USRE22588E - Electrical control system - Google Patents

Description

Jan. 9, 1945. 5 w Re. 22,588

ELECTRI CAL CONTRbL SYSTEM Original Filed July 31, 1940 2 Sheets-Sheet 1 V fl/zarles E ltkw.

Jan. 9, 19 45. c; W n Re. 22,58

' ELECTRICAL CONTROL SYSTEM Original Fild July 51-, 1940 2 Sheets-Sheet 2 W a i l a a a 1,2 1.9 142? 61 60 2'0,.

5;, 0 0 20 I I I r 201? /20 v 4* A2911? 1019 4 I 3mm aeama Jan. 9, 1945 ELEc'rnrcAr. oon'raor. SYSTEM Charles E. Kew, Hamburm N. Y., assignor, by

memo assignments, to General Motors Corporation, Detroit, Mich a corporation of Delaware Original No. 2,250,673, dated July 29, 1941, Serial No. 343,685, July 31, 1940. Application-tor reissue July 29, 1942, Serial No. 452,?899

2% Claims.

My invention relates to an improvement in electrical control systems for a self-propelled vehicle with a 'prime mover and a direct current electric motor drive such as a Diesehelectric locomotive.

The chief object of this system of electrical control is to provide means for automatically eliminating wheel slippage upon starting the we hicle. A second object is to provide a system of control for a self-propelled vehicle which. automati cally overcomes any wheel slippage that may occur upon opening 01' the throttle for starting and which, upon elimination of said wheel slippage, automatically governs the acceleration of the vehicle until the speed of said vehicle corresponds to the setting of the throttle.

Another object-is to provide means to sand the track in front of the leading. wheels auto= matically and simultaneously with the slip prevention means and to assist in stopping the slippage and in restarting the vehicle.

In a sew-propelled vehicle of this type each pair of wheels has an axle to which an electric motor is permanently coupled and the only mechanical connection between the motors is through the track upon which the wheels of the vehicle travel. These motors are usually series wound direct current motors and initially are connected in series because a greater starting torque is obtained with such an arrangement with less current drain on thegenerator. In starting, one pair of wheels driven by one of these motors may begin to slip on the track due to either too rapid acceleration or insufliclent. As a result adhesion between track and wheels. of the increase in speed the back electromotive force 01' that motor will rise. Consequently, since the motors are connected in series, the current flowing through all the motors will decrease and, therefore, will diminish the torque of the motors driving the non-slipping wheels. Once the slip- .page or the wheels is started, the only way of eliminating it is to reduce the supply of current to the motors. This necessitates reaccelerating, and the possibilit still exists'that the slipping may reoccur if the acceleration is again too rapid.

Such slipping causes undue wear of both tracks I l and wheels and results in loss of time during starting. To prevent this undesirable reaction, a number of control systems have been devised for various types of electric motor driven vehicles but none were adapted to the self-propelled type such as the Diesel-electric, and none 2 ever achieved either the complete automatic characeonsis'ting of four series wound motors.

. the starting winding ll.

Figure 1 shows an elevation of a typical selfpropelled vehicle;

Figure 2 gives diagrammatically the circuit of a self-propelled vehicle with the slip prevention circuit and the track sanding device;

Figure 3 illustrates a typical master controller and the associated circuits for governing the operation of the motors under ordinary conditions.

Figure l. on sheet-,2 shows a typical sell-propelled vehicle a with two trucks 2 each having two sets of wheels 3, 3a, 4, and 4a, and each set being driven by an individual motor as shown by t, t, l and a.

Figure 2 shows diagrammatically the electrical circuit of a typical self-propelled vehicle with a prime mover driving a direct current generator which supplies current to the electric motor drive The prime mover- 9 is shown with a drive shaft ill to which are coupled a main generator II, a generator field exciter 2, and an auxiliary generator 53. The generator II is provided with three windings comprising the separately excited field winding M, the commutating windings i6, and The field winding II is separately excited by the generator field exciter l2 and has in'series with it the generator field resistance 18 and IS. The exclter I2 also has three windings comprising a shunt field wind"- ing 20 separately excited by the storage battery ii, a series fieldwinding Illa, and a difierential field winding ii. The series field 20a carries the current passing from the exciter armature I! to the main generator shunt field l4. The'differentlal field I5 is in series with the main generator armatureh H and the commutating fields Ill. The differential field I5 is wound so that it is cumulative to the shunt field 20 and difierential tothe series field 20a. The auxiliary generator H, which supplies current for battery charging, is sell excited by its shunt field 22. Regulation of the auxiliary generator I: may be maintained by means 01 a Tirrell voltage regulator which is not shown. The battery II is operated in parallel with the auxiliary generator I I. Batteryswitch I47 connects the control circuits to the battery 2| and is normally on when the vehicle isoperating.

To start the prime movers the generator II is operated as a'motor using the starting winding .energization of these coils will be discussed in relation with the master controller 21. shown in Figure 3.

The main generator Ii supplies direct current to four series wound motors 5, 5; and 3 shown in Figure 1, the armatures of which are shown in Figure 2 as 28, 29,30 and 3|. fields for these motors are 32, 33. 34 and 35, respectively.

I The operation of these motors is normally governed by the prime mover throttle I54 and the master controller 2| both ofwhich are shown in Figure 3. The throttle regulates the supply of'current to the motors by its control over the prime-mover 9 which drives the main generator Thus the rate or acceleration and the final speed of the vehicle are dependent on the setting 0f the throttle.

The master controller establishes the electrical circuits that govern the operation of the motors. The motors are initially connected in series when the master controller is closed. The further changes in circuit connections are con- The series trolled by the current supplied to them. As the voltage increases suitable transition relays ac- '4|, 42, 43, 44 and 45 and is adapted to complete a circuit governing forward movement of the vehicle when in position F and a circuit governing reverse movement when in position R. When in position 0 as shown intermediate between posi-.

tion F and R the controller is in off position.

