Improvements in Electro-magnetic Variable Speed and Clutch Gearing.
Year: 1898

page_text: Date of Application, 13th Oct., 1898
Complete Specification Left, 7th Feb., 1899-Accepted, 1st Apr.,
1899
PROVISIONAL SPECIFICATION.
Improvements in Electro-magnetic Variable Speed and Clutch
Gearing.
We, HENRY APPLEBY WOLLASTON, of W. Pope & Sons, Gotha Works, Managing
Director, Slough, and RANKIN KENNEDY, Electrical Engineer, of 89, Gathorne
Terrace, Leeds, do hereby declare the nature of this invention to be as follows:-
These improvements relate to an electromagnetic gear or clutch, for trans-
mitting power, and varying the speed between a driving and a driven shaft, pulley,
or wheel.
Our improved gear or clutch, consists essentially of an alternating current
generator of simple design, with a short circuited armature, and a separately ex-
cited field magnet. The field magnet can be varied in strength by a rheostat,
so that the action and the counteraction between the armature and field magnet
are varied, and thereby the speed of the driven shaft, pulley, or wheel is varied.
The armature is carried by the one shaft, pulley, or wheel, while the field magnet
is carried by the other shaft, pulley, or wheel; the one being free to rotate without
the other rotating.
When no electric current is let into the field-magnet, the driven shaft stands at
rest, while the driver-rotates; but on passing electric current into the field magnet,
electric currents are induced in the armature circuit, and these currents interlock
with the field magnet so as to produce a torque or turning force driving the driven
shaft, wheel or pulley at a speed dependant upon the strength of the field magnet
and the load on the driven shaft, pulley or wheel.
The speeds of the driven and driving parts must always differ, as the currents
induced in the armature depend upon the difference of speed between the armature
and the field magnet.
The field magnet may have any of the well known forms commonly used in
alternators and may be similarly excited.
The armature, preferably, consists of a soft steel core with a copper tube or
plate securely fixed to said core, for the circulation of the induced currents therein.
The field magnet is excited from any available continuous electric current source.
The essential features of the invention are the driving of one shaft, pulley or
wheel by another, by means of a field magnet reacting on induced currents of
electricity in an armature acted upon by said field magnet.
And the varying of the speeds of the driven shaft, pulley or wheel, by varying
the electromagnetic strength of the said field magnet.
And the transmission of the power and the variations in speed being accom-
plished by electromagnetic induction alone, between the driving and the driven
mechanisms.
Dated this 11th day of October 1898
HY. APPLEBY WOLLASTON.
RANKIN KENNEDY.

page_text: Improvements in Electro-maguetic Variable Speed and Clutch
Gearing.
We, HENRY APPLEBY WOLLASTON, of W. Pope and Sons, Gotha Works, Slough,
in the County of Buckingham, Managing Director, and RANKIN KENNEDY, of
89, Gathorne Terrace, Leeds, in the County of York, Electrical 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:-
These improvements relate to electro-magnetic clutch gearing, and our object
is to enable power to be transmitted gradually and without jar from a continuously
rotating shaft to another shaft or pulley, the speed of transmission being varied as
desired by varying the force of hold exerted by the clutch.
In order that our invention may be clearly understood we will proceed to
describe the same with reference to the accompanying drawing, in which similar
letters refer to like parts in both figures.
Figure 1 is a longitudinal section of a clutch constructed according to our inven-
tion, and Figure 2 is an end view of the same.
Our invention consists essentially of adapting an alternating current generator
having a short circuited armature and a separately excited field magnet, for the
purpose of connecting and disconnecting a continuously rotating shaft and a driven
shaft or pulley, hereinafter described with reference to a pulley. In the drawing
we have shewn the major portion of the clutch, vir.: the field magnet A mounted
on a continuously rotating shaft B, and motion is to be transmitted to a pulley C
mounted loosely on the shaft B. The field magnet A is made up of pole pieces D, D
and a field magnet coil E, and the latter is connected to an insulated ring F which
receives an electric current from a brush G and generator H, the other end of the
coil E being.connected to the shaft B and thus back to the generator H by way
of a rheostat J. The pole pieces D are all of one polarity such as
south," and
the pole pieces I are all of the opposite polarity such as north." The pulley C
carries a disc K, and on the periphery of the said disc an armature is carried which
is composed of a copper or other suitable hoop L and a soft iron or other ring M.
When, no electric current is let into the field magnet A, the pulley C stands at
rest, but on passing an electric current through the coil E, electric currents are
induced in the armature circuit, and these currents interlock with the field
magnet A so as to produce a torque or holding force, tending to prevent the exterior
of the field magnet A from travelling at a higher speed than that of the interior of
the armature L, and the pulley C is thus driven at a certain speed less than that of
the field magnet A, the difference being dependent upon the strength of the field
magnet A and the load on the pulley C.
66
The speed of the field magnet A must always differ from the speed of the arma-
ture L, as the currents induced in the latter depend upon the difference of speed
between the armature L and the field magnet A. The strength of the field magnet A
may however be varied as desired, by varying the strength of the exciting current
by means of the rheostat J, thus enabling the strength of the torque to be varied
a. will to suit the load, which can thus be started gradually and without shock.
Any field magnet in which the poles of any one side are of similar polarity may
be used in the construction of the clutch, and the said field magnet may be excited
from any available continuous electric current source.
The above described apparatus enables the greatest amount of torque to be
obtained with the smallest difference of speed between the armature and the field

page_text: magnet, and also allows the strength of the clutch to be varied at will, thus making
the said clutch most suitable for transmitting mechanical power.
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 an electro-magnetic gear or clutch, the armature composed of rings L
and M, carried on one side of the clutch; in combination with a separately excited
fiell magnet substantially as and for the purposes set forth.
2. In an electro-magnetic gear or clutch, the construction of a field magnet in
which the poles of any one side are of similar polarity, in combination with rings L
and M, whereby the greatest amount of torque is obtained with the smallest
difference of speed between the armature and the field magnet, substantially as
set forth.
3. In an electro-magnet gear or clutch, a field magnet having the poles of any
one side of similar polarity carried on one shaft, in combination with a pulley or
shaft carrying an armature consisting of a compound ring of copper and iron,
arranged in close proximity to the ends of the poles of the field magnet, sub-
stantially as set forth.
4. In an electro-magnetic gear or clutch, the transmission of power by mans of
electro-magnetic induction alone, between the driving and the driven mechanisms,
substantially as and for the purposes set forth.
Toted this 7th day of February 1899
BREWER & SON,
London and Leeus,
Agents for the Applicants