Improvements in Controllers for Electric Motors.
Year: 1899

page_text: Date of Application, 16th May, 1899
Complete Specification Left, 16th Feb., 1900--Accepted, 7th Apr., 1900
:
PROVISIONAL SPECIFICATION..
[Communicated from abroad by HARRY PILLIPS DAVIS, of Pittsburgh, GILBERT
WRIGHT, of Wilkinsburg, and ALEXANDER JAY WURTS, of Pittsburgh,, all in
the County of Allegheny, and State of Pennsylvania, United States of
North America, Electrical Engineers.]
"
Improvements in Controllers for Electric Motors.
I, REGINALD BELFIELD, Electrician, of 32, Victoria Street, Westminster, in
the County of London, England, do hereby declare the nature of this invention
to be as follows:-
My invention relates to controllers for electric motors and in particular to
devices of this character which are employed for controlling the power and speed
of electric railway motors.
One object of my invention is to provide means whereby before any changes
are made in the circuit connections or in the resistances in circuit, said circuit
will be positively closed through an independent switch; said means further-
more operate to open the circuit prior to the change from series to parallel con-
nection of the motors when more than one motor is employed, and prior to a
reversal of the direction of motion of the controller handle, and also preclude
the closing of the circuit by a forward movement of the controller handle from
any position except such as will insure the inclusion of considerable current
reducing resistances. My invention further comprises means for reducing the
current prior to breaking the circuit so that the formation of arcs at the con-
troller contacts is prevented.
In the accompanying drawings:
-
Figure 1 is a front elevation partly sectional of a controller constructed
according to my invention, the cover being removed.
Figures 2 and 3 are sectional views on line x-x and y-y of Figure 1-respectively.
Figures 4, 5 and 6 are views shewing three positions of a portion of the
mechanism.
Figures 7, 8 and 9 are detail views hereinafter explained.
Figure 10 is a diagrammatic development of the controller drum and the
combined reversing and cut-out switches, shewing the circuits.
Figure 11 is a diagram shewing the circuits through the motors and resis-
tances in various positions of the controller drum.
Figure 12 is a vertical section of a switch for breaking the circuit; and
Figures 13 and 14 are detail views of the same hereinafter described.
The same reference numerals denote the same parts throughout the drawings.
1 is the supporting frame or stand, and 2 is the controller drum which is
rigidly secured to a sleeve 20 surrounding the shaft 21, being free to turn on
said shaft. The shaft 21 is mounted in bearings secured to the frame of the
controller and can be rotated by means of a handle carried on its upper end
when necessary. 3 and 4 are the drums of the combined reversing and cut-out
switch, and 5 is the series switch for making and breaking the circuit. The

page_text: controller drum is provided with contact strips 6, 7, 8, 9 and 10 with which
the stationary contacts 11 to 18 are adapted to engage. The shapes and relative
positions of the contact strips on the drum and the location of the stationary
contacts will be understood from Figures 1 and 10.
The drums 3 and 4 for the reversing and cut-out switch are loosely mounted
on the shaft 24, carried in bearings on the frame or stand, and means
are provided for locking each drum to the shaft independently when desired, said
drums are provided with suitable contact strips indicated by the numerals 54
to 59 on the upper drum, and 541, 551, 561, 571, 581 and 591 on the lower
drum. Stationary contacts co-operate with said contact strips and are indicated
by the references 60 to 65 and 601, 611, 621, 631, 641 and 651. The shapes and
relative positions of the contact strips are similar on each drum and will be
understood from Figures 1 and 10, the latter figure also indicating very clearly
the location of the stationary contacts.
I will now describe the mechanical devices connected with the controller
drum. 22 is a notched plate secured to the lower end of the sleeve 20, the
number and position of the notches in which correspond with the various
running positions of the controller drum. 23 is a bell crank lever pivotally
attached to the frame (in the present instance loosely mounted on the shaft 24),
one arm 233 of which lever is attached by a coil spring 25 to the frame,' the
other arm 231 being provided with a roller 2332 which engages with the notches
in the plate 22. Secured to the shaft 21 below the plate 22 is a cam plate 26
provided with an upwardly projecting lug or pin 261 which is located between
downwardly depending lugs 221 on the notched plate 22 so as to engage the one
or the other of said pins according to the direction in which the shaft 21 is
rotated when the handle is turned. A second cam plate 27 is secured upon the
shaft 21 below the cam 26 as shewn in Figure 9, said plate being substantially of
the shape shewn in Figures 4 to 6, and having seven projecting points or
teeth 271, 272, 273, 274, 275, 276, 277, divided into two groups as shewn. The
cam 26, the position of which is invariable with respect to the plate 27, is
so located that its projecting ends separate the two groups of teeth on the plate 27
as clearly shewn in Figure 4. 28 is a rock shaft mounted in suitable bearings
on the frame and carrying a head 29 on its upper end. Said head is shewn in
plan in Figures 2, 4, 5 and 6 and in clevation in Figures 1, 7 and 8, Figure 7 being.
a view looking in the direction of the arrow y in Figure 4, and Figure 8 being
a view looking in the direction of the arrow w in said Figure. 30 is a pawl
pivoted to the head 29 and provided with a roller 32 and a shoulder 301 adapted
to engage a corresponding shoulder on the head 29, being held there by the
spring 31. 34 is a pawl similar to pawl 30, having a roller 35 and a shoulder 341
pressed against the corresponding shoulder of the head 29 by means of a spring 36.