Associated with the master controller are the reverser'switch interlock 45, the push-button switchboard 41, and the throttle switch 43 directly connected to the throttle I54. The reverser switch interlock 45 comprises two movable contact segments 49 and 50, the former assuring that the proper direction circuits are completed by the master controller and the latter determining the proper set of sand distributors that will be operated when the sanding device circuit is actuated. When in position F the forward direction circuits will be completed and the forward sand distributors will be actuated whereas when in R position the reverse. will function,

' On the push-button switchboard 41 are three push-button switches 5!, 52 and 53. The first one, 5|, connects the entire control system to the source of current. This source may be either the battery 2| alone as shown or the battery 2| in conjunction with 'the auxiliarygenerator |3 as shown in Figure 1. The second one, 52, completes the prime mover starting circuit. This starting circuit operates in thcfollowing manner. On closing switche 5| and 52, current flows from 7 [2, ground relay bridging contact 13, conductor.

positive conductor 54 through conductor 55, the bridging contact of switch 5|, conductor 55, bridging contact of switch 52, conductor 51, contact finger 45, bridging contact segment 45, contact finger 44, conductor 59, where it divides passing through coils 25 and 25 to negative conductor 59. Coils 25 and 25 actuate switches 23 and 24 connecting the starting field H, the battery 2|, and the main generator all in series. The generator is operated as a motor under the excitation from the starting field and it drives the prime mover 9. This will start the prime mover which will then operate under its own power whereupon push-button switch 52 may be to either position F or R so that the prime mover starting circuit is positively opened when the motors are started.

Push-button switch 53 closes the circuit of the exciter field 2|! by energizing coil 53 which closes the exciter field circuit switch 5| as shown in Figure 2. The throttle switch 49 finally completes the circuits for starting the motors as established by the master controller 27, the reverser switch interlock 4 5, and the push-button switchboard 41.

To start the motors the sequence of operations to be performed are as follows: Initially pushbutton contacts 5|, 52, and 53 are closed. These energize the control circuits of the master controller, startthe prime mover as previously described, and complete the exciter field circuit. The masterv controller 21 is moved to position F or R depending on the direction of motion desired, whereupon the reverser switch interlock When the throttle I54 is opened the throttle switch 4915 closed, the motors are placed in series connection, and the vehicle is started. If the master controller is in the forward position 25..

coils 52, 53 and 54 will be energized.

v The circuit is as follows: current flows vfrom positive conductor 54 through" conductor 55, bridging contact 5|, conductor 55, throttle switch 48, conductor 55, contact fingers 43 and "by means or contact segment 39, .conductors 51 and .53, contact segment 49, conductor 59 to conductors vIll and 'II.. From conductor 10 the current flows on through bridg ng contact 53, conductor I4, exciter field contactor coils 5|),to negative condoctor 59,- and from conductor 'H the current flows on through bridging contact 15, conductor 15, coils I1 and 54 to negative conductor 59. Also current. flows from conductor 51 through conductor l8 and coil 52 to negative conductor 59. The

energization of coil 52 actuates reversing switches 19 shown in Figure 2 so that the current flows through the series fields 32, 33, 34 and 35 of the motors in such direction as to cause forward roposite direction through the fields, thus reversing the rotation of the motors. The exact circuit for these reversing switches is not shown, but the mechanism is well known in the art so that it need not be described further. Qoil is eneras to prevent any seriousdamage.

sized when the master controller 21 is moved to position R. V

The ground relay bridging contact 19 is actuated by the ground coil in Figure 2 whenever any grounds occur in the motor circuits so A similar bridging contact, 82 is placed in the generator field contactor exciting circuit. The circuit for the actuation of. these ground relay bridging contacts is shown but it is not necessary to the ordinary operation of the master controller circuits.

The energization of coil 64 actuates series switch 36, connecting the pairs of motors in series. At the sometime, coil IT is energized and it actuates interlock relay 03} Relay 83 closes a circuit which energizes interlock switch coil 84% actuating, interlock switch 95 which is normally closed. 'This opening of the interlock switch 95 makes it impossible for the parallel switch 31 to be closed by its actuating coil 80.

At this time current also flows from conductor 99 through conductor 81, hridgingcontact as of relay 00, conductors 90 and M, ground relay bridging contact 82, conductor 92, generator field circuit contactor coil $3 to negative conductor 09. The cnergization or cell 53 actuates contactor 93 which. shunts a portion of the generator field re-.

sistance it, thus increasing the excitation.

The prime mover 9 drives the main generator l I, the exciter l2, and the auxiliary generator 55. With the movement of the master controller N to position F the circuits are in position to connect the motor in series to the generator ll. Upon the closing of the throttle switch t8, the control circuits are energized as described above and current flows to the motors connected in series. 'As the throttle is opened wider the prime mover drives thegenerator at a faster rate and the voltage delivered to the motors increases, accelerating them.

Across the motors are connected two automatic transition relay coils t and 95 with their respective resistances S6 and 9'5 as shown in Figure'2. Coil St 'is connected from Junction 90 by means of conductor 50 to junction I100 by means of conductors WI and 502 such that when the motors are connected in series circuit, coil 94 shunts the four motors or when the motors are connected in series-parallel combination, the coil il shunts the parallel combination. Coil 95, is connected from junction I00 by means of conductor-I02 to junction I03 by means of conductor I04 such that it always shunts the one pair'of motors whose armatures are 28 and 29. Thus when the motors are in series connection, coil 95 shunts just this one pair of motors and when the motors are in se ries-parallel connection, the coil 95 shunts both pairs of motors. These transitionrelays are set to operate at certain definite values of voltage. Thus when the voltage supplied to the motor reaches the critical value for transition relay 89,.

it is automatically actuated. When transition relay 99 is actuated, bridging contact 88 as shown in Fig. 3 is opened, deenergizing generator field contactor coil 63, and'bridging contact I05 at relay 89 is closed, completing a control circuit from conductor 69 through conductor 81, bridging con- -tact I05, conductors I06 and I01, interlock relay coil'llli, parallel contactor coil I09 to negative conductor 59;""The energization of interlock relay coil I09 actuates interlock relay I III which in turn actuates interlock switches I5, I I I, and 2. Opening of interlock switch 15 disconnects the circuit of series contactor coil 54 and interlock relay coil 11 which allow the series contactor 39 to open and the interlock switch 95 to close. Ac-

relay H9;

oi interlock switch 15 before the parallel contactor 31 is actuated since the circuit of parallel contactor coil 96 is held open by, interlock switch 95. which is controlled by interlock relay 03 whose coi1 I1 is in series with .the series contactorcoil 64. Thus when the circuit of coils H and is opened by the operation of interlock switch it, interlock switch 85 in the circuit of coil Kit of parallel contactor 31 is allowed to close energizing coil 86 which actuates parallel contactor 9?. By this system of interlocking circuits it is impossible for series contactor 36 to close when parallel contactors 31 or 39 are closed or vice verse.-

