Improvements in Variable Pulleys.
Year: 1895

page_text: PROVISIONAL SPECIFICATION.
Improvements in Variable Pulleys.
We, WILLIAM HENRY HARRAP, Engineer of Richmond Hill, Salford,
Manchester and ALBERT MITCHELL, Engineer of Croydon Terrace, Manchester
Road, Bury, do hereby declare the nature of this invention to be as follows:-
Our improvements relate to that class of pulley in which the diameter of the
driving surface can be varied in size, for the purpose of obtaining alterations in
the speed of machinery where such variation is desired.
The pulley may consist of two separate drums, preferably in the form of cones
with their small ends together & their axes coincident with that of the shaft on
which the drums are mounted. One drum may be keyed fast on the shaft, while
the other drum may be arranged to move to & from the aforementioned drum in
the direction of the axis. Each drum contains a suitable number of recesses, or
perforations preferably four, and both drums are so placed that the projecting parts
of one can slide into the recesses of the other.
To prevent the abrasion of the driving rope or band, by the edges of the recesses,
and also to give a continuous driving surface, we fit suitable sliding pieces in the
said recesses, in such manner that the inner edges of the pieces in one drum bear
on the surface of the projecting parts of the other drum, a suitable spring or
springs being employed, if necessary, to keep the said pieces in contact with the
aforementioned surfaces. It will be readily understood that the driving surface
will be at or near the intersection of the surfaces of the two drums, and as the
drums approach one another the said driving surface will be increased in diameter,
and vice versa.
The movement of the drum or drums can be by any of the usual well known
means; and where two variable pulleys are employed, the one driving the other,
the operating gears may be arranged to work simultaneously but in opposite
directions. By this means one pulley will be made larger while the other is
reduced, and consequently a greater variation in speed obtained.
We prefer to operate the moveable drum through the ordinary extension
provided with a recess, or collars, in which a suitable ring, or pads, work. The
pads may be carried in a sliding piece actuated by a screw carrying a sprocket
wheel, over which a suitable pitched chain runs. The said chain will pass over
the wheels on the screws of the two pulleys, so that the rotation of one will cause
the other to rotate equally. One screw would be right hand and the other left,
to produce the effect desired. A second sprocket wheel & chain may be provided
on one of the screws, to enable the workman to operate the mechanism.
1
1005
G. T. HARRAP,
Agent for Applicants.

page_text: Improvements in Variable Pulleys.
We, WILLIAM HENRY HARRAP, Engineer of Richmond Hill, Salford,
Manchester, and ALBERT MITCHELL, Engineer of Croydon Terrace, Manchester
Road, Bury, 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 :-
Our improvements relate to that class of pulley in which the diameter of the
driving surface can be varied in size, for the purpose of obtaining alterations in
the speed of machinery where such variation is desired.
In order that our invention may be more readily understood we have caused to
be attached hereto one sheet of drawings in which similar letters refer to similar
parts.
Fig. 1. is an elevation of two of the improved variable pulleys working in
conjunction with each other; one pulley being more or less vertically under the
other.
Fig. 2. is an elevation and part section of two of the improved variable pulleys
working in conjunction with each other; one pulley being more or less horizontally
situated with regard to the other.
Fig. 3. is an end elevation of the arrangement as described for Fig. 2.
Fig. 4. is a section through an improved variable pulley.
The pulley consists of two separate drums A, B, or A¹, B' in the form of cones
with their small ends together and having their axes coincident with that of the
shaft C, or C¹ on which the drums are mounted. The shaft may be supported
in suitable bearings or brackets D, or D'. An ordinary belt driven pulley E is
also shown fixed to the shaft C in Fig. 1. for driving from main shaft. One drum A
or A is keyed fast on the shaft, while the other drum B or B' is arranged to
move to and from the aforementioned drum A or A¹ in the direction of the axis.
Each drum contains a suitable number of recesses or perforations F, preferably
four, and both drums are so placed that the projecting parts of one can slide into
the recesses of the other. To prevent the abrasion of the driving rope or band by
the edges of the recesses, and also to give a continuous driving surface, we fit
suitable sliding pieces G in the said recesses, in such manner that the inner edges of
the pieces in one drum bear on the surface of the projecting parts of the other
drum, a suitable spring or springs H preferably of a spiral form being employed if
necessary to keep the said pieces G in contact with the aforementioned surfaces.
If necessary a spindle K fixed to the drum B and passing through the spring H
may be used to keep the said spring in place, a suitable hole being formed in the
sliding piece G to allow it to pass over the aforesaid spindle K. Suitable
projections may be formed on the sliding pieces to work in corresponding grooves
or guides J formed in the recesses F." It will be readily understood that the
driving surface will be at or near the intersection of the surfaces of the two drums,
and as the said drums approach one another the said driving surface will be
increased in diameter and vice versa. The movement of the drum or drums may be
by any of the usual well known means; where two variable pulleys are employed,
the one driving the other by means of a suitable rope or band L the operating
gears may be arranged to work simultaneously but in opposite directions as hereafter
described.
By this means one pulley will be made larger while the other is reduced
and consequently a greater variation in speed obtained. We prefer to operate the
movable drum through the ordinary extension provided with a recess or collars M
in which a suitable ring or pads N work. The pads may be carried in a sliding
piece O, said piece sliding on a suitably shaped projection P of the bracket D and

page_text: being actuated by a screw R carrying a suitable wheel, which may be either a
toothed wheel S as shown in Fig. 1 or sprocket wheel T or T' as in Figs. 2 & 3,
or any other suitable form of wheel.
In Fig. 1 the toothed wheel S is driven by another toothed wheel U, mounted
on shaft V running in suitable bearings in continuations of brackets D, D'. On
end of shaft V is mounted a grooved wheel W driven by another suitable wheel ✗
by means of the rope or band Y. The wheel X is operated by means of the hand
wheel Z.
In Fig. 2, as before mentioned, the sprocket wheel T¹ is mounted on the screw R¹
aud is driven by a suitably pitched chain I from a sprocket wheel T mounted on
the screw R. A second sprocket wheel 2, and chain 3, may be mounted on the
screw R beside the aforementioned wheel T to enable the mechanism to be operated
from below.
Having now particularly described and ascertained the nature of our said inven-
tion, and in what manner the same is to be performed, we declare that what we
claim is;
(1.) In variable pulleys, consisting of two conical drums having recesses and
projections sliding the one into the other, the sliding pieces as G moving in
suitable guides in the recesses of one cone and maintained in contact with the
driving surface of the other cone by means of springs or other suitable device
substantially as and for the purposes herein described with reference to all the
figures.
(2.) In variable pulleys, the combination of two variable pulleys and suitable
operating mechanism by which one pulley may be made smaller in diameter,
simultaneously with the enlargement of the other substantially as and for the purposes
herein described with reference to all the figures.
Dated this 29th day of February 1896.
G. T. HAKKAP,
Agent for Applicants.