Year: 1899

page_text: Date of Application, 27th Feb., 1899
Complete Specification Left 22nd Nov 1800
Accented
30th Des 1000
I, HAROLD DENNIS TAYLOR, of Trenfield, Holgate, York, in the County of York,
Optician, do hereby declare the nature of this invention to be as follows:-
-
This invention has for object a variable speed gear for cycles, and it is
designed to provide a gear which can be adjusted to enable the cycle to be driven
at a low speed, such as is reguired when carrying a heavy load, or in ascending
hills, or at a higher speed or speeds, such as are required with light loads or
in travelling on level surfaces or on down grades.
One way of carrying my invention into effect is as follows. I provide a
driving chain connecting the front sprocket wheel on the crank axle to the
sprocket wheel on the back or driving wheel of cycle. This driving chain in
the course between the two wheels is made to engage and drive an intermediate
sprocket wheel, which latter has fastened to it firmly one smaller sprocket wheel,
and a second still smaller wheel, all three being on the same shaft and therefore
rotating together preferably upon a ball bearing carried by a small bracket fixed
either to the chain stay or to the vertical stay of the frame. On the hub of the
driving wheel there are in addition to the usual sprocket wheel which is driven
directly by the driving chain, two additional ones placed side by side concen-
trically, all three moreover being severally in alignment with the intermediate
sprocket wheels aforesaid. The main intermediate sprocket wheel is geared to
the main sprocket wheel on the driving wheel by the driving chain as already
described. The next intermediate sprocket wheel is geared to its corresponding
sprocket wheel on the driving wheel by a short chain encircling both, and the
third intermediate sprocket wheel is likewise connected with the third sprocket
wheel on the driving wheel by another short chain encircling both. All the
sprocket wheels on the hub of the driving wheel are so arranged as to be capable
of being free from any connection with the said wheel rotating freely around
the hub upon ball bearings, but there is a mechanism provided, which enables
the said sprocket wheels to be locked to the back wheel of the cycle one at a time,
and thus by this arrangement (the intermediate sprocket wheels being of different
diameters) I am enabled to obtain three speed gears obtaining either a high
speed, a medium speed, or a low speed, and enabling the rider to accommodate
his speed and available power to the load, or to the nature of the ground over
which he is riding.
The locking or unlocking of the respective sprocket wheels on the driving chain
may be effected in a variety of ways, but the plan I at present prefer is as
follows:-
The end of the driving wheel hub has one or more key-ways (preferably three)
cut out longitudinally in its surface. A pair of steel rings are pushed tightly
over the hub, their outer surfaces furnishing inner ball tracks for the two inside
ball races out of the four upon which the hub sprocket wheels rotate. The inner
edges of the three sprocket wheels of the back wheel only just clear the hub or
form a loose fit over it. The inner edges both of the steel rings, and of all

page_text: three back wheel sprocket wheels, have longitudinal keyways cut in them corre-
sponding to the keyways cut into the hub.
The keyways in the rings are kept in coincidence with the hub keyways by
means of a pin which prevents rotation of the rings, also the keyways in the
rings are cut larger than the keyways in the sprocket wheels, in order to insure
plenty of clearance for the travelling key or keys. This key consists of a long
strip of steel passing from one end of the back wheel hub to the other. This
strip lying wholly within the keyways cut in the hub, does not in itself project
above the cylindrical surface, but its end terminates in a short key of about
double depth or thickness. This key fits into the keyway on the hub, and at the
same time into the keyway cut into any one of the sprocket wheels, and thus locks
the latter to the hub. In this manner one of the sprocket wheels can be locked
to the driving wheel hub, while the other two sprocket wheels thereof are quite
free, and can rotate about the hub quite independently, and in a frictionless
manner upon their own ball bearings. At the opposite end of the hub and out-
side of the spoke flange, the key shanks terminate in a circular flange or ring.
The three keys and this ring thus form one piece and are capable of sliding longi-
tudinally backwards and forwards' upon the hub.. Thus these keys can be brought
successively under either one of the back wheel sprocket wheels, and lock them
respectively and one at a time to the hub, while the other two can rotate freely
around it. When however the keys are mid-way between any of the sprocket
wheels, that is to say, exactly underneath one of the two rings, then all three
sprocket wheels are free from any connection with the hub and therefore the riders
feet may rest quietly upon the pedals, the sprocket wheels and pedals remaining
stationary while the bicycle runs on. Thus between the changes in the gearing
I get free pedals while in other positions I get variable speeds adjustable at
pleasure.