With the motors connected in series parallel connection by means of parallel contactors ill and 38, the motors gain speed-until the voltage in transition coil 95 reaches that value which actuates transition relay IIB completing a cirsuit from positive conductor 59 through conductor l H, bridging contact of interlock, switch i it. conductor I'IB, bridging contact of interlock switch H2, conductor H9, transition relay iii; to con ductor I20 where it divides and passes through coils I2I and I22 actuating, a shown in Figur 2,

relays I23 and I24, respectively. The closing-of relay H23 shunts the motor fields 32 and 333 with a resistance I25 and of relay Q20 shunts the motor fields 34 and 35 with a resistance Hill. This alecreases the resistance of the circuit and increases the flow of current through the armatures with a resultant increase in speed. Thus the motors are accelerated to their maximum speed.

In case the throttle is now closed part way the main generator voltage will decrease to such a point that the voltage through the transition relay coil 95 is below that value which will actuate the As a result the circuit or the motor field shunting contactor coils I2I and I22 will be opened, and the resistances I25and I26 will he removed from shunting the fields 32 and 33, and

34- and 35, respectively, The motors will operate in the series-parallel position until the i.throttle I54 is brought back to idling position which will necessary control ior the functioning of my sys-;

tem of control. 1 v

A detailed description of my invention for elim mating wheel slippage on a sell-propelled vehicle will now be given.

For preventing slipp e, resistors I21 and I28 in series and resistors I29 and I30 in series are placed shunting the armatures 20 and 29, and 30 and, respectively as shown in Figure 2. These resistors are equal in value if the resistances oi the armatures are equivalent or else they are proportionalto the resistances of the respective armatures which they shunt. At points m and I32 between the armatures 29 and 29 and between the resistors I21 and I28 respectively, are connected conductors I33 and I34, respectively, which lead to coil I35 of relay I35. Likewise at point I31 between armatures 30 and 3| and at point I39 between resistors. I29 and I30-are connected conductors I39 and I40, respectively, which lead to coil I of relay I35.

.Now when the wheels driven by one of the motors slip an unbalanced condition arises. For

' instance, ifthe motor with armature 28 should be the one involved, the increased back electromotive force in 28 would cause an unbalanced condition toarise. This unbalanced electrical circuit would produce a current in coil I35 actuating relay I35. Upon operation of relay'l35 bridgingcontacts I42 and I43 afllxed to relay I35 complete the circuits controlling the wheel slip prevention device and the sanding device, resped tively.

The circuit completed by bridging contact 142.

causes a current to flow from the circuit of auxiliary generator I3- at junction I44 on positive conductor 54 through conductors I45, I48, I49,

I50, bridging contact I42, and conductor I I' to the coil I52 which is 'thus energized and thence back throughconductors I53 and" to junction I55. The energiz'ationoi' coil I52, in turn, actuates contactor mechanism, I51. The sliding contacts I58 and I59 which are attached to cone tactor mechanism I51 and which are electrically insulated from each other, are moved upward. Contact I58 adds a portion of resistance I50 by means of taps I5I into the field circuit of exciter I2, which decreases the field excitation of the main generator II. This results in the reduction of power supplied to the motors .and, depending on the degree of slipping, only that amount of resistance is inserted thatis necessary to decrease th power supplied to a point where the slipping is stopped and the motor circuits rebalanced. If

.the unbalance'is of large enough magnitude, the

exciter field circuit is broken completely by raising sliding contact I58 to the open tap I52 and the field excitation of the main generator I I is interrupted. Likewise slidingcontact I59 leaves contact bar I53 to engage open contact I54 whereupon resistance I9 is inserted in the field circuit of the main generator II.

This is accomplished by the deenergization of .coil I55 which drops relay I55, removing the shunt from resistance I9.

This latter circuit involving relay I55 need not be used if the residual magnetism in the shunt field I4 of the generator II is negligible. However, when this residual magnetism is large, resistance I9is absolutelynecessary because the residual will excite generator II sufliciently to slow down the correction of the slipping condition.

The circuit may also be so arranged that the exciter field circuit is not opened but Just has the resistance I50 inserted when slipping occurs and removed gradually when the, slipping is checked. However, the most ei'llcient method is as indicated in the diagram and this is my preferred method.

On the resistance I50 four taps I5I are illustrated, but the advisable method is to use as many as are needed to prevent arcing between sliding contact I58 andtapsl5I.

When the slipping has ceased, the motors are again in balanced relation with respect to the resistors I21, I28, I29 and I30. Consequently current no longer flows through either of coils I35 or I and relay I35 isdeenergized. This .ergizes coil I52 allowing relay I51 tov fall.

cases in turn opens bridging contact In which deen- However, contactor mechanism I51 is provided with a plunger I51 operating in dashpot I59 which will permit contactor mechanism I51 to rise rapidly but regulates its return at a controlled rate of acceleration slow enough to avoid wheel slippage under normal operating conditions. This allows "either the insertion of resistance I50 in the circuit. of the exciter field and its gradual re-' the same time; if the former condition prevails,

sliding contact I 59 engages contact bar "I53 energizing coil I55 whereupon resistor I9 in the ciricuit of exciter I2 is shunted by relay I55. This gradual removal of resistor I50 slowly builds up the voltage delivered by plain generator II. This regulated increase in voltage automatically accelerates the motors smoothly without the operator changing the throttle position.

