Improvements in Crank Driving Mechanism.
Year: 1896

page_text: PROVISIONAL SPECIFICATION.
Improvements in Crank Driving Mechanism.
I ROBERT GROOM. of New Street Ford near Shrewsbury Bootmaker do
hereby declare the nature of this invention to be as follows:-
The object of my invention is to improve the driving action of all kinds of
velocipedes or other machinery where such a motion is required by foot power or
otherwise velocipedes in particular.
My invention has for this object the construction of two small cranks and a lever
combined in the place of one ordinary crank. The ordinary crank as is known by
most mechanics to be an imperfect piece of machinery and as is also known the
ordinary crank when in certain positions a certain amount of power applied when
in these positions is wasted and at the same time causing more load and heavy
friction on the crank axle. To improve this my invention is constructed and
arranged in such a manner that it is capable of obtaining over half a circle of
driving power with each lever thus completing a whole circle of continual driving
power with two levers one stroke with each lever without applying pressure to
either of the levers in the up or back stroke thus a continual steady driving power
can be obtained.
It must be observed my invention when in motion the cranks are revolving in
opposite ways to each other that is when the front cranks are revolving in a forward
direction the back cranks are revolving in a backward direction (this is when the
machine is going forward) this gives the extra leverage required and removes the
imperfection before mentioned in the ordinary single crank. Refer here to drawings
Fig. 1 is side view of my invention fitted on the end of the axles (or otherwise
called outside cranks that is outside of bearings) showing one lever with cranks only
letter A is a roller fitted in a groove (one or more rollers may be fitted) in that end
nearest the axle of each crank preferable (although they could be fitted otherwise)
which is secured by means of a pin or rivet passing from one side through the roller
to the other and secured in each side the roller or rollers being allowed to revolve.
Or the rollers may be dispensed with and one or more plain cogs may be fitted.
The other ends of the cranks letter d is a groove or cam into which the roller
or rollers A slides when in motion (one or more grooves may be fitted) this
gives the lever the power desired when the cranks are in a line with each other
the lever itself keeps them right when in all other positions thus when in motion
the roller A in back crank passes into the cam groove D in front crank and the
roller A in front crank passes into cam groove D in back crank both cranks
being alike at the ends this gives the desired effect. The lever is attached to
the cranks at C by means of a pin passing through the bearing hole and also
through the lever in which it is secured by means of riveting or set screw or
otherwise or the pin can be made secure to the cranks in the ways mentioned and
have the bearings in the lever the former being preferable they can be fitted with
ball bearings or plain or other kinds either in the crank or lever at C. The back
crank at B revolves on a stationary pin or axle made stationary to the machine
frame and secured on its axle on the same principle as ordinary wheels revolving on
stationary axles and can be fitted with ball bearings plain or other kinds. The
front crank at B is made stationary to the chain wheel axle in the ordinary way.

page_text: When in motion the lever will be seen to take three positions of leverage see
Fig. 1. 2. 3 in drawing. It must be observed that my invention can be used for
other machinery or gear where the cranks are required in the middle or any part
of the axle between the bearings and can be fitted and worked on the same principle
as the end cranks before mentioned. The pedal is made in the ordinary way except
the bearings and is secured to the lever at E the bearings instead of a round hole
and pin they have a hole of nearly triangular shape being a little circular at the
bottom the pin is made to nearly fit this allowing sufficient room for the top corner
of the bearing hole to swing on the top corner of the pin the required distance only
this pedal is much safer and is nearly without friction other kinds may be used if
prefered Fig. 4 is another way of fixing the cranks with another kind of lever
preferable for driving some kinds of machinery or gear where no forward or
backward throw is required this being an up and down motion.
The cranks can be fixed in many different ways all giving the levers different
motions without leaving my invention. The cranks and levers to be made any
desired shape or length and also the cranks to be fixed any desired distance apart
and any desired position and also to be used for other machinery or gear (were
required without pedals or treadals) of large or small dementions.
Dated this 8th day of June 1896.
ROBERT GROOM.
Improvements in Crank Driving Mechanism.
I ROBERT GROOM of New Street Ford near Shrewsbury Bootmaker 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:-
The object of my invention is, to improve the driving action of all kinds of
velocipedes and other machinery where such a motion is applicable by foot power
or otherwise, but velocipedes in particular. My invention has for its object the
arrangement of two small cranks and a lever combined in the place of each
ordinary rotary crank. The ordinary rotary crank is known by many inventors to
be an imperfect piece of machinery for some of its uses, and, as is also known,
with the ordinary crank when in certain positions, a certain amount of the power
applied, when in these positions, is wasted, at the same time causing more load on
the crank axle. To improve this my invention is arranged in such a way
that a continuation of power can be applied by the operator (or other power
that is applied) with two levers, one stroke with each lever to each
revolution, thus giving the operator power over the whole of the circle, and,
as will be seen, before the one lever has lost power entirely the other can
commence which I consider is almost an impossibility without considerable waste
of energy with the ordinary crank used for driving bicycles and the like and
many other kinds of machinery, but those driven by foot power in particular. And
as must be observed, the operator has control over his machine when back pedaling
is required by applying pressure to the upstroke of the levers. I am aware that
many attempts have been made at continuous motion which have been minus the
advantage of back pedaling, or if not this in others there has been a considerable
amount of power lost in the mechanism. In describing my invention in detail
reference is here made to the accompanying drawings which shows one side only
both sides being alike. It must be observed that with my invention when in
motion the two cranks here shown revolve in reverse ways to each other, that is,
when the front cranks are revolving in a forward direction the back cranks are
revolving in a backward direction. This gives the continuous leverage required

