US1427355A - System of control - Google Patents

Description

A. H. CAN DEE.

SYSTEM OF CONTROL.

APPLICATION FILED OCT. 13. 1917.

Patented Aug. 29, 1922.

a SHEETS-SHEET I. F/ Z5eco/7d/Vw2 ii .iiuiim 0 4 4 mm, 1 A L n: I l B h /5/ 77 46:2 15 -/74 7/ l I 4| 1f 72" 72 -72 WITNESSES fofiwm INVENTOR Andrew H andee ATTQRNEY A. H. CANDEE.

SYSTEM OF CONTROL.

APPLICATION FILED OCT. 13, 1917.

1 ,427, 355 Patented Aug. 29, 1922".

3 SHEETS-SHEET 2.

WITNESSES: INVENTOR ATTORNEY entree srnrsis PATENT oFFIcE. I

ANDREW H. cannnn, orfwrnxinseone, PENNSYLVANIA, nssleivon 'ro WESTING- nousn- ELECTRIC & MANUFACTURING compan A oonrone'rron'or PENNSYL- VANIA.

SYSTEM OF CONTROL.

Specification. Letters Patent. Patented Aug. 29,1922.

Application filed October 13,-;1-917. Serial no. 196,411.

To all whom it may. con-corn:

Be it known that I, ANDREW H. CANDEE, a citizen of the United States, and a resident of V\ ilkinsburg, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Systems of Control, of which the following is a speci fication. I

My invention relates to systems of control and especially to the remote control of orer-arrying vehicles, or the like, from .a tower or station without requiring the presence of an operator upon the vehicles, under normal operating conditions. I

One of the objects of my invention is to provide a relatively simple and effective system of the above-indicated character for remotely controlling the acceleration and retardation periods, through a certain operating cycle, of a plurality of electric'vehicles which, however, are capable of indivdual control by an operator, if desired.

Another object, ofmy invention is to pro-v vide, in conjunction with a system of the class under consideration, a plurality of safety devices that are connected to the system in a novel manner for preventing certain undesirable conditions such as overspeeding of the vehicle and false operation of circuits. v

A further object of my invention is to provide an interlocking system for the control 'tower, whereby contiguous trackzones or sections are prevented from being oppositely energized, which would result in nnury to the rolllng stock.

Other minor objects of my invention will become evident from the following detailed description and are set forth with particularity'in the appended claims.

My invention may best be understood by reference to the accompanying drawings, wherein Fig. 1 is a. diagrammatic view of the main circuits of a system of control embodying the invention; Fig. 2 is a diagrammatic view of the auxiliary circuits that are located upon one vehicle for governing the switching devices corresponding to one of the motors of Fig. 1; Fig. 3 is a detailed diagrammatic view of one of theswitches that are employed in the system of Fig. 1; Fig. 1 is a digramnmtic view of the energizing circuits and interlocking arrangement that is employed in acontrol tower or station;

is a View, in side elevation, of a portion of the interlocking apparatusthat is shown in 1 Fig. 4; and Figs. 6 and 7 are, views in perspective illustrating the above-noted interlockingarrangement in detail.

Referring first'to the control-tower apparatus (Fig. at and Fig. 5), theillustrated system' comprises a plural ty of operating handles or levers 135, 136 and 137; two ungrounded three-phase supply-circuit con;- d'uotors 1 19 and 150; a plurality of independent trackzones or sections 151, 152 and 153 severally comprising pairs of third rails T1 and T2 and aplurality of sets of switches 154 to 157, 158 to 161, and 162to 165, all inclusive, these sets respectively corresponding to track zones 151, 152 and 153. A battery.

13, 01 other suitable source of auxiliary energy,; is provided for effecting the actuation of the several switches.

It will be understood that one or more control towersor stations will'be advantageously located onthe rail-way property, and

each track section is governed by a separate interlocking lever of the type 1 indicated, whereby the entire normal vehicle operation may be remotely controlled.

The power system that is employed in connection with my invention is of the threephase type, the illustrated rails T1 and-T2 constituting two of the phase conductors, while a ground returnis utilized as the other conductor of tl e'system, as more fully 111118? tratedin Fig. 2. Each operating lever is adapted to occupy the illustratedintermediate position off and-a plurality of ,posi

tions respectively marked Coasting and Forward when the lever is moved in one direction, and Coasting? and Reverse when'the lever is actuatedin the other direction from the off position. The positions forward and reverse correspond to the interchange of connection between the third rails T1 and T2 and the supply-circuit conductors 149. and 150, such reversal. of two phases ina three-phase system serving to effect the reverse rotation ofthe driven induction motors, as is well understood.