During this sametime, the sanding device has been functioning automatically. To more fully. I illustrate this, a plan view of a typical self-propelled vehicle, such as was shown in Figure 1, and

the arrangements for sanding are shown at I59 in Figure 2. on this vehicle are shown two trucks.

each having two sets of wheels and axles, and

, each axle being permanently coupled to a motor (not shown). The wheels are designated by 3, 3a, 4, and 4a., and their corresponding axles by I10, I19a, HI and I1Ia. In front of wheels 3 and 4 are sand distributors I12 and likewise in front of wheels.3a and 4a are sand distributors I13.

Now when relay I35 is actuated, as noted before, it closes two bridging contacts I42 and I43. Contact*'l43 establishes the sanding device electrical. circuit from positive conductor 54, through conductors I45, I49, I49 and I14, contact I43, conductor I15, push-button contactor I15, conductors I11, I 19 and I19, contact finger I90 of the reverser interlock segment and, depending on whether through either contact finger I9I, conductor I92,

- and magnetic valve coil I93, or contact finger I94,

conductor I95, and magnetic valve coil, I85, to junction I91 and back through conductor I88 to negative conductor 59. The coils I 83 and I95 actuate magnetic valves I99 and I90, respectively.

Magnetic valves I99 and I90 each operate identical sanding systems, the former operating the sanding distributors I12 and the latter the sanding distributors I 13. As to which one is operated depends entirely on the direction in which the vewith the master controller 21, automatically se-' lects the proper sanding circuit.v Push-button I15 provides a means for manual sanding by the operator.

Since the two sanding systems are identical it will be necessary to describe only one. When magnetic valve I99 is closed, compressed air from reservoir I9I ilows through pipe I92, valve I99,

- slippage.

to junction I98 where, the flow divides. Part follows pipes I and I 95 to the sand distributors I12, one being used for each of wheels 3 and 4 and each being supplied with sand from boxes I88. The other part follows pipe I91 to the one way check valve I98 through which the air can only flow in the direction indicated by the arrow, that is, from pipe I81 to I99. Thence it flows through pipe I99 to junction 200 from which lead pipes 20I and 202. One-way check valve 203 which will allow air to flow only from pipe 204 to 20I as indicated by the arrow, prevents the flow through pipe 20I so that all the air flows through 202 to the timing reservoir 205. The surge of compressed air into 205 actuates pressure switch 208. This shorts out the bridging contact I" of relay I36.

When contactor mechanism I88 is opened upon cessation of the slipping, as explained above, contact I48 opens, but pressure switch 206- remains closed due to the action of the timing reservoir 208 and the sanding is continued until the pressure in the timing reservoir-is relieved by the pressure release 201. When this occurs, pressure switch 208 is opened and coil I88 is deenergized.

I This releases the magnetic valve I88 and the sanding ceases.

Should slipping reoccur, the operations would be repeated until either the desired speed was achieved or it was found impossible to move the vehicle without slipping. Such a condition would be probably due to an overloaded train of cars drawn by the self-propelled vehicle and reduction of the load would be necessary to make starting possible.

From the detailed description given, it is evident that once slipping starts, the operation of the vehicle is completely taken out of the hands of the operator until the vehicle reaches the wheel speed for which the operator has initially set the has only to wait until the vehicle reaches the speed for which his throttle is set. If wheelslippage occurs, my control system automatically eliminates that as hereinbefore described. Immediately following this, my system of control automatically takes over the acceleration of the vehicle at a rate slow enough to avoid any wheel The reason that wheel slippage occurs is that the rate of acceleration is a variable dependent on the operator. If he opens the throttle too far, rapid acceleration will result and wheel slippage will occur. Once slipping has occurred my control system eliminates this human element in starting, and is set for a specified rate of acceleration slow enough so that no slipping will result under ordinary conditions. When the speed of travel is reached for which the throttle is set, the control of the vehicle is automatically restored to the operator.

Inthe system of control described, the acceleration of the vehicle normally is dependent on two transition relays which functionautomatically with the amount of voltage supplied to the driving motors. The rate which the voltage is increased controls the rate of, acceleration of the vehicle and is dependent on the acceleration of the prime mover. The prime mover is directly controlled by the throttle. Thus the operator can set the throttle at that position which will give him the rate of acceleration he wants. Consequently, the operator would tend to try to avoid slipping by accelerating slower than necessary. With my invention he need not consider slipping, but merely accelerate as fast as possible and, when slipping occurs, it will be automatically eliminated. Then the vehicle will be automatically accelerated at a rate controlled by my system until the speed for which the operator is holding the throttle is reached.

In case the normal system for starting the vehicle is difl'erent from that which has been described, my invention can be readily adapted to it, since my system of control functions independently of the normal control circuits. For instance, if the normal control circuit consisted of a master controller which manually governed the circuits of the pairs of motors as to whether they are in series or parallel connection, my system of control could be readily adapted to eliminate slipping in such a system Just as well as in the preferred system. This adaptability to any start- ,ing control system increases its utility. The only restriction that can be placed on it is the fact that there must be one or more pairs of motors and the motors constituting each pair must be permanently connected in series. Outside of this one limitation as to the fundamental electrical claim as new and desire to secure by Letters Patent is:.

1. In combination, a self propelled vehicle and an automatic wheel slip prevention circuit, said vehicle comprising aplurality of pairsof motors,

the motors of each pair being permanently conmeans for controlling the ordinary operation of said vehicle; and said wheel slip preventionv circuit comprising a plurality of pairs of series resistanoes, each pair shunting one pair of motors, a plurality of coils, each coil being connected from the terminal common to both motors to the terminal common to both resistors such that upon the occurrence of wheel slippage acurrent will flow through one of said coils due to an increase in the back electromotive force of the motor driving the slipping wheels, means severally actuated by said coils for interrupting the field excitation of said generator whereby the current supplied to said motors will be substantially reduced, eliminating said wheel slippage and further means for automatically, gradually restoring the excitation tosaid generator thereby accelerating-said motors independent of said governing means.

