US2360092A - Electrical control system - Google Patents

Description

Oct. 10, 1944. H. s. YOUNG ELECTRICAL CONTROL SYSTEM Filed Aug. 7 1942 INVENTOR. HenPyS.

BY a

Ybung.

1L5 Zli 501 HISATTORIVEY.

Patented Oct. 10, 1944 UNITED PATENT OFFICE ELEoTRIoALcoN'rRoL sY s'i'EM Henry S Youngi wilkinsburg, Pa., assignor to The Union Switch & Signal Company, Swissvale, Pin, a corporation of Pennsylvania Application August 7, 1942} Serial No. 453,977

1 claim.

My invention relates to electrical control systems such, for example, as systems for the con trol of railway track switches and is particularly directed to improved means for interrupting the supply of energy to the switch motor or other electrical load in the event of an overload. or a defect in the control circuits M In some types of switch control systems the switch motor is controlled from a remote point, such as an interlocking tower, by current supplied from a source at the control point over suitable control wires to control: relays, while energy is also supplied from this source over the control wires to the switch motor to operate the motor.

It is an object of this inventionito provide improved means for use in a system of this type to interrupt the supply of energy to the switch motor in the event that the motor draws atnormal current for an excessive period-.-

Another object of the invention is to provide an improved system. of the type described and arranged to employ an overload relay of standard design. V

A further object of the invention is to provide improved means for detecting defects in the control wires employed in systems of the type described. W

Another object of the invention is to provide in a system of the type described improved cross detecting means which will detect crosses between wires associated with different switches as well as between wires associated with the same switch. V g

A further object of the invention is to provide an improved switch control system.-

I shall describe two forms of apparatus embodying my invention, and shall then point out the novel features thereof in the claim;

In practicing my invention I' employ a normally energized stick relay to control the supply of energy from a source tothe control wires over which energy is supplied to the control relays and to the motor for a switch, while I employ an overload relay of standard design to detect abnormal flow of current in these wires, and, in such an event, to interrupt the circuit of the stick relay. In addition, a contact of a cross detecting relay is included in the circuit or. the

stick relay, while a pick-up circuit for the stick relay is established on movement of the switch control lever to its intermediate position.

In one form of the invention the cross detecting relay is provided with two opposing= wind ings one of which is connected in series with the wire leading from one terminal of the source and the other of which is connected in series with the wire leading from the other terminal of the source. Normally these windings are equally energized and offset each other so that the: relay contact remains released, but if a defect develops the windings will not be equally energized and the relay contact will pickup and interrupt the circuit of the stick relay to prevent supply of energy from the source.

In the drawing,

Fig. 1 is a diagram of a switch control system embodying my invention. and

Fig. 2 is a diagram illustrating a modifiedform of Fig. 1, also embodying my invention.

Similar reference characters refer to similar parts in both views.

Referring to Fig. I of the drawing. there is shown therein a railway track switch W which is moved. between a normal and a reverse position by means of an electric motor M. The motor drives the switch through a suitable mechanism, not shown. V

The switch W' is controlled by a switch control lever L which may be located at ariy suitable control pointj this lever may for-in part of an interlocking machine. The lever L is movable between a normal position N, and a reverse position R, and controls connection from one terminal of a source of current, such a battery I0, to a normalwire' I I and a reverse wire 12,. while the other terminal of the battery is connectedte a common wire I5. The lever L has associated therewith overload' relay OR, a normally energized stick relay a. polarized cross detecting relay X, and a lamp Relay X is of the well-known type in which the polar contact 28,. when once closed by the push; button PB, remains closed thereafter even though the relay is deenergized, and openswhen energy of reverse polarity is applied to the winding. When opened, contact 28 will remain in its open position until it is reset by operation of the push button- The switch W has associated therewith. a normal control relay NC and a reverse controlrelay RC which are energized by current supplied over thenormal and reverse wires l l and [2-, respectively, and which control the supply of energy over these wires tothe motor v Inaddition, the switchW has associated therewith contacts Il and [8 which are operated in accordance withmovement of the switch. The contact H controls the circuits of the relays NC and RC and is arranged so that it engages a the normal position thereof.

I I v 2,360,092 @stationary contact 26 in all positions of the 7 switch except its reverse position, and, engagesv a contact 2| in all positions of the switch except 9 controls the circuit of the switch motorand is arranged so that it engages a contact 22in all positions of the switch except the reverse po- The contact [8 sition thereof and engages a contact 23 in all po sitions of the sw' on except the normalcposition thereof. r

Theequiprnent is shown in the condition which it assumes when the control lever Land the switch W are in their normal positions. v As the Ll establishes connection from the positiveterminal of the battery [6 to normaljwire IL, This connection includes in series therewith front con= tact 25 of relay CR, and .thermalresistance 26 and winding: of relay OR in multiple. time the relay CR is energized by current supplied over its stick circuit which is traced from the positive "terminal of the battery through front contact ,25'of relay CR, back contact-2T of relay OR, 'nermal polar contact 28 of relay X; and

the battery.