The keys may be actuated and this variable gearing changed by the rider
without dismounting, by means of a rotating sleeve operated by means of a
handle or lever placed within reach of the rider. This sleeve comprises a steel
tube loosely fitting over the vertical stay. At the top, the sleeve terminates
in a lever or handle having a spring engaging into detent notches cut in the edge
of a disc which is firmly fixed to the vertical stay just below the saddle. The
bottom end terminates in a small toothed wheel and this engages in a plunger or
piston which is provided with rings or teeth of the same pitch as the teeth
of the wheel. This plunger or rack fits freely into a socket drilled through the
centre of the step which latter is carried by a special bracket piece which forms
the mutual attachment for the left-hand stay and hub. The free end of the
plunger or rack terminates in a sort of flanged bobbin engaging between its two
Hanges the key ring aforesaid. Thus if the plunger or rack be driven outwards
by the rotation of the sleeve, then the three keys are forced to travel from
left to right, and the pedals are freed or the gear is changed as desired by the
rider, who has thus simply to rotate the lever round into the appropriate detent
notch. As an additional precaution to insure the keys keeping accurately in
the position required of them, a spring can be fixed to the hub engaging in its
free end with bevelled notches cut in one of the key shanks at proper positions.
The main driving chain can be slackened or tightened by an eccentric adjustment
within the crank bracket, but if the coupled or intermediate chain wheels are
mounted on an attachment fixed to one of the vertical stays, then both the latter
may be what are known as swing stays, having their lower ends bored to receive
the ends of the hub spindle. Thus, when tightening up the main chain, the hub,
vertical stays and coupled wheels can be moved back all of a piece without dis-
turbing the tension of the short chain or chains, whose tension can be adjusted
by shifting the bearing of the coupled wheels up or down the vertical stay.
I have described my invention in the form of a three speed gear giving changes
from high to low, in the ratio of for example, one, five-sixths and two-thirds,
but the principle of my invention can be applied in that form giving two or

page_text: other number of changes of gearing with free pedals between. Furthermore the
sprocket wheels on the hub of the driving wheel may either be equal in size
and number of teeth, or they may be successively larger or smaller, in which case
the intermediate sprocket wheels are by preference made of a size instead of
different sizes. Furthermore I wish it to be understood that I do not confine
myself to the details herein set forth, as these can be considerably varied without
departing from the nature of the invention.
The intermediate sprocket wheel and hub sprocket wheel which are driven by
the main chain must be chain wheels, but the other two intermediate wheels and
the two hub wheels may if desired be spur wheels each gearing into its fellow
wheel.
I, HAROLD DENNIS TAYLOR, of Trenfield, Holgate, York, in the County of York,
Optician, 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 has for its object. a variable speed gear for cycles and it is
designed to provide a gear which can be altered by the rider without dismounting
so as to enable a cycle to be driven at a low speed, such as is required when
carrying a heavy load or in ascending hills, or at a higher speed or speeds such
as are required with light loads or in travelling on level surfaces or on down
grades, or to enable the pedals to be used as stationary foot rests while the cycle
runs on.
Since filing my provisional specification I have added certain additional
improvements to my invention, namely the arrangement for giving the spindle
of the intermediate sprocket wheels adequate support so as to resist the strains
which tend to twist the vertical stay, also the arrangement for adjusting the
ball bearings on which the chain wheels run. And as these added features are
not foreshadowed in the provisional specification, I do not claim them per se
as part of my patent. As however the law prescribes that the best mode known
to me in carrying the invention into effect should be disclosed I have described
the invention as originally applied for, but with all my latest improvements added.
