to the employment of an eccentrically mounted disc, but:-
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. A device for adjusting the tension of the driving chain of a cycle, consisting
of the combination with the forked rear end of the bottom tube or stay of the
frame of a circular recess formed in the said rear end, a circular disc having an
eccentric hole through it fitting loosely into the said recess, a second disc also
having an eccentric hole through it fitting loosely into the aforesaid
disc and mounted fast upon the spindle of the back road wheel, substantially as
described and illustrated in the accompanying drawings.
2. In a device for adjusting the tension of the driving chain of a cycle, the
combination of two discs one fitting loosely and eccentrically within the other,
the enclosed one mounted fast upon the spindle of the back road wheel and the
surrounding or outer one fitting concentrically and loosely into a recess formed in
the rear forked end of the bottom tube or stay, substantially as described and
illustrated in the accompanying drawings.
1000
PHILLIPS & LEIGH,
No. 22, Southampton Buildings, Chancery Lane, London, W.C.,
Agents for the Applicant.