, Each interlocking lever comprisesya rod or bar l38 which.is pivotally mounted at a central. point 139 and the lower end of which constitutes a suitable contact tip 140.

the contact terminals 144 and 145.

An insulating grip-or handle 1 11 is provided, and an insulating sleeve 1411a extends from the grip 14:1 to the central pivotal point 189. Attached to the upper portion of the, insulating sleeve ltla'is an arcuate member or strip 142 that is symmetrically disposed with respect to the sleeve lella and in substantially the same plane, while a pair of arcuate strips 143, of the same radius as the strip 142, but located in a different plane behind the lever rod 138, as clearly shown in Fig. 5, are attached to the opposite ends of the intermediate strip 142. A spring contact clip 1441 is located in a position to be engaged by the contact ti 140 when the lever occupies its right-hand coasting position, and, when the operating lever is moved to its position reverse, the contact tip 140 slides over'the spring clip 1 1 1, which is forced into' engagement with a stationary contact terminal 145, whereby the contact tip 1 10 is electrically connected to both of Similar contact members 1-16 and 147 are provided in the remaining positions coasting and forward of the operating lever. Thus, when the interlocking lever occupies either of'its coasting positions, only one contact terminal is energized, whereas, in either the forward or the reverse position, corresponding to full-speed operation of the vehicle, both terminals of the one or the other pair, corresponding to forward or reverse operation, are energized.

As previously mentioned, the opposite energization of: contiguous track zones should be prevented in order to obviate cur rentsurges and mechanical difficulties in 'the'vehicle motors by reason of sudden reversal thereof. The purpose of the illustrated interlocking arrangement for which, of course, any other equivalent structure may be substituted within the spirit of my invention, is tolinsure that an intermediate dead or tie-energized track zone or section is interposed between two zones that are oppositelyenergized, for example, in connection with switqhing or shunting of vehicles when not being employed in their regular run orcycle of operation.

It will be observed that the illustrated interlocking levers may all be thrown to either'the forward or the reverse position without mutual interference, but, if,

under such conditions. when the lever 137 occupies its forward position, for example. (see Fig. 7) it is attempted to throw the lever 136 to its reverse position, such action is prevented by the mechanical interlocking of the arcuate strips 143 of the respective levers as soon as the lever 136 is moved to its intermediate or of? position. HoweverQif the lever 136 occupies such intermediate position, it is then possible to actuate the third lever 135 to its reverse position. In this way, the track zones 151 and 153 may be oppositely energized, with a dead section 1532 between them, but it is impossible to oppositely energize any two contiguous sections.

On the other hand, if the interlocking lever 13'? is assumed as occupying its reverse position, (see Fig. 6) then movement of the succeeding lever 136 beyond its 0d position in a forward direction is prevented by the mechanical engagement of the arcuate strips 142, and again track zones 151 and 153 may be oppositely energized by manipulation of the corresponding levers 137 and 135 only when the intermediate lever 13$ occupies its oh positionf By providing an equivalent interlocking a1- rangement between contiguous pairs of the entire complement of interlocking levers in the control tower or station, the opposite energization oitany two contiguous track zones or sections is efi'ectively prevented.

Referring now to Fig: 1, illustrating the complete main-circuit connections for one driving induction motor of a vehicle and partial connections for the second driving motor that is preferably provided, the system shown comprises the third rails T1 and T2 and the ground return, whereby a threephase source of power is available; a main driving motor lot the familiar induction type comprising delta-connected primary C and co-operating switcheslfil to R6, in-

clusive, for varying the secondary-circuit resistance of the induction motor to govern the operation thereot inaccordance with familiar principles; a plurality of limit switches L1 and L2 for automatically governing the operation of the system; a plurality of current relays 5 and 6. severally having two contact disks, and currentrelays 7 and 8, each provided. with a single contact disk, for governing certain auxiliary-circuit connections to be set forth; and a plurality of electrica ly-controlled switches 10 to 13, inclusive, which are employed in pairs to effect forwaid or reverse operation of the in d uction motor 1 when controlled from the individual vehicle, irrespective of the relative energization of the third rails T1 and I primary induction-motor winding, dependent upon the particular set of directioircorr.

trolling switches 10 and 13, or 11 and 12. that is employed. 7

The current relays 5 and 7 have their actuating coils respectively connected in series relation with the supply conductors 21 and 20 to be energized by the current traversing the primary winding of the illustrated induction motor, while a similar pair of current relays 6 and 8 have their actuating coils connected in the primary circuits that correspond to the third'rails T1. and T2 of the second driving induction motor (not shown) for which the conductors 23, 24t and 25, re spectively corresponding to Ground, thirdrail shoe 18 and third-rail. shoe 19, are provided. p