The invention will be understood from the following description, reference
being made to the accompanying drawings, in which:
Figure 1 is a longitudinal section through the hub and the two sets of sprocket
wheels;
Figure 2 a side elevation:
Figure 3 is a side view of the intermediate sprocket wheels and part appertaining
thereto;
Figure 4 a general plan of the invention applied to a bicycle;
Figures 5 and 6 detail views of a hand lever and parts appertaining thereto
for actuating the variable gearing;
Figures 7 and 8 detail views showing the piston or plunger with its operating
tooth wheel;
Figure 9 an edge view of the bracket V:

page_text: Figure 10 a detail view of the spring locking device used as an additional
precaution to ensure the keys keeping accurately in the position required of them;
Figure 11 a cross section through the hub showing the sliding keys I¹ and
the ring M;
Figure 12 an elevation of the locking plate 1;
Figure 13 an elevation of the locking plate 7;
Figures 14 and 15 show in elevation and plan respectively the arrangement
of my invention when spur wheels are substituted for the sprocket wheels DE
and de;
Figure 16 a detail sectional view thereof on an enlarged scale.
Referring first to Figures 1, 2, 3 and 4, I provide a driving chain A connecting
the front sprocket wheel B on the crank axle and the sprocket wheel C on the
back or driving wheel of the cycle. This driving chain is not carried straight
to the back wheel hub but is looped up and carried over an intermediate
sprocket wheel c, which in conjunction with one or more sprocket wheels such
as d and e preferably of similar size and fastened firmly to the sprocket wheel c
revolves freely on ball bearings about a spindle firmly fixed to the
vertical stay F. After passing over wheel c the chain A laps round
the hub sprocket C and returns underneath direct to the crank sprocket wheel B
again. Thus c, d and e being all three on the same shaft and fastened together
are always rotating together as one piece so long as the main chain is running.
On the hub of the driving wheel there are in addition to the usual sprocket
wheel C which is driven directly by the driving chain A, one smaller one 1,
and a second still smaller one E all placed side by side concentrically, all three
moreover being severally in alignment with the intermediate sprocket wheels
aforesaid. The main intermediate sprocket wheel c is geared to the main
sprocket wheel C on the driving wheel by the driving chain A as already described.
The next intermediate sprocket wheel d is geared to its corresponding sprocket
wheel 1) on the driving wheel by a short and independent supplementary chain A¹
encircling both, and the third intermediate sprocket wheel e is likewise connected
with the third sprocket wheel E on the driving wheel by another short and
independent supplementary chain A² encircling both. These chain connections
are best shown in Figure 2 of the accompanying drawings. Figure 1 shows how
the three hub chain wheels C D E are mounted each upon independent but
mutually adjustable ball bearings. All the sprocket wheels C D E on the hub
of the driving wheel are so arranged as to be capable of being free from any
connection with the said wheel, and from each other, rotating freely around the
hub upon ball bearings, but there is a mechanism provided which enables the
said sprocket wheels to be locked to the back wheel hub of the cycle one at a
time, and thus by this arrangement (the main sprocket wheels CD and E being
of different diameters) I am enabled to obtain three speed gears, obtaining either
high speed, intermediate speed or low speed and enabling the rider to accommodate
his speed and available power to the load or to the nature of the ground over
which he is travelling.
The locking or unlocking of the respective sprocket wheels C D E and the
driving chain may be effected as follows: The end of the driving wheel hub
is made considerably thicker beneath the chain wheels so as to have cut in it
one or more (preferably three as shown) longitudinal grooves or key-ways H,
one of which is shown at top side in Figure 1 and all three endways in Figure 11.
In each of these three key-ways H there slides a key shank I (Figures 1, 4,
15 and 16) consisting of a long strip of steel passing from nearly one end of the
back wheel hub to the other, this key I lying wholly within the key-ways
cut in the hub does not in itself project above the cylindrical surface but its
end terminates in a short projecting key or head I of about double depth or
thickness which projects considerably above the groove or key-way, while the
key shank I lies concealed within the latter. These keys I fit into the key-ways
in the hub and at the same time the projecting keys I fit into the short key-

page_text: ways H cut in the inner circumference of the sprocket wheels and thus lock
the latter to the hub, while the other sprocket wheel or wheels rotate freely
without connection. In this manner one of the sprocket wheels can be locked to
the driving wheel hub, while the other two sprocket wheels thereof are quite
5 free, and can rotate about the hub quite independently and in a frictionless manner
upon their own ball bearings. At the opposite end of the hub and outside the
spoke flange the key-ways I terminate in a circular flange or ring J (Figures 1,
4, 7, 10 and 15) which disc is capable of sliding easily to and fro upon the
cylindrical portion of the hub outside the spoke flange. The three projecting
keys I, the key shanks I and this disc J, thus form one piece sliding to and
fro longitudinally upon the hub parallel to its axis, and thus the three keys I¹
can be pushed simultaneously into the key-ways of any one sprocket wheel CDE
at a time, and lock them respectively, and one at a time to the hub, while the
other two can rotate freely round it. The roots of the two spoke flanges K are
pierced by three rectangular apertures to allow the key shank's to pass through
them, the key shanks lying closely upon the cylindrical surface of the hub L.