331 is a roller mounted in a projection 33 of the head 29 in a position ver-
tically above the normal position of the roller 35. The rollers 331 and 32 are
opposite the cam 26, the roller 35 being opposite the plate 27. Secured to the
rock shaft 28 below the head 29 is a plate 37 provided with a circular rack 38,
said rack meshing with a pinion 39 keyed to the upper end of a rock shaft 40
which is mounted in bearings 41 and 53. Secured to the shaft 40 is a bar 42 pro-
vided at its ends with spring contact arms 43.
Also secured on the shaft 40 is a
plate 44 having two notches 441 and 442, with which notches a holding pawl 45
pivoted to the frame and having a roller 46 can engage, said pawl being pressed
toward plate 44 by a spring 47. These devices are clearly shewn in Figure 3.
The spring contact. arms 43 which constitute the movable contacts of the
switch 5, the pieces 48 being the fixed contacts, are adapted to engage in suc-
cession a series of pins 49 as the shaft 40 is rotated. Each of these pins 49 is
connected to a resistance coil 50 which coils are joined in series being em-
bedded in insulation 51, enclosed in a casing or frame 52 as will be clearly seen
from Figure 1.
I will now proceed to describe the operation of our improved devices. When

page_text: the circuit is open and the controller not in use the positions of the several
parts will be those indicated in Figures 1 and 4 of the drawings. If now the
shaft 21 is rotated in the direction shewn by the arrow in Figures 1 and 4
the cams 26 and 27 will turn with it until the pin 261 on the cam 26 engages
with the rearmost pin 221 on the notch plate 22. As soon as the two pins
come into engagement the drum 2 and plate 22 will turn with the shaft 21.
It will be observed however that owing to the distance between the pins 261
and 221 there will be considerable lost motion between the drum 2 and the
shaft, owing to this lost motion the cam 26 engaging with roller 32 moves
the rocking head 29 and its shaft 28 into the position shewn in Figure 2 before
the stationary contacts 11, 12 and 13 come into engagement with the contact
plates 6 and 8 on the drum. Also from the same cause the final movement of
the drum as the spring actuated pawl 231 is pressed into one of the notches of the
plate 22 takes place very quickly and independently of the movement of the
shaft 21 since the instant that the end of any tooth of plate 22 has passed the
roller 232 the spring 25 acting on the bellcrank 23 forces said roller towards the
shaft 21 which causes the plate 22 to rotate in the direction of the arrow in
advance of the movement of the shaft 21. The possibility of arcing between
the stationary contacts and the strips on the drum by reason of failure of moving
the controller handle quickly to a running position is thereby avoided. When
the head 29 is moved from the position shewn in Figure 4 to that shewn in
Figure 2 as above-mentioned the plate 37 will be moved in a similar manner, and
by means of the circular rack 38 and pinion 39 will rotate the shaft 40 and
bar 42 causing the movable contact 43 of the switch 5 to move over the pins 49
and finally attain the position shewn in Figure 3 in which the switch is closed.
The roller 46 on the end of the lever 45 will be held in the notch 442 of the
plate 44, any accidental or shaking movement of the parts will not displace the
movable contacts of the switch 5. Furthermore the roller 35 of the head 29
will be moved into contact with the front face of the tooth 271 on the cam
plate 27 and since the spring 36 is only strong enough to maintain the shoulder
of the pawl 34 against the corresponding shoulder of the head 29 when no force
is opposing, said pawl will be rotated on its pivot by the pressure of the
tooth 271 so as to permit said tooth to pass the pawl, after which said pawl
resumes its normal position under the influence of the spring 36. This position
of the mechanism is shewn in Figure 2.
The further movement of the shaft 21 in the direction shewn by the arrow
in Figure 1 will not have any effect on the head 29 and switch 5 for the reason
that the teeth 272, 273, 274 will merely rock the pawl 34 on its pivot against
the action of spring 36, when, however, the tooth 274 has passed said pawl
the end 262 of the cam 26 will reach the roller 331 and this occurs when the
drum 2 is in such a position that the change from series to parallel connection
of the motors is about to be made. Since the bearing of roller 331 is fixed with
regard to the head 29, said head will be pushed out of the path of the cam 26
and take up the position shewn in Figure 5.
consequently move in the direction of the arrow shewn in Figure 3, and through
The plate 37 on shaft 28 will
rack 38 and pinion 39 will move the contacts 43 quickly over resistance con-
tact pins 49 to the open position of said switch until the roller 46 of arm 45
rests in the notch 441 of the plate 44. The resistances 50 which are succes-
sively brought into circuit by the movement of the contacts 43 over the pins 49
are so proportioned that the current will be gradually reduced until its volume
is insufficient to form any injurious are between the moving contacts and the
last contact pins. The opening of the circuit as above described occurs before
the fixed contacts 11 to 16 have left the contact plates 6, 8 and 9 of the drum 2,
and the ultimate separation of these parts will obviously be upon open circuit.
