Improvements in and in the Manufacture of Round Twisted Steel Wire Ropes with Hempen Cores.
Year: 1899

page_text: Date of Application, 15th June, 1899-Accepted, 15th July, 1899
COMPLETE SPECIFICATION,
Improvements in and in the Manufacture of Round Twisted Steel
Wire Ropes with Hempen Cores.
I, JOHANNES CORNELIS DEN HAAN, of Gorinchem, in the Kingdom of The
Netherlands, 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:-
This invention relates to an improvement in the manufacture of round twisted
steel wire cables and ropes, and has for its object to impart to the steel wire
cable or rope in addition to greater tensile strength, the increased flexibility of a
hempen rope, which, as is well known is not possessed by steel wire ropes.
The spiral twisting together of the steel wires as is well known diminishes the
tensile strength to a proportionate extent as the curves become shorter. The
shorter therefore the twist with which the wires forming the cable are twisted
together, the weaker will be the cable.
The length of the coils or rather the twists is however limited because coils or
twists of too great length resist the forming of the cable or rope. The steel wires
of the strands from which the round twisted steel wire ropes or cables according
to the present invention are composed, are twisted together with approximately
only half the number of coils usually deemed necessary for ordinary steel wire
ropes. The tensile strength of the rope is thus considerably increased whilst the
same number of steel wires is employed.
Each strand of this improved rope or cable is formed of a number of steel wires
twisted round a hempen core, and then provided with a woven or twisted covering,
consisting of strands of a long fibred material, each strand of this covering consist-
ing in turn of four hard spun threads so that a double spun covering is formed
which possesses an extraordinarily greater durability.
This covering makes the strands thicker so that they are wound in longer coils.
or twists round the central core, which also in itself increases the tensile strength
of the cable or rope.
As regards the increased flexibility of such improved steel wire rope made accord-
ing to my invention, it may he pointed out that it is attained by means of this
covering. The flexibility of the strands is however in the highest degree
diminished by twists in the strands, because the strands encounter one another on
their outer peripheries, and on the rope being bent act on one another, owing to
their spiral position.
Efforts have already been made where the action of the strands on one another
towards the interior comes in question, to neutralise such action by the use of a
central hempen core, but usually the aforesaid action which so deleteriously
affects the flexibility of the cord, has simply been allowed to exist. In the
improved rope however which also has a central core, this action is avoided by
reason of the covering previously mentioned. The steel wire strands no longer
come directly in contact with one another, so that on the bending of the rope the
wires no longer act one on the other, and thereby can no longer break off. The
strands in bending only press against the cover and the hempen core, and thus the
flexibility obtained is very great,

page_text: 1
The improved round twisted steel wire rope is shown in the accompanying
drawings, in which,
Figure 1 is an elevation and Figure 2 a cross section of the cable on an enlarged
scale. The rope or cable A contains as usual a hempen core B which is spun
from a sufficient number of threads. Steel wires 1) are twisted in a sufficient
number round a hempen core E to form a strand and are provided
with a covering C of strands c which themselves each consist of four hard spun
hemp threads. The cable usually contains six such strands. The right hand
side of Figure 1 and the cross section seen in Figure 2 clearly show the position
relative to one another of the hempen core, and the steel wire strands surrounded
with hempen strands and which are in turn wound round a hempen core.
In order to provide the slightly twisted strands which are usually of considerable
length (mainly up to 200 metres) in the usual manner with the said covering,
they would have to receive so many twists that their tensile strength would be
very much affected. Now I have removed this drawback by causing the twists
which are required for winding on the cover of the strands at the fixed end, to
have an equal number of untwistings at the free end. By this means the covering
may be placed thereon without giving the strand more twists than the same
originally received.
This untwisting or slackening of the twists at the free ends of the steel wire
strands takes place with a number of strands all together in an equal manner to
that in which they were twisted up at the fixed end, that is to say in opposite
directions, and my invention consists not only in the covering hereinbefore
described for the strands, but also in the method of laying on this covering,
namely, by untwisting again, at the free ends of the strands, the twists which it
was necessary to make for the purpose of the covering.
Another drawback of ordinary steel wire ropes is that the wires after being bent
have a tendency to again assume a bent position whereby there results a tangling
and unsaleability of used steel wire ropes, and finally a breaking off of the separate
steel wires.
The covering of this improved rope affords sufficient resistance to this tendency so
that these drawbacks are avoided, and in case a wire should break off, the cover
affords sufficient protection against injury to the hands of the men handling the
ropes.
Should the cover get worn out, there always remains available a complete round
twisted steel wire rope.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what
I claim is:-
1. A round twisted steel wire rope with a hempen core, characterised by the
provision of a covering of hard spun hemp threads on the steel wire strands which
form the cable or rope and which are in turn provided with hempen cores, whereby
on the bending of the rope, any direct contact of the steel wire strands with one
another is prevented, and the flexibility and tensile strength of the rope is
increased, substantially as hereinbefore set forth.
2. In the manufacture of wire rope of the kind described, the method of apply-
ing or laying the cover on the steel wire strands, consisting in the twists which
are imparted to the strands for such object at their fixed ends, being untwisted
to an equal extent at their free ends, substantially as hereinbefore described.
Dated this 18th day of June 1899.
WM. P. THOMPSON & Co.,
Of 6, Lord Street, Liverpool, Agents for the Applicant.