The common ball race between the chain wheels C and D has to be specially
arranged for, so as to be out of the way of the travelling keys. A tightly fitting
steel ring M (Figures 1 and 11) is pushed tightly over the hub into the position
shown, its outer surface furnishing an inner ball track for one inside ball race m
out of the four upon which the hub sprocket wheels rotate. This ring has three
clearance key-ways cut in its inner circumference rather larger than the
travelling keys I so that the latter may pass freely through and under the
ring. This ring is held in proper position in the following manner so that its
key-ways are kept in coincidence with the hub key-ways. First a rectangular
groove N (Figures 1 and 11) is turned out all round its inner surface. Three
pins », each one of a size just fitting into the groove aforesaid are firmly fixed
into the hub. The ring M is pushed on to the hub with its three clearance
keyways coinciding with the three pins n until centrally over the latter,
when it is rotated until the three clearance key-ways coincide with
the three hub key-ways, and the cross rivet (Figure 11) comes
against one of the pins n. A small tightly fitting cross screw n² is then put in
and firmly screwed home. Thus the ring M cannot rotate again owing to the
rivet n' and screw n² forming stops on each side of the pin (») and it cannot get
displaced sideways owing to the three pins n fitting into the rectangular groove
cut in its inner circumference. A similar ring may also be fitted between the
sprocket wheels D and E if desired but preferably they can have their mutual
set of balls carried between two face grooves or ball races as shown. The
vertical support however for the ball races, as is easily seen, is only required for
all but one of the ball races but if there are three sprocket wheels on the hub
as shown, then it is preferable to place the ring M under the ball race common
to wheels C and D for a reason which will be seen hereinafter in connection with
the description showing how the hub with three sprocket wheels may be converted
into a hub with but two sprocket wheels. The keys I are made short enough
to safely keep clear of both sprocket wheels C and D or D and E when brought
exactly midway between either couple, and in such case all three sprocket wheels
are free from any connection with the hub, and therefore the rider's feet may
rest quietly upon the pedals, the sprocket wheels and pedals remaining stationary
while the bicycle runs on. The pedals in such case can be used as stationary
foot rests, the hub sprocket wheels remaining motionless while the hub revolves
inside them. and thus the rider is enabled when descending hills etcetera to
use his pedals as stationary foot rests. This is especially desirable in the case
of lady cyclists. Thus between the changes in the gearing, I get free pedals
while in other positions I get variable speeds adjustable at pleasure.
Figures 1 and 10 show a simple spring detent arrangement at the base of the
dise J for detaining the keys in the five separate positions, namely (1) for locking
C to the hu; (2) free pedals; (3) locking sprocket wheel D to hub (4) free

page_text: pedals and (5) locking sprocket wheel E to hub. Spring ; carries a hard steel
pin at its end, which passes through a hole in the base of J and presses into
one of a series of five countersunk shallow notches J¹ in the hub and whenever
the keys. come into one of the five above mentioned positions, this device is
just enough to retain the keys I¹ in their position, while at the same time a
slight force applied to J is sufficient to displace the keys into a fresh position
whenever a change of gearing is required.
The keys are actuated and this variable gearing changed by the rider without
dismounting by means of a rotating sleeve 0 (Figures 1, 5 and 7) operated by
means of a handle or lever P placed within reach of the rider below the saddle.
Figure 5 is a view from behind of the upper ends of the vertical stays. One
of these stays O¹ is preferably of smaller calibre than the other stay F and has
the sleeve of thin metal tube mounted outside it capable of rotation. At
the upper end, this sleeve terminates in the lever P, and locking plate P¹ shown
in Figures 5 and 6. Nicks in the edge of the locking plate P₁ engage with the
spring which is most conveniently attached to the back stay F. At its lower
end, the sleeve terminates in a toothed wheel 02, Figures 7 and 8, and this
engages with a plunger or piston R. (Figures 1 and S) which is provided with a
series of rings or teeth turned upon its periphery of the same pitch as the teeth
of the wheel in which they engage. This plunger R fits freely into and slides
backwards and forwards in a socket, drilled through the centre of the step S which
is formed all in one piece with the lug which forms the lower termination of
the vertical stay O, the latter being brazed into the inside of the lug, Figure 7.
