Improvements in and connected with Driving Pulleys and Chain Wheels.
Year: 1894

page_text: Date of Application, 23rd Oct., 1894
Complete Specification Left, 23rd July, 1995-Accepted, 24th Aug., 1895
PROVISIONAL SPECIFICATION.
Improvements in and connected with Driving Pulleys and
Chain Wheels.
I, JOHN GEORGE AULSEBROOK KITCHEN of 28 Rose Grove, Ardwick,
Manchester, in the County of Lancaster Manufacturer do hereby declare the
nature of this invention to be as follows:-
This invention relates to pulleys for transmitting power from one shaft to
another by means of chains, ropes or belts and consists in improvements in the
construction of the driving pulley and arrangements connected therewith, the
object of said improvements being to reduce the acting radius of the driving pulley
when the load on the driven pulley increases. The invention is more particularly
intended for the driving chain pulleys of velocipedes but applicable to other driving
pulleys.
In carrying out my invention I fix upon the pedal shaft or other shaft from
which power is to be transmitted, a boss or hub and connect the rim of the driving
pulley thereto by means of an elastic medium of such construction, strength and
stiffness that while the load on the driven pulley or tension on the pulling side of
the chain or its equivalent remains under a certain amount, the elastic medium
holds the rim central with the hub, but if the load or tension increases, the elastic
medium yields or is compressed so that the rim approaches nearer to the centre on
the pulling side and the acting diameter is reduced, in consequence of which the
same force exerted upon the pedals or the driving shaft is able to overcome the
increased load and drive the second shaft at a reduced speed.
The elastic medium is preferably formed of a number of suitably bent spring
blades fixed at one end to the hub and at the other to the rim of the driving pulley
but may consist of hinged arms under spring pressure and sliding on the rim or the
hub or parts connected therewith, or may be formed of an indiarubber cushion or
a hollow rubber cushion inflated with compressed air and interposed between the
hub and rim. In order to prevent the springs or other elastic medium from being
overstrained 1 may form the hub with a disc or its equivalent upon which the rim
will bear when the springs or their equivalents have been compressed or bent to a
certain amount.
I may also arrange one or more guide pulleys bearing upon the moveable rim on
its inside or outside or both sides and supported on the frame or its equivalent in
any suitable way for the purpose of keeping the distance from the centre of the
driven shaft to the centre of the moveable driving rim constant or approximately
so and preventing the chain or its equivalent from becoming slack in consequence
of the rim altering its position relatively to the hub or driving shaft.
D
R. J. URQUHART,
57, Barton Arcade, Manchester, and 5, Clayton Square, Liverpool,.
Consulting Engineer and Patent Agent.

