Improved Methods of and Means for Controlling Electric Motors.
Year: 1897

page_text: [Communicated from abroad by THE WESTINGHOUSE ELECTRIC AND MANUFACTURING
Co., of Pittsburg, in the County of Allegheny, and State of Pennsylvania,
U.S.A., Electrical Engineers.]
Improved Methods of and Means for Controlling Electric Motors.
I, REGINALD BELFIELD, of 32, Victoria Street, in the City of Westminster,
Electrician, do hereby declare the nature of this invention to be as follows:-
This invention relates to methods of and means for controlling electric motors
and is especially applicable for use with two electric motors arranged to drive
one vehicle.
The objects of the invention are to provide methods and apparatus whereby
changes in the connections of the motors may be made quickly and effectively
without injury to the contacts by the formation of sparks at the time of changing
the connections. The invention further comprises an improved construction of
controller whereby inspection and repair of the contacts is facilitated.
The improved controllers take the form of a cylinder supported in suitable bear-
ings in which it can be rotated by means of a handle, various contact bars being
secured to said cylinder adapted to connect with fixed contact pieces to which
the terminals of the motors and resistances are joined. The shape, number, and
general arrangement of the contact bars on the cylinder varies according to the
method of control adopted as will be readily understood. The general method
of control is as follows. In the first working position of the controller the two
motors are in series with all the resistances, as the cylinder is turned to successive
positions the resistances are gradually cut out until the two motors are running
in series without resistance. In the next set of working positions of the cylinder,
the motors are in parallel one or more resistances being in series with each motor
separately or in series with the two motors in parallel, and in the final working
position of the cylinder the two motors are joined in parallel without resistance.
To ensure the working positions of the cylinder being readily found by the operator
we provide a spring controlled arm which engages in notches in a disc secured on
the shaft of the controller handle when the cylinder is in a working position but
which runs on the smooth periphery of the disc when the cylinder is in intermediate
positions. When the cylinder is being rotated from the last working position
with the motors in series to the first position with the motors in
parallel we arrange that the change of connections shall not occur
suddenly but that in the intermediate positions of the cylinder, the re-is-
tances shall first he gradually reinserted in the motor circuit, then the whole
circuit broken, and lastly the motors connected in parallel each with resistances in
series with it. Or after the reinsertion of the resistances one of the motors is
shunted by a resistance, then cut out of circuit and finally connected in parallel
with the other motor the shunting resistance being shortcircuited.
In order to avoid injurious sparks occurring at the contacts when the changes

page_text: in connection are made we provide that the fixed contacts shall be supported on a
block of magnetic material surrounded by a coil of wire which is always in the
motor circuit, the magnetic field set up at the contact preventing destructivo
sparking. A construction of fixed contact which we prefer to use comprises an
arm pivoted in a cradlo secured to the magnetic block aforementioned, said arm,
and cradle are both of magnetic metal but the contact piece carried by the arm may
be of brass or copper or the like. A spring is provided to press the arm towards
the cylinder. A switch of any suitable construction is provided for reversing the
direction of the current through the field magnets of the motors and so reversing
the direction of rotation of the motors and it is sometimes arranged that said
reversing switch cannot be rotated unless the cylinder of the controller is in such
a position that the motor circuit is broken. It is furthermore preferred to SO
arrange that the handle of the reversing switch can only be removed when the
said switch is in a position intermediate between its two working positions, that
is to say when the circuit is broken, by this means when the operator removes
the handle of the reversing switch any tampering with the controller cylinder
bandle will have no effect. For a similar purpose the controller cylinder may be
arranged so as to be rotatable when the reversing switch is in one or other of its
working positions, and not when said switch is in any other position.
A plug switch is inserted in the circuit of each motor by means of which the
motor can be cut out when desired, and interlocking mechanism is preferably
arranged so that when either of the motors is cut out the handle of the controller
car can only be turned to its "half speed" position, that is, to that position in
which ordinarily the two motors are joined in series without resistance. The
plugs for these switches are conveniently constructed from a cylindrical piece of
metal having a rounded end. This piece is split from the base or part nearest the
handle so as to form three separated longitudinal strips connected at their outer
ends, the two outside strips being free at their inner ends. The cylinder is now
split longitudinally from the outer rounded end as far as the handle, the slits being
perpendicular to those above described. The plug will now consist of nine strips
alternately united at the inner and outer ends, a form which is very compressible,
the resiliency of the metal ensuring a good electrical connection when the plug is
inserted in its socket.
In the improved construction of controller for permitting ready access to the
contacts the cylinder is supported in pivoted brackets so that it can be swung away
from the base and fixed contacts so as to permit of ready and effective inspection
and repair. The shaft of the operating handle is in this modification required to
be separable from the shaft of the cylinder to permit of its displacement as above
lescribed.
Improved Methods of and Means for Controlling Electric Motors.
1, REGINALD BELFIELD, of 32, Victoria Street, in the City of Westminster, .4
Electrician, 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 means for controlling electric motors, and is especially
applicable for use with two elèctric motors, arranged to drive one vehicle.
50

