Improvements in Bicycles.
Year: 1890

page_text: Date of Application, 19th Aug., 1890
Complete Specification Left, 6th Apr., 1891-Accepted, 16th May, 1891
PROVISIONAL SPECIFICATION.
Improvements in Bicycles.
I, THOMAS JEFFERSON THOMPSON of Greystones, in the County of Wicklow,
Ireland, Member of the Institution of Civil Engineers, do hereby declare the
nature of this invention to be as follows:-
My invention relates to the type of bicycle described in my Specifications
No. 17789 of 1889 and No. 5250 of 1890 in which a practically invariable distance
is maintained between the saddle and the treadle axis notwithstanding the pro-
visions made to enable the wheels to freely mount obstructions on the road. The
object of my present invention is to reduce the number of parts required in order
to carry out my system of suspension and I accomplish this for the rear or driving
wheel by constructing the entire frame in a rigid manner and mounting the rear
wheel axle on a sliding piece or pieces which move or moves through suitable
guides. The sliding piece or pieces is or are free to move vertically in its or their
guides, or nearly so, and a fork or side rods similar to those described in the two
Specifications hereinbefore referred to, connect or connects the axle to a flat pro-
jecting spring or springs firmly attached to the rear end of the upper part of my
rigid bicycle frame. In this manner the axle is free to move the slide or slides up
and down resisted by the flat or laminated spring above, and connected by side rods
or fork with the said spring.
T may use more than one sliding piece if I desire it, but suitable guides are
provided fixed to the rigid frame so that the rear wheel is free to move up and
down but is constrained to remain accurately in the same place, that is, the slides
do not permit the axle to twist.
I carry the front or steering wheel in a vertical or nearly vertical fork & the
upper part of this fork attaches to the steering fork working in the upper part of
the rigid frame by a flat or laminated flat spring similar to that used for the
rear wheel.
The ordinary inclined steering fork is used in combination with the vertical
spring fork but the wheel axle is carried by the spring fork, the lever ends of the
fork working in guides formed in the lower end of the inclined steering fork. The
spring fork thus allows the front wheel to rise but still permits the inclined steering
fork to control the wheel.
The action is similar to the front wheel action described in my Specification
No. 525000 but I dispense with the bottom links. For the rear wheel a link similar
to a locomotive reversing" link may also be adopted and the slides or slides and
guides may be of different constructions. The system described for the front or
steering wheel may also be adopted when the steering fork is vertical instead of
inclined. In this case I sometimes return the laminated spring upon itself or
provide a projection from the steering fork to carry it.
By these simplified devices I obtain ali the flexibility of wheel action when
mounting obstacles in the road which I may desire, and yet am enabled to utilise
a frame of strong and rigid construction and keep the distance from saddle to
treadle axle constant by reason of the rigidity of the frame. In this case both
saddle and treadle axle are carried in fixed positions in the bicycle frame.
Dated this 18th day of August 1890.
MARKS & CLERK,
13, Temple Street, Birmingham, Agents for Applicant.

page_text: COMPLETE SPECIFICATION.
Improvements in Bicycles.
I, THOMAS JEFFERSON THOMPSON, of Greystones, in the County of Wicklow,
Ireland, Member of the Institution of Civil Engineers, 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 :--
My invention relates to the type of bicycle described in my Specifications
No. 17789 of 1889 and No. 5250 of 1890 in which a practically invariable distance
is maintained between the saddle and the treadle axis notwithstanding the
pro-
visions made to enable the wheels to freely mount obstructions on the road. The
object of my present invention is to reduce the number of parts required in order
to carry out my system of suspension, and I accomplish this for the rear or driving
wheel by constructing the entire frame in a rigid manner and mounting the rear
wheel axle on a sliding piece or pieces which move or moves through suitable
guides. The sliding piece or pieces is or are free to move vertically in its or their
guides or nearly so and a fork or side rods similar to those described in the two
Specifications herein before referred to, connect or connects the axle to a flat pro-
jecting spring or springs firmly attached to the rear end of the upper part of my
rigid bicycle frame. In this manner the axle is free to move the slide or slides up
and down resisted by the flat or laminated spring above and connected by side rods
or fork with the said spring. I may use more than one sliding piece if I desire it,
but suitable guides are provided fixed to the rigid frame so that the rear wheel is
free to move up and down but is constrained to remain accurately in the same
plane, that is, the slides do not permit the axle to twist. I carry the front or
steering wheel in a vertical or nearly vertical fork and the upper part of this fork
attaches to the steering fork working in the upper part of the rigid frame by a flat
or laminated flat spring similar to that used for the rear wheel. The ordinary
inclined steering fork is used in combination with the vertical spring fork, but the
wheel axle is carried by the spring fork, the lever ends of the fork working in
guides formed in the lever end of the inclined steering fork. The spring fork thus
allows the front wheel to rise, but still permits the inclined steering fork to control
the wheel.
