Improvements in or relating to Driving Pulleys.
Year: 1892

page_text: Date of Application, 23rd Feb., 1892
Complete Specification Left. 23rd Nov., 1892-Accepted, 31st Dec., 1892
PROVISIONAL SPECIFICATION.
Improvements in or relating to Driving Pulleys.
I, WALTER HUMBERSTONE of 20 Longley Road, Tooting Junction, in the
County of Surrey, Engineer, do hereby declare the nature of this invention to be
as follows:-
Engineers and others are well aware that leather and other driving belts slip
upon the drums or pullies around which they are passed for the purpose of
conveying rotary motion from one to the other. This slipping results in a con-
siderable loss of power and many plans have from time to time been devised to
overcome such loss, but without success. Now the object of this invention is to
construct driving drums or pullies in such a manner that it is all but impossible for
the driving belts to slip upon them.
In carrying this invention into practical effect I form the driving pulley in such
manner that it has the general form of a polygon instead of that of a cylinder as is
usual. In other words the rim is formed of a series of faces lying at angles to each
other and tangentially to a circle struck from the centre of the pulley. It is
preferred that the number of these faces should be such that a circle passing
through their extremities should not be more than one-sixteenth of an inch apart
from a smaller or concentric circle passing through their centres or innermost
points. It is found that with pullies so constructed the driving belt is caught by
the angles on the rim of the wheel and does not slip to any appreciable extent
while if the faces are kept small the belt is almost free from vibration.
It is obvious that the polygonal faces. may be formed upon the wheel itself, or
upon separate plates screwed thereto in any suitable manner.
Dated this 23rd day of February 1892.
CASTLE SMITH,
"Invention" Office, 54, Fleet Street, London, E.C.,
Agent for the Applicant.
COMPLETE SPECIFICATION.
Improvements in or relating to Driving Pulleys.
I, WALTER HUMBERSTONE, of 20 Longley Road, Tooting Junction, in the
County of Surrey, 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 :-
Engineers and others are well aware that leather and other driving belts slip
upon the drums or pulleys around which they are passed for the purpose of
conveying rotary motion from one to the other. This slipping results in a con-
siderable loss of power and many plans have from time to time been devised to
overcome such loss, but without success. Now the object of this invention is to
construct driving drums or pulleys in such a manner that it is all but impossible
for the driving belts to slip upon them.
In carrying this invention into practical effect I form the driving pulley in such
a manner that it has the general form of a polygon instead of that of a cylinder as
is usual. In other words the rim is formed of a series of faces lying at angles to
each other and tangentially to a circle struck from the centre of the pulley. It is
preferred in the case of small pulleys that the number of these faces should be such
that a circle passing through their extremities should not be more than one-
sixteenth of an inch apart from a smaller and concentric circle passing through

page_text: their centres or innermost points. It is found that with pulleys so constructed the
driving belts are caught by the angles on the rim of the wheel and do not slip to
any appreciable extent if the faces are kept comparatively small and the belt is
almost free from vibration.
It is obvious that the polygonal faces may be formed upon the wheel itself, or
upou separate plates secured thereto in any suitable manner.
And in order that my invention may be more fully understood and carried into
practice I will now proceed to describe the same with reference to the accompanying
sheet of drawings of which Figure 1 is an elevation of a portion of the rim of a pulley
constructed according to this invention, and Figure 2 is an edge or face-view of the
same. An inspection of Figure 1 will show that the surface of the pulley
illustrated is filed or otherwise shaped into a series of flat faces lying at angles to
each other and tangentially to a circle struck from the centre of the pulley. In
this figure I have shown two dotted circles, one passing through the extremities of
the flattened surface and the other passing through the centres of the innermost
parts of the same. I have found in my experiments that with pulleys of less than
two feet diameter the best results are obtained when the distance between these
two circles does not exceed one-sixteenth of an inch. This amount of difference in
what I may term the two diameters of the pulley I have found to be amply
sufficient to afford a good grip upon the belt without causing the same to sway, or
vibrate, which may be the case if this difference is exceeded to any great extent;
with larger pulleys this difference may be increased to give a face of greater
length.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, 1 declare that what I
claim is :-
The construction and use of driving pulleys having their rims formed by a series
of faces lying at angles to each other and tangentially to a circle struck to the
centre of the pulley, substantially as and for the purpose hereinbefore described
and set forth and illustrated in the accompanying drawings.
Dated this 23rd day of November 1892.
CASTLE SMITH,
"Invention" Office, 54, Fleet Street, London, E.C.,
Agent for the Applicant.
CASTLE SMITH,
Invention" Office, 54, Fleet Street, London, E.C.,
Agent for the Applicant.