2. In combination, a self propelled vehicle and a system of electrical control including means for eliminating wheel slippage, said vehicle comprising a plurality of pairs of motors furnishing the motive power for said vehicle, a prime mover for producing mechanical energy, converting means for changing the mechanical energy of said prime mover to electrical energy for the use of said mo-' tors, a throttle for governing said prime mover, and controlling means for regulating the electrical output of said converting means; said system of electrical control comprising, a plurality of balanced circuits each consisting of one of said pairs of motors, a pair of series connected resistors shunting said pair of motors and a coil connected between said pairs whereby any wheel slippage which unbalances one of said balanced circuits causes a current to flow in the associated coil, switching means severally actuated by the current in any one of said coils, said switching means causing said controlling means to interrupt the flow of current to said motors, substantially'stopping said motors and eliminating said wheel slippage, whereupon said switching means automatically causes said controlling means to gradually increase the electrical energy supplied to said motors from said converting means, accelerating said motors without wheel slippage to the speed corresponding to the setting of said throttle but independent of said throttle.

3. In combination, a self propelled vehicle, a wheel slip prevention mechanism, anda track sanding device; said self propelled vehicle com prising a plurality of pairs ofmotors, the motors in each pair being permanently connected in series, a prime mover for producing mechanical energy, a conversion means for changing the mechanical energy of said prime mover to electrical energy for use by said motors, a throttle for governing the prime mover, and controlling means for regulating the supply of electrical energy from said conversion means; said wheel slip prevention mechanism comprising a plurality of balanced circuits, said, balanced circuits each comprising one of said pairs of motors. a pair of series connected resistances shunting said pair of motors and a coil connected between said pairs such that upon the occurrence of wheel slippage the equilibrium of those balanced circuits will be disturbed in which are connected the motors coupled to the slipping wheels, and current will flow through the associated coils, switching means severally actuated by the current flowing through any one of said coils, said switching means causing said controlling means to suspend the supply of electrical energy to said motors, substantially stopping said motors and eliminating said wheel slippage, whereupon said switching means automatically and gradually accelerates said motors without wheel slippage by reconnecting said controlling means, all independent of said throttlef said sanding device comprising sand distributing means, relay means for controlling said distributing means, said relay means being actuated by said switching means, and interlocking means for shorting out said switching means retaining said distributing means in operation for a time after the elimination of said wheel slippage to assist in restarting.

4. In combination with a self-propelled vehicle, a system of electrical control comprising a plurality of pairs of motors which drive said vehicle, the motors of each pair being connected in series, a plurality of pairs of series connected resistors, a plurality of coils, a plurality of balanced circults each consisting of one of said plurality of pairs of motors shunted by one of said plurality of pairs of resistors with one of said coils connected between said pairs, a relay severally actutially balanced circuits will be automatically eliminated.

5. In combination, a self-propelled vehicle and a system of electrical control, said vehicle comprising a plurality of pairs, of motors, the motors of each pair being connected in series, a generator supplying current-to said motors and a prime mover driving said generator; and said system of control comprising a plurality of resistors, a plurality of coils, a plurality of electrical balanced circuits consisting of one of said plurality of pairs of motors shunted by one of said plurality of pairs of resistors with one of said coils connected between said pairs, a relay severally actuated by said coils, and means actuated by said relay whereby any unbalance of said bal anced circuits will be automatically eliminated.

6. In combination, aself-propelledvehicle and a system of electrical control for wheel slip prevention, said vehicle comprising a plurality of pairs of motors, the motors of each pair being permanently series connected, a generator supplying current to said motors, a prime mover driving said generator, a throttle regulating said prime mover and a master controller governing the ordinary series and series-parallel operations of said motors; and said system of control for wheel slip prevention comprising a plurality of by said coils, means actuated by said relay whereated by said ,coils, and means actuated by said relay whereby any unbalance'in any of said inipair shunting one of said pairs of by when one of said balanced circuits is disturbed due to wheel slippage, said unbalance is removed independent of said throttle and said master controller.

' 7. In combination, a self propelled vehicle and a system of electrical control, said vehicle comprising a plurality of motors driving said vehicle, the motors of each pair being permanently connected in series, a generator supplying current to said motors, an excitenproviding external excitation for said generator, a prime mover driving said generator and said exciter, a throttle for regulating said prime mover, a master controller for governing said motors, and control circuits assisting said master controller to connect said motor for series and series-parallel operation; and said system of electrical control consisting of a plurality of pairs of resistors, each motors, a plurality of coils, each coil being connected between correlated pairs of motors and resistors such that any unbalance in the back electromotive force between correlated motors in any pair will cause a current to flow in the associated coil, a relay severally actuated by said coils, a contactor mechanism actuated by said relay, the movement of said contactor mechanism whereby said unbalance is eliminated, the elimi-= nation of said unbalance deenergizing said relay and allowing said contactor mechanism to return to normal position, means limiting said return movement of said contactor mechanism to a dellnite measured time travel, restarting and accelerating means for said motor controlled by the return movement means actuated by of said contactor mechanism, all said means functioning independently of 'said the wheel slippage is eliminated.

of each pair being connected in series, a generator supplying current to said motors, a prime mover driving said generator, a throttle regulating said prime mover, and a master controller governing the regular operations of said motors: said system of electrical control comprising a plu- Iunctioning independently of said throttle and rality of pairs of series connected resistors, a

eliminating said difference in counter electromotive force and for accelerating said motor to the desired speed independent of said throttle and said master controller.

9. In combination, a self-propelled vehicle, a

system of electrical control for preventing wheel slippage, and a track sanding device, said vehicle comprising a plurality of pairs of motors, the

motors of each pair being connected in'series, a

generator supplying current to said motorsan exciter supplying excitation to said generator, a 1

master controller governing the operation of said motors, control circuits associated with said master controller for connecting said motors in series and series-parallel operation, a prime mover driving said generator and said .eXciten and a throttle for regulating said prime mover; said system of control comprising a plurality of pairs of series connected resistors, a plurality of coils, a pillrality of balanced circuits, each consisting of one of said pairs ofmotors shunted by one of said pairs of resistors with one of said coils connected between said pairs, a relay severally actuated by said coils, means actuated by said relay whereby any unbalance in any of said balanced circuits produced by wheel slippage will be automatically eliminated and the track sanding device will be operated simultaneously; and said track sanding device comprising a magnetic valve actuated by said relay, sanding means controlled by said magnetic valve, and timing means actuated by said magnetic valve, said timing means shunting said relay and retaining said sanding means in operation independent oi! said relay whereby the sanding is continued for a time after 10. In a system of electrical control for wheel slip prevention, a self-propelled vehicle, a plurality of pairs of motors driving said vehicle, the motors of eachpair being permanently series connected, a generator supplying current to said motors, a primemover driving said generator, 9. master controller governing the operation of said motors, a throttle governing said prime mover, a,

plurality of pairs of resistors, a plurality of coils, a plurality of balanced circuits, each consisting of one of said plurality of pairs of motors shunted by one said plurality of pairs of resistors with one of said coils connected between said pairs, such that if anywheel slippage occurs on starting said vehicle with said throttle and said master controller, the equilibrium of one of said balanced circuits will be disturbed causing a current, to flow through the correlated coil, a relay severally actuated by said coils, and means actuated by said relay whereby the balance of said circuit is restored and said vehicle is automatically accelerated to the desired speed, aid means said master controller. I I

