Improvements in Controlling Devices, for Electric Motors.
Year: 1899

page_text: Date of Application, 13th May, 1899-Accepted, 8th July, 1899
COMPLETE SPECIFICATION.
Improvements in Controlling Devices, for Electric Motors.
We, THE BRITISH THOMSON-HOUSTON COMPANY LIMITED, of 83, Cannon Street,
in the City of London, Electrical. Engineers, do hereby declare the nature of this
invention (which has been communicated to us from abroad by William B. Potter,
residing at Schenectady, in the County of Schenectady, State of New York,
United States of America, Electrical Engineer) and in what manner the same
is to be performed to be particularly described and ascertained in and by the
following statement: —
The present invention relates to controllers for electric motors; and has for its
object to obviate a difficulty which arises either from inexperience or carelessness
of the motorman. In many cases the acceleration of the car is more rapid than
it should be, because the motorman does not stop long enough on the different
positions of the controller to allow the motors to come to the full speed corre-
sponding to each position before turning to the next; resistance is cut out too
rapidly, or the change from series to parallel is made too fast. This not only makes
the car jerk, which is very unpleasant to passengers, but it is injurious to the
apparatus; in installations where a number of motors are employed on each car,
and the currents are necessarily greater than those in ordinary tramways, the
difficulty is particularly apparent, and the danger of accident to the apparatus
correspondingly increased. To obviate it, the apparatus of the present invention
has been devised, which consists in its essence of a lost-motion connection between
the handle and the switch controlling the motors, together with means for causing
the switch to follow the motion of the handle at a uniform rate, irrespective of the
speed with which the motorman may operate the latter. The particular device
which is shown here for this purpose is a spring, with suitable-speed governing
apparatus, by which the progress of the switch is regulated. Of course other
mechanisms might be adopted, and still be within this invention.
With the apparatus which is employed for this purpose, stops are placed for
of the switch, as they are
the handle only at the actual "running positions
commonly called; that is to say, when the handle is moved from one position
to another, it is always from a position in which the motors may be operated for
any convenient length of time, to another similar position. In most..controllers,
as is well understood, there are a number of positions in which the motors are not to
be allowed to run for any length of time; these are commonly called "transition
points." Some of these are resistance points, and others. are the points at which
the transition from series to parallel is made in this particular type of controller.
The advantage of this invention in this regard consists in the fact that however
careless or inattentive the motorman may be, his controlling apparatus will,
still be in one of its proper running positions, and no injury will come to any
of the apparatus.
- To effect the purposes of the invention, an ordinary cylindrical switch and a
handle for its rotation is employed; the handle and the switch being connected
by a volute spring. A governor of the centrifugal type, is connected to the