This lug terminates beneath in a fork embracing the back wheel spindle as shown.
The free end of the plunger or rack terminates in a sort of flanged bobbin T
engaging loosely between its two flanges the key ring J aforesaid. Thus the
backward motion of the lever P results in the plunger or rack R being driven
outwards by the rotation of the sleeve 0. Then the three keys are forced to
travel correspondingly until the desired gear or else free pedals are obtained,
the change taking place while the cycle is running and preferably when no force
is being put upon the pedals. The rider has thus simply to rotate the lever
round into the appropriate detent notch. The detent notches in the plate Pl
are partly for the purpose of safeguarding and supplementing the other detent
notches J already described, which latter are provided as an additional precaution
to ensure the keys keeping accurately in the position required of them and partly
to keep the flanges of the bobbin T from actually touching the disc J when the
keys are home in one of the five positions since any scraping or rubbing be-
tween the two is better avoided except when the keys are being shifted.
If desired the actuating lever P may be placed at the steering head or other
convenient part of the cycle, in which case the sleeve O must be in two or more
parts, connected by bevel wheel or other rotative joints.
Since the spindle carrying the supplementary sprocket wheels c d and e is
subjected to great strains when the rider is putting great tension upon the
chain, and such strains tend to twist the vertical stay F it is highly advisable
to give the spindle of the intermediate sprocket wheels some support. For this
purpose I have devised the strut U U shown in Figures 2 and 3. Its two upper
ends terminate in semi-circular forks the larger one embracing and supporting
the boss which forms part of the bracket V and the smaller fork at the other
extremity U of the strut embraces and supports the free end of the spindle, a
circular groove in the end of the latter shown in Figures 1 and 3 preventing
any tendency to slip off the end of the spindle. The bottom of the strut is
formed into a sort of rectangular trough W open at the ends (Figures 2 and 3)
which comes more or less centrally over the chain stay X on which is mounted
a travelling sleeve Y which bears upon its upper side a spherical knob Y¹ which
just fits between the sides of the aforesaid trough W. When the supplementary
wheels ce have been adjusted to their proper position relatively to the hub.
and the chains set to their proper tension, then the strut UU₁ is introduced

page_text: underneath the spindle, and the sleeve Y is pushed back and twisted about until
the spherical knob jams tightly under and inside the rectangular trough so as
to wedge it up and support it. Then the sleeve Y is firmly clamped in that
position. The strut U is prevented from rotating about the bearing spindle either
towards the left or right as seen in Figure 2 by the termination of the bracket V
(Figures 2 and 9) being slotted at VI, and embracing the end of a rib V2 in the
inside of U, or else a screw may be put through both at or about the same point.
This method of supporting the supplementary sprocket wheel spindle is thus
universally adjustable within reasonable limits. The vertical stay F is carried
up perpendicular to the hub spindle for a few inches, and the sliding part of the
bracket is firmly clamped around the stay by means of the split tug, and two
screws with lock nuts as shown in Figures 2 and 9.
In Figure 1, Z is the cone for adjusting the ball bearings on which the chain
wheels run.