The current relays 7 and 8 have a relatively high setting andare provided with a single contact disk or bridging contact member for closing certain auxiliary circuits, to be de-,

scribed, when the relays occupy the illustrated lower positions. The current relays 5 and 6, however, are of a similar doubledisk type, the relay 5 being shown as comprising two disks or bridging contact mem bers 26 and 27 which are loosely mounted upon the stem of the current relay and are biased, by an intermediate coil spring 28, towards engagement with a corresponding nut or stop member 29. Thus, in the illustrated normal position of the relay 5, the lower contact disk 2'? closes a certain auxiliary circuit while the upper disk 26 is prevented, by the allied nut 29, from engaging an upper pairof stationary contact members. Upon energization of the relay to a certain value, which is lower than the setting of the single-disk current relays '7 and 8, the

upper contact disk 26 engages the upper stationary contact members before the spring 28 permits the lower contact disk 27 to become disengaged from the corresponding stationary contact members. A similar action occurs when the current relay 5 drops to its lower position, and, in this way, whichever auxiliary circuit is closed by the current relays 5 or '6 is maintained until the other auxiliary circuit has been energized by the relay movement, thus preventing an open-circuit of the auxiliary connections.

The limit switches L2 and L1 are adapted to control certain auxiliary circuits in accordance with relatively light and relatively heavy main-current conditions, respectively, although, by reason of the peculiarlocation of the two limit switches, such. action is se,

cured by the use of identical limit switches and without any variation in the setting thereof. I

In the present system, it is desired to manipulate the secondary-circuit resistors of the driving induction motors in accord ance with the load condition of the vehicle;

that is, w'henthe vehicle is carrying a capacity load it is desired to vary the secondarycircuit resistance to automatically. maintain a relatively, heavy draft of motor current through the agency of the limit switch L1, while, under light-load conditions,,when the vehicle is empty, it is desired to vary thef motor operation in accordance with'relatively light-current conditions, as governed by thelimit switch L2. Since the limit switch L1 is connected in the conductor for the second driving motor and receives only single-motor current, whereas the limit switch L2 is connected in the common ground-circuit conductor 1? to receive twu motor current, it follows that the desired governing of motor circuits, in accordance with the load condition o't'the vehicle, may be effected by the two, limit switches. The peculiar auxiliary-circuit ar 'angen'ient of the contact members of the two limit switches to'perinit of the desired automatic operation of the driving motors will be set forth in detail in connection with Fig. 2. i I

Reference may now be had to Fig; 2, wherein the systen'i shown comprises the polyphase supply-circuit conductorsTl, T2 and Ground; the auxiliary contact members of the current relays5, 6, T and 8; a brake relay 30 and a centrifugal switch 31 for governing the operation of an air-brake valve 32; the actuating coils of the several switches that areshown in Fig. lytogether with a plurality of electrical interlocksof the familiar type that is shown in F 3;

bridging contact. members 36, 37 and 38.

The centrifugal switch 81 may be of any familiar type for actuating a movable member, under predetermined speed conditions of the vehicle and is here shown as comprising amechanism 40 of the well-known flyball type, which is'connected, through a suitable transmission mechanism All, to the truck-axle 16. A movable'switch rod 42 is pivotally associated with the fly-ball mechanism 40, being normally biased to the illustrated upper position, wherein a plurality of bridging'contact'ineinbers 4A, 45 and 46 close certain auxiliary circuits to be described. The contact disk et is rigidlysecured to the rod 42, whereby its circuit is established only while the vehicle is at rest. Un the contrary, the contact IS ano l6 111 in opposition to the biasing ac ion of the are loosely mounted upon maintain their circuit connec the event of over-speed con" fly-ball mechanism 40. after the vehicle speed as reachet value sufficiently high to throw the fly-ball device into such a position that the switch rod 42 is actuated to a complete open-circuit position to pe mit the locking engagement of the latching member t7 and the co-operating block 429.

The air-brake valve may be of any familiar type and is shown as comprising a shell or encasing member having an inlet or supply pipe 51 and an outlet or delivery pipe 52 between which is interposed a suitable plug-valve member 53 to which is secured a double core member 54: that is provided with a plurality of cumulatively-related actuating coils 55 and 56.

The purpose of the air-bralre valve 32 is to admit fluid pressure tO'l-Jfi familiar vehicle brake-cylinder (not shown) except when the one or the other of the actuating coils 55 and 56 is energized in accordance with circuits to be traced, whereby the airbralres are maintained inoperative during normal running or coasting conditions of the vehicle motors.

i The control transformer CT is employed for the purpose of preventing certain false operations or energizations of the auxiliary circuits, which would occur if an uninterrupted metallic circuit from the third rails T1 and T2 through the master controller to the various switch-actuating coils were employed. However, by .interposing-the control transformer CT between the third rails and the switch-actuating coils. the formation of undesirable or false connections or energizations during the operation of the vehicle is effectively prevented.

