Improvements in Bicycles and Tricycles.
Year: 1889

page_text: Date of Application, 8th Nov., 1889-Accepted, 8th Mar., 1890
COMPLETE SPECIFICATION.
Improvements in Bicycles and Tricycles.
I, THOMAS JEFFERSON THOMPSON Member of the Institution of Civil Engineers
of Greystones, County of Wicklow, Ireland, 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 a new system of supporting the rider of a Bicycle Tricycle
or similar machine by springs and its main object is to so arrange the framing connec-
tions and springs that the vibration jar or vertical displacement of the wheels is not
communicated to the rider while at the same time the distance between the saddle
treadle and steering handles is kept practically invariable.
In most previous attempts to support the saddle and rider upon springs the saddle
was permitted to move relatively to the treadle axis so that much annoyance was
occasioned to the rider.
By my invention this difficulty is overcome and although the rider is so sustained
by springs or elastic connections that all shocks and jarring are done away with
including shock or jarring at the steering handles yet the distance between the saddle,
treadle axis, and steering handles always remains constant and unvarying.
allows of greatly increased comfort and permits the necessary effort to be more easily
applied to the treadles.
This
In applying my invention to a Bicycle I support or suspend the entire frame of
the machine carrying the saddle, treadle, and steering rod upon or from the two wheels
and I further attach the frame to the trailing wheel by means of a fork which may be
horizontal or inclined and is hinged or pivotted to the frame so as to permit free move-
ment in a vertical plane. The end of the hinged fork is sometimes carried forward
towards the leading wheel and suitably guided in order that the fork may move
accurately in a vertical plane notwithstanding considerable wear at the axis upon
which it hinges or pivots. But I may guide it in other ways. I may for example
carry the end of the fork up at right angles to its general direction and guide that end
between suitable plates.
Sometimes I suspend or support that end also from or by a spring attached to the
frame carrying the saddle.
The leading wheel of the Bicycle I also attach to the frame carrying the saddle by
means of a flat forked spring in which the wheel runs, which spring is securely
fastened to the steering rod mounted in the frame of the Bicycle.
The steering rod is so carried in suitable bearings in the frame and it may be inclined
as in some types of Tricycle to permit of the rider having easy access to the steering
handles.
The axis of the steering rod may also be vertically above the leading wheel centre
and its connection with the wheel is made by spring so as to avoid shock and jar as
already described.
In this case the steering handles with riders grasp are connected by suitable links.
In order that my invention may be readily understood and carried into effect I
hereunto append three sheets of explanatory drawings to which I shall hereinafter
refer. Figure 1. Sheet 1. is a side diagramatic elevation of my improvements as
applied to a Bicycle of the kind now known as the safety type. Figures 2. 3 and 4
of Sheet 2 are details of the various forks. Figure 5 Sheet 3 shews a modified form