The action is similar to the front wheel action described in my Specification
No. 5250/90 but I dispense with the bottom links. For the rear wheel a link
similar to a locomotive "reversing" link may also be adopted and the slides, or
slides and guides may be of different constructions. The system described for the
front or steering wheel may also be adopted when the steering fork is vertical
instead of inclined. In this case I sometimes return the laminated spring upon
itself or provide a projection from the steering fork to carry it.
By these simplified devices obtain all the flexibility of wheel action when
mounting obstacles in the road which I may desire, and yet am enabled to utilize
a frame of strong and rigid construction and keep the distance from saddle to
treadle axle constant by reason of the rigidity of the frame. In this case both
saddle and treadle axle are carried in fixed positions in the bicycle frame.
Referring to the three sheets of accompanying drawings-
Figure shows in elevation one method of applying my invention to the front
and rear wheels of a bicycle with inclined steering fork.
Figure 2 is an end view of the rear wheel spring fork H.
Figure 3 shows a modified mode of arranging the steering fork as
spring fork.
Figures 4 and 5 are respectively clevation and plan illustrating the mode of
connecting the rear wheel axle K with the rear spring fork H shown on a larger
scale than in Figure 1.
Figure 6 shows the connection of the fork or rods D Fig. 1 with the ends of the
steering fork A.

page_text: Figures 7 and 8 show elevation and end view respectively of that modification in
which curved sliding pieces are adopted; and
Figures 9 and 10 show a method of dispensing with the flat spring I for the rear
wheel by the use of spiral springs.
Referring to Figures 1 and 2; the rigid frame G carries the saddle and also the
treadle axle L so that the distance between the saddle and treadle axle is
necessarily invariable. The fork H is expanded as shown and carries in the
expanded portion the rear wheel axle K, and the lower ends H' of the fork slide
freely through the swivel guide pieces H³ which swivel on the axis H2 carried at
the extreme ends of the rigid frame. The upper part of the fork H is connected
by lugs with the flat spring or springs I firmly attached to the frame. The rear
wheel P is thus free to rise relatively to the rigid frame G in order to surmount
obstructions on the road. It is however necessary that the rising motion should be
constrained to follow a curve struck from the centre of the treadle axle in order
that the driving chain may operate freely.
If the line followed be different from
the curve struck from the centre of L, then the driving chain will work badly, as
it will be tightened or slackened as it changes position. In order that the centre
of the axle K shall follow the curve of the arc N struck from L as shown in dotted
lines, arrange the angle at which the flat spring I is attached to, or works from,
the rigid frame G in such manner that the curve described by the upper end Q of
the fork H shall cause the centre K to follow closely the curve N (Figures 1
and 4). When the spring I is set as shown in Fig. 1 the end Q will follow the
curve M and this will constrain the lower part carrying the axle K to follow
the are N as indicated in dotted lines. I thus cause the axle K to move in the
necessary curve to allow efficient working of the driving chain, and provide that
in all positions the wheel P rotates in the same plane, that is, the fork Has attached
above and guided below prevents any twisting of the wheel when it rises to
surmount an obstacle.
The details of the swivel guides and the lower ends of the fork H are more
clearly illustrated at Figures 4 and 5 on a larger scale.
The lower end H' of each side of the fork H slides freely through the swivel
guides H³ which swivel in the ends of the rigid frame G on the axis H² which
are held in position by the block pieces H and suitable fastening pins or screws.
