Year: 1887

page_text: Date of Application, 10th Oct., 1887
Specification Accepted, 11th Nov., 1887
I, WILLIAM JOHN PRISMALL, of Errol Street, Footscray, in the Colony of
Victoria, Miller, 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 that description of rope driving gear in which the one
endless rope is used, such rope passing several times around the driving and the
driven wheels and leading off from the driver to a tension pulley by which the rope
is kept taut. Now my invention consists, first, in providing a slipping groove on the
driving wheel at the side which takes the rope off the tension pulley. As the rope
touches the bottom of this groove and consequently embraces the driving wheel at a
lesser diameter than the part of the rope which is in gear with the driving grooves,
such slipping groove is made quite free for the rope to allow it to slip as that part of
the rope which is in it travels at a slower speed than those parts which are in the
driving grooves. My invention also consists, secondly, in arranging the frame upon
which the tension pulley carriage slides, at an angle parallel with the rope leading
from the driving wheel to such tension pulley, thus dispensing with the necessity for
weights to retain the rope taut as the pulley carriage will gravitate on its inclined
frame sufficiently for that purpose.
The drawing hereto attached illustrates the arrangement of a rope-driving gear
constructed according to my invention.
Figure 1 shewing a side elevation and
Figure 2 a plan of it, while
Figure 3 shews an enlarged cross section of the rim of the driving wheel with the
slipping grove shewn in it, and
Figure 4 an enlarged cross section of the rim of the rope wheel to which the motion
is imparted.
A is the driving wheel-B the driven wheel-C the tension pulley-D the rope
and E the inclined framing. The driving wheel A has the ordinary rope grooves A¹
and the slipping groove A³ formed in it, the latter being made, say, to about the
depth of the ordinary grooves, but free enough in width to allow the rope to bear
freely on its bottom without being gripped at its sides. The driven wheel B has all
En

page_text: of its grooves B¹ made of a suitable section to grip the rope. The tension pulley C
has its groove formed to allow of the rope travelling freely through it and it lies
obliquely to the plane of the driving wheel to lead the rope straight to it from the
outer grooves of the driving wheel. Its bearings are supported on a frame C¹ which
slides upon the inclined frame E.
Although I have shewn and described the tension pulley with its sliding carriage
arranged between the ropes it may instead be placed over or under them. In any of
these positions, however, care should be taken to have the frame parallel with that
part of the rope which leads from the driving wheel to the tension pulley.
The mode of operation is as follows in a rope driving gear constructed as shewn
and described the rope is driven in the direction indicated by the arrows and it is
arranged on the wheels so that the rope which is taken off the tension pulley is led to
the slipping groove formed near the edge of the driving wheel. From this groove
it is led to the driven wheel and is then wound over all the grooves of the two wheels
and is then again led from the other edge groove of the driving wheel to the tension
pulley by the sliding of the carriage of which on its inclined frame the slack is taken
up and the rope retained taut.
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. Forming the side groove in the driving wheel which takes the rope off the
tension pulley, of a section which allows the rope to bear freely on its bottom and to
thus provide a slipping groove, substantially as herein described and explained and
as illustrated by a section of the rim of the wheel in Figure 3 of my drawings.
2. The combination with driving wheels having a slipping groove, of the tension
pulley arranged on a sliding carriage supported on an inclined frame substantially as
and for the purposes described and as illustrated in Figures 1 and 2 of my drawings.
Dated this Twenty-ninth day of August One thousand eight hundred and
eighty-seven.
Dated this 10th day of October 1887.
WILLIAM JOHN PRISMALL.
Abel & Imray,
Agents for the Applicant.