page_text: and removes the imperfection before mentioned in the ordinary crank. Fig. 1 on
Sheet 1 is side view of my invention fitted on the end of the axles commonly called
outside cranks, that is, outside of bearings showing one lever with cranks only, the..
arrangement being alike on both sides of the machine. I here only describe one
side, in which letter's A show what I hereinafter call cams. One, two or more
may be fitted in either ends of both cranks but that end nearest the axle is
preferable. Letter B is ball hearings which revolve on an axle made stationary
to the machine frame: letter C is ball bearings: letter D is the cam roller which
revelves on a pin letter E in front crank is a cam: letter F is where the crank is
secured to the driving axle in the ordinary way: letter G is ball bearings:
letter H is cam rollers: letter I is chain wheel circle: letter J is the lever. The
lever at G has a stationary pin which passes through the ball bearings and also
the same at C, thus, when in notion, the cam roller D passes into cam in the
down stroke and the cam rollers H passes into cams A in the upstroke. To see
different positions of leverage see Fig. 2 on Sheet 1 and also see Figurs 3 and 4 on
Sheet 2 and Fig. 5 on Sheet 3. The cams above mentioned may be dispensed with
and one or more plain cogs may be fitted in the place of the cams. It is preferable
to fit the roller cams or cogs to the front crank on that side next the machine and
to bend the lever in that shape as shown by Fig. 4A on Sheet 2 (back view). This
brings the lever in range with the back crank and removes side strain, and the
back crank is thereby situated close against the machine frame. As I have only
described one kind of gear it must be understood that this invention can be
applied to other kinds of gear and inachinery, and also that it can be fitted to the
middle or any part of an axle between the bearings on the same principle and also
as there is only one size shown it must be understood that it can be made of
smaller or larger dimensions and also that a longer stroke can be obtained by
fixing the cranks nearer to each, other and the cams and rollers nearer to the
bearings or by lengthening the levers. A shorter stroke can be obtained by fixing
the cranks further apart and the cams and rollers further from the bearings or by
shortening the levers. When the up stroke is too quick this is caused by the
cranks being fixed too near to each other and when the up stroke is too slow
power is lost proving them to be too far apart from each other. I have shown
large roller cams but smaller may be used if prefered. The back crank may be
fixed in other positions such as above the front crank, below it, or in other positions
between by altering the shape of the levers. The pedal is made stationary to the
lever. Another kind of pedal is a swinging pedal having a bearing hole which is
nearly of three corners or triangular shape being a little circular at the bottom.
The pin is made to fit this allowing sufficient room for the pedal to swing on the
top corner of the pin the required distance only. The lever and pedal pin and
back pin C are preferably made all in one piece, the front pin G being secured by
means of riveting, or set screw, or otherwise. This aforesaid invention to be
applied to bicycles and the like and other machinery where such improvements
are necessary.
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
Improvements in crank driving mechanism.
1. The arrangement and combination of two cranks revolving when in motion in
reverse ways.
2. A combination of treadle levers and cranks consisting of two levers with
two of the said cranks combined to each lever for each operator substantially as
and for the purposes set forth.
Dated this 5th day of March 1907
ROBERT GROOM.