11. In combination, a self propelled vehicle and a system of electrical control including means for eliminating wheel slippage, said vehicle comprising a plurality of pairs of motors, the motors or each pair being in series, a generator supplying current to said motors, a prime mover driving said generator, 9, throttle controlling said prime mover, and auxiliary circuits for controlling the ordinary operations of said motors associated with said throttle; said system of control comprising a plurality of pairs of series connected resistors, each pair shunting a pair of motors, a plurality of coils, each coil connected between a pair of motors and the corresponding pair of resistors such that, ii any material difference in the counter electromotive forces of the motors forming a series pair arises on starting said plurality of motors by means of said throttle, a current will flow through the correlated coil, a relay severally actuated by said coils, and means actuated by said relay whereby the current supplied by said generator is interrupted, substantially stopping said motors and eliminating said difference in counter electromotive force, and further means whereby said motors are re started and accelerated smoothly without said.

diflerence recurring, all of said means functioning independently of said throttle and said aux-' iliary circuits.

' 12-. In combination, a self propelled vehicle, a system of electrical control, and a track sanding' device, said vehicle comprising a plurality of pairs of motors-the motors of each pair being permanently connected in series, a generator supplying current to said motors, a, prime mover driving said generator, a throttle controlling said prime mover, and suitable auxiliary control circuits responsive to'said throttle for governing said motors; said system of control comprising a plurality of pairs of series connected resistors, a plurality of coils, a plurality of balanced circuits each consisting of a pair of said resistors shunting a pair of said motors with one of said coils connected between said pairs, a relay severally actuated by said coils when the equilibriumof 7 any of said balanced circuits is disrupted, means actuated by said relay to restore said balance and to operate said track sanding device simultaneously, independent of "aid throttle and said auxiliary, circuits. 1

13. In combination, a self propelled vehicle and a system of electrical control, said vehicle comprising a plurality of pairs of motors driving the vehicle, the motors of each pair-being permanently connectedin series, a main generator supplying current to said motors, a separately excited field for said generator, an exciter supplying current to said generator field, a prime mover for'driving said generator and exciter, a throttle for governing the speed of said vehicle by controlling the power output of said prime mover, and a master controller and suitable auxiliary control circuits for governing the operation of said motors; and said system of control comprising a plurality of pairs of resistors. each pair shunting an individual pair of mot-arse plu rality of coils, each coil being connected between corresponding pairs of motors and resistors such that any material difference in speed between the motors in any one ofv said pairs will produce a current in the associated coil, means severally actuated by said coils for interrupting the excitation of said generator from said exciter whereby the supply of current to said motors is interrupted thereby substantially stopping said motors momentarily and eliminating said speed diiierence, and further means whereby the motors are automatically restarted andaccelerated smoothly to the desired speed, said system of electrical control functioning independently of said throttle and said master controller. 1

14. In combination, a self propelled vehicle and a system of electrical control, said self propelled vehicle comprising a plurality of pairs of motors driving said vehicle, the motors in each pair being permanentlyv connected in series, a main generator supplying a current to said motors, an exciter providing field excitation for said main generator, a separately excited field for said exciter, a control circuit for regulating the operation of said motors, a master controller governing said control circuit, a prime mover driving said main generator and exciter, a throttle for governing the speed of said prime mover, an auxiliary source of current" for supplying said control circuit, and a switch controlled by said throttle for connecting said auxiliary source of current to said control circuit, said system of electrical control comprising a plurality of pairs of series connected resistors, a plurality of coils, a plurality of balanced circuits each comprising one of said, pairs of motors shunted by one of s said pairs of series connected resistors with one of said coils connected between said pairssuch that a difference of speed between said motors in said pair due to wheel slippage will cause a current to flow'through said coil, a relay severally actuated by said coils, a contactor mechanism and a sanding device controlled by said relay, said contactor mechanism consisting of a movable shaft, a plunger attached to the lower end of said shaft, a, dash-pot in which said plunger circuit and inserts the second resistance in themain generator field circuit, thereby interrupting the sourceoi current to said motors, elimihating wheel slippage, and restoring the equilibrium of saidbalanced circuits; whereby said contactor mechanism is allowed to return to its initial position but at an automatically controlled rate dueto the action of said dashpot said rate being such that the first resistance is slowly removed from the exciter field circuit thereby slowly accelerating said motors automatically at a, controlled rate slow enough to avoid .wheel slippage; and said sanding devicecomprislng magnetic valves actuated bysaid relay, pneumatic sand distributorscontrolled by said magnetic valves, a pneumatic pressure switch actuated by; said magnetic valves, and a timing pressure release. valve for controlling the operation of said pressureswitch whereby the track in frontof the wheels-is sanded automatically and thesanding is'oontinued after the elimination of wheel slippage, due to the action '.of said pressure asslstin restarting, said system of control operating independent of said throttle and master controller.

