Improvements in Friction Gear for the Transmission of Power.
Year: 1892

page_text: Date of Application, 19th Dec., 1892
Complete Specification Left, 19th Oct., 1993-Accepted, 25th Nov., 1893
PROVISIONAL SPECIFICATION.
Improvements in Friction Gear for the Transmission of Power.
I, THOMAS DRAKE HOLLICK, of 602, Commercial Road, in the County of
Middlesex, Engineer, do hereby declare the nature of this invention to be as
follows:-
My invention relates to friction gear used for the transmission of power, as for
instance where a rotating shaft driven by any motive power is required to drive
another shaft at the same or different speed, the transmission of power from the
driving shaft to the driven one being effected by means of pullies of suitable
diameter and width fixed upon the shaft, their peripheries being in contact and
being pressed together by means of weights, levers, screws, springs, or other
equivalent means.
When so
Such friction gear is valuable as a substitute for toothed gear especially in cases
where great speed of revolution is required with an evenness and smoothness of
motion as perfect as possible, as for instance in driving what are well known as
electric dynamos for lighting or other purposes or for electric motors.
used, however, there is frequently considerable wear in the bearings of the shafts,
or axles (and consequent loss of power) on account of the force with which it is
necessary that the driving and driven pullies should be pressed together in order
to transmit the required power, and my present invention has for its object more
especially novel methods of constructing and operating mechanisin of the kind
described by which the objections ordinarily met with are overcome.
For this purpose where two parallel shafts or axles are to be used, one of which
when revolving acts as a driving shaft and sets the other in revolution, both shafts
being provided with friction wheels or discs (plain or grooved at their peripheries)
of the required diameter and width, and their shafts revolving in suitable bearings,
I use a third similar wheel or disc of any convenient diameter fixed upon or
revolving upon a third shaft or axle parallel with the other two and arranged in
most cases between the latter. Any one of the three parallel shafts or axles is
arranged so that its position can be adjusted more or less, its bearings or other
supports which carry it being arranged so that whilst always remaining parallel
with the other shafts it can be brought more or less out of a plane. passing through
such other two shafts.
Round the two discs upon the two outer shafts, (the bearings of one of which
are made moveable, so that the shafts can approach to or recede from each other.
for a short distance, whilst always remaining parallel) or round pullies of similar
relative diameters fixed upon the said shafts, I pass an endless band or belt of
leather, flexible metal, or other sufficiently strong material, by which the two shafts
are prevented from separating.
The pulley or disce upon the central shaft is of sufficiently small diameter to
prevent the band or belt from ever touching it.
Assuming that the bearings of the two outer shafts are fixed (except that those
of one of them can approach to or recede from the other, as already described)
and that the bearings of the third shaft are adjustable so that its centre can be
brought more or less near to a line or plane passing through the centres of the
two outer shafts, then if it be brought into such a position that the periphery of
the disc upon it presses with sufficient force against the peripheries of the discs
upon the other two shafts, it is evident that motion will be transmitted from the
driving shaft to the other two shafts by the friction of the discs, whilst the two
outer ones will revolve in the same direction so that the belt also travels with the
pullies round which it passes, its tension being at the same time sufficient to prevent

page_text: any injurious pressure and wear and tear upon the bearings of the shafts. More-
over the pressure of the peripheries of the discs against each other can be stopped
when desired by withdrawing the central axle so that the disc upon it no longer
presses against the discs upon the outer axles, and the transmission of power then
ceases as the belt stretches, a pulley or pulleys of larger diameter may be
substituted for those first used.
Where however great power is to be transmitted through the several discs, and
the tension of the belt or band might not therefore be sufficient to prevent
objectionable friction upon the bearings, I use instead of an endless band or belt a
rigid or only slightly elastic ring of metal or other sufficiently strong material.
This ring passes round the discs upon the two outer shafts, or round discs or
pullies of corresponding relative diameters upon the shafts, and it prevents the
shafts from separating sufficiently (when the third disc is pressed in contact with
the others) to exert undue pressure upon the bearings. In effect therefore, each
of the outer discs is compressed between the ring upon one side and the disc on
the central shaft upon the other side, whilst the latter is pressed with equal
pressure upon both sides.
There is consequently no injurious pressure upon the bearings of either of the
three shafts, which on the contrary can revolve perfectly freely.
The ring described may be carried and guided upon one or more rollers or
guides, and where my invention is applied to such a purpose as driving the wheels
of tramcars, the ring nay itself serve as one of such wheels, its outer periphery
being properly shaped, and resting upon the rail. Or such periphery may be
provided with teeth for driving other toothed wheels.