It being observed that the movement of the shaft 40 is very much more rapid
than that of the shaft 21 by reason of the gearing employed. The position of
the cams and head 29 being that shewn in Figure 5, further movement of the

page_text: shaft 21 in the direction of the arrow in said figure will cause the end 261 of
cam 26 to engage with roller 32 and rock the head 29 into the position shewp
in Figure 6, closing the switch. 5 in the manner hereinaboye described. . The
roller 35 will thus be brought into contact with the cam plate 27 just before
the tooth 275. Further movement of the shaft 21 in the same direction will
not affect the position of the head 29 as the teeth 275, 276, 277 will be able to
move past the roller, merely rocking the pawl 34 on its pivot as hereinabove
mentioned. This position of the parts will be maintained until the roller 232
of the bell-crank 23 rests in the last notch on the plate 22, in which case, the
position of the controller drum will be such that the motors are joined in
parallel without resistance and the position of the cam 26 and head 29. will be
that shewn in Figure 6 in which the roller 331. will prevent any further move-
ment of the cam 26 in the direction of the arrow.
F,
Since when the controller drum is in one of the running positions the
pawl 34 is in engagement with one of the teeth 271.........of the plate 27 the
turning of the controller drum in the direction from one of such positions will
through the tooth on the plate 27 act on the pawl 34, and rotate the head 29
from the position shewn in Figure 2 to that shewn in Figure 4, thereby through
shaft 28 and tooth plate 37 rotating shaft 40 and opening the switch 5, also
owing to the lost motion between the pin 261 and the pins 221 this opening of
the switch 5 will precede any opening of the circuit by reason of the movement
of the controller drum. The head 29 being once moved into the position shewn
in Figure 4 the controller drum may be moved backwards to its initial or zero
position without any movement of the head 29 since the pawl 30 will rotate
on its pivot to allow the cam 26 to pass. It will further be observed that
the movement of the head 29 from the position shewn in Figure 4 to that shewn
in Figure 5 can only be effected by the cam 26, consequently when once the
controller drum has been moved in a backward direction the switch 5 can only
be closed after the parts have been brought into the position shewn in Figure 5
or to that shewn in Figure 4, in the latter case the controller drum will have
been rotated completely back to its initial or zero position. Consequently if
the motors are connected in parallel and the controller handle is moved. back
the circuit is at once broken and cannot be closed again except to rotate the
handle backwards until the position of the controller drum is intermediate
between that wherein the motors are connected in parallel and connected in
series. Also if when the motors are connected in series the controller handle is
moved backwards the circuit will immediately be opened and cannot be closed until
the handle has been moved to its initial or zero position. It follows therefore
that whenever the circuit is opened for the purpose of stopping or reducing the
speed of the motors the latter cannot be again connected without at the same
time including all or the greater portion of the starting resistance.
Instead of employing a resistance with the switch for breaking the circuit as
above described, I sometimes employ a simple switch without resistance, but
arranged so that the break shall occur within a vessel under the surface of a
suitable liquid in which case the switch arm is merely secured to the shaft 40
and will be operated to break the circuit at the proper times through the gearing
above described. We may, however, utilize different gearing for this purpose which
is exemplified in Figures 12 to 14. 80 is the shaft of the controller drum having
the usual notched plate 81 corresponding to the plate 22 in Figures 1 and 2 of
the drawings. 82 is the shaft of the switch carrying a switch arm 83 to which
is secured a contact 84 connected by a flexible lead 85 with the earth terminal
of the controller. This terminal is marked 16 in the diagram Figure 10. The
other terminal of the switch indicated at 86, Figure 13, is connected to earth.
Said terminal 86 is secured to a curvilinear piece 87 supported from the bottom
of the containing vessel 88, said piece also has mounted on it an insulation
piece 89 which forms a continuation of the earth contact 86. The shaft 82 is
located eccentrically with reference to the piece 87, so that the contact 84 will

page_text: bind or seize at the end of said piece, and will therefore always be in connection
with either the insulation 89 or the earth contact 86. The shaft 82 carries an
arm 90 to which are secured two plates 91 and 92 pressed together by spring
pressure substantially as shewn. These plates are adapted to grip a disc 93
secured at the bottom of the shaft 80, said disc being provided with a notch 94
which is wider than the parts of the plates 91, 92 which grip the disc 93. The
shaft 82 is provided with a spring 95, one end of which is attached to the frame-
work of the controller, the force of said spring tending to rotate the shaft 82 in
such a direction that the contact 84 rests on the insulation piece 89. The
box for containing the liquid within which the switch contacts are located is
provided with a top piece, an enlarged sectional view of which is shewn in
Figure 14, said top piece has a raised portion 96 through an orifice 97 in which
any superfluous liquid can escape when the contents of the box are expanded
by change of temperature, or owing to the production of a spark between the
switch contacts, and a valve 98 opening inwards is also provided through which
liquid expelled through the orifice 97 can return into the box. The box is
filled with any suitable liquid which is a non-conductor or bad conductor of
electricity, and which preferably will not be liable to freeze, such a liquid for
example as glycerine, though various liquids may be used.