In combination, a self propelled vehicle, a system of electrical control, and a track sanding device, said vehicle comprising a plurality of pairs of wheels adapted to travel on a track; an axle for each pair of wheels, a plurality of pairs of motors, the motor of each pair being permanently connected in series and each motor being permanently coupled to,a separate axle, a main generator supplying current to said motors, a separately excited field circuit for said generator, an

exciter providing the external excitation for said motors; said system of control comprising a plur rality of pairs of resistors, each pair shunting a pair of motors, a plurality of coils, each coil connected from the terminals between motors of each pair to the terminals between the resistors of each p'airsuch that when one pair of wheels slips on the track a current will be produced in the coil connected in the circuit of the motor coupled to said pair of wheels due to the difierence in counter electromotive force between said motor and its series pair, a relay severally actuated by said coils, a contactor mechanism actuated upwardly by said relay, a variable resistance, means whereby on the upward movement of said contactor mechanism said resistance is inserted in' the exciter field circuit, a resistance in the generator field circuit, shunting means normally short circuiting said resistance in the generator field circuit, means whereby on further upward movement of said contactor mechanism the" exciter field circuit is opened and the' shunting means is removed from said resistance in the generator field circuit such that the current supply to said motors is interrupted, the motors are substantially stopped, said slipping is eliminated, said coils are deenerg'ized, said relay is released, and said contactor mechanism is allowed to move downward; a. dashpot for providing definitely measured downward time movement of said condownward movement of said contactor mechanism replaces said resistance in the exciter field circuit and replaces said shuntingmeans around said resistance in the generator field circuit, further means whereby said controlled downward movement of said contactor mechanism progressively removes by small increments said resisting reservoir andheld closed for an interval of ance in the exciter field circuit such' that the -motors are automatically restarted and accelerated tothe desired speed smoothly and without slipping of said wheels, all said means functioning independently of said-master controller and its associated circuits and of said throttle; said track sanding means operating simultaneously with said slip prevention means, and comprising a magnetic valve actuated by said relay simultaneously withsaid contactor mechanism, pneumatic means whereby said magnetic valve controls the sanding of said tracks. a timing reservoir which functions when said magnet c valve is closed, a pressure'switch operated by said timtime determined by said timing reservoir, said a system of electrical control, said vehicle comprising a plurality of pairs of motors, the motors in each pair being permanently connected in series, a generator to supply current to said motors, a separately excited field circuit for said generator, an exciterjor supplying said field excitation, a prime mover driving said generator and exciter, a throttle controlling the speed of said prime mover, a master controller governing the operation of said motors, and control circuits associated with said master controller for gov ernlng the ordinary series and series-parallel operations of said motors; said system of control comprising a plurality of pairs of series connected resistors, a plurality of coils, a plurality of balanced circuits each composed of one pair of said motors shunted by one pair of said resistors with one of said coils connected between said pairs such that any unbalance of currents through said pair of motors will produce a current in said coil, a relay switch severally actuated by current flowing through any one of said plurality of coils, switching means operated by said'relay switch whereby the field excitation of said generator is interrupted thereby substantially stopping said motors and restoring the equilibrium of said balanced circuits, whereupon said switching means will automatically reestablish the excitation of said generator at a controlled rate so as toaccel- .erate said motors without unbalance of currents independent of said throttle and master controller.

1'7. In combination, a self propelled vehicle and a system of electrical control, saidvehicle comprising a plurality of pairs of series motors driving said vehicle, the motors in each pair being permanently connected in series, a .main generator for supplying current to said motors, a

separately excited field for said generator, means for exciting said field, a prime mover for driving said generator, and a throttle for governing said prime mover; said system of electrical control comprising a plurality of pairs of series connected resistors, a plurality of coils, a plurality of balanced circuits eachconsisting of one pair of said motors shunted by one of said pairs of resistors with one of said coils connected between said pairs of motors and resistors such that a current will flow through said coil whenever there is a difference of speed between the motors constituting said pair, switching means severally actuated by said coils whenever a current passes through one of them, said switching means interrupting said field excitation for said generator, whereby said motors are substantially stopped and said speed difference is eliminated, and further switching means whereby said field excitation is gradually restored to its original value.

automatically so that said motors are accelerated at such a rate that no speed difference arises, all independent of said throttle.

18. In combination, a self propelled vehicle and a. system of electrical control, said vehicle comprising a plurality of pairs of motors driving said vehicle, the motors in each pair being permanently connected in series, a generator for supplying current to said motor, a. separately excited fleld for said generator, exciting means for said field, a prime mover furnishing the driving energy for said generator, and a throttle for govpair of series connected resistors shunting said pair of motors, and a coil connected between said pairs, such that any wheel slippage will disturb the electrical equilibrium of said balanced circuits due to an increase in back electromotive force of the motor associated with the slipping wheel and current will flow through said coil, switching means severally actuated by the current flowing through any one of the coils of-said balanced circuits; a. mechanism for sanding the tracks, said switching means interrupting the field excitation of said generator and actuating said mechanism for sanding the tracks thereby substantially stopping said motors and eliminating said wheel slippage, whereupon further switching means will automatically gradually restore said field excitation accelerating said motors at a controlled rate without wheel slip-page independent of said throttle, said sanding mechanism operating for a time after the elimination of said wheel slippage to aid in restarting.

19. In combination with a self propelled vehicle and a wheel slip prevention means, a track sanding device comprising sand distributing means, relay means actuating said sand distributing means, said relay means being responsive to wheel slippage, interlocking means shorting out said relay means and maintaining said sand distributing means in operation for a time after elimination of wheel slippage by said wheel slip prevention me ans.

20. In combination, a self-propelled vehicle and a system of electrical control including a means for controlling wheel slippage, said vehicle comprising a pair of motors permanently connected in' series, a generator-supplying current to said motors, and a prime mover driving said generator; said system of electrical control comprising a pair of series connected resistors, a coil, an electrically balanced circuit which assumes an unbalanced condition upon the occurrence of wheel. slippage comprising said pair of motors shunted by said pair of resistors with said coil operatively connected between said motors and resistors so that when whee1 slippage unbalances said circuit said coil is energized, and means actuated by said energized coil to eliminate said unbalanced condition.

