IMPROVEMENTS IN BICYCLES
Year: 1879

page_text: LETTERS PATENT to Thurstan Forshaw, of Smalley, in the County of Derby,
for the Invention of "IMPROVEMENTS IN BICYCLES."
Sealed the 24th February 1880, and dated the 4th September 1879.
PROVISIONAL SPECIFICATION left by the said Thurstan Forshaw at the
Office of the Commissioners of Patents on the 4th September 1879.
THURSTAN FORSHAW, of Smalley, in the County of Derby.
BICYCLES."
" IMPROVEMENTS IN
Heretofore bicycles have been constructed with a back bone either solid or hollow
in one piece Now I propose to divide the whole or portion of the back bone in two
parts lying rallel to each other, each such part at its hinder extremity being pro-
vided with a fixed or swivelled axle or bearing carrying a trailing wheel. Both
wheels being of the same diameter while running close together act as one wheel, a
stud at the centre of one wheel going inside the nave of the other, both wheels
running in the same plain as the front wheel. The divided back bone is provided
with a handle and two cogged segments and suitable links, so arranged that by
turning the handle one way the rider is enabled to separate the two parts of the
back bone so that the wheels stand apart from each other, each running in a line
parallel to each other and to the front wheel, such parallelism being obtained by
the peculiar shape of the extremities of the parts of the back bone, thus forming a
three wheel vehicle at will, and by turning the handle the opposite way a two
wheeled vehicle, while the machine is going along.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
tho said Thurstan Forshaw in the Great Seal Patent Office on the 25th
February 1880.
THURSTAN FORSHAW, of Smalley, in the County of Derby. "IMPROVEMENTS IN
BICYCLES."
Heretofore bicycles have been constructed with a back-bone either solid or hollow
in one piece. Now I propose to divide the whole or portion of the back-bone into
two parts lying parallel to each other, each such part at its hinder extremity being
provided with a fixed or swivelled axle or bearing carrying a trailing wheel. Both
wheels being of the same diameter while running close together act as one wheel, a
stud at the centre of one wheel going inside the nave of the other, both wheels
running in the same plane as the front wheel. The divided back-bone is provided
with a handle and two cogged segments and suitable links, so arranged that by
turning the handle one way the rider is enabled to separate the two parts of the
back-bone so that the wheels stand apart from each other, each running in a line
parallel to each other and to the front wheel, such parallelism being obtained by
the peculiar shape of the extremities of the parts of the back-bone, thus forming a
three wheel vehicle at will, and by turning the handle the opposite way a two
wheeled vehicle, while the machine is going along.
Figure 2 is a side view enlarged of the hinder extremity of one part of the back-
bone and trailing wheel, hereafter referred to.
Figure 3, a plan of the same shewing portions of the back bone and two
trailing wheels.
Figures 4, 5, and 6 shew respectively a side view, plan, and back end view of the
swivelled upper front ends of the back bone and parts severally referred to here-
after.
The corresponding parts in each Figure are indicated by the same letters where
necessary.
My improvements consist in constructing a bicycle with the back bone A in two
parts lying close to and parallel to each other, except when separated by the rider.
The hinder extremity of each part forms an axle, which turns in and is carried by
a bearing on the outer side of a vertical bearing bar B, the axle being secured in the
bearing by a nut and washer. The vertical bar terminates at its lower end in a
boss B¹, which forms a bearing in which the axle of a trailing wheel C revolves.
The axle shewn by dotted lines at Figure 3 is secured in or forms part of the trailng
wheel nave, from the outer side of which it projects. The inner side of the nave of
one trailing wheel is bored out to receive a stud or pin, which projects from the
centre of the nave of the other trailing wheel. When they are running close together,
both wheels being of the same diameter act as one wheel. The two vertical bearing
bars B are kept parallel to each other by two sets of parallel links, cach set con-
sisting of six links, four short links D, which are forked at their outer ends to clip
the outer ends of two longer links D1 and D2. The link D is slotted at the centre
of its length, as seen at Figure 3a, to clip the centre of the link D2; the outer ends
of the eight short links are hinged to the upper and lower ends of four vertical axle
pins E, the centres of the links D' and D2 being hinged to the upper and lower ends
of a central vertical axle pin E¹, and the inner ends of the eight short links arc
hinged to and carried by four axle pins, each secured in a projecting bracket F,
shown by dotted lines at Figure 2, the upper ones being seen in plan at Figure 3.

page_text: The above described sets of parallel links keep the bearing bars in a vertical
position when closed, as shewn at Figure 3, or when opened by the following
means:-
The upper front end of each part of the back bone forms an axle which turns in
a bearing G, which forms part of or is secured to the swivel socket G' of the fork of
the fore wheel, the bearing G being_provided with two caps G on each side, held
to the bearing by bolts and nuts. Between the front caps and the swivel there is
a toothed boss secured on the end of each part, the teeth of which gear into each
other. The toothed boss to the left of the rider is provided with a handle C*, shewn
at Figures 4, 5, and 6; the handle is kept locked in position, either when closed or
open, by spring clip G, by which means the rider is enabled to separate the two
parts of the back-bone by simply moving the handle to the right of the position
shewn at Figure 6. The trailing wheels then stand apart from each other, and run
in a line parallel to each other and also parallel to the front wheel, thus forming a
three wheeled vehicle or a two wheeled vehicle at the will of the rider while the
machine is going along or at rest.
In witness whereof, I, the said Thurstan Forshaw, have hereunto set my hand
and seal, this Twenty-fourth day of February, in the year of our Lord One
thousand eight hundred and eighty.
Witness,
H. W. GOUGH, C.E.,
Nottingham.
THURSTAN FORSHAW. (L.S.)