The operation of the apparatus is as follows:-
Assuming that the parts are in the position shewn in Figure 13, if the shaft 80
be rotated in the direction of the arrow, the frictional engagement between
the plates 91, 92 and disc 93 will cause the shaft 82 to rotate until the contact 84
makes connection with the earth contact 86; when this is done the circuit is
closed and will continue closed because further movement of the shaft in the
same direction will be prevented by the contact 84 binding against the end of
the contact 86 owing to the curvature of the plate 87. Further rotation,
therefore, of the shaft 80 in the said direction will simply cause the disc 93 to
move between the plates 91 and 92. When, however, the change from series
to parallel connection of the motors is to be made the shaft 80 would have
been turned so far that the plates 91, 92 coincide with the notch 94, and when
this happens the spring 95 will be able to act to rapidly rotate the shaft 82 in
the reverse direction, thus breaking the connection between the contacts 84, 86.
Just before the parallel contacts are made through the controller drum, the
plates 91, 92 will again embrace that portion of the disc 93 on the other side
of the notch 94, and movement of the shaft 80 will rotate the shaft 82 and cause
the contact 84 to again make connection with the earth contact 86. It will be
seen, therefore, that the circuit is broken automatically at the switch before it
is broken at the controller drum. Any movement of the controller drum in the
reverse direction will at once, through the agency of the disc 93 and the
plates 91 and 92, rotate the shaft 82 in the reverse direction, thereby withdraw-
the contact 84 from the contact 86 and breaking the circuit. Any arc which
takes place between the contacts 84 and 86 will be within the liquid where it
can have no detrimental effect. The switch is designed electrically to take the
place of the switch 5, Figure 10, in fact, in every respect it is an equivalent to
said switch 5.
I will now describe the various circuit connection and changes which can be
made through the controller. Assuming that the position of the reversing
switch is such that the stationary contacts 60 and 61 will be in engagement
with plate 54, and contacts 601 and 611 in engagement with plate 541, con-
tacts 62 and 63 in engagement with plate or strip 58, contacts 64 and 65 with
plate 59, contacts 621, 631 with plate 581, and contacts 641 and 651 with plate 591.
If the controller drum is rotated to bring the stationary contacts 17 and 18 into
the position marked "a" of Figure 10 the contacts 11 to 16 will come into the
5 position "h." Current entering at the contact 17 will pass from plate or strip 7
to strip 6, these two being electrically connected as indicated in the drawing,
thence through the contacts 11, 63, 58 and 62, the field magnet 70 of the first

page_text: motor contacts 64, 59 and 65, the armature 71 of the first motor, stationary
contact 13, strip 8, contact 12, contacts 60, 54 and 61, contacts 631, 581 and 621,
field-magnet 72 of the second motor, contacts 641, 591, 651, the armature 73 of
the second motor, the contacts 601, 541 and 611, contact 14, resistances 74 75
and 76, contact 16, and out through the series switch 5.
Without following the circuits in detail for the various subsequent positions
of the controller drum, it will be seen by reference to Figure 11 that in the
second running position, designated as 6 the resistance 74 is short-circuited. In
position c resistances 74 and 75 are short-circuited, and in position d all of the
resistances are short-circuited, the motors in each of these three positions being
in series. In positions e, f, g, and h the circuit is open. In position the
motors are in parallel and resistance 74 is short-circuited. In position the
motors are in parallel and resistances 74, 75 are short circuited, and in position k
or the final position, the motors are in parallel and all the resistances short-
circuited.
If the reversing switch drums be rotated so as to bring the stationary con-
tacts 62, 63, etc., into contact with the corresponding contacts 55, 56, etc., the
circuits will be the same as above described, except that the current will be
reversed through the field-magnets 70 and 72 of the motors.
While I have illustrated and described specific mechanism for practising my
invention, I desire it to be understood that changes may be made in the details
of construction and the arrangement of parts without departing from the spirit
and scope of the invention.
1
A
1000
W. P. THOMPSON & Co..
322, High Holborn, London, W.C., Patent Agents for the Applicant.
improvements in Controllers for Electric Motors.
I, REGINALD BELFIELD, Electrician, of 32, Victoria Street, Westminster, in
the County of London, England, 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:―.
My invention relates to controllers for electric motors and in particular to
devices of this character which are employed for controlling the power and speed
of electric railway motors.