page_text: The object of the invention are to provide apparatus whereby changes in the
connections of the motors may be made quickly and effectively without injury
to the contacts of the controller by the formation of sparks at the time of changing
the connections, and to construct a controller in which inspection and repair of
the contacts is facilitated.
The improved controller takes the usual form of a cylinder supported in bear-
ings in which it can be rotated by means of a handle, various contact bars being
secured to said cylinder, adapted to communicate with fixed contact pieces to which
the terminals of the motors and resistances are joined. The shape, number and
general arrangement of the contact bars on the cylinder, varies according to the
method of control adopted, as will be readily understood.
One feature of the present invention consists in the means whereby the controller
drum may be swung back away from the base in order to expose the whole of the
drum and the fixed contacts for the purposes of inspection and repair. Another
feature of the invention consists in the manner of building up the controller drum
so that the desired cross-connections between the contact strips may be made with
ease and certainty.
The invention is illustrated in the accompanying drawings, in which Fig. 1 is
a side elevation, partly sectional of the improved controller showing the movable
drum swung back.
Fig. 2 is a side elevation partly sectional of the drum and spindle shown in
Fig. 1, illustrating the method of building up the same.
1 is the base or stand which can be secured to the platform or other portion of
the car by means of lugs 2 or otherwise. 3 are the stationary contacts and 4
indicates the drum provided with contact pieces 5 in position to be engaged by the
contacts 3 as the drum is rotated. 8 is a reversing switch shown in section in
Fig. 1, 7 being its operating handle. The operating handle of the controller
drum is shown at 9, and this fits upon a square at the end of a shaft 10 which passes
through a sleove 6 to which the reversing switch 8 and its handle 7 are secured.
The connection between the shaft 10 and the controller drum is clearly shown in
Fig. 2, 11 being a square at the lower end of said shaft adapted to fit a corresponding
socket 12 in the top of the drum, a pin 13 securing these parts together. In order
that the drum 4 may be swung back from the base as shown in Fig. 1, it is clear
that some means such as those described must be provided for permitting the
shaft 10 to be disconnected from the drum. The invention however, is not limited
to the precise means above described and shown in Fig. 2.
The drum is rotatably supported by the brackets 14, 15, which are hinged
as shown at 16, and 17 to the base 1 of the controller. Hence after the shaft 10
has been disconnected from the drum, the latter can be swung backward, as shown
in Fig. 1 so that the fixed contacts and the whole of the drum is entirely exposed.
If the method above described of connecting the shaft 10 to the drum be em-
ployed, the pin 13 will require to be removed and the shaft 10 raised out of its
socket 12, before the drum can be swung back.
The manner of building up the drum 4 is shown in Fig. 2 and will now be
described. A rod 18 extends through a cylinder of wood or other insulating
material 19, and the latter is provided with suitable recesses in which are located
strips of copper or other conducting material 20 by means of which the proper
electrical connection between the contact pieces 5 is effected.
Upon the cylinder 19 are placed alternately rings 21 and discs or plates 22, the
cylinder having a spline 23 fitting into a corresponding notch in cylinder 19 and
with each other.
Upon the peripheries of the rings 21, which are preferably made of porcelain,
stoneware or like material are borne the contact pieces 5, these latter being elec-
trically connected to the strips 20 and at the same time properly fastened to their
rings and the cylinder 19 by means of screws 24, as shown in Fig. 2.
When all the rings and discs have been placed upon the cylinder 19, they are
firmly pressed and held together by means of the nuts 25 and 26, at the top and

page_text: bottom of the rod 18. The socket 12 hereinbefore mentioned, may be located in
the top of this rod 18. The discs 22 being of a diameter considerably greater than
that of the rings 21, serve to prevent arcing between adjacent stationary contact
pieces 3, thereby contributing very considerably to the life of the controller.
The invention is not limited to the details of construction shown and described,
and many variations may be made by one skilled in the art, without departing
from the spirit of the invention. It is, furthermore, applicable to all controllers
of the general type described without regard to the method of varying the connec-
tions of the motors adapted.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, as communicated to me
by my foreign correspondents, I declare that what I claim is;
1. A controller of the class described in which the bearings supporting the
rotatable drum are hinged to the base, substantially as described.
2. In the controller claimed in Claim 1 a drum built up of insulating rings
carrying the contact pieces, said insulating rings being mounted upon a founda-
tion cylinder of insulating material having embedded in its surface metallic strips
for connecting the contact pieces upon the outside of the rings, and either with or
without insulating discs of large diameter interposed between adjacent rings,
substantially as described.
3. A controller constructed substantially as described with reference to the
accompanying drawings.