page_text: Improvements: in and connected with. Driving Pulleys and
Chain Wheels.
I, JOHN GEORGE AULŞEBROOK KITCHEN of 28 Rose Grove Ardwick,
Manchester in the County of Lancaster, 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 :-
This invention relates to pulleys for transmitting power from one shaft to
another by means of chains, ropes.or belts, and, consists chiefly in. improvements in
the construction of the pulley or wheel with the object of reducing, the acting
radius of the periphery when the load. on the pulley or wheel increases. The
invention is particularly applicable to the driving chain wheels of velocipedes.
The improvements consist chiefly in the manner of construction of the driving
chain wheel or pulley by which the rim.of the wheel is carried or supported on the
boss by spring or flexible arms or spokes or other elastic medium which under
normal conditions hold the rim concentric with the boss, the constructive arrange-
ment being such that a greater or lesser thrust on the crank driving the loaded
pulley or wheel will cause the periphery of the pulley at that part upon which the
stress of the load acts to move towards the centre of the pulley and so, as the
pulley rotates, the acting radius is momentarily reduced by the stress and according
to the amount thereof. According to this construction and arrangement the
greater the load is upon the wheel or pulley, the slower is thie. power transmitted
and vice versa, producing an economical application of power.
The accompanying drawings are intended to illustrate the application of this
principle, the several figures showing also several of many methods of construction
of chain wheels for velocipedes. The same constructions apply also in the case of
flat belt and rope pulleys.
Figure 1 represents the elevation of a chain wheel constructed with flexible arms
or spokes.
Fig. 2 a similar view of a modification of the wheel.
Figure 3.a similar view of another modification in which. the elastic medium
consists of an elastic ring.
Figure 4 represents an end elevation of a chain wheel made according to my
invention mounted on the crank axle of a velocipede in position, and
Figure 5 a side elevation of the same, these two views showing also a device
consisting of a ratchet wheel and pawl applied for the purpose. of preventing the
reaction of the spring arms or elastic medium upon the axle in a backward
direction.
Referring to Figure 1 the rim a of the wheel here shown is carried by flat
curved springs or spring arms b6 which are secured to the boss c by screws or rivets,
or in any other suitable manner. The connection of the arms to the rim may also
be made in a similar manner. d represents the pedal crank, and the transmitting
chain or band is indicated by dotted line e. The dotted eccentric circle a' shows
the position of the rim a assumed when pressure is applied to the crank d'in the
direction indicated by the arrow and a-load exceeding the normal one is put upon
the chain e.
Figure 2 represents a modified construction of the wheel in which the springs or
spring arms bare belical and either arranged in tension or compression. In either
case sufficient play should be allowed between the coils to give the necessary
amount of eccentricity to the rim a. In this case the springs may also be
connected to the rim and boss respectively in any suitable and convenient way.
In Figure 3 the elastic medium b consists of an annular elastic ring which is
securely fixed to the rim a and boss c by grooving the opposing faces of the rim
1

page_text: and boss, and inserting metal plates in the ring and securing these plates to the
rim and boss by screws, or by other suitable means. The elastic ring is made of
india rubber or india rubber and canvas and may be made solid in section or
hollow, and if desired provided with a non-return valve by which it may be
inflated.
Figure 4 shows the application of the improved chain wheel to the driving axle
of a velocipede. In some cases I may, in order to prevent the axle from turning
backwards so as to direct the reaction of the elastic medium forwards, fix a ratchet
wheel upon the axle and a pawl upon the frame or bearing h. The ratchet
wheel and pawl are shewn in side elevation in Figure 5.
In order to direct the movement of the rim a so that the greatest advantage may
be taken of its eccentricity when acting under a load I may in some cases fix a
guiding roller inside the rim a which may be broadened for the purpose, or two.
guiding rollers i, i, so formed and disposed that they shall roll upon the periphery
of the rim and prevent a backward movement of the rim towards the driven shaft
in order that the distance from the centre of the driven shaft to the centre of the
driving chain wheel or pulley may remain the same and the chain or its equivalent
does not become slack.
I do not confine myself to the particular construction of the wheels or pulleys.
herein described, any suitable construction of spring arms or equivalent connection
may be employed.
I am aware that spring chain wheels have been employed previous to my inven-
tion, but for a different purpose and have not been capable of assuming an eccentric
position of the rim to the centre, which is an essential point in my 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. The arrangement of springs or equivalent elastic media for connecting the
rim and boss of a driving pulley or chain wheel in such a manner that the rim
assumes an eccentric position to the boss and the acting radius of said pulley or
wheel becomes reduced when the load on the belt or chain is increased substantially
as described.
2. In connection with a driving pulley or chain wheel having an elastic
connection between the boss and rim, allowing the rim to assume an eccentric
position to the boss when the load is increased, the arrangement of one or more
guide pulleys to maintain the distance between the centre of the rim and the driven
shaft substantially as described.
3. The construction and arrangement of a driving chain wheel or pulley having
an elastic connection between the boss and rim and ratchet wheel and pawl or
equivalent thereof to prevent a retrograde movement of the axle substantially as
and for the purposes described hereinbefore and in and by the accompanying
drawings.
Dated this 22nd der of July 1895
R. J. URQUHART,
57, Barton Arcade, Manchester, and 5, Clayton Square, Liverpool,
Consulting Engineer and Patent Agent.