The change-over switch CO may be of any suitable two-position or double-throw type and is shown in a dis amine-tic mannor as adapted to occupy vwo positions 72 and Z, respectively corresponding to heavy load and light load of the vehicle, or, in the case of orecarr ving cars. for example, respectively corresponding to full and to empty condition. In conjunction with the change-over switch, the limit switches L1 and L2 are employed to properly accelerate t e vehicles in accordance'with the load conditions thereof, as previously explained.

it will be understood that any suitable method :lor actuating the change-over switchto the one or the other of its operative positions may be employed, for example, ordinary manual operation or actuation by suitable track ramps that are located at proper points along the road-bed.

As previously stated, the vehicles are normally started and stopped from the control to ver or station, and the master controller MC upon each vehicle is employed only in special instances where individual control is desire jl. N rmally, the master controller occupies its illustrated full-speed position corresponding to forward operation.

that the interlocking switches 'issuminr in the control tower have been manipulated to energize the third rails T1 and T2 so that the three-phase supply circuit is in operative condition corresponding to forward operation, the opposite terminals of the primary winding 57 of the control transformer are connected through conductor 20 and rail-shoe 18 to the third rail T1 and through conductor 21 and rail-shoe 1.9 to the other third rail T2, respectively.

An electromotive force is thus produced in the secondary winding 58 of the control transformer, a circuit being established from one terminal thereof through bridging contactmeinbers 61 and 62 of the single-disk current relays 8 and 7, respectively, conductor fifllower contact members 64 and 27 of the current relays 3 and 5, respectively, conductor 66 and control finger 67 to a. contact figment 68 of the master controller. One circuit is continued from the contact segment 68 through control finger 69, conductors 70 and 71, interlock 11-out, actuating coil of the switch 13 and conductors 72 and to the opposite terminal of the secondary transformer winding 58. Upon the closure of switch 13, another circuit is completed from the conductor 71, through conductor 74, interlocks 13-in and 12-outand the actuating coil of the switch 10 to the terminal conductor 72.

By reference to Fig. 1, it will be observed that the closure of the switches 13 and 10 connects two of the terminals of the primary induction motor winding P1 to the third-rail shoes T1 and T2, and, since the remaining motor terminal is permanently connected to Ground, the induction motor is set in operation in the direction to be considered as forward, all of the secondary circuit resistors 2. 3 and 4: being actively connected in circuit by the closure of switch R1, in a manner about to be described. It will be understood that the remaining vehicle. motor is preferably controlled in asimilar manner.

The traversal of current through the stator windings oi the two inductionmotors first causes the current relays 5 and 6 and, subsequently, the current relays]- and 8 to be moved to the upper positions, whereby the upper terminal of the secondary wind ing 58 of the control transforn'ier CT is connected to the conductor (56 through conductor 75 and the upper contact members 76 and 26 of the current relays 6 and 5, respectively. As previously explained, the peculiar construction of the current relays 5. and 6 causes the upper set of iircuits to be closed before the lower set is opened, and, consequently, an uninterrupted flow of current energy through the circuit ust traced is maintained. The further functions of the current relays 5 to 8, inclusive, will be hereinaften described in connection with the regenerative operation, of the driving motors and other similar conditions entailing a substantial interrup tion of supply-circuit energy in the control system.

Assuming that the vehicles to be con trolled are heavily loaded and that the change-over switch CO consequently occupies its position It, another auxiliary circuit is'continued from the conductor through interlock 13-in, conductor 81, movable contact member 82 of the change-over switch CO, in its position it, conductor 83, directly to the actuating coil for the switch R1, and thence to the terminal conductor 73. The switch R1 is thus closed to connect the entire secondary-circuit resistors 2, 3 and 4c in ac tit e circuit relation with the secondary motor winding S1.

Since the changeover switch CO occupies its heavy-load position it, a further auxiliary circuit is continued from the master controller contact segment 68 through control finger 91, conductor 92, interlock lO-in, movable contact member 93 of the change-over switchbridging contact member 94: of the single-motor current limit switch L1, when occupying its lower position, conductor 95, interlock 96-R1in, conductor 97, interlock 98-R2-out and thence, through the actuating coil for the switch R2, to the terminalconductor 73. As soon as the switch R2 is closed, a holding circuit for its actuating coil is completed from the lower terminal thereof through interlock 9S-R2-in and conductors 99,-1.00 and 101, to the vabove-mentioned interlock 10-in, which is positively energized whenever the master controller 00- cupies its illustrated position.

