Improvements in the Driving Gear of Velocipedes.
Year: 1892

page_text: Date of Application, 17th June, 1892
Complete Specification Left, 17th Mar., 1893-Accepted, 29th Apr., 1893
PROVISIONAL SPECIFICATION.
Improvements in the Driving Gear of Velocipedes.
We, MAURICE JOHAN SCHULTE and SIEGFRIED BETTMANN both of No. 11,
Grosvenor Road, Coventry in the County of Warwick Cycle Manufacturers, do
hereby declare the nature of this invention to be as follows:-
Our invention relates to the gearing of those velocipedes in which the pro-
pelling power is transmitted through an endless pitch chain running on a driving
and a driven toothed or "chain" wheels, and in which the open parts of the
chain into or through which the teeth on the wheels project are not shorter
than the closed parts which alternate them, these distances being calculated along
the pitch circle of the wheel for the time being in gear with the chain. If one
wheel be larger than the other then the distances are calculated on the larger
wheel.
The objects of our invention are the following:-
:-
(1) Increase, of durability, (2) decrease of weight and, in some cases (3) ease of
obtaining certain ratios of gearing.
Chain wheels are usually provided with as many equidistant teeth and depressions
on the periphery as there are corresponding apertures in a piece of the chain equal
in length to the circumference of the pitch circle of the chain wheel.
To attain these objects we double the usual number of depressions on the
periphery of oue or both the wheels but place them only half the usual distance
apart.
The duplication of the number of the depressions necessarily doubles the number
of teeth, but the teeth so formed measure much less from face to face than those
usually employed with this class of chain.
Thus there are two teeth and two depressions to the pitch and consequently an
even number of each. The formation of the duplicate or second series of
depressions entails the removal of a certain amount of material and so reduces
weight.
As the chain may be moved from gearing with one series of teeth to gear with
the other the durability of the wheel or wheels is greatly increased.
Or, we can employ chain wheels of diameters midway between those usually
employed by setting the teeth and the depressions at half the usual distance apart.
In this case there will be an odd number of teeth and an odd number of depressions
and the chain will necessarily and automatically gear with each tooth in turn,
those teeth which are missed at one revolution of the wheel coming into gear in
the next and so on. A chain wheel so formed will have an effect on the ratios of
the gearing in accordance with its diameter, which effect could only be obtained by
at least doubling the diameters of both the wheels if the usual number of teeth to
the pitch were employed, with a considerable increase in weight.
Provided the open parts of the chain are sufficiently longer than the closed parts.
We may use more than two teeth and two depressions to the pitch if convenient
with corresponding effects on the durability, weight and ratios of gearing.
Dated this 11th day of June 1809
WILLIAM BESTWICK MAXFIELD,
Applicants' Agent.

page_text: COMPLETE SPECIFICATION.
Improvements in the Driving Gear of Velocipedes.
We, MAURICE JOHAN SCHULTE and SIEGFRIED BETTMANN, both of
11 Grosvenor Road, Coventry, in the County of Warwick Cycle Manufacturers,
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:—-
Our invention relates to the gearing of those velocipedes in which the propelling
power is transmitted through an endless pitch chain running on a driving and a
driven toothed or "chain" wheels and which the open parts of the chain, into or
through which the teeth on the wheels project, are not shorter than the closed
parts which alternate them, these distances being calculated along the pitch circle
of the wheel for the time being in gear with the chain. If one of the two wheels
in the gear be larger than the other then the distances are calculated on the pitch
circle of the larger wheel.
The objects of our invention are the following
:―
(1) Increase of durability, (2) decrease of weight, and in some cases (3) ease of
obtaining certain ratios of gearing.
Chain wheels are usually provided with as many equidistant teeth and depressions
on the periphery as there are corresponding open parts or apertures in a piece of
the chain equal in length to the circumference of the pitch circle of the chain
wheel.
To attain these objects we double the usual number of depressions on the
periphery of one or both of the wheels but place them only half the usual distance
apart.
The duplication of the number of the depressions necessarily doubles the
number of teeth, but the teeth so formed measure much less from face to face
than those usually employed with this class of chain. Thus, there are two teeth
and two depressions to the pitch and consequently an even number of each. The
formation of the duplicate or second series of depressions entails the removal of a
certain amount of material and so reduces weight. As the chain may be moved
from gearing with one series of teeth to gear with the other, the durability of the
wheels is greatly increased, being approximately doubled, for, when the first series
of teeth is worn out of shape the second series may be brought into use.
Or we can employ chain wheels of diameters midway between those usually
employed by setting the teeth and the depressions at half the usual distance apart.
In this case there will be an odd number of teeth and an odd number of
depressions and the chain will necessarily and automatically gear with each tooth
in turn, those teeth which are missed at one revolution of the wheel coming into
gear in the next revolution and so on. A chain wheel so formed will have an effect
on the ratios of the gearing in accordance with its diameter, which effect could
only be obtained in some cases by at least, doubling the diameters of both the
wheels, if the usual number of teeth to the pitch be employed, with a considerable
increase in weight.
Provided the open parts of the chain are sufficiently longer than the closed parts,
we may use more than two teeth and two depressions to the pitch if convenient
with corresponding effects on the durability, weight and ratios of gearing.
In order that our invention may be well understood we append drawings which
show the general form and arrangement of the parts of our invention but modifica-
tions can be made without departing from the spirit of our invention. In the
drawing similar letters of reference refer to similar parts.
Figure 1 is a side view in elevation of an ordinary chain wheel A gearing with
part of an ordinary chain B in which the open parts C, into or through which the
eight teeth D on the wheel A project between the side plates E, are not shorter
than the closed parts F, which alternate them when measured along the pitch circle

