Improved Means for Taking or Transmitting Power from Electro Motors, applicable also for Driving Dynamos, Machine Tools, and other Machinery.
Year: 1893

page_text: Date of Application, 10th May, 1893
Complete Specification Left, 8th Feb., 1894-Accepted, 5th May, 1894
PROVISIONAL SPECIFICATION.
Improved Means for Taking or Transmitting Power from Electro
Motors, applicable also for Driving Dynamos, Machine Tools,
and other Machinery.
We,
CHARLES RILEY GARRARD, of The Avenue, Acocks Green, in the County
of Worcester, Engineer, and THOMAS WILLIAM BLUMFIELD, of 10 Saint John's
Terrace, Queen Victoria Road, Coventry, in the County of Warwick, Engineer, do
hereby declare the nature of this invention to be as follows :—
This invention relates as hereinafter described to an improved means of taking
or transmitting power from electro motors, at varying ratios of speed, between the
electro motor and the axle or machinery driven, and of allowing the motor to start
with no load on beyond its own inertia and bearings.
Our said invention is especially advantageous to accumulator traction, effecting a
great saving of current at starting, and by transmitting the power to the driven axle,
so that the motor remains practically at constant speed, while the driven axle may
be varied in speed anywhere within the range provided for. By our invention great
advantage is obtained in the co-efficient of friction being extremely low, as practically
no reaction has to be sustained by the bearings.
Our invention is especially applicable to electric vehicles hereinafter referred to,
as described in our Specification Number 21147, dated November 21st 1892,
whereby carriages having compressed air tyres and propelled by electricity through
differential or balance gearing.
In carrying our invention into practice we place the axis of the motor at right
angles to the axis of the shaft to be driven, we then construct a double disc having
two parallel faces inside or face to face; between these inside faces are two friction
rollers of suitable sizes, one only need be attached in such a manner as to be driven
by the motor, the other friction roller which need not be the same size as the driving
roller, being placed diametrically opposite the driving roller. In this arrangement,
the latter roller may be termed the intermediate roller, as it has for its object to
transmit about one half the power from its periphery to the opposite face of the
double disc in the same direction.
We cause sufficient pressure for adhesion between the double disc by suitable
means, generally by making the driving and intermediate rollers of such diameters
that they will not lie with their centres parallel to the axis of the driven shaft, but
preferably a few degrees out of line when pressed by an eccentric device in such
direction that both driving and driven rollers tend to lie in the same radial line from
the driven shaft, but as the distance from face to face of the double disc, is a fraction
less than the sum of the two diameters of the driving and driven rollers, any degree
of pressure required from nil for adhesion may be obtained by a simple cam or
eccentric device, actuating preferably the intermediate roller and jamming it
between the two faces or relieving it to start as desired.
To avoid setting up much friction, from the fact that a parallel or cylindrical
roller is rolling on the face of a disc, and if the said parallel roller were broad, a
difference of surface speed on the disc would be encountered, and a severe rubbing
set up; we prefer to make the periphery of the driving and intermediate rollers
crowned or convex on their peripheries, so that their paths of contact on the faces
of the double discs should be as narrow as practicable.
We may sometimes obtain the varying pressures for adhesion or bite by making
one of the faces of the double disc movable, but it is obvious that in actuating this,

page_text: some mechanical reaction is set up, except where springs are used to keep the faces
hard enough together. In this case the two rollers have to be drawn right out from
between the double disc to admit of starting the motor with no load on.
The advantages of this mode of taking or transmitting power from electro
motors are :-
Firstly. That the motor may be started with no load on and thereby effect an
immense saving of current.
Secondly. That any shaft, countershaft, or axle, may be driven at any desired
speed within its range, from the greatest ratio required, differentially, gradually
down to the smallest ratio provided, which in the case of electric traction on
varying loads, inclines, wind and the like, results obviously in a great economy of
current, leaving the motor at a practically constant speed.
Thirdly. The co-efficient of loss by friction is extremely small owing to the fact
that in the improvements aforesaid a very small portion of the reaction of the
pressure necessary for adhesion or bite of the surfaces in contact has to be borne by
the bearings, especially in the case with the motor bearings, which are practically
in equilibrium, torque and pressure on one side being approximately counter-
balanced by corresponding torque and pressure in an opposite direction on the
opposite side.
In applying our improvements to our electric vehicles herein before referred to,
that is to say carriages having compressed air tyres and propelled by electricity
through differential or balance gearing, we insert between the double disc aforesaid,
at any convenient position, suitable brake blocks held firmly to the tubular or other
frame but free to be forced apart against the inner faces of the said double disc, the
retarding effect of such a brake is imparted equally to the two driving wheels
through the differential or balance gearing just in the same manner as the driving
effect is also felt equally when moving in all sorts of curves or in a straight line.
We may when desired apply part of this invention to driving dynamos, machine
tools, and any kind of machinery requiring to be varied gradually, in its ratio with
some constantly speeded source of power.
In the case of a dynamo, the order is generally reversed vz.:-the double disc
aforesaid is made the driver and the dynamo desired to be varied is attached to
one of the friction rollers, is thereby made the driven, the other then becoming the
intermediate roller, thus when less energy is required from the dynamo, it may
be run slower, instead of dissipating the energy through resistances inserted in the
circuit.
In applying our invention to machine tools, it is especially advantageous where
the cutting tool acts from the periphery towards the centre or vice versa, such as in
turning the faces of discs, steam cylinder covers, etc., or in cutting or parting
off material from the bar, it is then made to vary the speed of the work, by being
connected to the tool which is traversing and thereby made to maintain an
approximately even cutting speed.
This connection however forms no part of our invention, we are aware this device
has been used for a similar purpose where a single disc has been used.
The bearings of the friction rollers and double dises are preferably mounted on
anti-friction balls.
The double disc is preferably made of metal, but the friction rollers are sometimes
made of compressed leather, paper, vulcanite or other suitable material.
Our invention may be modified in any detail as may be necessary to the
carrying of the same into effect without departing from the nature or principle
thereof.
Dated this 10th do…. ^ M.- 1000
GEO. H. RAYNER,
37, Chancery Lane, London, W.C., Agent for the Applicants.