One object of my invention is to provide means whereby before any changes
are made in the circuit connections or in the resistances in circuit, said circuit
will be positively closed through an independent switch; said means further-
more operate to open the circuit prior to the change from series to parallel con-
nection of the motors when more than one motor is employed, and prior to a
reversal of the direction of motion of the controller handle, and also preclude
the closing of the circuit by a forward movement of the controller handle from
any position except such as will insure the inclusion of considerable current
reducing resistances. My invention further comprises means for reducing the
current prior to breaking the circuit so that the formation of arcs at the con-
troller contacts is prevented..
In the drawings accompanying my Provisional Specification:-
Figure 1 is a front elevation partly sectional of a controller constructed
according to my invention, the cover being removed.
Figures 2 and 3 are sectional views on line - and y-y of Figure 1 respectively.

page_text: es, and 6 are views shewing three positions of a portion of the
mechanism.
Figures 7, 8 and are detail views hereinafter explained.
Figure 10 is a diagrammatic development of the controller drum and the
5 combined reversing and cut-out switches, shewing the circuits.
Figure 11 is a diagram shewing the circuits through the motors and resis-
tances in various positions of the controller drum.
Figure 12 is a vertical section of a switch for breaking the circuit, and
Figures 13 and 14 are detail views of the same hereinafter described.
The same reference numerals denote the same parts throughout the drawings.
1 is the supporting frame or stand, and 2 is the controller drum which is
rigidly secured to a sleeve 20 surrounding the shaft 21, being free to turn on
said shaft. The shaft 21 is mounted in bearings secured to the frame of the
controller and can be rotated by means of a handle carried on its upper end
when necessary. 3 and 4 are the drums of the combined reversing and cut-out
switch, and 5 is the series switch for making and breaking the circuit. The
controller drum is provided with contact strips 6, 7, 8, 9 and 10 with which
the stationary contacts 11 to 18 are adapted to engage. The shapes and relative
positions of the contact strips on the drum and the location of the stationary
contacts will be understood from Figures 1 and 10.
The drums 3 and 4 for the reversing and cut-out switch are loosely mounted
on the shaft 24, carried in bearings on
are provided for locking each drum to the shaft independently when desired, said
the frame or stand, and means
drums are provided with suitable contact strips indicated by the numerals 54
to 59 on the upper drum, and 541, 551, 561, 571, 581 and 591 on the lower
drum. Stationary contacts co-operate with said contact strips and are indicated
by the references 60 to 65 and 601, 611, 621, 631, 641 and 651. The shapes and
relative positions of the contact strips are similar on each drum and will be
understood from Figures 1 and 10, the latter figure also indicating very clearly
the location of the stationary contacts.
I will now describe the mechanical devices connected with the controller
drum. 22 is a notched plate secured to the lower end of the sleeve 20, the
number and position of the notches in which correspond with the various
running positions of the controller drum. 23 is a bell crank lever pivotally
attached to the frame (in the present instance loosely mounted on the shaft 24),
one arm 233 of which lever is attached by a coil spring 25 to the frame, the
other arm 231 being provided with a roller 232 which engages with the notches
n the plate 22. Secured to the shaft 21 below the plate 22 is a cam plate 26
provided with an upwardly projecting lug or pin 261 which is located between -
lownwardly depending lugs 221 on the notched plate 22 so as to engage the one
r the other of said pins according to the direction in which the shaft 21 is
otated when the handle is turned.
haft 21 below the cam 26 as shewn in Figure 9, said plate being substantially of
A second cam plate 27 is secured upon the
he shape shewn in Figures 4 to 6, and having seven projecting points or
eeth 271, 272, 273, 274, 275, 276, 277, divided into two groups as shewn. The
am 26, the position of which is invariable with respect to the plate 27, is
located that its projecting ends separate the two groups of teeth on the plate 27
clearly shewn in Figure 4.
the frame and carrying a head 29 on its upper end. Said head is shewn in
28 is a rock shaft mounted in suitable bearings
an in Figures 2, 4, 5 and 6 and in elevation in Figures 1, 7 and 8, Figure 7 being
view looking in the direction of the arrow y in Figure 4, and Figure 8 being
view looking in the direction of the arrow w in said Figure. 30 is a pawl
voted to the head 29 and provided with a roller 32 and a shoulder 301 adapted
engage a corresponding shoulder on the head 29, being held there by the
ring 31. 34 is a pawl similar to pawl 30, having a roller 35 and a shoulder 341
essed against the corresponding shoulder of the head 29 by means of a spring 36.
1 is a roller mounted in a projection. 33 of the head 29 in a position ver-

page_text: tically above the normal position of the roller 35. The rollers 331 and 32 are
opposite the cam 26, the roller 35 being opposite the plate 27. Secured to the
rock shaft 28 below the head 29 is a plate 37 provided with a circular rack 38,
said rack meshing. with a pinion 39 keyed to the upper end of a rock shaft 40
which is mounted in bearings 41 and 53. Secured to the shaft 40 is a bar 42 pro-
vided at its ends with spring contact arms 43. Also secured on the shaft 40 is a
plate 44 having two notches 441 and 442, with which notches a holding pawl 45
pivoted to the frame and having a roller 46 can engage, said pawl being pressed
toward plate 44 by a spring 47. These devices are clearly shewn in Figure 3.