Under some circumstances, as for example when it is inconvenient or difficult to
arrange the position and proportions of the spring I, so as to make the axle K
follow the correct curve when constrained as indicated in Figure 1, 1 adopt the
arrangement shown in Figures 7 and 8 where curved sliding pieces R pass through
bored holes in lugs GG forming the extremities of the rigid frame G. The
axle of the rear wheel P is connected as shown in end view at Figure 8. The
fork connects to the axle K and not to the sliding pieces R, and the axle K
connects to the sliding pieces so that it is constrained to move in the curve of these
pieces and is independent so far as the curve of its rising and falling motion is
The curve
concerned of the movement of the upper end attached to the spring I.
of the pieces R is struck from the centre of L as indicated and the position of the
holes in the lugs G1 G is arranged to permit of this curve being followed. Straight
pieces may be adopted but curved pieces are preferable.
Instead of adopting a flat spring a spiral spring may be used as illustrated at
Figures 9 and 10 where the frame G is extended at G to carry the end of the
fork H and constrain its motion by the spiral springs d, e, the lower sliding pieces
shown in Figures 7 and 8 being adopted.
My method of arranging the leading wheel is shown at Figures 1 and 3 where
A is the steering fork and F the upper part connected to the handles. In Figure 1
the steering fork A has suitable holes at the projections C to carry the lower
ends D' of the fork D. The upper part of the fork D is attached to the steering
fork A by the flat spring B, and the axle E of the leading wheel is carried in the
fork D. By this arrangement the spring B yields, and the wheel O rises when
surmounting an obstacle, the ends D₁ sliding in C. prefer to cause the ends D to

page_text: slide in C with some frictional resistance and to that end I adopt the construction
shown on a larger scale at Figure 6 where D is the spring fork, the leading wheel
axle, D' the lower part of the fork D sliding in an aperture in the end C of the
steering fork A which has a compressible packing ring D³ fitted in it compressed
by the screw nut D. By this method I cause the ends D₁ to move with some
frictional resistance and so tend to damp vibration caused by irregularities in the
roadway.
Another modification of leading wheel spring fork is shown at Figure 3 where
the lower ends C of the fork A are formed with springs, and the fork D passing at
its upper part D' through a guide carried in a projection A¹ from the fork A
prevents the wheel from twisting, that is, it keeps it always in the same plane,
although it allows freedom of rising and falling motion.
In all these modifications it will be observed that I use forks as H and D to keep
the wheels in one plane and for such forks may be substituted side rods suitably
connected above and practically forming forks.
In Figure 1, I have shown dash boards at a and b, and a dash board stay at 6,
but these it will be readily understood do not form part of my invention.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, 1 declare that what I
claim is-
1. In bicycles the use of a combination for supporting the frame and its load on
the rear wheel consisting of a spring or springs as 1, a fork as H carrying the
rear wheel axle in which the lower ends as H of the fork H slide through
swivelling guides working in the ends of the rigid frame, the spring I being so
proportioned and set, that the curve followed by the upper end of the fork
constrains the centre of rear wheel axle K to move through an arc of a circle
struck from the centre of the treadle axis L, so that the rear wheel rises to surmount
an obstacle and the adjustment of the driving chain is not disturbed, substantially
as and for the purposes hereinbefore described, with reference to Figures 1, 4,
and 5 of the accompanying drawings.
2. In bicycles the use of a spring as I, a fork as H carrying the rear wheel axle,
together with sliding pieces as R, for allowing the rear wheel axle to rise in or
near the correct curve substantially as and for the purposes herein before described
and illustrated in the accompanying drawings with special reference to Figures 7
and 8.
3. In bicycles the use of the spiral spring arrangement shown in Figures 9 and 10
for supporting the rear wheel in combination with the sliding pieces R substantially
as and for the purposes hereinbefore described.
4. In bicycles the use of a spring as B with a fork as D the lower ends of which
slide through holes in the end of the steering fork A the combination supporting
the leading wheel so as to readily surmount obstacles substantially as and for the
purposes hereinbefore described and illustrated with special reference to Figs. 1
& 6.
5. The combination of the spring fork A Figure 3 with the fork D one end
passing through a guide in the upper part of A substantially as described.
Dated this 4th day of April 1891.
MARKS & CLERK,
13, Temple Street, Birmingham, Agents for Applicant.