page_text: It is obvious that the higher speed shaft C, whether driven or driver, lies in its
bearing B practically in equilibrium; the pressures both for adhesion and driving
are taken about equally on two diametrically opposite sides so that the co-efficient
of loss is extremely small.
We control the position of the rollers F and F by the action of the lever K
which is arranged to allow of movement within the two extreme positious indicated
at 1 and 2 Figure 4, so far as motion of the shaft E in the direction of its axis is
concerned. This motion permits the rollers F and F¹ to be held at any position
radially within the limits shown by the full line roller F¹ and the dotted
roller F¹.
The lever K is also so mounted by means of universal joints L L' and two pivot
pins K' and K' that the shaft may be oscillated when desired to engage or disengage
the roller F by the crank lever E'.
Figure 5 shows a front view of the pivot pins K' K' of the lever K.
Figure 6 shows the connection of the crank lever E¹ with the shaft E.
We may sometimes obtain the varying pressures for adhesion or bite by making
one or both of the faces of the double disc D moveable, but in actuating this some
mechanical re-action is set up except where springs are used to keep the faces hard
enough together, and in this latter case the friction rollers F F¹ may be drawn right
out to disengage the shaft C from the double disc D; the said shaft C is, when
required, made to telescope into the hollow shaft G of the armature.
We have hereinbefore mentioned this invention in connection with electro-motors
and dynamos, but we do not confine ourselves to this application; we may apply
the invention to machine tools or any kind of machinery required first for driving
any two shafts at right angles to each other, replacing bevel or mitre wheels.
Second in addition to this driving, we may engage and disengage the said shafts
while in motion or stationary. Third we may vary the speed ratio at will between
the said shafts gradually anywhere within the limits provided, such variation of
ratio may be effected by hand or automatically; the latter, for instance, would be
especially advantageous in turning the faces of discs in lathes, or cutting off
material from the bar, connection is made to the traversing tool so that as the tool
moves across the face, the speed of the work varies so as to maintain an approxi-
mately constant surface speed where the tool is acting or cutting. This automatic
connection, however, forms no part of our invention, it being well known in
connection with single discs.
The double disc is preferably made in metal in one or several parts; the inner
faces may be protected by plates of comparatively harder or more dense material;
we may also place an elastic medium between the said protecting plates and the
said double disc to give a suitable contact and diminish noise.
The friction rollers may be made of metal, compressed leather, paper, vulcanite or
other suitable material.
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. The method of transmitting power from an electro-motor or to a dynamo, by
means of a double disc with opposing working faces between which rotate two
driving or driven rollers forced into contact with the said opposing faces and with
each other in such manner as to produce any desired driving friction between the
working surfaces and at the same time avoid or minimise reactionary pressures and
so diminish frictional loss substantially as hereinbefore described.
2. The method of transmitting power from an electro-motor or to a dynamo by
means of a double disc with opposing working faces between which rotate two
driving or driven rollers forced into contact with the said opposing faces and with
each other, the said rollers being so coupled or connected that on moving a lever
they are moved out of contact with the disc faces or the pressure of contact
reduced, and on further operating the lever the rollers may be drawn out or pushed

page_text: in to engage the disc at a position of greater or less diameter or clear of the discs-
altogether so as to vary the speed of rotation of the driven part or to enable the
motor part to revolve free from the driving part, substantially as herein before set
forth.
3. The method of producing driving frictional contact on the opposing surfaces.
of a double disc by means of rollers between them forced in by a wedging action,.
the united diameter of the two rollers being greater than the distance between the
disc surfaces so that a small pressure applied to force in the rollers causes a great
pressure between the rollers themselves and the opposing surfaces of the discs.
substantially as hereinbefore described.
4. Mechanism for transmitting power from an electro-motor or to a dynamo_or
from one shaft to another comprising in combination :-A double disc such as D ;
a roller such as F attached to the armature or other spindle G and suspended from.
or connected by a link as H to a rocking shaft as E; a roller such as F1 suspended
by a link as H¹ from a lever as E', the said lever operating from the shaft E and
so arranged that the roller F¹ when moved into contact with one surface of the
disc D and the roller F, causes both rollers to press upon the opposing surfaces of
the disc D with any desired degree of pressure without bringing any corresponding
pressure to bear upon the roller bearings or on the disc spindle bearings, substan-
tially as hereinbefore described with reference to Figures 1, 2 and 3 of the accom-
panying drawings.
5. The mechanism hereinbefore described with reference to Figures 1, 2, 3 and 4
of the drawings, comprising in combination, the double disc D with the rollers F Fi
carried on the links H H¹, the said links being moved by the shaft E mounted in
suitable bearings and the shaft E being controlled by a lever as K so mounted as
to allow of the movement of the said shaft either way in the direction of the axis
or a movement of oscillation or rotation about its axis so as to enable the rollers FF'
to be forced between the surface of the disc D with any desired degree of pressure
or placed in any position of the disc diameter.
Dated this 7th dow of Fohm 1801
MARKS & CLERK,
18, Southampton Buildings, London, W.C., and
13, Temple Street, Birmingham, Agents for the Applicants.