page_text: of the wheel A. The said wheel A is provided on the periphery with equidistant
teeth D and depressions G such teeth and depressions corresponding to the open
parts or apertures C and closed parts F in the chain B. In carrying out our
invention we double the usual number of depressions by cutting out the central
portions of the teeth D as indicated by the dotted lines at G"; this necessarily
doubles the number of teeth by forming each tooth D into two D", D. Or the
depressions G may be made at the same time as the depressions G. The teeth Dº,
and D measure much less, from faces d and d³, to faces d¹ and d³ respectively, than
the teeth D measured or would measure from face d, to face d³. Thus there are two
teeth D, D, and two depressions G, Ga, to the pitch of the chain and conse-
quently an even number of each, both teeth and depressions. The formation of
the depressions G" reduces the weight of the wheel by the amount of material
removed in the operation. The chain B may be fitted to the wheel A so that the
closed parts F engage with the depressions G when, if the wheel A be a driven
chain wheel and the normal direction of the travel of the chain B, be that indicated
by the arrow the faces d³ of the teeth D will take the wear. The faces d³ were
the only wearing surfaces of the original teeth D and when these were worn out of
shape the wheel A became useless, but according to our invention when one set of
teeth, e.. the teeth D are worn out the chain B may be shifted on the wheel A so
that the closed parts F engage with the depressions G and the faces d' of the
teeth Da will take the wear and the durability of the wheels be thus approximately
doubled. A similar result will be obtained, though the wheel A be a driving chain
wheel and or though the normal direction of travel of the chain B he opposite to
to that indicated by the arrow.
Figure 2 is a side view in elevation of a chain wheel A' of diameter midway
between those of two ordinary wheels, adapted to gear with a chain B as herein-
before described, and having eight and nine teeth respectively. The teeth D¹ and
depressions G' are set at half the usual distance apart. In this case there are
necessarily an odd number 17 of teeth D¹ and the same odd number of depressions G¹
and the chain necessarily and automatically gears with each tooth in turn, those
teeth which are missed at one revolution of the wheel come into gear in the next
revolution, and so on. For example if the closed parts F of the chain B engage
with the teeth 1, 3, 5, 7, 9, 11, 13, 15, and 17 in one revolution, the next closed part
will engage with tooth 2 and the following closed parts with teeth 4, 6, 8, 10, 12, 14,
and 16 when the next then following closed part will engage with tooth 1 and so on
again. This wheel weighs less than the average of the two wheels hereinbefore
described as having eight and nine teeth respectively, by the correspondingly
smaller quantity of material in the teeth. The wheel A¹ effects the ratios of the
gearing in accordance with its diameter and consequent number of teeth, 17, which
equals 8.5 ordinary teeth, a number which could not be employed in practice, and
an equivalent effect could only be otherwise obtained by doubling, or similarly
multiplying, both the wheels included in the gear. And this will be the case
whenever the number of teeth on one of the wheels, made according to our invention
and used in a gear, is a prime number unless the number of teeth on the other wheel
be equal to or a multiple of the number of teeth on the first wheel; the numbers of
the teeth on the respective wheels, corresponding to the diameters of such wheels.
Figure 3 is a side view in elevation of a chain B2 in which the open parts C³ are
more than twice as long as the closed parts F2 and this enables us to use three
teeth D³ to the pitch of the chain f2 with corresponding effects on the weight, wear
and ratios of gearing according to the number of teeth used on the wheel (A³).
Figure 4 is a plan view of the chain B and
Figure 5 a plan view of the chain B³.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed we declare that what we
claim is:-

page_text: number of both teeth and depressions, such teeth and depressions being set two or
more to the pitch of the chain substantially as and for the purpose described.
2. In chain gearing for velocipedes, forming the chain wheels with an odd
number of both teeth and depressions, such teeth and depressions being set two or
more to the pitch of the chain substantially as and for the purpose described.
3. In chain gearing for velocipedes, forming the chain wheels with two or more
teeth to the pitch of the chain substantially as and for the purpose described.
4. The improvements in the driving gear of velocipedes substantially as herein
described and illustrated.
Dated this 16th day of March 1893.
WILLIAM BESTWICK MAXFIELD,
The Central Office for Patents, &c.,
19, Bowling Green Street, Leicester, Applicants' Agent.