Improvements in Controlling Electric Motors, and Switches therefor.
Year: 1898

page_text: Date of Application, 3rd Jan., 1898-Accepted, 20th May, 1898
COMPLETE SPECIFICATION.
Improvements in Controlling Electric Motors, and Switches therefor.
I, KERBEY BOWEN, of 55, Regent Street, London, W., in the County of London,
Electric Launch Builder, 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:-
In electric launches it is found necessary to temporally increase the speed, for
short intervals, for which purpose I employ a special switch entirely separate from
the ordinary regulating switch.
Referring to the drawings Sheet 1 shows the switch without case in plan and
elevation, Sheet 2 the elevation of the case. A is a cylinder of ebonite or other
suitable material, mounted on a spindle B working in bearings C and provided
with a handle D. On the surface of the cylinder A are fixed metallic bridge
pieces E in suitable positions, on which bear the fingers F mounted on the insulat-
ing block G, to which the electric connections are made by means of the
thimbles H. The cylinder A is provided with a ratchet wheel I and a pawl K
and the whole mounted on a metal casting L.
I take a shunt wound motor, the field circuit being so arranged and proportioned
that the motor developes its full normal speed when the different circuits into
which the magnetizing coils are divided are connected in parallel across the
brushes.
In a two pole motor of the ordinary type I connect four wires, two to the
terminals of the shunt coils of each limb of the magnet and two to the motor
brushes or battery terminals, and two to the terminals of a suitable artificial
resistance, connecting these eight wires to the eight metallic fingers F. These
bear upon the cylinder A, on the face of which are the bridge pieces E, which are
so placed that by rotating the cylinder A, in its bearings C by means of the
handle D, the following connections are made.
1. The shunt circuits of the motor are connected in parallel and to the positive
and negative terminals of the motor or battery respectively.
2. The shunt circuits of the motor connected in series and to the positive and
negative terminals respectively, or the resistance if connected in series with the
field coils, short circuited.
3. The shunt circuits connected in series and in series with the resistance and
these to the positive and negative terminals respectively.
The switch is fitted in a case arranged to lock up and so constructed that it is
impossible to close it except when the switch is in the first position. This is
arranged by making a hole M in the cover O, the handle being of such length that
except when projecting through the hole in the cover, the case cannot be closed.
The handle D is arranged to move over a dial P which may be marked with the
speeds of the boat or vehicle.
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same may be performed. I declare that what
I claim is :-
1. The connection of the motor field circuits in parallel, and in series with a

page_text: resistance for increasing the speed of a vehicle or electric launch as herein before
described.
2. The construction of the switch as described and illustrated in the drawing.
3. The switch case, so constructed that it is impossible to close it except when
the switch is in one desired position, as described and illustrated in the drawing.
Dated this Third day of January 1898.
JOHN HEWETT, B.A.,
8, Great Portland Street, London, W., Agent for the Applicant