improvement in Ropes.
Year: 1898

page_text: Date of Application, 20th Jan., 1898-Accepted, 16th Apr..
1898
AI
improvement in Ropes.
We, BERNHARD KIRSCH, of 59, Wahringer Strasse, Vienna, Austria, Professor,
and ADOLF PESSL, of 8, Kleine Sperlgasse, Vienna, Austria, Manufacturer, 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:-
It has been proposed to manufacture ropes by laying upon a central core
successive cylindrical layers of threads or yarns, all applied with a certain degree of
tension, in order on the one hand to obtain a more equal distribution of the strain
applied by a load throughout the fibres than can be effected in ropes of ordinary
manufacture, where by twisting together a bundle of yarns or threads, the inner
threads are practically not subjected to any strain when the rope is loaded, and aro
consequently useless: on the other hand, by the said manufacture of ropes of
cylindrical layers of threads, the further advantage is obtained of avoiding the
production of interstices such as occur in ordinary ropes composed of a number of
twisted strands, and consequently such a rope while containing the same amount of
fibre, is both stronger and of a less diameter than the ordinary rope.
Such a construction of ropes was described in the Specification to our Patent
No. 24276 of 1894 and Pessls Patent No. 4990 of 1895.
The present invention has for its object to still farther increase the strength of
such ropes by not only insuring that a certain strain shall be put upon each thread
of which the rope is composed, as was heretofore done, but so arranging the threads
in the several layers that an absolutely equal strain shall be put upon every
individual thread of each layer when the rope is loaded, and I effect this by laying
each thread of each layer with exactly the same angle of twist, and consequently
with exactly the same length in a unit of length of the rope.
In the arrangements heretofore proposed for the manufacture of such ropes, it
was proposed to lay all the threads in such manner that the helical lines formed
thereby should all be of the same pitch. By this arrangement the result would be
obtained as shewn in the diagrams Figs. 1 and 2 of the accompanying drawing,
where in Fig. 1, a is the helical line formed by a thread laid upon a cylindrical
surface of the small diameter d with the pitch x, while A is the helical line formed
by a thread upon a cylindrical surface of the larger diameter, D, also with the same
pitch x.
Now it will be seen, in the first place that the thread A has a considerably greater
length in the distance of the pitch than the length of the thread a, so that on
applying a strain to A. it will be capable of stretching to a correspondingly greater
extent than the thread a when this is subject to strain; and secondly, if the threads A
and a be subject to the same downward strain in the direction W, then as the
angle a formed by the thread A with the vertical W is much greater than
the angle a formed by the thread a, it follows that a much smaller proportion of the
vertical strain W will be transmitted as a longitudinal strain to A than the
proportion that will be transmitted to a, so that although by this construction it is
insured that all the threads in all the layers, shall be subject to a certain strain,

page_text: yet these strains will be very unequal, both on account of the different angles of
twist and the different degree of stretching in a unit of length of the rope.
If, on the other hand, all the threads of the different layers be laid with precisely
the same angle of twist according to the present invention it will be seen that,
firstly, all the threads contained in a unit of length of rope will be of exactly the
same length, and will consequently be stretched to the same extent on being
subject to strain, and secondly, as they will all form an equal angle with the
vertical, they will all be subject to the same proportion of the vertical strain.
Thus if the line A. Fig. 3 represent part of a helical thread laid round a cylinder
of infinitely large diameter, at an angle of twist a, and Fig. 4 represent part
of a helical thread laid round the cylinder of the diameter d with the same angle of
twist a, it will be evident that in the length x of each cylinder, the lines A
and a will be of exactly the same length, and will make the same angle a with
the vertical W.
Fig. 5 shews a length of rope constructed according to my above described
invention in which at the several superposed layers A, B, C, D, the threads a b c d
are all laid with the same angle of twist and are consequently all of the same
length in a length x of the rope, and form the same angle a with the vertical line
of strain W.
As usual with this description of rope, the consecutive layers of the rope are
laid with their twist to the opposite hand, for obviating the tendency to untwist
or kink.
Having now particularly described and ascertained the nature of this invention
and in what manner the same is to be performed, we declare that what we
claim is :-
1. In the manufacture of ropes constructed of superposed cylindrical layers of
thread, the method of laying all the threads of all the layers with exactly the same
angle of twist, whereby all the threads in one and the same length of rope will be
of equal length and will form the same angle with the line of strain, thus con-
stituting a rope of maximum strength for a given diameter, substantially as
described.
2. Ropes made of superposed cylindrical layers of thread the threads of each
layer being laid with an identical angle of twist substantially as described.
Dated this 20th day of January 1898.
ABEL & IMRAY,
Agents for the Applicants.