The details of my invention and the method of carrying it into operation may
be varied more or less to suit varying circumstances and the different purposes to
which it is to be applied. For instance instead of three parallel shafts or discs,
five may be used. Or instead of one central shaft or axle, two such shafts or axles
provided with similar discs may be used, one being arranged upon each side of a
plane passing through the centres of the two outer shafts, and the two central
shafts being arranged so that they can be made to approach to or recede from
each other, for the purpose of bringing the friction discs upon them into contact
with, or withdrawing them from, the friction discs upon the two outer shafts.
The shafts or axles may be used simply as means of transmitting motion to other
shafts driving machinery of any kind, by means of bevilled or other toothed wheels
or drums and belts, or other equivalent devices, or they may drive such machinery
direct.
Either of the shafts may be made the driving shaft.
The apparatus may be arranged in any convenient position to suit the purpose
to which it is to be applied and by its use, for many purposes, great efficiency is
obtained, accompanied with absence of wear and tear, and simplicity of construction
and operation.
Dated this 10th de
2002
EDWARDS & Co.,
35, Southampton Buildings, London, Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements in Friction Gear for the Transmission of Power.
I, THOMAS DRAKE HOLLICK, of 602, Commercial Road, in the County of
Middlesex, 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 and accompanying drawing, that is to say :-
My invention relates to friction gear used for the transmission of power, as for
instance where a rotating shaft driven by any motive power is required to drive

page_text: another shaft at the same or different speed, the transmission of power from the
driving shaft to the driven one being effected by means of pullies of suitable
diameter and width fixed upon the shafts, their peripheries being in contact, and
being pressed together by means of weights, levers, screws, springs, or other
equivalent means.
Such friction gear is valuable as a substitute for toothed gear, especially in cases
where great speed of revolution is required with an evenness and smoothness of
motion as perfect as possible, as for instance in driving what are well known as
electric dynamos for lighting or other purposes, or for electric motors actuating
cranes or other machinery.
When so used, however, there is frequently considerable wear in the bearings of
the shafts or axles, and consequently loss of power, on account of the force with
which it is necessary that the driving and the driven pullies should be pressed
together in order to transmit the required power, and my present invention has
for its object, more especially, novel methods of constructing and operating
mechanism of the kind described, by which the objections ordinarily met with are
overcome.
For this purpose, where two parallel shafts or axles are to be used, one of which
when revolving acts as a driving shaft and sets the other in revolution, both shafts
being provided with friction wheels or discs, (plain or grooved at their peripheries)
of the required diameter and width, and their shafts revolving in suitable bearings,
I use the well known method of arrangement in which a third similar wheel or disc
is used of any convenient diameter fixed upon, or revolving upon, a third shaft or
axle parallel with the other two, and arranged in most cases between the latter, an
endless belt passing round the two outer wheels and having sufficient tension to
hold them with sufficient force against the centre one. Any one of the three
parallel shafts or axles is arranged so that its position can be adjusted more or less,
its bearings or other supports which carry it being arranged so that, whilst always
remaining parallel with the other shafts, it can be brought more or less out of a
plane passing through such other two shafts, the bearings of one of which are made
moveable, so that the shaft can approach to or recede from the other shaft for a
short distance, whilst always remaining parallel with it.
The pulley or disc upon the central shaft is of sufficiently small diameter to
prevent the band or belt from ever touching it.
The bearings of the two outer shafts are fixed, (except that those of one of them
can approach to or recede from the other, as already described) and the bearings
of the third shaft are adjustable so that its centre can be brought more or less near
to a line or plane passing through the centres of the two outer shafts, and when it is
brought into such a position that the periphery of the disc upon it presses with
sufficient force against the peripheries of the discs upon the other two shafts,
motion is transmitted from the driving shaft to the other two shafts by the friction
of the discs, whilst the two outer ones will revolve in the same direction so that the
belt also travels with the pullies round which it passes, its tension being at the same
time sufficient to prevent any injurious pressure and wear and tear upon the bearings
of the shafts. Moreover the pressure of the peripheries of the discs against each
other can be stopped or adjusted when desired by altering the position of the
central axle, so that the disc upon it no longer presses against the discs upon
the outer axles, and the transmission of power then ceases. As the belt stretches,
a pulley or pullies of larger diameter may be substituted for one or more of those
first used.
In apparatus of the kind just described, where great power is to be transmitted
through the several discs and the tension of the belt or band would not therefore
be sufficient, I use instead of an endless band or belt a rigid or only slightly
elastic ring of metal or other sufficiently strong material, (as illustrated in
Figures 1 and 2 of the accompanying drawing, Figure 1 being an elevation and
Figure 2 a plan).