As the relay CR windingof relay CR to, the negative terminal of is energized, its contact 36 is picked up and establishesconnection from the negative terminal of the battery to common wire l5, while its contact 25 interrupts the circuit of the indication lamp K. r a l t ,As ,thejlever Lis in itsnorrnal position, contact g L2 connects one terminal of the Winding of relay Xto reverse wire;|2, but at this time wire 12 is not connected to a "source of current so the polar thereby interrupt the circuit tracedfabove for supplying =energy'to the motor, while contact I1 is moved out of engagement with contact to interrupt the circuit of relay RC so that its contact 32 releases and additionally interrupts the circuit of the switch motor. 7

Similarly,'if while the switch is in its reverse 6 position thec'operator desires to move it to its normal position,.he can doso by moving the switch control'lever L to its normal position. On

this movement of the lever L, contact Ll interrupts connection from the battery to the reverse lever L is in' its normal position, its Contact 'At this wire I2 and connects the battery to the normal 7 'wire I I, whilecontact L2 transfers connection of the relay X from the normal to the reverse wire.

On connection of the battery to the normal 1 wire I], energy is supplied to the relay NC over the circuit which is traced from wire H' through {armature 34, back contact 320i relay RC, concontact'28oi relay X remains in its closed position. a l l As the switch W is in its normal position; con-- tact l! is out of engagement with contact 2| and thus interrupts theicircuit of the relay NC so thatits contact 3! is released and interrupts connection from wire I l to the switch motor M. The

motorptherefore, is deenergized at this time.

'-If the operator wishes to move the SWitch'W to its reversepositioml he may do so by movingthe lever L to, its 'reverseposition. On movement of the lever L to its reverse position, contactLl 1 interrupts connection from the positive terminal of the battery to normal wire II and connects it I to reverse wire I2, while contact L2 interrupts connectionof one terminal of the winding of relay X'withwire l2 and connectsit to wire ll.

, When connection is established from the bate tery to reverse wire l2, the'reve'rse control relay RC is energizedover the circuit which istraced from wire l2 throughf'winding of relay RC, contacts 26 and l'!,common wire [5, and front coni tact 36 ofrelay OR to the negative'terminalof a the battery [6; Accordingly; contact 32 of relay RC picks up'an'd establishes the' 'circuit' to energize the'motor M to cause it to movethe switch minal of the battery I0 through front contact 25 of relay CR, thermal resistance 26 and wind- V contact 3! releases and additionally the circuit of the switch motor.

tacts 23 and I8,'motor field winding 35, common Wire" [5, and front contact 36 of relay CRto the negative terminal of the battery. The motor, therefore, operates to move the switch to its normal position, and when thelswitch reaches 'its normal" position, contact, I8 is moved out of engagement with contact 23 to interrupt the supply of energy to the, switch motor, while contact I! is'moved'out of engagement withcontact 2i to interrupt ,the circuit of relay NC so that its interrupts It will be-seen that each of'the circuitsior supplying energy to the switch motor includes in series therewith theresistance 26'and the winding of relay 'OR. The relay OR and the re- "sistance 26 are proportioned so that undernormal conditions most of the energyvsupplied the motor -M is supplied through the resistance 26 L and 'too little energyis supplied through the I W to its reverse position. The circuit for ener-l gizing'the motor ,istr'aced from the positive tering of relay OR-in multiple, contact Ll in its re-g verse position, reverse wire 12, front contact 32'of relay RC, motor armature 34, back contact 3! of r'elay NC, contacts 22 and I8, motor field wind-' ing 35," common wire l5, and front contact 30 of ,relay CRto the negative terminal of the batin tery. The motor, therefore, operates to move the switch W to its reverse position, and when the switch reaches its reverse position, contact I8 is moved out of engagementwith-contact 22 to I winding of the relay OR to pick up: the relay contact. Accordingly, contact 21 of relay OR remains released and maintainsthe circuit of relay CR so that the contacts of relay. CR remain picked up in readiness to supply energy to the switch motor.

Furthermore, the relay OR is of a type the i I contacts of which 'are'slowto pick up sothat they will not become picked up on momentary abnormally high current'ilo'w in the motor circuit; such as occurs when movement of the switch is initiated, or when the switch is reversed in mid-stroke.

' .Theresistance 26 has a thermal coeflicient of resistance such that the resistance of the unit increases as the temperature oi the material of which the-unit is constructed increases. IAccordingl'y, if the motor draws current of unusually highva'lue for an abnormallylong period, as occurs when movement of the switch is ob structed, the resistance 26 willbec ome heated to a temperature such-that itsfres'ista'nce increases to a degree effective to cause the current supplied through the winding of the overload relay OR to be great enough to pick up the relay contact 21.