page_text: switch, and gearing is interposed between the governor and the switch, so as
to render the rotation of the former more rapid and the regulation more minute
and accurate. The arrangement is such that the handle is moved freely towards
the running positions of the controller, and when brought to rest at one of these
positions; the controller cylinder will, at predetermined speed, follow it up,
making the successive transitions at a rate preadjusted to the best and most
regular acceleration. The acceleration of the car thus becomes uniform, either
from rest to a desired speed, or from one speed to another. It is thus also impos-
sible to hold the controller in a position in which it should not remain, for any
length of time. It is unnecessary, however, to regulate the turning off of the
current in the way just named; emergencies are apt to occur in which the motor
current should be at once shut off; this is provided for by so arranging the
connection between the controller cylinder and its operating handle that in the
reverse direction it is positive, while in turning on the power there is the lost motion
already referred to..
The invention will be better understood from the accompanying drawings,
showing one particular form, in which Fig. 1 is a plan of the apparatus; Fig. 2 is
a rear elevation of the parts shown in Fig. 1; Fig. 3 is a side elevation of the
governor, partly in section of the line 3-3 of Fig. 4; Fig. 4 is a sectional plan
of the parts shown in Fig. 3, upon the line 4-4 of the latter figure; Figs. 5
and 6 are details of the connection between the handle and the controller cylinder,
by which the motion of the latter is positive in turning off.
In Figs. 1 and 2, A is the operating handle, having the latch, a², controlled by
a spring a, and lifted out of the notches 1, 2, 3 or 4 of the sector B by the rod, a,.
the link A2 and the handle A'. So much of the device resembles in general the
lever of an ordinary locomotive. The sector B is held in place by the bolts 13, B',
being secured to the base plate H of the apparatus, the latter being provided with
a bracket H, to one end of which the sector B is secured.. The base H is so
constructed that it may take the place of the cap-plate of the ordinary controller.
The lever A rotates the shaft K; to the shaft K is secured one end of the spring I;
the other end being secured at I¹ to the segment C; the latter meshes with a train
of gears driving the governor L. The segment drives the pinion C¹, and this
latter drives the second pinion C2, which rotates the shaft F of the controller (see
Figs. 2, 5 and 6). The gear C³ is driven from this shaft by means of a ratchet D,
being connected to the ratchet by the pawl D', operated by the spring 12; the
purpose of this will presently appear, and the construction is best seen in Figs. 5
and 6, to be more fully described hereafter. The gear C meshes with the
pinion C, driving the gear 0%, the latter driving the governor L through the
pinion C. The rotation of the governor causes the balls or weights L1 (see
Figs. 3 and 4), to fly outward, and thus force the friction pawls L², L against the
inner face of the cylinder L³; the latter being stationary and held in place by
the screw m. which connects it to the guard M fixed to any part of the apparatus.
Stops prevent the friction pawls from being so far drawn in that the weights L¹
will rub on the outer surface of the cylinder. The pawls are pivoted at 1, and
a packing, of leather, or other suitable material, serves to increase their adhesion.
Referring now to Fig: 2, which should be read in connection with Fig. 1,
it will be seen that to the hub K', to which the lever A is secured, is fixed an
arm K. which may be made integral with the hub; against this arm bears a
stop C7, fixed to. the segment gear C. As the lever A is moved, the arm. K² is
brought away from the stop C, the motion of the lever putting the spring I under 5
tension. The spring, being fixed at 1' to the gear C, tends to draw this gear around
until the stop. C7 rests against the arm K2. This communicates motion to the
entire train of gears, and through the shaft F, to the controller, the governor L
controlling the rate at which the controller shall be rotated. As soon; as the
stop C7 strikes the arm K², the movement of the controller ceases.
may be moved in any one of the notches 1, 2, 3, or 4, of the segment B, and the
The lever A 5
controller will then start and follow it up at the desired rate of speed.
13

page_text: In order to provide for the positive return of the controller mechanism
and the turning off of current, the arrangement shown in detail in
Figs. 5 and 6, and indicated in dotted lines in Fig. 1, is employed.
The gear C³ rotates upon the stud G, the upper part of which is made round,
the gear being held in place by the pin g. The lower part of the stud G, as shown
at g, is shaped like the upper part of f of the controller shaft F. The gear C
is mounted upon, or formed integral with, a collar fi, which fits over the upper
part of the shaft F and rotates the controller; and in this collar the part of
the stud G also fits. The ratchet D is formed to fit the lower part g' of the stud;
thus, as the gear turns, it turns the ratchet 1 by means of the stud G and
also the shaft F of the controller. The gear-wheel however, being connected
with the ratchet through the pawl D', will rotate when the ratchet turns in one
direction, but is stationary when it is turned in the other. When, therefore,
by the motion of the handle, the gear C¹, mounted on the shaft E, rotates the
gear C2 so that the ratchet turns in the direction of the arrow (as shown in Fig. 5),
the gear C³ rotates, and the governor is brought into play; but when the mechanism
is reversed, the pawl D slips over the ratchet, and the motion of the handle is
independent of the governor. The backward motion of the handle thus forces
back the arm K, and through the stop C7 moves the segment C backward, thus
rotating the gears C and C2 (and through them the shaft F of the controller. P),
positively backward. By removing or fastening back the pawl D', the controller
evidently becomes one of ordinary type, the governor L being thrown entirely out
of action.
In the particular type of controller which has been selected for embodying
the invention, the change from series to parallel is made by shunting one of the
motors. Any other controller in which a regular and moderate movement will
give a substantially uniform acceleration of the motors may he employed, as is.
well understood. It is desirable for several reasons, unnecessary to recite, that
the change from series to parallel should be made with reasonable rapidity, and
therefore the device illustrated is so arranged that the governor will be thrown
out of action during this part of its rotation.
Referring to Figs. 1 to 4, 0 is a disc on the top of the controller cylinder (seen
best in Fig. 2). Upon this disc is mounted a cam o. Pivoted at ¹ is a lever
having a fork N provided with friction rollers n rotating in the collar N¹ fixed to
the shaft of the governor by a feather key, so that the collar is free to slide up
and down within certain limits. Cords or wires pass through holes in the
pin 75, and are connected to the friction pawls L2 and the weights L'. The lower
part N of the lever is provided with a friction roller ², travelling on the disc ()
and the cam 0. The position of the cam o is such that as the transition point
from series to parallel is reached in the revolution of the controller, the cam o'
passes under the roller 2, the fork N is slightly depressed, thus depressing the
collar and pulling on the cords or wires, and drawing in the weight L!,
releasing the friction pawls so that the governor is thrown out of action. This
part of the movement of the controller is therefore accomplished more quickly
than the rest. In order to prevent too great a rotation of the controller stops K*, K5
are employed (see Figs. 1 and 2), which strike a projection from the base H, and
thus limit the movement of the handle A.
In the ordinary operation of the device, the motorman will bring the lever A
at starting of the notch 3, which corresponds to the full series position of the
controller, and after the train or car has acquired full speed in this position, the
lever will be brought over to the notch 4, and the change of motor connections
from series to parallel will be effected. This change can be made with safety,
as already pointed out, much more rapidly than the change from rest to full series
position. In high-speed service, the handle may be brought at once to the last
running position, and thus the maximum even acceleration will be attained with-
out further attention from the engineer.
In practical operation it has been found that the acceleration of the train could