The spring contact arms 43 which constitute the movable contacts of the
switch 5, the pieces 48 being the fixed contacts, are adapted to engage in suc-
cession a series of pins 49 as the shaft .40 is rotated. Each of these pins 49 is
connected to a resistance, coil 50 which coils are joined in series, being em-
bedded in insulation 5.1, enclosed in a casing or frame 52 as will be clearly seen
from Figure 1.
I will now proceed to describe the operation of our improved devices. When
the circuit is open and the controller not in use the positions of the several
parts will be those indicated in Figures 1 and 4 of the drawings. If now the
shaft 21 is rotated in the direction shewn by the arrow in Figures 1 and 4
the cams 26 and 27 will turn with it until the pin 261 on the cam 26 engages
with the rearmost pin 221 on the notch plate 22. As soon as the two pins
come into engagement the drum 2 and plate 22 will turn with the shaft* 21.
It will be observed however that owing to the distance between the pins 261
and 221 there will be considerable lost motion between the drum 2 and the
shaft, owing to this lost motion the cam 26 engaging with roller 32 moves
the rocking head 29 and its shaft 28 into the position shewn in Figure 2 before
the stationary contacts 11, 12 and 13 come into engagement with the contact
plates 6 and 8 on the drum. Also from the same cause the final movement of
the drum as the spring actuated pawl 231 is pressed, into one of the notches of the
plate 22 takes place very quickly and independently of the movement of the
shaft 21 since the instant that the end of any tooth of plate 22 has passed the
roller 232 the spring 25 acting on the bellcrank 23 forces said roller towards the
shaft 21 which causes the plate 22 to rotate in the direction of the arrow in
advance of the movement of the shaft 21. The possibility of arcing between
the stationary contacts and the strips on the drum by reason of failure of moving
the controller handle quickly to a running position is thereby avoided. When
the head 29 is moved from the position shewn in Figure 4 to that shewn in
Figure 2 as above-mentioned the plate 37 will be moved in a similar manner, and
by means of the circular rack 38 and pinion 39 will rotate the shaft 40 and
bar 42 causing the movable contact 43 of the switch 5 to move over the pins 49
and finally attain the position shewn in Figure 3 in which the switch is closed.
The roller 46 on the end of the lever 45 will be held in the notch 442 of the
plate 44, any accidental or shaking movement of the parts will not displace the
movable contacts of the switch 5. Furthermore the roller 35 of the head 29
will be moved into contact with the front face of the tooth 271 on the cam
plate 27 and since the spring 36 is only strong enough to maintain the shoulder
of the pawl 34 against the corresponding shoulder of the head 29 when no force
is opposing, said pawl will be rotated on its pivot by the pressure of the
tooth 271 so as to permit said tooth to pass the pawl, after which said pawl
resumes its normal position under the influence of the spring 36. This position
of the mechanism is shewn in Figure 2.
The further movement of the shaft 21 in the direction shewn by the arrow
in Figure 1 will not have any effect on the head 29 and switch 5 for the reason
that the teeth 272, 273. 274 will merely rock the pawl 34 on its pivot against
the action of spring 36, when, however, the tooth 274 has passed said pawl
the end 262 of the cam 26 will reach the roller 331 and this occurs when the
drum 2 is in such a position that the change from series to parallel connection

page_text: motors is about to be made. Since the bearing of roller 331 is fixed with
regard to the head 29, said head will be pushed out of the path of the cam 26
and take up the position shewn in Figure 5. The plate 37 on shaft 28 will
consequently move in the direction of the arrow shewn in Figure 3, and through
5 rack 38 and pinion 39 will move the contacts 43 quickly over resistance con-
tact pins 49 to the open position of said switch until the roller 46 of arm 45
rests in the notch 441 of the plate 44. The resistances 50 which are succes-
sively brought into circuit by the movement of the contacts 43 over the pins 49
are so proportioned that the current will be gradually reduced until its volume
0 is insufficient to form any injurious arc between the moving contacts and the
last contact pins. The opening of the circuit as above described occurs before
the fixed contacts 11 to 16 have left the contact plates 6. 8 and 9 of the drum 2,
and the ultimate separation of these parts will obviously be upon open circuit.
It being observed that the movement of the shaft 40 is very much more rapid
5 than that of the shaft 21 by reason of the gearing employed. The position of
the cams and head 29 being that shewn in Figure 5, further movement of the
shaft 21 in the direction of the arrow in said figure will cause the end 261 of
cam 26 to engage with roller 32 and rock the head 29 into the position shewn
in Figure 6, closing the switch 5 in the manner hereinabove described. The
roller 35 will thus be brought into contact with the cam plate 27 just before
the tooth 275. Further movement of the shaft 21 in the same direction will
not affect the position of the head 29 as the teeth 275, 276, 277 will be able to
move past the roller, merely rocking the pawl 34 on its pivot as hereinabove
mentioned. This position of the parts will be maintained until the roller 232
of the bell-crank 23 rests in the last notch on the plate 22, in which case the
position of the controller drum will be such that the motors are joined in
parallel without resistance, and the position of the cam 26 and head 29 will be
that shewn in Figure 6 in which the roller 331 will prevent any further move-
ment of the cam 26 in the direction of the arrow.
