Improvements in and in the Manufacture of Driving or Transmission Belts or Cords.
Year: 1898

page_text: Date of Application, 11th May, 1898-Accepted, 9th July, 1898
COMPLETE SPECIFICATION.
Improvements in and in the Manufacture of Driving or Transmission
Belts or Cords.
I, FRITZ BECK, of 68, Nurnberger-strasse, Berlin, in the Empire of Germany,
Engineer, 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:-
The object of my invention is:
1. To increase the flexibility of transmission elements, such as cords or belts,
and their resisting power by means of a certain process of manufacture as described
below under A, and B ;
2. To render possible the profitable application of friction cords for trans-
missions of variable power. This possibility is due to a particularity in the con-
struction of the element below described under C.
A. Method of manufacturing the endless cord (threads). Figures 1, 2 and 3.
By means of a reel a thread a, of organic fibres having the proper length, is
wound into a skein S, its required resisting power being determined by a sufficient
number of windings. The skein having obtained the required thickness is bound
together by cross-threads cat proper intervals. Taken off the reel, it is sur-
rounded with raw india-rubber and then the whole is vulcanized in a mould, or
without the use of a mould.
B. Method of manufacturing the endless belt (ribbon or strip of fabric).
Figures 4 and 5.
A ribbon or strip of fabric r, of convenient width, covered with a thin layer
of raw india rubber, is wound by means of two reels under a gradual increase of
axial pressure, into a belt g, its thickness being again determined by a sufficient
number of windings. The raw india-rubber acts as a binding agent between
the separate layers of fabric r. This belt being taken off the reels is then sub-
jected to a slight vulcanisation, which unites the layers definitely without a seam.
The advantages of the improved transmission element manufactured according
to the method before described under A. and B consist in:
1, a total absence of spliced parts;
2, a great flexibility due to the parallelism of the fibres;
3, an equal distribution of the bending strain over the whole cross-section, due
to the winding over the reels of one layer over another. In other words, by this
mode of winding, the outer layers naturally become longer than the inner ones,
a property, which driving belts and cords of usual kind only acquire in the course
of use with a loss of resisting power.
4, in belts, an approximately uniform distribution of the stretching strain over
the entire cross-section, because the layers are wound under a gradual increase of
axial pressure.
5. in cords. the absence of bending work. The outer india rubber covering is

page_text: made thick enough to render the whole cord elastic in a radial direction. In
consequence thereof, the work of bending performed while running on the wheel
acts as energy at the point of running off, a great advantage for all friction trans-
missions with wheels of small diameter.
C. Particularity of the transmission-element for transmissions of greatly varying
power. Figures 6 and 7.
In order to render profitable the application of a friction cord for transmitting
greatly varying power, I modify the cord of my invention, as described, in the
following way:
At equal intervals on the india rubber cover are located globular knobs d, the
resisting power of which may be still increased by surrounding said knobs by a
metallic jacket 2 consisting of two parts. The said two parts may be jointed,
for instance by means of a groove and nose engaging each other, as clearly shown
in Figure 6, but I wish it to be understood that I do not limit myself to this
particular mode of making the two parts of the globular jacket engage.
The driving wheel, as well as the driven wheel, contain on their circumference,
cavities or recesses to correspond with the knobs d of the driving cord.
A driving cord of this kind will act as follows:-
When the power to be transmitted exceeds a certain limit, the tension with
which the cord was mounted on its pulleys would no longer be sufficient. An
ordinary friction cord, in such case, would begin to slip. With this improved
driving cord, however, the knobs d will have the tendency to leave their seats
or bed in the wheels, which immediately necessitates an increase of tension in
the cord. Accordingly the tension of the cord automatically and instantaneously
adapts itself to the actual power to be transmitted. The portions of the cord
between the knobs d act like an ordinary friction cord.
In the accompanying drawings,
Figure 1 represents the endless thread skein S made by the windings of a
thread a, and bound together by cross threads c, the whole serving as a core for
transmission cords.
Figure 2 drawn to a larger scale illustrates a portion of the skein S bedded in
india rubber b.
Figure 3 shows a cross section through the skein taken on the line at of
Figure 2.
Figure 4 illustrates the principle of manufacturing an endless belt g by winding
a strip of fabrics r on to the reels t.
Figure 5 is a section drawn to an enlarged scale on the line y-y of Figure 4,
and serves to illustrate the separate layers of fabrics r in the belt q.
Figures 6 and 7 represent, respectively, in side view and in cross section on the
line za modification of the cord provided with special knobs d of globular
shape and arranged at equal intervals, said knobs being surrounded by metallic
jackets p.
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:-
1. The mode of manufacturing endless transmission elements, cords or belts,
without splicing, characterised by a long thread or strip of fabric being wound
into a skein of convenient cross section, substantially as described and for the
purpose set forth.
2. A transmission-element manufactured in the manner described by winding
a long thread into a skein, substantially as described and for the purpose set forth.
3. A transmission-belt manufactured in the manner described by winding a long
strip of fabric over reels, substantially as set forth.
4. A transmission element, manufactured as described, surrounded by a cover
of india rubber and carrying spherical knobs adapted to fit corresponding recesses
in the wheels substantially as and for the purpose set forth.

page_text: 5. A transmission element consisting of a long thread wound into a skein covered
with india rubber and carrying spherical knobs enclosed in metallic two-part
jackets, substantially as and for the purpose set forth.
Dated this 10th day of May 1898.
WM. P. THOMPSON & Co.,
Of 6, Lord Street, Liverpool, Agents for the Applicant.