In the figures two rings r, r, are shewn, passing-not round the discs B and C

page_text: upon the two outer shafts,-but round discs or pullies s, 8, of corresponding
relative diameters upon the shafts of the driven pulley B and the third pulley C,
and preventing the shafts from separating sufficiently, (when the third disc or
driving pulley A is pressed into contact with the others,) to exert undue
pressure upon the bearings D, E. In effect therefore each of the outer discs B
and C is pressed (by means of the pulleys s, s,) by the rings r, r, against the
disc A upon the central shaft, whilst the latter is pressed with equal pressure upon
both sides.
There is consequently no injurious pressure upon the bearings of either of the
three shafts, which on the contrary can revolve perfectly freely.
The ring or rings r, r, described may be carried and guided upon one or more
rollers or guides F, F, and where my invention is applied to such a purpose as
driving the wheels of tramcars, the ring may itself serve as one of such wheels, its
outer periphery being properly shaped and resting upon the rail. Or such periphery
may be provided with teeth for driving other toothed wheels.
The bearings G of the central or driving pulley A are shewn carried by the
arms H, the lower ends of which are jointed to levers I actuated by a handle K, so
that the pulley A can be raised or lowered slightly as desired and pressed with
more or less force against the pullies B and C.
The bearings of the axle of the pulley C may be made slightly elongated (as
shewn), so that the pulley may come out of contact with the ring r when the central
pulley A is raised out of contact with the pullies B and C.
It is necessary where a belt is used that the position of the moveable disc should
be capable of very accurate adjustment, so that the proper pressure requisite may
be communicated to it as desired from the driving disc, and so that the attendant
may have perfect command over the apparatus, (in the case for instance of an
electric crane,) and may be able to start the driving gear, stop it, or supply any
required amount of friction and pressure.
In the accompanying drawing, in Figures 3 and 4, the apparatus is shewn
applied to such a purpose as driving a crane by an electric motor as above
described, a motor driven by electricity being arranged so that it can be made to
communicate its movement when desired to the hoisting mechanism of the crane,
such movement being stopped and regulated as required instantly and without
trouble by the attendant.
In such cases I use preferably adjustable stretching bolts for tightening the belt
and keeping a definite strain upon it. Such bolts also form when so adjusted an
arrangement for driving, when the load exceeds that which the tension of the belt
is sufficient to drive. In Figures 3 and 4, a is the shaft of an electric motor
provided with a small friction pulley b. This pulley drives the larger pulley c the
shaft of which d actuates the crane or other machinery which is to be driven.
e is a third pulley, the shaft of which revolves in bearings f, f, in the levers 9, 9,
which can be raised or lowered for a short distance by means of the connecting
rods and levers i operated by an attendant by the lever or handle k.
The
pullies cand e are connected by the endless belt which passes over them, and the
greatest tension upon which exists when the pulley e is lowered until the centres of
the axles of the three pullies are in the same plane, as shewn in the figures.
When the pulley e is raised by means of the lever k the tension of the belt is
reduced.
The ends of the levers 9, 9, are prolonged sufficiently above and below, and
are connected by the adjustable bolts m, m, with the ends of similar levers n, n,
the centres of which turn freely upon the shaft d, or upon suitable bosses carried
by the bearings o, o, in which the said shaft revolves. The ends of the bolts m, m,
are adjustable in the levers n, n, (or in those g, g,) by means of nuts p, p.
Preferably the bolts m, m, are so adjusted that when the belt is at its tension for
the pulley to be properly driven, the axis of the pulley e is somewhat above the
plane of the axes of the pullies b and c, and there is then practically no friction
upon either of the shafts.

page_text: The outer nuts p upon the bolts m are so adjusted that they press against the
levers n when, or just before, the axis of e comes into the same plane as the other
two axes. By means of the lever k the pulley e can be lowered or raised to or from
the plane of the centres of the axes, so as to vary the pressure on the driving wheel
or pulley b, or take it off altogether. The driving shaft a is preferably arranged so
that its bearings have a very slight lateral movement, in order that when the
pressure is removed it may come out of contact with the pulley c.
The arrangement shewn enables me to use smaller gear than I should be other-
wise able to use, and also in case of a belt giving out or breaking I should still
be able to go on driving, though not so efficiently as when the belt is doing all the
work.
The electric motor is carried upon the axle a and is free to slide or rock on its
bed for a short distance, so that the pulley b may be able to come out of contact
with the pulley c.
The shaft on which the pulley e is keyed is slightly loose in its bearings, and
the pulley is capable of being moved vertically or nearly so without the adjustment
of the belt varying materially, the pulley e really moving on a radius centred on
the shaft d.