page_text: of steering bar. I may state that the drawings are not intended to indicate the
exact mode of constructing the framework of the Bicycle which I prefer but only to
show clearly in what manner my new system of suspending or carrying any frame of
common construction from the leading and trailing wheels may be efficiently carried
out.
The saddle A is carried upon a frame B which may be constructed in any con-
venient way preferred by any individual firm or manufacturer.
This frame is formed to carry the steering rod C securely by means of any upper
and lower member carrying well fitted bearings D, D', as shewn on Figure 1, but the
steering rod may be carried from the upper member only if desired and held in
position by a deep tubular or other bearing. The leading wheel runs upon an axle E
which does not rotate with it but is firmly fixed or clamped by the ends of the forked
spring Fattached at one end to a collar G fixed to or forming part of the rod C
another spring H is rivetted, bolted or fastened in any other secure and convenient
way to the back part of the frame B and connects to the trailing wheel axle I by the
fork or side rods K and the bolt or pin L. The horizontal fork M passes from the
spindle or axle 1 to the pivot N which is the point of attachment of the fork M with
the frame B. The fork M is prolonged in M as seen in Figure 1 to work between
guiding strips which constrain it to move in the same plane notwithstanding some wear
of the pivot N, and the rod P connects by pins or other suitable means with the
spring Q. The treadle axis R is made to coincide with the axis N or when this is
impracticable it is placed as closely as possible to it as shewn in Figure 1. The pitch
circle S of the chain driving wheel is shewn and from it by chain is driven the
wheel T attached to the axle of the trailing wheel. The action of the Bicycle is as
follows. When the rider mounts the saddle A the frame B is depressed to some extent
by bending the springs H and F and this causes the point N of the lower fork to move
downwards relatively to the trailing wheel axis I and consequently the end M' is
lowered relatively to the frame B and therefore the rod P in tension pulls down the
spring Q. The whole frame of the Bicycle B with the saddle A and steering rod C
and the rider is supported from the wheels upon the springs F. H and Q-but as the
treadle axis R is very near the pivot or fulcrum N the wheels may move up and down
or the frame B may rise and fall freely relatively to the wheels without practically
altering the distance between the saddle and the treadle axis. The rider is thereby
enabled to act effectively upon the treadles with his feet without causing a rise and
fall of the machine due to his action and without experiencing the inconvenience of
a varying distance from the saddle to the treadle axis. When the steering handle W
is moved the machine is guided to either one side or the other as is usual in
bicycles.
On Sheet 2, Figure 2 is a plan of the fork M showing also the prolongation M
Figure 3 is an end elevation of the vertical fork K connecting to the trailing wheel
and Figure 4 is a plan of the spring fork F showing the collar G by which it is
attached to the steering rod (and the clamping arrangement by which the fixed
axle E is held firmly in the end of the spring. By binding the two ends of the spring
together in this way twisting is prevented and the two portions are caused to rise and
fall simultaneously.
Sometimes I dispense with the spring Q and make the spring H sufficiently strong
to support the whole weight.
The prolongation M' of the fork M need not be curved as shown but may be
straight or at right angles to the direction of M and have guiding plates or other
guiding arrangements to keep the fork in one plane.
A spiral spring may be used in place of the flat spring Q.
When the arrangement of Tricycle is such that the axis N can be made long enough
or the fork has such width that two separate pins in line form the axis N, then the
prolongation M¹ may be dispensed with as the distance between the bearing
points will be sufficiently great to ensure the correct action of M without the constraint
of the guides such as O.
In some cases I prefer to mount the steering rod so that its axis is vertically or

page_text: nearly so above the axis E of the leading wheel Y as shewn at Figure 5. In this
case the portion of rod C is bent to allow of the spring fork F which if necessary I
stay by side rods a.
The frame B is modified to suit the altered attachment and the steering links
or rods Z carry back to the steering handles within easy grasp of the rider.
The bolt X is used to clip the guide plate between the two portions of the fork M'
in Figures 1 and 2 as well as to connect by the rod or rods P with the spring Q so
that some friction may be applied if it is desired to limit the extent of rise and
fall of the frame. It acts in fact as a brake or damper to extinguish up and down
movement.
I am aware that previous to the date of my patent it has been proposed to construct
bicycle and like frames of flexible flat bars in such a manner as to keep the distance
between the saddle and pedal crank axle practically invariable. I make no claim at
large therefore for this method of constraction.
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:
I. In Bicycles the use of a spring supported frame combined with a fork such as M
pivotted at an axis such as N which fork connects to the trailing wheel axis and
carries the treadle axis at a point coincident with or near to the pivot N so as to
support the frame and rider entirely upon springs while preserving a constant and
practically unvarying distance between the saddle and treadle axis substantially as
and for the purposes hereinbefore described and illustrated in the accompanying
drawings.
II. In Bicycles the combination of a fork such as M springs such as F, H and Q
and a steering rod such as C together with any convenient frame such as B sub-
stantially as and for the purpose hereinbefore described and illustrated in the accom-
panying drawings.
III. In Bicycles the use of the system of support or suspension consisting of springs
acting such as H and F whether the rods or forks used to make the connections to the
frame be in compression or tension or whether the springs be flat or laminated
substantially as and for the purpose hereinbefore described and illustrated in the
accompanying drawings.
Dated this 7th day of November 1889.
CLERK & MARKS,
13, Temple Street, Birmingham, Agents for Applicant.