As previously explained, the limit switch L2 carries the total current of both driving motors, whereas the limit switch L1 is energizedin accordance with the current of only one of such motors. Consequently, under heavy-load conditions of the vehicle, the limit switch L2 maintained in its upper position, and the automatic control of the several resistor short-circuiting switches is dependent upon the single-motor-currrit limit switch L1 alone. Thus, when the limit switch L1 again drops to its lower position,

after the closure of the short-circuiting switch R2, an auxiliary circuit vis continued fromthe conductor 97through interlock 102- R2-in and thence to the actuating coil for the switch R3. In this way,the remaining resistor-shorttircuiting switches are progressively closed in accordance with the movements of the limit switch L1, as will,

mentioned manner, and, upon re-energizw,

tion of the third rails T1 and T2, the switches 13 and 10 are again closed. However a new circuit for the actuating coil of the switch R1 is completed fromthe master-controller contact segment 68 through control finger 91, condnctor92 andinterlock 10-in to conductor 101,when"e circuitisconiplete through contactdisk 85 of the totalmotor-current-limit switch L2 to interlock S ilwll-out ,and the actuating coil for the switch R1. The single-n1otor-current-limit switch L2 is inoperative under light-load conditions of the vehicle, since the changeover switch (0 occupies its position Z to intcrrupt the connection of the contact disk 943 of the limit switch L1 to conductor 101.

The remaining resistor-short-circiiiting switches are progressively closed in accordance with the movements of the'limit switch L2, whereby a relatively light current .is automatically maintained in the stator winding of the induction motors to effect proper acceleration under the light-load conditions i o l the vehicle.

The normally operative auxiliary brake i a ircuits may be traced as follows: I

One such circuit 15 establlshedfrom the third-rail shoe 19 throughconductors 21 andlOS, control fingers 10 i and 105, which are bridged by contact segment- 106 of the master controller, conductor 107, junction, point 108, conductor 109, actuatingcoil 35 of the brake relay 30, conductor 11 0, bridging contact member a lot the centrifugal switch 31, in its stationary or normal position, and conductors 111 and 112 to the Ground.

The brake relay 30 is thus actuated to its upper or circuit-closing position, whereupon a holding circuit, including contact disk 36 of the brake relay, is utilized to directly connect the conductors 110and 112, thus rendering the energization of the relay independent of the position oi the centrifugal switch 31, which interrupts the circuit through its contact disk 44; whenever the vehicle is in motion.

A new circuit is completed from the junction-point 108 through conductor 1'13, contact disk 37 of the brake relay, (ZOHCllli tor 114, contact disk 45 of the centritt'igal switch, conductor 115, actuating coil 55 tor theair-b 'ake valve 32 and conductor 116 to Ground. The valve is thus closed to prevent access of fluid pressure to the brakecylinder pipe 52, and. consequently, the airbrakes are maintained inoperative whenever the actuating coil 55 is energized.

A duplicate set of circuits is established from the third-rail shoe 18 through conductor 20, control fingers 117 and 1.18, which are bridged by contact segment 119 of the master controller, conductor 120, actuating coil for the brake relay 30 and thence, through conductor 1.10, to Ground, as ah ready traced. A further circuit is completed, when the brake relay occupies its upper position, from the conductor 120 through contact disk 38 of the brake relay, conductm: 123, contact disk 46 oi the centrifugal switch 31,'conductor 124i and the actuating coil for the air-brake valve 32 to the conductor 116. i

In this way, the brake relay 30 and the air-brake valve 32 are maintained in their upper or energized positions whenever either one of the third rails T1 and T2 is energized, and the master controller MC concurrently occupies any position except the intermediate position marked Br-aka" The necessity for the duplicate set oi auxiliary brake circuits will be evident from the fact that either of the third rails T1 and T2 may be de-energized to produce coasting conditions of the driving motors, dependent upon the particular coasting positions occupied by'the interlocking switches that are shown in Fig. t. As previously described, the actuation of the interlocking device 135, for example, to either of its coasting positions de-energizes the one or the other third rail T1 or T2 and thus tie-energizes one of the main-circuit conductors tor the primary induction motor windings P1. Consequent ly, the control transformer CT (Fig.2) is, tie-energized. and the previously-tinced auxiliary circuits are all likewise tie-energized to disconnect the primary motor windings From thesupply circuit by opening the sets oi" switches 13 and 10 or 12 and 11,, dependent upon the direction of operation of the motors.

in this way, the vehicles permited to coast by de-energizing one of the third rails T1 and T2, although the one or the other of the duplicate auxiliary brake circuits is maintained energized to thus prevent the operation of the air-brakes when it is desired to effect coasting operation of the vehicle.