When the pulley e is raised out of gear with the pulley, the pulley c ceases to
be driven, because being sufficiently loose in its hearings it falls away from the
pulley which continues to revolve.
The pulley moreover being mounted upon the motor axle a, which is free to
move toward and from the pulley c, moves from the latter to a small extent, the
effect being that it comes out of gear with the pulley c.
When the pulley e is put in gear with the pulley b by pressing it down, the reverse
of the above described action takes place, and the three pullies may be pressed
tightly together, without any appreciable loss of power or strain on the bearings so
long as the belt tension does the work, but if the pulley e is pressed down, the
nuts p will not allow it to pass the centre. There is then a certain loss, varying
with such pressure, but even then the loss is very much less than that usual in
ordinary friction gear.
The novel arrangement described and illustrated is highly efficient for trans-
mitting power from electro-motors to their work, and enables me to use constant
speed motors, and to stop and start the work without interfering with their
speed, and it affords means for very delicate adjustment, failing which the loss
of power becomes considerable.
In connection with the arrangement of three pullies described, I also sometimes
use a fourth pulley, carried on either fixed or adjustable bearings below the belt, (or
above as the case may be,) so that if the latter stretches beyond a predetermined
amount, the act of drawing the third pulley nearer the centre line presses the belt
against the fourth pulley and consequently deflects and tightens it.
Or in some cases, and particularly where used for driving dynamos, the pulley e
being on the centre line, the lower pulley may be adjustable so as to tighten the
belt.
And sometimes, instead of one central shaft or axle, two such shafts or axles
provided with similar discs may be used, one being arranged upon each side of a
plane passing through the centres of the two outer shafts, and the two central
shafts being arranged so that they can be made to approach to or recede from each
other, for the purpose of bringing the friction dises upon them into contact with, or
withdrawing them from, the friction discs upon the two outer shafts.
The details of my invention and the method of carrying it into operation may be
varied more or less, to suit varying circumstances and the different purposes to
which it is to be applied. For instance, instead of three parallel shafts or discs,
five may be used. The shafts or axles may be used simply as means of trans-
mitting motion to other shafts driving machinery of any kind by means of
bevelled or other toothed wheels, or drums and belts, or other equivalent devices,

page_text: or they may drive such machinery direct.. Either of the shafts may be made the
driving shaft.
The apparatus may be arranged in any convenient position to suit the purpose to
which it is to be applied; and by its use, for many purposes, great efficiency is
obtained, accompanied by absence of wear and tear and simplicity of construction
and operation.
1 do not claim broadly the driving of a small pulley driven by the friction
of two larger ones placed on each side of it, over which a belt passes, nor the
mounting one of the pullies out of the centre line of the other two pullies; but
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. The combination with a driving friction pulley arranged between two friction
pullies, one on each side of it, of a sufficiently rigid ring embracing the two outer
pullies and holding them together when the central pulley is forced between them,
and of the means for so forcing the central pulley between them, substantially as
and for the purposes described and illustrated in Figures 1 and 2.
2. In the combination claimed in Claim 1, the method of arranging one or more
sufficiently rigid ringe round separate pullies or discs fixed upon the axles of the
two outer pullies, instead of round the two outer pullies themselves, substantially in
the manner described and illustrated in Figures 1 and 2.
3. In the combinations described and claimed in Claims 1 and 2, the bearings G
of the adjustable pulley, the arms H, levers I and handle K, for the purpose of
accurately adjusting the position of the adjustable pulley A, substantially in the
manner and for the purpose described and illustrated in Figures 1 and 2.
4. In combination with a friction pulley situated between two other friction
pullies, one on each side of it, the two outer pullies being surrounded by a flexible
band by which they are held in contact with the central pulley, the adjustable
bearings, bars h, levers i and handle k, for the purpose of accurately adjusting
the position of the adjustable pulley e, substantially in the manner and for the
purpose described and illustrated in Figures 3 and 4.
5. In combination with the devices described and claimed in Claim 4, the
levers g, g, n, n, and the connecting rods m, m, having adjustable nuts p, the
positions of which are so adjusted that when the axis of the adjustable pulley is
coming into the same plane as the axes of the other two pullies, the nuts p come
into operation and prevent the further separation of the axes of the two outer
pullies, substantially in the manner and for the purpose described and illustrated in
Figures 3 and 4.
6. In the combination of apparatus described and claimed in Claims 4 and 5, the
use of separate pullies upon the axles of the two outer friction pullies, such separate
pullies carrying the endless band and having the same relative diameters as the two
outer friction pullies, substantially as described.
Dated this 19th day of September 1893.
EDWARDS & Co.,
35, Southampton Buildings, London, Agents for the Applicant.