Improved Chain Gearing principally adapted for Cycles.
Year: 1896

page_text: Improved Chain Gearing principally adapted for Cycles.
I, FREDERICK PURBRICK, of "Bromley" Orrong Road, Caulfield, near Melbourne,
in the Colony of Victoria, Engineer, do hereby declare the nature of this invention
to be as follows:-
Chain gearing as heretofore constructed has many disadvantages, thus the
friction of the chain around the sprocket wheels is very great and there is no
provision for readily replacing a broken link.
Now the object of this invention is principally to provide a chain gearing which
will be adapted for use on cycles where it is of paramount importance to reduce
the frictional resistance of the driving gear as much as possible and at the same
time to provide facilities for readily replacing a broken or worn link.
According to this invention I make both the driving wheel and the pinion with
a deep peripheral groove in the bottom of which are
are teeth preferably of
epicycloidal or approximately epicycloidal form. The chain itself is made of
stamped or malleable cast steel or other sufficiently tough material each alternate
link being formed with an inwardly projecting tooth corresponding to the recess
formed between the teeth of the wheels with which it gears. The links having the
teeth on them are not continuous but are formed with an opening so that they can
be placed in engagement with the other links by turning them at an angle to
each other. To effect this it is necessary to slacken the bearings of one of the
wheels and move it nearer to the other one so as to loosen the chain.
In this way a broken or a worn link can readily be replaced by a new one.
Dated this Twelfth day of May One thousand eight hundred and ninety-six
COMPLETE SPECIFICATION.
Improved Chain Gearing principally adapted for Cycles.
I, FREDERICK PURBRICK, of "Bromley" Orrong Road, Caulfield near Melbourne,
in the Colony of Victoria, 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:-
Chain gearing as heretofore constructed has many disadvantages thus the
friction of the chain around the sprocket wheels is very great and there is no
provision for readily replacing a broken link.
Now the object of this invention is principally to provide a chain gearing which
will be adapted for use on cycles and machines where it is of paramount importance
to reduce the frictional resistance of the driving gear as much as possible, and
[Price 8d.1

page_text: at the same time to provide facilities for readily replacing a broken or worn link.
The invention will be readily understood from the following description reference
being had to the accompanying drawings wherein,
Figure 1, is a view partly in side elevation and partly in section of this improved
gearing as it would be used for instance on a bicycle.
Figure 2 is a central section of the drive wheel and,
Figure 3, is a plan of a portion thereof drawn to a larger scale.
Figure 4, is a side elevation, and
Figure 5, a plan of one of the toothed links of the chain, whilst,
Figures 6 and 7, are respectively a longitudinal section and plan of one of the
cther links, and
Figure 8 is a side elevation of a few links of the chain illustrating how said
links may be detached from each other.
Figure 9, is a plan of a modified form of link, whilst,
Figure 10, is a view of a toothed link for use therewith.
In
The same letters of reference indicate the same parts in all the figures.
According to this invention I make both the driving wheel A and the pinion B
with a peripheral groove C (see Figures 2 and 3) in the bottom of which are
teeth D preferably of epicycloidal or approximately epicycloidal form.
practice I find it preferable to make the teeth 1) integral with the driving wheel A
as illustrated in Figure 1 although they might be made of a separate block as
shewn in Figure 2. The chain itself is made of stamped or cast steel or other
sufficiently tough material each alternate link E, E being formed with an inwardly
projecting tooth F corresponding to the recess formed between the teeth D of the
wheels with which it gears.
The links E having the teeth Fon them are not continuous but are formed with
openings G so that they can be placed in engagement with the other links H by
turning them at an angle to each other as illustrated in Figure 8. To effect this
it is necessary to slacken the bearings of one of the wheels and move it nearer to
the other one so as to loosen the chain, or an adjusting link may be inserted.
In this way a broken or worn link can readily be replaced by a new one.
jections I, I are formed at intervals on the inner side of the groove C for the
links H to rest upon.
Pro-
If preferred the small bridge piece across the centre of the links H may be
dispensed with, as illustrated in Figure 9, if it is thought desirable to increase
the area of the protruding part of the die used for stamping them, in which case
the toothed links would be formed as illustrated in Figure 10, with a projecting
shoulder J on each side to prevent the links becoming disengaged without first
being turned into the relative positions shown in Figure 8. This construction
however need only be adopted if it is found impossible to get the dies to stand.
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:-
That herein described driving chain gearing consisting essentially of wheels
having comparatively deep peripheral grooves in combination with chains having
inwardly projecting teeth to gear with the teeth in said wheels substantially as
and for the purposes herein described and explained and as illustrated in the
accompanying drawings.
Dated this Twenty-second day of August One thousand eight hundred and
ninativ
FREDERICK PURBRICK.
G. F. Redfern & Co.,
4, South Street, Finsbury, London, Agents for the Applicant.