To stop the vehicle, the corresponding interlocking switch 135 or the like is thrown to its off position, whereby the remaining third rail is de=energized to thus permit the brake relay 30 and the air-brake valve 32 to assume their illustrated lower positions to thereby permit fluid pressure to enter the brake=cylinder to apply the vehicle airbrakes and rapidly arrest the vehicle inovement. The air-brakes remain applied until the one or the other of the third rails T1 and T2 is again energized by movement of the corresponding interlocking lever to an operative position.

During such coasting and braking conditions, the control transformer CT, in conjunction with the several current relays 5 to 8, inclusive, functions to prevent false operation by. undesirable circuit energizations. When one third rail is tie-energized from the control tower to effect vehicle coasting, a three-phase regenerative circuit tends to be maintained by reason of the fact that the other two phase-conductors are still energized, and the momentum-driven machine attempts to re-energize the dead thirdail. Even when both rails are de-energized, the motors tend to maintain voltage for a very short interval. This inherent action also tends to energize the control transformer and maintain the directioncontrolling switches 10 and 13 in their closed positions. However, such tendency is counteracted in the following manner by the current relays 5 to 8, inclusive. If third-rail T1 is ole-energized, current relays 6 and 7 drop, thus completely opening the auxiliary circuit and causing the desired opening of the motor-governing switches. On the other hand, tie-energizing third-rail T2 drops relays 5 to 8 and opens the switches in the same way.

The arrangement of the current relays 5 to 8, inclusive, is also adapted to prevent an interruption of the main circuits upon a transition of machine operation from acceleration to regeneration. Such transition, as, is well known, inherently occurs in an induction motor whenever the speed tends to exceed the synchronous value. Under such conditions, the current in each main machine will pass through a minimum value to attain the necessarily reversed flow of the regenerated current. As the operating range of the relays cannot always be adapted to hold them closed at such minimum upper circuits are maintained until the lower circuits are closed, as previously explained.

In this way,'the auxiliary circuits remain energized to prevent interruption of the motor circuits, and, as soon as the regenerative current assumes a normal value, the various" relays again assume their upper positions without, however, opening the auxiliary circuits. acceleration to regeneratiomcr vice versa, may occur at any tin'ie without modifying the vehicle operation, practicallyspeaking.

f, at any time under itull-speed'or coasting conditions, the vehicle speed exceeds a predetermined critical value, the centrifugal switch 31 operates to open the auxiliary circuits including contact disks 45 and 4:6, to

(le-energize both actuating coils, for the air? brake valve'32 and thus apply the vehicle brakes to bring the ear to astandstill. As previously explained, when the centrifugal switch 31 is actuated. to its emergency position, the latching device 47 locks with the notchedblock 49 to maintain the switch in its open position until thelatching member 47 is manually actuated to permit the spring 43 to return the centrifugal switch to its illustrated position; a

T he present system automatically functions to prevent sudden; reversal of motor operation which, as is well known, is undesirable, for both electrical and mechanical reasons. Whenever the corresponding interlocking leveroiFig. at is actuated from its forward to its reverse position, the

1 third rails T1. and T2 are temporarily deenergized. as the lever passes through its position -ofl:' and the vehicle brakes are thus applied to arrest the movement of the vehicle, whichcannot be again set in operation until after a 'complete standstill has been effected This result is attained by reason of the fact that thepreviously-traced circuit for the actuatingxcoils of the brake relay 30 is interrupted by bridging contact member 44 of the centrifugal switch 31 whenever the vehicle is in motion, and, since the holding circuit, including contact disk 36 01 the brake relay, is also interrupted when the relay drops to its lower position upon the temporary de-energization of the third rails T1 and T2, it follows that the brake relay cannot be raisedto its operative position to releasethe air-brakes untll the vehicle 'has'come to rest, as evidenced by the occupation of its .uppermost position by one or both of the double-disk Thus, transition from t the contact disk e icit the centrifugal switch.

If it is desired, for switching or other pub poses, to control any one vehicle independently of the others during the period of energization of both the third-rail conductors T1 and T2, the corresponding master controller MC may be manually actuated to its position marked Switching, whereby control finger 9lbecomes disengaged from the contact segment 68, and, consequently, the driving induction motorswill operate, at a relatively low speed by reason of the high value of resistance that is thereby included in the secondary circuits thereof. In this way, switching operations, for 2 example,

may be readily reduced speed.

By manually actuating the master controller MC to its position marked Coast, the actuating coils for the main-circuit switches are tie-energized to disconnect the motors from the supply circuit, but, inasmuch as the ,actuatingcoils for theair-brake valve 32 remain energized in such,coast position ofthe master'controller, the airbrakes are not applied, and, consequently, the vehicle is permitted to coast at a speed dependent upon its own momentum.