Its thin outer edge projects just beyond the outermost chain wheel E
and is milled, so that it may be rotated by the fingers when adjusting. 1 is a
locking plate shown in elevation in Figure 12. The cone Z is provided with
one or more detent pins 2 projecting from its face which protrude into the holes 3
in the locking plate 1. This locking plate is provided at its inner edge with one
or more projections 20 which protrude into the hub keyways. Thus it cannot
possibly rotate. This locking plate is turned down to a thin Hange 4 in its outer
edge, which is bezelled into a groove in the edge of the lock nut 5. Thus on
rotating 5 either by a two pinned tool or by the fingers so as to unscrew it, the
locking plate 1 is gradually drawn outwards until the detent pin or pins 2 in
the cone Z are free from the holes 3 in the locking plate. Then the cone Z
can be screwed up until the ball bearings are sufficiently tight; the lock nut 5
is then screwed up again which causes the locking plate 1 to approach the cone
without rotating, and the pin or pins in the latter to engage into the holes in
the locking plate, after which the lock nut 5 is firmly tightened up by a two
pinned tool. The cone Z cannot now possibly rotate and work loose. An essen-
tially similar device is used for locking the bearing spindle 6 of the intermediate
chain wheels c d and e. The spindle 6 as shown in Figure 1 screws at one end
firmly through the boss of the bracket V and has a key-way cut longitudinally
through the threaded part. The locking plate 7 shown in Figure 1 in section and
in face elevation in Figure 13 has a projection 8 in its inner edge which protrudes
into the said key-way in the spindle. A detent pin 9 is fixed into the bracket
boss V which protrudes into one of the holes 10 in 7. Thus if it be required
to adjust the bearings of the intermediate wheels c d and e the lock nut 11 is
first unscrewed sufficiently to bring the locking plate 7 back free from the detent
pin 9; then the spindle is screwed inwards or outwards as the case may require
by means of a screwdriver until the bearings are sufficiently tight. The locking
plate 7 will of course rotate with it. Then the lock nut 11 is screwed up again
when one of the holes 10 in the locking plate 7 passes over the detent pin 9.
The spindle 6 is now firmly secured and cannot possibly rotate or work loose.
The cone 12 at the free end is of course permanently fixed or brazed to the
bearing spindle.
The tension of the main chain A can be adjusted in the usual manner by pulling
back the back wheel spindle within the fork ends of the chain stays, when the
vertical stays will swing back with it and thus the tension of the two short chains
round D and d and E and e will not be disturbed. Their tensions can be
adjusted by sliding the bracket V up the vertical stay and then clamping it in
position.
As I have drawn out the gearing in Figures 1 and 2, the sprocket wheel C is
supposed to have 12 teeth the wheel D 10 teeth, the wheel E 8 teeth and the
intermediate three-fold wheels c d and e each 9 teeth. The teeth and chains are
of the usual one inch pitch. It is decidedly preferable that the number of teeth
in c or d or e should be intermediate between the numbers of teeth in D and E,
otherwise the two short chains cannot be adjusted to equal tensions.

page_text: The changes of gearing obtained by the employment of the above wheels are of
course in the ratio of 8, 10 and 12 or 4, 5 and 6. Thus if wheel E is locked to the
hub and the crank sprocket wheel has 22 teeth and the driving wheel is 28
inches diameter, then the cycle is geared up to 77, when D is locked to the hub
the gearing is 61% and when C is locked to the hub the lowest gear of all is
obtained namely 513.
If desired spur wheels may be substituted for the sprocket wheels D and d
and E and e, as shown in Figure 15 in plan, in Figure 14 in elevation, and
Figure 16 in section. Here C and c are sprocket wheels (with 9 teeth in drawing),
both driven by the main chain A, only in this case the chain has to pass round c
on its underneath side as shown in Figure 14 and the bearing spindle carrying
the intermediate wheels is carried by the bracket 13 which slides upon the chain
stay 14, and can be firmly clamped thereto. In this case the chain stay is
preferably brought out a few inches perpendicular to the back wheel spindle
as shown in Figure 15 and an extra vertical stay 15 is brought down
from the seat lug and firmly fixed to 14 just in front of the bracket 13, for the
purpose of strengthening the chain stay against twist under the upward strains
brought to bear upon the intermediate wheels. The spur wheels 15 and 16 and
the sprocket wheel are all keyed together upon the inner barrel and revolve
together upon ball bearings which are adjusted exactly as in Figure 1. Figure 16
is a section through the hub and the intermediate wheels, showing half of the
former, from which it will be seen that the inner parts of the sprocket wheel C
and of the two spur wheels 17 and 18 and the adjustments of their mutual ball
bearings are precisely the same both in character and dimensions as the same
parts shown in Figure 1 and are therefore marked with similar reference letters.
I have not shown the teeth in these spur wheels, but supposing their pitch is
12 teeth per inch of diameter of their pitch circles then wheel 15 has 36 teeth
gearing into 17 with 44 teeth and 16 has 32 teeth gearing into 18 with 48 teeth
and thus the gears are in the ratios of 1, 3/4ths and 32/48; or 1, %ths and 2/3rds.
