Improvements in the Manufacture of Flexible Shafts.
Year: 1897

page_text: Date of Application, 1st June, 1897-Accepted, 24th July,
1897
Improvements in the Manufacture of Flexible Shafts.
I. ADOLPH STRIEMER, of 8, Mohrenstrasse Berlin in the Empire of Germany,
Merchant, 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:-
Flexible shafts have hitherto been made by various methods of manufacture, but
hi herto no shaft could be produced which was available for transmitting a great
amount of power, and which was durable in wear. Long flexible shafts in one
piece, that is to say without fixed coupling pieces could not be made. The greatest
attainable length did not exceed as a rule 1.5 metres, and further such shafts made
the processes hitherto employed were only available for one direction of rotation,
A main
that is to say either for running only to the right or only to the left
difficulty in the former processes consisted in that it was impossible during the
work to inspect any irregular tensions of the material of the separate spirals. The
tension or strain on the material was so arranged in the various spirals that they
all had a tendency to burst or spring to the outside as soon as a spiral was broken
from any cause.
And as the spirals hitherto employed had only one thread, that is
to say were only formed of one wire, the whole shaft must in such cases become
unusable. This strain of the material of the spirals herein before mentioned caused
unequal strengths in the shafts even in the manufacture, and more particularly pro-
duced widenings which were very noticeable at the ends of the shafts. In order
to remove these it was usual to file down the thicker parts, by which of course the
wire was weakened and the firmness of the same greatly diminished.
These defects are removed by the process hereinafter described. The spirals in
this case are not directly wound one over the other and soldered at the ends, or
made from the outside to the inside in such a way that two successive inner spirals
for instance which are mounted on the wrapping core and soldered to the end of
the latter are loosely inserted in the next outermost and considerably wider spiral,
and the inserted spirals, by the removal of the soldering places, allowed to spring
off from their core into the spiral lying over them, the same manipulation being
adopted with those lying further to the inside:- but the single or multiple spirals
are screwed in a finished condition over one another, a commencement being made
with the weakest spirals, so that when the shaft is finished only the innermost spiral
has the tendency to spring from the interior to the outside, but is hindered in this
by the numerous layers lying over it, because in consequence of the mechanical
expansion which has taken place during the screwin into place all have a tendency
to press towards the interior and to return to their original position. The flexible
afts made by this improved process, which are formed of finished spirals coiled
alteretele to the right and to the left, from the interior to the outside, have a
great advantage over other flexible shafts in that they are not only suitable for
transmitting large power, but may also be employed with equal advantage for

page_text: machines working with right and left hand movement, which was not the case with
the flexible shafts hitherto employed.
In the accompanying drawings
Figure 1 shows an elevation of the wire spirais wound over one another in
different directions of the coil;
Figures 2 and 3 show a shaft in various stages of treatment.-
The manufacture of the shaft commences from the interior to the outside in the
following manner:
A core is inserted in the first spiral, for instance 2, of the smallest diameter,
over which core it is previously wound. As the spiral, after the winding and
releasing of the winding core, is somewhat expanded, the core r will be held loosely,
in the spiral z, and serves only to hold the spirals on the further treatment and to
give a support to the innermost spiral in order that, when the second spiral is
wound, the innermost one shall not be too much compressed or narrow.
The spiral z is flattened or smoothed on the core r until the threads all stand side
by side at an equal height, Figure 2, and after this it is held for instance at the
point in the chuck of a lathe or other suitable apparatus, and rotated whilst the
spiral for instance is held against the other end of the same. If the spiral z has
a right hand coil, the spiral z' is given a left hand coil. By rotating the spiral z and
holding the spiral against it, the spiral is screwed into the outer one, the spiral 1
being so firmly held, as shown for instance at y, Figures 2 and 3 by means of a
suitable device, tongs or the like, that it can adjust itself but not revolve. The
position of the holding point y is suitably altered in the course of the work to suit
the constantly shifting screwing forward, that is to say it is kept constantly out-
side the spiral z which is to be screwed in Figure 3. During this process the
spiral has become narrowed and the outer spiral somewhat expanded so that
both spirals are held tightly one on the other by their own spring pressure or
stretching of the material, the interior one acting outwardly and the outer one
acting inwardly. The spiral is then smoothed as was previously the case with
the spiral so that the thread lies at the same height in proximity to the next one
and then a third spiral 2 (or further successive spirals up for instance to + and so
forth) is placed on in the same manner always with an opposite direction of coil,
and then smoothed down or flattened. After the last spiral has been fixed, the core
is removed and the ends are cut even. It follows consequently that apart from the
innermost spiral z all the spirals 2¹ to screwed thereon have the tendency to press
inwardly and bear firmly on one another in an unalterable equal diameter while the
actual spring power of the multiple spirals is utilised to mutually stiffen and
support one another and the pressure acts only inwards. The mutual screwing on
of the left and right hand spirals does not require a special apparatus but it may be
effected by hand or by means of any suitable machine.
The effectiveness and utility of flexible shafts are so much increased by this
'method of manufacture that they not only compete with solid transmission shafts
but even excel the latter for certain purposes and more particularly for angular
transmissions replacing bevel gearing and other suitable means of transmission for
conveying rotation round corners.
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:-
-
on
The improved manufacture of flexible shafts of wire spirals having right and left
hand coils, which consists in the smallest spiral being placed loosely
a core, then flattened or smoothed and then screwed into the next larger
spiral in such a way that the inner spiral is compressed and the outer
spiral expanded, SO that all the coils lie tightly on one another, the
spirals thus connected being then flattened or smoothed and again screwed
into a further spiral which similarly expands whilst being screwed on, the same
action continuing up to the last outermost spiral when the core is removed; whereby

page_text: the spirals are held firmly against one another by means of their own spring
pressure, and the pressure is directed exclusively inwardly from the second up to the
last spiral, for the purpose of producing the highest possible torsional strength and
security against breakage and of avoiding any springing or bursting of the spirals
to the outside substantially as hereinbefore set forth.
Dated this 31st day of Now 1897
WM. P. THOMPSON & Co.,
Of 6, Lord Street, Liverpool, Agents for the Applicant.