Since when the controller drum is in one of the running positions the
pawl 34 is in engagement with one of the teeth 271...of the plate 27 the
turning of the controller drum in the direction from one of such positions will
through the tooth on the plate 27 act on the pawl 34, and rotate the head 29
from the position shewn in Figure 2 to that shewn in Figure 4, thereby through
shaft 28 and tooth plate 37 rotating shaft 40 and opening the switch 5, also
owing to the lost motion between the pin 261 and the pins 221 this opening of
the switch 5 will precede any opening of the circuit by reason of the movement
of the controller drum. The head 29 being once moved into the position shewn
in Figure 4 the controller drum may be moved backwards to its initial or zero
position without any movement of the head 29 since the pawl 30 will rotate
on its pivot to allow the cam 26 to pass. It will further be observed that
he movement of the head 29 from the position shewn in Figure 4 to that shewn
n Figure 5 can only be effected by the cam 26, consequently when once the
ontroller drum has been moved in a backward direction the switch 5 can only
e closed after the parts have been brought into the position shewn in Figure 5
r to that shewn in Figure 4, in the latter case the controller drum will have
een rotated completely back to its initial or zero position. Consequently if
he motors are connected in parallel and the controller handle is moved back
he circuit is at once broken and cannot be closed again except to rotate the
andle backwards until the position of the controller drum is intermediate
etween that wherein the motors are connected in parallel and connected in
ries. Also if when the motors are connected in series the controller handle is
oved backwards the circuit will immediately be opened and cannot be closed until
e handle has been moved to its initial or zero position. It follows therefore
at whenever the circuit is opened for the purpose of stopping or reducing the
eed of the motors the latter cannot be again connected without at the same
ne including all or the greater portion of the starting resistance.
.

page_text: Instead of employing a resistance with the switch for breaking the circuit 'as
above described; I sometimes employ a simple switch without resistance, but
arranged so that the break shall occur within a vessel under the surface of a
suitable liquid in which case the switch arm is merely secured to the shaft, 40
and will be operated to break the circuit at the proper times through the gearing
above described. We may, however, utilize different gearing for this purpose which
is exemplified in Figures 12 to 14.. 80 is the shaft of the controller drum having
the usual notched plate 81 corresponding to the plate 22 in Figures 1 and 2 of
the drawings. 82 is the shaft of the switch carrying a switch arm 83 to which
is secured a contact 84 connected by a flexible lead 85 with the earth terminal
of the controller. This terminal is marked 16 in the diagram Figure 10. The
other terminal of the switch indicated at 86, Figure 13, is connected to earth.
Said terminal 86 is secured to a curvilinear piece 87 supported from the bottom
of the containing vessel 88, said piece also has mounted on it an insulation
piece 89 which forms a continuation of the earth contact 86. The shaft 82 is
located eccentrically with reference to the piece 87, so that the contact 84 will
bind or seize at the end of said piece, and will therefore always be in connection
with either the insulation 89 or the earth contact 86. The shaft 82 carries an
arm 90 to which are secured two plates 91 and 92 pressed together by spring
pressure substantially as shewn. These plates are adapted to grip a disc 93
secured at the bottom of the shaft 80, said disc being provided with a notch 94
which is wider than the parts of the plates 91, 92 which grip the disc 93. The
shaft 82 is provided with a spring 95, one end of which is attached to the frame-
work of the controller, the force of said spring tending to rotate the shaft 82 in
such a direction that the contact 84 rests on the insulation piece 89. The
box for containing the liquid within which the switch contacts are located is
provided with a top piece, an enlarged sectional view of which is shewn in
Figure 14, said top piece has a raised portion 96 through an orifice 97 in which
any superfluous liquid can escape when the contents of the box are expanded
by change of temperature, or owing to the production of a spark between the
switch contacts, and a valve 98 opening inwards is also provided through which
liquid expelled. through the orifice 97 can return into the box. The box is
filled with, any suitable liquid which is a non-conductor or bad conductor- of
electricity, and which preferably will not be liable to freeze, such a liquid for
example as glycerine, though various liquids may be used.
The operation of the apparatus is as follows:-
Assuming that the parts are in the position shewn in Figure 13, if the shaft 80
be rotated in the direction of the arrow, the frictional engagement between
the plates 91, 92 and disc 93 will cause the shaft 82 to rotate until the contact 84
makes connection with the earth contact 86; when this is done the circuit is
closed and will continue closed because further movement of the shaft in the
same direction will be prevented by the contact 84 binding against the end of
the contact 86 owing to the curvature of the plate 87, Further rotation,
therefore, of, the shaft 80 in the said direction will simply cause the disc 93 to
move between the plates 91 and 92. When, however, the change from series
to parallel connection of the motors is to be made the shaft 80 would have
been turned so far that the plates 91, 92 coincide with the notch 94, and when
this happens the spring 95 will be able to act to rapidly rotate the shaft 82 in
the reverse direction, thus breaking the connection between the contacts 84, 86.