If the crank sprocket wheel has 24 teeth then when C is locked to the hub the
highest gear of 74% is obtained, when 17 is locked to the hub then the gear is 61/11
and when 18 is locked to the hub the lowest gear of about 49%/3rds is obtained.
The remainder of the hub and its travelling keys etcetera is precisely similar to
that shown fully in Figure 1. I will now show how both forms of these three
speed gears may be converted into two speed gears. I have made the distance
apart between centre and centre of the three hub sprocket wheels or spur wheels
exactly half an inch and the same between centre and centre of their inner locking
rings. All that has to be done in converting (in the case of the chain driven
mechanism as in Figure 1) the three speed hub into a two speed hub, is to shorten
the hub by half an inch exactly at each end, take out the inner sprocket wheel C
and the ring M. Then D goes into the place of C and E goes into the place of D,
and may have its size and number of teeth increased if a greater change of
gearing than 4 to 5 is desired. Also the barrel forming the intermediate sprocket
wheels is shortened by ½ inch and one ring of teeth left out, and the bearing
spindle also shortened by half an inch. Also the distance between the vertical
stay ends will be one inch less, and the total travel of the plunger R will only
be half an inch instead of one inch. The sector P1, Figure 6, will be shorter and
only require 3 detent notches instead of 5. The strut U U₁ may perhaps be
dispensed with. Turning to Figure 16, all that is necessary in order to convert
the three speed gearing into a two speed gearing is to shorten the hub by half
an inch at each end, take out sprocket wheel ring M and intermediate spur
wheel 15, convert 17 into a sprocket wheel of not less than 9 teeth and put it
in the place of C and put spur wheel 18 into the place of 17 and let it gear into
intermediate spur wheel 16 which is now put into the place of 15, while the barrel
upon which e and 16 are mounted and its bearing spindle are shortened half
an inch. As regards the gearing shown in Figures 1 and 2 it is not necessary,
although most convenient, to place the largest hub sprocket wheel C the nearest

page_text: Or
to the centre of hub, for C may be made the smallest of the set but in that
case could not be made with less than 9 teeth owing to considerations of room.
Also it is far preferable to have the three intermediate sprocket wheels c, d and e
all alike so that the three sets of teeth can be cut all together and having a
number of teeth intermediate between the numbers of teeth in D and E, although
it is quite possible to make it larger or smaller than either D or E or both.
clse all the hub sprocket wheels may be made of the same size and the inter-
mediate sprocket wheels c d and c be made of different sizes with the largest
wheel either on the inside or the outside, but in such case it is also highly
desirable that the number of teeth in the hub sprocket wheels should be inter-
mediate between the numbers in the intermediate sprocket wheels d and e.
The spur wheel gearing shown in Figures 14, 15 and 16 also admits of some
variation. The sprocket wheel e may have a number of teeth either greater or
less than the number of teeth in C, the spur wheel 18 may be made smaller than
17 and inversely 16 larger than 15, but no variations such as I have indicated
at all affect the principle of my invention.
In order to adapt any of the above described forms of changeable gearing to a
tandem bicycle, it will be necessary to increase somewhat the size of the hub
sprocket wheels owing to the greater calibre of the hub and make their teeth 5/16
inch wide instead of ½ inch to suit 1 inch tandem chains. The smallest hub
sprocket wheel E could not have less than 9 teeth. The hub barrel and the
interior diameter of the hub chain wheels will be increased by about 1th inch,
but the travel of the keys and all other longitudinal dimensions except perhaps
the distance between spoke flanges, will be the same as shown in Figure 1 or
Figure 16, while the bearing spindle and barrel for the intermediate chain wheels
or spur wheels must be made proportionally stronger. The spur wheel form of
the gearing, as is shown by the drawings, can be made much more compact than
the form consisting of sprocket wheels, owing to the fact that the main chain has
to pass on the underside of the intermediate sprocket wheel and thus is looped
downward towards the line of centres, instead of outwards. Thus a more elegant
form of gear case may be adapted to it.
