Improvements in Rope or Cable Brakes.
Year: 1897

page_text: Date of Application, 20th Nov., 1897-Accepted, 8th Jan., 1898
Improvements in Rope or Cable Brakes.
We, RICHARD PETRICK, Engineer, 16 Karlsgartenstrasse, Rixdorf, Germany,
and CARL WOHLFAHRT, Engraver, 33 Dieffenbachstrasse, Berlin, Germany 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:-
This invention relates to a rope-brake intended principally for use in conjunction
with winches or windlasses and works in such manner that the action of the brake
wire cable, or rope of other suitable material. In the construction of the brake,
is automatically controlled and regulated by the weight suspended from the band,
in its simplest form, the brake-power varies in direct proportion with the magnitude
of the weight held suspended by the rope. In the improved form of the brake,
the power of the same is automatically regulated in such manner that, by way of
example, when the weight is made twice as heavy, the brake has, in action, more
than double the original power, consequently the degree of safety to be obtained
with the brake rises in the same ratio with the increase of the weight.
In the accompanying drawings:
Fig. 1 is a vertical section of a box-winch provided with one of the rope-brakes
in question.
Fig. 2 is a front view of the same and Fig. 3 is a diagram exhibiting the increase
in the degree of safety provided by the construction of the above mentioned im-
proved brake.
From the drum a (upon which the rope is wound) the rope 7 is at once passed
over the roller b which tightens the brake-bands e passing over the friction slides d
of the drum a as a consequence of the rotary action of the lever c turning upon
pivot n. According to the weight of the load suspended from the end of the rope
this roller b will now be more or less powerfully depressed, and each brake-band e
will, in like proportion, more or less forcibly impinge upon and be in contact with
the friction slide d.
Now in order that, as already mentioned, the action of the brake shall not increase
merely in proportion as the weight is made heavier but that, on the contrary, it
shall be increased in an enhanced degree so that the increase of the weight shall
be accompanied by an increase in the relative degree of safety of the brake, the
descending portion of the rope passing downwards over the roller is not guided
downward in a direct vertical line but is led over a roller g supported by springs.
The frames containing this last named roller admit of a horizontal motion and are
usually held in position by sufficiently strong spiral springs h, whose strength
must correspond to the size of the winch, and be sensible to the slightest pressure
exerted upon it. f is a guide roller.
g to
As soon as an increased weight is borne by the rope, it will cause the roller
move in such a manner as to compress the spiral springs h. Thereupon the angle
formed by the rope with the roller bis diminished, as shown by the varying
resultants of the pressure of the rope upon the roller b in the diagram (Fig. 3), and
the resultant R, which, when the roller b only is operated upon, would retain the

page_text: same relative proportion to the components y, x, is transformed into the greater
resultant R', which, expressed in other words, really means that the brake-power,
upon an increase of the weight held suspended by the rope does not bear the same
ratio of increase as is produced by affixing a heavier weight, but a relatively greater
proportion of development, thus also materially augmenting the degree of security
consequent upon the enhanced brake-power.
In order to be able to wind up the rope or cable when no weight is suspended
with the greatest possible rapidity the gearing i, k, has been arranged in such
manner that a crank or winch-handle can be fitted upon the large spur wheel k
whilst the pinion i is keyed upon the drum on which the rope is wound.
Having now particularly described and ascertained the nature of our sail
invention and in what manner the same is to be performed we declare that what
we consider novel and desire to claim is:-
1. A rope brake having a guide roller (6) carried by two levers (c) over which the
Fope runs from the drum (a) in such a manner that the roller is pressed downwards
by the action of the suspended load and thereby tightens the brake bands (e), sub-
stantially as set forth.
a second
2. A brake, such as claimed in claim 1, in which the rope (1) runs off the roller (b)
at an angle and only assumes a vertical position after passing over
roller (9) (held in position by yielding supports) which upon an increase of the load,
alters its position so that the angle formed by the rope in passing over the
roller (b) is diminished, substantially as and for the purpose set forth.
Dated this 18th day of November. 1897.
H. D. FITZPATRICK,
70 Wellington Street, Glasgow, Agent.