However, to manuallyeffect braking of the vehicle, the master controller is moved to its middle position marked Brake, whereupon the actuating coils for the airbrake valves 32 are dc-energized to permit application of the. mechanical brakes and bring the vehicle to astandstill,

The above-mentioned provision of preventing reversed operation ,of-the driving motors ,until after the vehicle has been accomplished at a desirably stopped, is rendered inoperative whenever the mastercontroller MC occupies any posi tion other than the full-speed positions cor responding to either forward or reverse op-J eration, since immediate reversal," under such reduced speed rond1tions,.w1ll work no ingury to the apparatus. The function just recited is made possible by reason of a new i return circuit that is established from the lower terminals of the actuating coils 84: and 35 for the brake relay 30 through conductor 125, control fingers 1-26 and '127,

which are bridged by contact segment 128 of the master controller in any of the above-v mentioned positions, and conductors 129 and l12 -to Ground. The brake relay is thus maintained in its upperor operative position to prevent applicationof the/air-brakes irrespectiye of the concurrent position of the centrifugal switch 31, except that the previously-mentioned over-speed protection is available at all times;

Inthe "iull-speed-reverse position of the tmastercontroller, the control finger 91 reengages thecontact segment ,68, while. a new control finger, 131 is substitutedfor the previously-mentioned control finger 69, circuit being completed from t i. ip er .31 through conductors 132 1. interlock lO-out and the actuating coil of the switch to the negative conductor 72. i-inother circuit is thereupon completed firom conductor 13 through conductor 12. interlocks IQ-in and 13-out and the actuating coil of the switch 11 to the negative conducted In this it. the two ungrounded terminals of the primary motor windings are connec ed to the opposite third rails from those utit (Ii dui" ing the forward operation, whereby the driving motor rotational direction is reversed, in accordance with familiar principles. I

Switching and coast positions are preferably provided dui" reversed operation'ot the vehicle, and periorin functions similar to those hereinbetore set forth in connection with the corresponding positions in the other portion oi the master controllen The remaining operation of the system during reversed rotation of the main motors is identical with that previously described, andno further description thereof deemed necessary.

I do not wish to be restricted to the specific eircuitconnections, structural details or arrangement of parts herein set forth, as various modifications thereof may be eflected without departing from the spirit and scope of my invention. I desire, therefore, that only such limitations shall be imposed as are indicated in the appended claims.

I claim as my invention:

1. In a system of control, the combination with a plurality of independent distribution-circuit sections, of plurality of switching devices corresponding to the respective sections for reversing the polarity thereof individually, and means forpreventing the relative reversal'ot polarity of pre determined sets off sections.

2. In a system of vehicle control, the combination with a supply circuit and a plurality or independent distribution-circuit sections adaptedto be energized therefrom, of plurality of switching devices corresponding to the respective sections for reversing the individual connection thereof to the supply circuit, a plurality of control means for governing said switching devices, and interlocking means associated with said control means for preventing the relative reversal of polarity of contiguous sections. 1 3. In a system of vehicle control, the combination with a supply circuit and a plurality of independent distribution-circuit sections adapted to be energized therefrom, of a plurality of switching devices corresponding to the respective sections for reversing the individual connection thereof to the supply circuit, a plurality of-control means for governing said switching devices, and interlocking means associated with said control means for insuring that two sections having relatively reversed polarity be separated by a de-energized section.

i. In a system of vehicle control, the combination with a two-conductor supply circuit and a plurality'or" independent two-conductor distribution circuit sections adapted to he ener 'ized therefrom, of a plurality of sets oi switching devices corresponding. to the respective sections for reversing the individual connection thereof to the "supply circuit, a plurality of multi-position control l-"ers for manipulating said switching devices, and interlocking members operated by said control levers for insuring that two sections having relatively reversed polarity be separated by a dc-energizedsection.

i 5. In a system of vehicle control, the combination with a supply circuit, of a pluralconductor distribution-circuit, and an electric vehicle op-eratively connected thereto and adapted to run, coast or brake, according to the number of energized conductors in said distribution circuit.

6. In a system of vehicle control, the combination with. a supply circuit, of a pluralconductor distribution-circuit, an electric vehi le embodying a motor-control system operatively connected to said distribution circuit, and remote-control means for ener- 'zing all, a portion and none, of the distribution-circuit conductors, said motor-control system being so organized that the vehicle thereby causedto run, coast and brake, respectively.

