Improvements Relating to the Braking Gear of Cycles.
Year: 1897

page_text: Date of Application, 8th June, 1897-Accepted, 17th July, 1897
COMPLETE SPECIFICATION.
Improvements Relating to the Braking Gear of Cycles.
1, PETER JENSEN of 77 Chancery Lane, London, W.C. Chartered Patent Agent,
do hereby declare the nature of this invention a communication to me from
Arno Wohlfarth of Braunfels, Wetzlar German Empire Chemist, and in what
manner the same is to be performed to be particularly described and ascertained
in and by the following statement :-
The cycle brakes heretofore usual have many known defects which have not yet
been successfully obviated. They are not only tiring (when applied by the hand)
but also dangerous to life and limb (when applied by the foot). This causes the
cyclist to have recourse rather to the easily regulated and more convenient back-
pedalling and to mostly leave the brake at home. But such brakeless cycles form
a growing danger to the street traffic. The "chainbrake now to be described
works with safety and certainty and is not tiring.
""
The brake acts on the hind wheel tyre and by means of the driving chain. In
order to produce this chain action the pedalling motion has only to be interrupted.
Hence the otherwise so dangerous and yet so much indulged in malpractice of
back-pedalling is thus rendered innocuous and made a useful necessity. A gentle
or a more vigorous back-pedalling causes a more or less powerful braking action.
The desired power of braking action can be beforehand adjusted by a spring. In
extreme need or when the leg muscles are tired out, the mere pressure of the
finger is enough to release a second adjustable spring, which of itself brakes
powerfully and again puts itself automatically out of action in the desired moment
when the speed of running has been diminished. The action of this chain brake
thus adapts itself to the self preserving instinct of the cyclist without giving him
any trouble or effort of thinking, while it ensures a very great security to him as
well as to the public.
The chain brake is based upon the well known fact that in working the crank
axle the upper part of the chain is the leading one and is stretched, while the
lower part is slack, and that when back-pedalling this is so far reversed as the crank
axle does not work any longer, but is merely turned by the chain from the rear
sprocket wheel because of the inertia of the machine, and the cyclist seeks to annul
this motion by back-pedalling. The lower part of the chain is then the leading
and stretched one, while the upper one is slack. The power to stretch one side or
the other of the chain arising by reversing these movements is the one that
according to this invention is utilized to brake the vehicle. It can be done in
various ways viz.
1) By taking the power from the lower part of the chain (Figs. 1 and 2).
2) By taking the power from the upper part of the chain Figs. 3 and 4 and
3) By taking the power from both (Figs. 5 to 8).
Figs. 1, 3 and 5 with their arrows show the position of the brake mechanism when
working the crank axle while the Figs. 2, 4 and 6 with their arrows show the
position when back-pedalling.
A toothed tension or jockey pulley z, Figs. 1 and 2, is applied to the lower end
of a vertically guided rod 8 and is normally by an adjustable spring f' on the rod s

page_text: held up against the lower part of the chain so as to keep it taut. When back-
pedalling (Fig. 2) this lower part is stretched or straightened and the tension pulley
is thereby drawn down, thus comprising the spring f₁ still more. At the upper end
of the rod s a brake lever b is arranged in any suitable manner: this lever is thus
also moved down and brakes or causes a braking when the rod moves down for
instance by a spoon brake block against the outer or inner wheel rim.
In another form, as shewn in Figs. 3 and 4, the tension pulley is by a downwardly
expanding spring f2 normally pressed down upon the upper part of the chain. As in
this case the guide rod 8 is à priori depressed and the brake lever b applied at the
same time, there is a constant automatic braking (without back-pedalling) and this is
only interrupted by the stretching of the upper part of the chain that is to say by
pedalling.
In another form, Figs. 5 and 6, two tension pulleys and z are applied to the
vertically guided rod 8. They press by springs f¹ and f2 upon the upper or upon
the lower part of the chain and thus stretch it both ways, but the pressures from
above or from below are not always the same; it depends upon the tension of the
springs f¹ and f* which are separated by an adjustable nut g and hence act against
each other. If the tension of the lower spring f¹ is the greatest, the lower tension
pulley is pressed up against the lower part of the chain, while the other upper
tension pulley 7 exerts no down pressure upon the upper part of the chain. The lower
pulley drops only when the lower part of the chain is pulled taut, consequently the
braking is affected by back-pedalling as in the first example Figs. 1 and 2, but if the
tension of the other spring f2 is the greatest the upper pulley presses on the upper
part of the chain and pulls it down taut, hence the action is a constant one (without
back-pedalling) and can only be annulled by forward pedalling as
in Figs, 3 and 4.
shewn
In order that the chain brake at all times and without altering the spring tension
while running may be able to be put on, with as well as without back-pedalling, the
tension of the two springs are beforehand adjusted to the desired brake action;
hence the tension of the lower spring f2 should be the most powerful and so the brake
action would really be a constant one. But in order that this be not so, and
especially not before starting running but only in the right moment the guided rod s is
held or locked in the upper inactive position by a nose n fixed thereto by a flat
spring m Fig. 5. By turning over a lever h this may be unlocked so that the brake
can act momentarily, Fig. 6, that is to say until the pedals act again. But when the
lower spring comes into action again and presses the guided rod s upwards the
brake is caught and locked in the upper inactive position.
Instead of an entire guided rod 8 there may, as shewn in Fig. 7, be only an upper
separate piece of it with spring f. The other lower separate part of it with its
spring f will then be lowered by back pedalling. But it will also be lowered without
back-pedalling (more powerfully however by back-pedalling) when the upper piece is
unlocked.
In yet another form, Fig. 8, of equal efficiency it is not the guided rod 8 nor yet a
piece of it that is locked, but merely the upper spring f which is held by some
suitable locking device.
The bearings, the shape and the section of the guided rod s may be of any conve-
nient form, and the brake lever may also be variously shaped and arranged. The
form and arrangement of the springs f¹ and f' may vary without affecting the
essence of the invention.
Having now particularly described and ascertained the nature of the said Invention
as communicated to me by my foreign correspondent and in what manner the same
is to be performed I declare that what I claim is.
1st. A cycle break actuated by the driving chain characterised by that a tension
pulley z guided on the Cycle frame and connected to the brake is by an adjustable
anring ₤1 normally pressed un against the lower part of said chain and depressed.

page_text: against the spring by the tightening of said part when back-pedalling for the purpose
of stretching the chain automatically and for braking by back-pedalling.
2nd. A construction of cycle brake as firstly claimed in which the tension pulley "
guided on the Cycle frame is by an adjustable spring f2 normally depressed against
the upper part of the chain and drops therewith when it slackens for the purpose of
putting the brake on by itself without back pedalling but taking it off when pedalling
forward.
3rd. A Construction of cycle brake as firstly and secondly claimed in which a tension
pulley z is provided acting upon the upper part of the chain and another against
the lower part and two adjustable springs f' and f2 for putting the brake on either
by back-pedalling or automatically according to the condition of the spring3.
4th. A construction of cycle brake as secondly and thirdly claimed in which the
guided rod s or a piece of it or only a spring f* is so held by a locking device n that
the upper tension pulley will not drop of itself but that said pulley when after
unlocking of the said device is by the spring f' pressed down upon the upper part
of the chain for the purpose of being able use the brake at will either with or without
back-pedalling.
ше к
JENSEN & SON,
77 Chancery Lane, London, W.C., Patent Agents.