Improvements in Driving Mechanism for Velocipedes, applicable also for other purposes.
Year: 1896

page_text: Date of Application, 28th July, 1896-Accepted, 12th Sept:, 1896
COMPLETE SPECIFICATION.
Improvements in Driving Mechanism for Velocipedes, applicable
also for other purposes.
I, HOSMER TUTTLE, a citizen of the United States of America, residing at
613 Fifth Street, in the City of Cedar Rapids, County of Linn and State of Iowa,
one of the United States of America, Mechanical Engineer, 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 mechanical movements, intended mainly for the
propulsion of bicycles, to take the place of the chain now generally used on
safety bicycles, and thereby reduce the expense and the amount of friction on the
machine.
Although the construction of the movement can be used in connection with
other machines, it is shown in the drawings in connection with a bicycle, the
frame of which may be of any suitable form.
In said drawings
Figure 1 represents a side view of a bicycle provided with a propulsion
mechanism constructed in accordance with my invention.
Figure 2 represents on a larger scale, a top view of the propulsion mechanism.
Figure 3 represents a side view of the same with the pedals and the horizontal
portion of the frame removed.
Figure 4 represents a side view of a sprocket wheel, provided with a larger number
of sprockets arranged to transmit a slower motion to the driving wheel.
In Figures 1 and 3 the propulsion mechanism shown is equal to what is termed
84 gear, but has more leverage on the sprockets. The shaft of the rear wheel makes
three revolutions to one of the pedal carrying shaft. If each pedal carrying sprocket
wheel has four sprocket teeth and is made of smaller diameter, as shown in Figure 4,
the hind wheel will make two revolutions to one of the pedal cranks and will
produce a suitable speed for climbing hills.
In said drawings, A represents the seat-carrying standard of the frame, and A' the
braces between the crank shaft 6 carrying the pedals B and the sprocket wheels C
and and the axle d for the hind wheel E, said axle d carrying also on its ends
disks D and D' carrying crank-pins. The wheel C has projecting from its periphery
at equal distances apart three teeth c to be received alternately between two teeth
constituting a pocket placed on the front end of the lower branch of a forked
connecting rod F. The distance between the front ends of the branches of the
forked rod F is about equal to the diameter of the wheel C with the addition of
one of its sprockets. Said distance is maintained by a curved brace F uniting said
branches. The front portion of the connecting rod F is suspended from the
standard A by means of a link Fs having its lower end pivoted at f³ to the curved
brace F, and its upper end pivoted upon a short shaft f* received in a sleeve-bearing F
secured to the standard A. The united rear ends of the branches of the connecting
rod Fare provided with an eye that receives a crank-pin d projecting from the
outer side of the disk D.
The above description relates to the left hand half of the driving mechanism,
but the mechanism on the right hand side is exactly similar and consists of the
forked connecting rod G having the curved brace G2 that has its front end suspended
from the link G, the upper end of said link is pivoted upon the short shaft f.
The lower branch of the connecting rod G has a pocket g and the upper branch

page_text: an inverted pocket 9. The united rear ends of said branches are provided with
an eye that receives a crank-pin d projecting from the outer side of the disk D
The wheel C is provided with three sprockets & equally spaced apart, but. so timed
relatively to the sprockets c of the wheel C as to be about 30 degrees in the rear
of each one of them. To obviate dead centres in the revolution of the disks, the
crank-pin of one of the disks is placed at 90 degrees, or one quarter of a
revolution in advance of the other.
The front and rear ends of the braces A2 of the frame can be provided with
ball bearings as commonly used on bicycles. Said frame is provided with a forward
brace A as usual.
In the operation of the mechanism the rocking up and down of the rear end of
the connecting rod F or G, causes an inverse motion of the front end of said rod.
In other words, when the crank-pin on the rear end begins to ascend above a
horizontal line passing through the centre of the disk D, its front end descends
and its pocket f receives into engagement the top sprocket c, as shown in
Figures 1 and 3, and said sprocket in its revolution pulls upon the rod F and
continues to revolve the disk D and the axle d. When the crank-pin 2 descends
below a horizontal line passing through the centre of the disk, the front end of
the rod Fascends, and its pocket f receives into engagement the bottom' sprocket
of the wheel C, and said sprocket pushes the connecting rod F rearwardly and
continues to revolve the disk D.
As there must necessarily be some moments in which the pockets of the rod Fare
not in engagement with either a top or a bottom sprocket, the duplication of the
mechanism is required to actuate the disk D' and its axle d during these intermediate
movements. Taking for example the position of the parts shown in Figure 3, the
next engagement will be the upper sprocket with the upper pocket g of the right
hand side rod G. This is followed by the engagement of a bottom sprocket c with the
bottom pocket f of the left hand side lever F, and this is followed by the engagement
of a bottom sprocket c with the bottom pocket g on the right hand side lever G.
The next engagement is as shown in Figures 1 and 3.
In Figure 4a sprocket wheel is shown with four sprockets c well adapted for
bicycles geared for slower motion. This wheel is to be accompanied by a similar
wheel having sprockets c³ suitably in the rear of the sprockets c. The sprockets c² are
represented as pins on the side of the wheel, as pins could be used in place of
peripheral sprocket teeth.
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. A mechanical movement consisting of an axle carrying two crank-pins, a forked
connecting rod mounted at one end upon each crank pin and having at the opposite
end two oppositely disposed pockets, a suspension link for each connecting rod, and
sprocket wheels for engagement with the pockets of each connecting rod, substantially
as described.
2. In a mechanical movement for bicycles, the combination of the axle of one of the
carrying wheels, two crank-pins carried by said axle, two branched connecting rods
mounted at one end upon each crank-pin and having at the opposite end two oppositely
disposed retainers for sprocket teeth, a suspension link for each connecting rod, and
sprocket wheels having sprocket teeth, for engagement with the sprocket-retainers
carried by the branches of the connecting rods substantially as described.
Dated this 28th day of July 1896.
JENSEN & SON.
77 Chancery Lane, London, W.C., Patent Agents.