page_text: not be made greater than the desired rate for which the device was designed,
whether the force applied to the handle be much or little; although where. it was
desirable to diminish this rate it could readily be done by moving the handle. so
slowly that the switch would follow it up closely. This is not ordinarily the
desired method of operation, but may be useful on occasion.
Having now particularly described and ascertained the nature of our said
invention (as communicated to us from abroad) and in what manner the same
is to be performed, we declare that what we claim is:-
1. A controlling device having lost motion between the handle and the switch,
with means for causing the switch to follow the handle at a determinate speed.
2. A controlling device having lost motion between the handle and the switch,
with means for causing the switch to follow the handle, and retarding means
preventing the movement of the switch at a speed greater than a determinate
maximum.
3. A controlling device for an electric motor or motors, having a handle free
to move, a switch, retarding means preventing the switch from moving faster
than a given maximum rate, and means for causing the switch to follow the
handle.
4. A controlling device for electric motors, comprising a handle free to move,
a switch with a lost-motion connection between the switch and the handle, a
governor for controlling the motion of the switch, means for causing the switch
to follow the handle, and means for throwing the governor out of action during
part of the movement of the switch.
5. A controlling device for electric motors, comprising a handle free to move,
a switch, means for causing the switch to follow the handle, a retarding means for
the switch, such as a centrifugal governor, the whole operating to retard the move-
ment of the switch in turning on current, and a positive connection between the
handle and the switch, operative only in turning the current off.
6. The combination of a switch for controlling a motor or motors, a handle
having lost-motion connection with the switch in one direction of movement, and
a positive engaging means between the handle and the switch, operative in the
reverse direction.
5
7. In a controlling device, the combination of a handle free to move in one
direction without immediately affecting the switch, means for causing the switch
to follow the handle, a governor for the switch, and means for throwing the
retarding means out of action during a certain part of the forward motion of the
switch with a positive engaging means between the handle and switch and a slip
connection between the governor and switch, operative as the movement of the
latter is reversed.
8. In a controlling device, means for retarding the motion of the switch in
turning on current, and a device for throwing the retarding means out of action
when the motion of the switch is reversed.
9. In combination, a switch, a governor for the switch, and a ratchet between
the governor and the switch, whereby the governor controls the motion of the
switch in one direction, but not in the other.
10. A controlling device having stops for the switch handle at only the running
positions of the controller.
11. A controlling device having a handle free to move relatively to the switch,
with means for causing the switch to automatically follow the handle, and stops
for the handle corresponding to the running points only of the controller.
12. A controlling device having a handle free to move in one direction relatively
to the switch, with the governor limiting the speed, a spring for driving the switch,
and stops for the handle, corresponding to the running points only; whereby the
transition points may be passed at a predetermined speed.
13. A controlling device having changes in the motor circuit connections at a
desired rate, irrespective of the movement of the handle or actuator.

page_text: 14. A controlling device automatically effecting changes in the motor circuit
resistance at a rate giving substantially uniform acceleration from rest to any
given speed or from one speed to another.
15. A controlling system having a hardle, a switch, motors and means for con-
necting the motors in series and parallel and for varying their resistance, and an
intervening device between the handle and the switch such that the handle may
be placed in the final running position at its first movement, and the switch will
then act to shift the motor connections in a predetermined order and at such
speed that a substantially constant acceleration from rest to full speed will be
given the motors.
THE BRITISH THOMSON-HOUSTON Co., LTD..
A. R. MONKS,
W. MARTINDALE,
Directors.
ALFRED CLEMENTS,
Assistant Secretary.