Just before the parallel .contacts are made through the controller drum, the
plates 91, 92 will again embrace that portion of the disc 93 on the other side
of the notch 94, and movement of the shaft 80 will rotate the shaft 82 and cause
the contact 84 to again make connection with the earth contact 86. It will be
seen, therefore, that the circuit is broken automatically at the switch before it
is broken at the controller drum. Any movement of the controller drum in the
reverse direction will at once, through the agency of the disc 93 and the
plates 91 and 92, rotate the shaft 82 in the reverse direction, thereby withdrawing

page_text: the contact 84 from the contact 86 and breaking the circuit. Any arc which
takes place between the contacts 84 and 86 will be within the liquid where it
can have no detrimental effect. The switch is designed electrically to take the
place of the switch 5, Figure 10, in fact, in every respect it is an equivalent to
5 said switch 5.
"
رو
I will now describe the various circuit connection and changes which can be
made through the controller. Assuming that the position of the reversing
switch is such that the stationary contacts 60 and 61 will be in engagement
with plate 54, and contacts 601 and 611 in engagement with plate 541, con-
tacts 62 and 63 in engagement with plate or strip 58, contacts 64 and 65 with
plate 59, contacts 621, 631 with plate 581, and contacts 641 and 651 with plate 591.
li the controller drum is rotated to bring the stationary contacts 17 and 18 into
the position marked of Figure 10 the contacts 11 to 16 will come into the
position." Current entering at the contact 17 will pass from plate or strip 7
to strip 6, these two being electrically connected as indicated in the drawing,
thence through the contacts 11, 63, 58 and 62, the field magnet 70 of the first
motor contacts 64, 59 and 65, the armature 71 of the first motor, stationary
contact 13, strip 8, contact 12, contacts 60, 54 and 61, contacts 631, 581 and 621,
field-magnet 72 of the second motor, contacts 641, 591, 651, the armature 73 of
the second motor, the contacts 601, 541 and 611, contact 14, resistances 74 75
and 76, contact 16, and out through the series switch 5.
Without following the circuits in detail for the various subsequent positions
of the controller drum, it will be seen by reference to Figure 11 that in the
second running position, designated as 6 the resistance 74 is short-circuited. In
position c resistances 74 and 75 are short-circuited, and in position d all of the
resistances are short-circuited, the motors in each of these three positions being
in series. In positions e, f, g, and h the circuit is open. In position i the
motors are in parallel and resistance 74 is short-circuited. In position j the
motors are in parallel and resistances 74, 75 are short circuited, and in position k
or the final position, the motors are in parallel and all the resistances short-
circuited.
If the reversing switch drums be rotated so as to bring the stationary con-
tacts 62, 63, etc., into contact with the corresponding contacts 55, 56, etc., the
circuits will be the same as above described, except that the current will be
reversed through the field-magnets 70 and 72 of the motors.
While I have illustrated and described specific mechanism for practising our
invention, I desire it to be understood that changes may be made in the details
of construction and the arrangement of parts without departing from the spirit
and scope of the invention.
Having now particularly described and ascertained the nature of my said
nvention and in what manner the same is to be performed, I declare that what
claim is
1. A controller for electric motors in which a separate circuit making and
reaking switch is provided for automatically breaking the circuit before the
onnections of the motors can be changed from series to parallel or when the con-
roller is moved backwards.
2. The special devices for automatically operating the circuit making and
reaking switch substantially as described with reference to Figures 1 to 9 of the
ccompanying drawings.
3. The combination with a controller for electric motors of a separate circuit
aking and breaking switch automatically operated by the movement of the
ontroller drum, and with its contacts located in a closed box filled with a suitable
quid such as glycerine, substantially as and for the purpose specified.
4. A controller for electric motors in which a certain amount of lost motion
play is provided between the operating shaft and the drum carrying the
ovable contacts, and a toothed wheel is provided on the drum co-operating with

page_text: a spring pawl so that when said drum has been rotated a certain amount by the
operating shaft the pawl and wheel act to cause said drum to move quickly and
in advance of the movement of the shaft through the next portion of its path
for the purpose specified.
5. The combination with a controller for electric motors of a separate circuit
making and breaking switch, the shaft of which is connected to the controller
shaft through a friction clutch which is arranged to be operative, to connect the
shafts while the controller is varying the resistance in circuit, but being inopera-
tive, while the connection of the motors is being changed from series to parallel,
at which time the circuit making and breaking switch is actuated by the agency
of a spring to break the circuit.
6. The combination with a controller for electric motors of a separate circuit
making and breaking switch operatively connected to the controller shaft and
arranged as described with reference to Figures 12 and 13 of the drawings.
W. P. THOMPSON & Co..
Of London, Liverpool, Manchester, and Birmingham.