21. In combination, a self-propelled vehicle and a system of electrical control including means for eliminating wheel slippage, said vehicle comprising a pair of series wound motor permanently connected in series, a main generator for supplying current to said motors, a separately excited fleld for said generator, electrical means for exciting said field, a prime mover driving said generator, and a throttle for governing said prime mover; said system of electrical control comprising a pair of series connected resistors, a coil, a circuit consisting of said pair of motors shunted by said pair of resistors with said coil connected between the pairs whereby a current will flow through said coil whenever there is a difference of speed between the motors of said pair due to wheel slippage, switching means actuated by said energized coil, said switching means interrupting said field excitation for said generator, whereby the current s pply to said motors is substantially stopped and said speed difference is eliminated, and whereupon said switching means automati- 1 cally restores said field excitation to its original value so that said motors are accelerated to the speed corresponding to the throttle setting, all independent of said throttle. V

22. In combination, a self-propelled vehicle,-

and a system of electricalcontrol including means for controlling wheel slippage, said vehicle comprising a pair of motors permanently connected in series, a generator supplying current to said motors, a separately excited field for said generator,

electrical means for exciting saidfield, a prime mover for driving saidgenerator, and a throttle for governing the operation of said prime mover; said system of electrical control comprising a pair or series connected resistors, a coil, a balanced circuit consisting of said pair of motors shunted by said pair of resistors with said coil operatively connected between said motors and resistors whereby upon the occurrence of wheel slippage said coil is energized, switching means actuated by said energized coil for interrupting the excitation of said generator field whereby the current supply tosaid pair .of motors is substantially trol comprising a p'air'of seriesconnected resistors, a coil, a balanced circuit arranged to be un- I balanced upon the occurrence of wheel slippage ing magnetic means responsive to said switching I means, sand distributing means actuated by said magnetic means, timing means actuated by said magnetic means, said timing means shorting said switching means so that the operation of said sand distributing means is maintained for a time after the elimination of wheel slippage.

stopped and said wheel slippage is eliminated,

said switching means restarting and accelerating said motors upon elimination of wheel slippage and upon continued repetition of said wheel'slippage, said system of control functions to eliminate each repetition, all independent or said throttle. f

23. Incombination, a self-propelled vehicle, a system or electrical control including wheel slip controlling means, and a track sanding device; said vehicle comprising a pair of motors to drive said vehicle, said motors being'permanently connected in series, a generator for supplying current to said motors, electrical means for separately exciting said generator, a prime mover i'or drivin'g said generator, and a throttle for governing the prime mover; said system of electrical control comprising a pair 0! series connected resistors, a coil, a balanced circuit consisting or said pair of motors shunted by said pair of resistors with said coil connected between said motors and resistors such that upon the occurrence of wheel slippage said circuit is unbalanced and a current flows through said coil, switching means actuated by said energized coil to eliminate said wheel slippage and to operate said sanding device simultaneously; said switching means interrupting said generator field excitation and substantially stopping said motors, and said switching means thereupon restoring said generator field excitation whereby said motors are accelerated automatically without recurrence of said wheel slippage; and said track sanding device comprising pneumatic sand distributing means,magnetic means responsive to said switching means and controlling said pneumatic sand distributing means, timing means pneumatically actuated by said magnetic means and arranged to maintain said sand distributing means functioning after elimination of said wheel slippage to aid' in restarting said vehicle.

324. In combination, a self-propelled vehicle; a system of electrical control including means to control wheel slippage, and a track sanding device, said vehicle comprising a pair of permanently series connected motors driving said vehicle, a prime mover for supplying mechanical energy to 'said vehicle, a conversion means for changing said mechanical energy to electrical energy for s the use of said motors, and governing means for controlling said prime mover; said system of con- I 25. In combination, itself-propelled vehicle and a system of electrical control including awheel slip controlling means, said vehicle comprising a plurality of pairs of motors driving said vehicle, th motors of each pair being permanently connected in series, a generator supplying current to said motors, a separately excited field for said generator, a prime mover driving said generator,

and governing means for operating said prime mover; said system of control comprising a plurality 0! pairs of series connected resistors, a plurality of coils, a plurality of balanced circuits, any one of which assumes an unbalanced condition upon the occurrence of wheel slippage, each comprising one 01' said plurality of pairs of motors shunted by one of said plurality of pairs of resistors with one of said coils operatively connected therebetween so that when wheel slippage unbalances any one-ot said circuits the corresponding coil is energized, switching means severally actuated by said energized coil, said switching means interrupting the field excitation of said generator thereby substantially interrupting thecurrent supplied to saidmotors and eliminating said wheel slippage, and said switching means thereupon automatically restoring said field excitation and accelerating said motors, all independent of said governing means. Y

26. In combination, a self-propelled vehicle and i a system 01' electrical control, comprising a plurality of traction motors, a generator supplying power to said motors, a prime mover driving said generator, power output regulating means forsaid generator, and control means for said power output regulating means for governing the power supplied to said motors whenever a diflerence in speed occurs between any of said motors.

27. In a drive and control system, a source of power comprising a generator, output regulating means therefor and aprime mover for driving said generator, a plurality of driving motors, means for connecting said motors in series to said generator and control means for said output regulating means, said control meansbeing responsive to slight difle'rences in speed between said motors to prevent over-speeding of any one oi said driving motors.

28. In a drive and control system for a vehicle comprising a plurality of driving axles having driving wheels fixed thereon, a plurality of traction motors, each motor being operatively conoases nected to drive an individual driving axle, a prime mover generator power plant suppiying'power to said motors, means for connecting said motors in series circuit relation with said generator, output regulating means for said power plant and control means for said output regulating means, said control means acting automatically and promptly in response to slight differences in speed between the motors resulting from driving wheel slippage to cause a reduction inthe output-of the power plant, thereby to promptly check overspeeding of any motor and wheel slippage.

29. In a vehicle drive and control system comprising a prime mover generator power plant, output regulating means therefor, a plurality of pairs of vehicl traction motors connected in series, means tor connecting pairs of motors in series or parallel relation with the generator of the power plant, generator excitation reducing Ole means operable to cause a reduction in the power output of the generator to a negligible value, and automatic control means having separateconnections witheach pair of motors and adapted to act promptly in response to slight differences in the back voltage between-the motors of each pair of motors due to a slight overspeeding of anymotor of any pair 01' motors to control operation of the generator excitation reducing means to promptly check overspeeding of any motor of a pair of motors.

CHARLES E. IKEW.

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