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed, I declare that what
I claim is
1. The improvement in speed gears for cycles or the like, which consists in
providing on an independent axis fixed to the cycle frame, two or more supple-
mentary sprocket or spur wheels or other gear wheels driven by a chain or
otherwise from the crank or driving shaft of the machine, placing concentrically
on the driving wheel hub two or more supplementary sprockets or spur wheels.
or other gear wheels respectively in alignment with the aforesaid wheels, and in
gearing these two sets of wheels together in pairs either by chains or directly by
spur teeth, one set of the wheels being mutually fixed together so as to rotate
in unison, while the other set run loose but are capable of being locked to their
axes one at a time, whereby if one or both of the wheels in each pair be of a
different diameter from the others a speed gear is obtained variable by bringing
the required pair of gear wheels into operation, substantially as described.
2. In cycles, that are driven by a driving chain, connecting the front sprocket
wheel on the crank axle with a back sprocket wheel on the driving wheel, pro-
viding two or more supplementary sprocket or spur wheels fixed together and
revolving freely on an independent axis fixed to the cycle frame, and driven by
looping or carrying the said driving chain over or under one of them, in combina-
tion with two or more supplementary sprocket or spur wheels inclusive of the
above mentioned back sprocket wheel placed concentrically on the driving wheel
hub so as to revolve freely and independently thereon, but provided with means
for locking any of them one at a time to the said hub, and gearing these two sets
of wheels together in pairs, either by chains or directly by spur teeth, the relative

page_text: number of teeth in each pair of wheels being chosen to produce a speed ratio
different to that prevailing between the other pair or pairs, whereby a speed gear
is obtained variable by bringing the required pair of gear-wheels into operation,
substantially as described.
or
3. In speed gears, having two or more pairs of gear-wheels having a speed ratio
different from that prevailing between the other pair or pairs, the arrangement
for locking or unlocking a gear wheel in each pair so that it will be either locked
to, or ride loose on its axis, which consists in cutting in the driving wheel
hub or other suitable part to which the arrangement is applied, one
more longitudinal grooves or keyways, and in the gear wheels similar grooves
or keyways, in combination with key shanks lying sunk in the hub
keyways but having their ends terminating in a short projecting head adapted
to engage in the keyways in the gear-wheels only one at a time, whereby any
particular one out of each pair of gear wheels can be locked to its hub, while
the other gear wheels on the same axis are free, and will revolve loosely on their
bearings, or by sliding the key shank so that the head shall be brought exactly
mid-way between any two such gear-wheels, then all the said gear wheels will
ride loose on their axes and free pedals are obtained, substantially as described.
4. The means of operating the said key shank or shanks which consists in
prolonging the shanks to the end of the hub opposite to that at which the heads
are, and there terminating them in a disc or flange, in combination with a
sliding ringed plunger or toothed rack having at its end a small bobbin or double
flange confining or embracing the edge of the disc, a tubular sleeve or rod.
made of one piece or several pieces jointed together by bevel wheels or other
rotative joints, having at its lower end a toothed pinion gearing into said rack,
and at its other end a lever placed within easy reach of the rider whereby by
operating this lever and rotating such sleeve or rod one pair of gear wheels can
be disconnected and another pair brought into óperation without the rider dis-
mounting, substantially as described."
5. In speed gears having two or more pairs of gear wheels with a speed ratio
different from that prevailing between the other pair or pairs and sliding key
shanks adapted to lock any particular one out of each pair of gear wheels to
the hub or release the same, the combination with a disc or flange forming the
termination of the end of said key shanks, whose edge is confined or embraced
between the flanges of a small bobbin or double flange forming the termination
of a ringed plunger or toothed rack sliding to and fro within the hollow step
fixed to the vertical stay of the cycle, of a tubular sleeve enclosing and revolving
upon the said stay and having at its lower end a toothed pinion gearing into the
said plunger or rack, and at its other or upper end a lever placed within easy
reach of the rider, whereby by operating the sleeve, plunger and key shanks by
means of the lever, one pair of gear wheels can be disconnected and another pair
brought into operation, or all disconnected without the rider dismounting, sub-
stantially as described.
6. In speed gears of the kind described, the combination with the driving
wheel hub of a tightly-fitting metallic ring M, its inner circumference formed
with clearance key-ways for allowing the keys to pass freely through under the
ring and on its outside formed to furnish a ball track for the bearing balls, and
pins engaging in grooves in the ring for keeping same in place, substantially
as set forth.
7. The general and combined arrangement and construction of parts forming
my improved variable speed gear for cycles, substantially as set forth.
201
1000
WM P. THOMPSON & Co.,
Patent Agents, of Liverpool, Manchester. Birmingham and London.