7. Ina system of vehicle control, the combination with a supply circuit, of a' pluralouductor distribution-circuit, an electric vehicle operatively connected thereto and adapted to run, coast or brake, according to thenumber o1 energized conductors in said distribution circuit, and means for governing the vehicle independently of said distribution circuit, under predetermined conditions. i

8. In a system of vehicle control, the, combination with a supply circuit, of a pluralconductor distribution-circuit, an electric vehicle embodying a motor-control system operatively connected to said distribution circuit, remote-control means for energizing all, a portion, and none. of the distributioncircuit conductors, said motorecontrol system being, so organized that the vehicle is thereby caused to run, coast and brake, respectively, and control means located on the vehicle for independently governing the operation thereof during periods of complete energization of said distribuearner 10. In a system of control, the combination with a pluralityiof motors for driving a common vehicle, of a plurality of relay devices, respectively having actuating coils energized by a portion, and by all, of the currents traversing said motors, for automatically governing the operation thereoftindependently in accordance with the load conditions of the vehicles.- a I 11. In a system of control, the combination with a plurality of motors for driving a common vehicle, of a plurality of identical relay devices, respectively having actuating coils energized by all and by one of the currents traversing said motors, for automatically governing the operation thereof under light-load and heavy-load conditions, respectively, of the vehicle.

12. In a system of control, the combination with a plurality of motors for driving a common vehicle, of a plurality of relay devices, respectively having actuating coils energized by one and by all of the currents traversing said motors, and a change-over switch having positions corresponding to materially diiterent load conditions of the vehicle for permitting automatic operation of the control system independently by the different relay devices under said ditlerent load conditions.

13. In a system of control, the combination with a plurality of wound-rotor induction motors for driving a coimnon vehicle, of a plurality of identical limit switches respectively having actuating coils energized by one and by both of the motor primary currents and having auxiliary-circuit COIl-r tact members connected in parallel relation, a change-over switch having positions corresponding to light-load and heavy-load conditions of the vehicle, a variable-resistance regulating circuit for each wound rotor, and auxiliary-circuit connections associated with said change-over switch for automatically governing said regulating circuit by the single-motor-current-energized limit switch and by the other limit switch under said heavy-load and light-load conditions of the vehicle, respectively, said change-over switch open-circuiting the contact members of the single-motor-current-energized limit switch under said light-load conditions.

14. In a system of control, the combination with a dynamo-electric machine, of means for reversing the direction of rotation there- 1 of, and speed-responsive means for prevent ing such reversal,

15. In a. system of control, the combination with a dynamoselectric machine, of means for reversing the direction of rot'ationthereof,

and speed-responsive means for. preventing suclrreversal until the machine is at rest.

1 16. In a system 01'. control, thecombination with a dynamo-electricmachine, or a controllerit'or reversing certain circuit energizations of said machine, and. centrifugally-controlled means forrendering said reversal inoperative, except undersubstantially stationaryconditions of the 'machine. I

17. In a system of control," the combination with a dynamo-electric machine, of a pluital-position controller having positions corresponding to forwarcPand reverse? full.- speed operation, independent control means for reversing theenergization of certain ma chine circuits, means for preventing actual machine reversal until the machine is at .rest when said controller occupies either.

full-speed position, and means associated with said controller forrendering said preventing means inoperative when said controller occupies positions other than said full-speed positions.

18. Ina system of control, the combination with an alternating-current supply circuit and a dynamo-electric machine, of a distribution circuit adapted to be connected to said machine, an auxiliary governing system for said machine, independent means for controlling and reversing the energization of said distribution-circuit from said supply circuit, and an auxiliary transformer hav ing one Winding connected across said 'distribution circuit for inductively supplying energy to said auxiliary system.

19. In a system of vehicle control, the combination with a dynamo-electric machine, and a switching device normally dependent for closure upon the continuous energization of said machine, of means operative upon a transition from acceleration to regeneration, or vice versa, for maintaining said switch ing device closed during the concurrent change of current conditions.

conductor distribution circuit, an induction motor, an auxiliary governing system energized from said distribution circuit-and including switches for connectlng said motor thereto, means for de-energizing one of said distrlbution-circuit conductors to eflect motor-coasting conditions, and means for insuring the opening of said switches under such coasting conditions. 22. In a system of vehicle control, the combination With a three-phase supply circuit,'

of said auxiliary system under such coasting conditions irrespective of the tendency of the induction motor to maintain a'threephase energization.

23. In a system of vehicle control, the combination with a three-phase supply circuit,

of a distribution circuit including two conductors, an induction motor, an auxiliary governing system energized from said conductors and including switches for connecting said motor thereto, means for de-energizing the one or the other of said conductors to efl'ect motor coasting conditions, and a plurality of sets of different relay devices energized from each conductor, one relay of each set being adapted, under conditions of normal motor operation, to maintain the energization of said auxiliary system and said relays being adapted, under said coasting conditions, to insure the de-energization of said auxiliary system irrespective of the particular one of said'conductors that is de-energized.

In testimony whereof, I have hereunto subscribed my name this lth day of Oct,

' ANDREW H. CANDEE,

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