When contact 27 of relay OR picks up, it interrupts the stick circuit of the relay CR and contacts 25 and 30 of this relay release and cut '7' oil" the supply ofenergy from the battery to the switch motor, and also to whichever control relay is energized. In addition, on release of the relay CR, the supply of energy to the overload relay OR is cut off and its contact 21 releases,

while release of contact 25 of relay CR interrupts the stick circuit for this relay so that on release of contact 21 of relay OR energy will not be supplied to relay CR and the contacts of this relay will remain released.

On release of relay CR, contact 25 establishes the circuit of the indication lamp K and this lamp is lighted to indicate to the operator that the supply of energy to been interrupted.

This system is arranged so that the operator may quickly regain control of the switch after an'overload. In order to secure control of the switch when the relay CR is released, the lever L is moved to its center position C so that contact L3 establishes the pick-up circuit for relay CR. This circuit is traced from the positive terminal of the battery through contact L3, back the switch motor has contact 27 of overload relay OR, normal polar contact 28 of relay X, and winding of, relay CR to the negative terminal of the battery. Accordingly, the contacts of relay CR pick up so that contact 25 establishes the stick circuit for therelay and also establishes connection from the positive terminal of the battery to contact Ll so that energy may be'supplied through this contact to the control relays and to the switch motor.

In addition, on picking up of relay CR, contact 25 interrupts the supply of energy to the lamp K, while contact 30 establishes connection from the negative terminal of the battery to wire IS.

The operator may now move the lever L to either its normal or its reverse position to energize one or the other of the control relays and thus cause the switch motor to be energized to move the switch to one position or the other.

The system of this invention is arranged so that the cross detecting relay X controls the energy is not supplied to the relay X and its contact 23 remains in its normal position and maintains the circuit of the relay CR.

However, if while the lever L is in its normal position a cross develops between the wires H and I2, 01' if for any other reason connection is established from the positive terminal of the battery to the relay X, the direction of flow of this energy through the winding of relay X is such that the contact 28' of the relay is moved to its right-hand or reverse position. On this movement of the contact 28 it interrupts the circuit of relay CR so that contacts 25 and 3|] of the relay CR release and cut off the supply of energy from the battery Ill. This prevents energization of either control relay or the switch motor and thus prevents movement of the switch after such a cross or other defects in the system has developed.

In addition, on release of relay CR, contact 25 establishes the circuit of the lamp K and this lamp is lighted to indicate to the operator that a possible defect may be present.

Similarly, if while the lever L is in its reverse position, energy is supplied to the normal wire I I, the relay X will be energized and its contact 28 will interrupt the circuit of the relay CR.

This system is arranged so that the contact 28 of relay X is included in the pick-up circuit of relay CR so that after movement of contact 28 to its reverse position, the pick-up circuit for the relay CR will not be established on movement of the control lever L to its intermediate position. Accordingly, after the relay X detects a defect in the system and relay CR releases and prevents movement of the switch, the operator cannot regain control of the switch by manipulation of the control lever L. The inability of the operator to secure control of the switch will inform him that there is a defect in the equipment and that he must take steps to have this defect corrected. After the maintainer corrects the defect, he may cause movement of the contacts of relay X to their normal 01 left-hand position by suitable means, such as push button PB.

As the relay X controls only the current of the relay CR, the relay X may be of much lighter and less expensive construction than is required when the motor current is controlled over contacts of the relay X.

' In Fig. 2 of the drawing there is shown a modification which provides increased protection against crosses between the wires connecting the control point and the switch. The modification shown in Fig.2 of the drawing is particularly desirable where two or more switches are governed from the same control point and are controlled and operated by energy supplied from the same source. In such situations the modification shown in Fig. 2 of the drawing operates to detect crosses between the wires associated with different switches as well as between the wires for one switch.

In the diagram forming Fig. 2 of the drawing the equipment for controlling two switches is shown but it should be understood that the invention is applicable to situations where more than two switches are involved.

Referring to Fig. 2 of the drawing, there is shown therein a first switch control lever IL which controls a first switch iW, and a second control lever 2L which controls a second switch 2W. The equipment in the field for each switch is the same as that shown in connection with the switch shown in Fig. 1.

The equipment associated with each control lever is the same as that shown in Fig. 1 except for the substitution of a cross detecting relay XR for the cross detecting relay X employed in the system shown in Fig. 1. Each relay XR has a winding 40 which is connected in series with the wire leading from the positive terminal of the battery [0 to the associated lever contact Li, and a winding 4| which is connected in series with the connection from the associated common wire l5 to the negative terminal of the battery l0. Each relay XR has a normally released contact I ciatedrelay CR. t

" 1 positions.

I tracedfor relay ICR.

the system shown in Fig. v1.

42 which is included in the circuits of the asso-' v The circuits of the windings 40 and M oi each 1 'relay XR, are arranged so that energy flows through winding 40 in one direction and through winding 4| in the other direction. As a result, these windings offset each other and if they are I equally energized, contactAZof the relaywill remain released and maintain the circuit of the I associated relay'CR. However, if for any reason these windings are unequally energized, the contact 42 will'be picked up and will interrupt the circuit of the relay CR. r

In the modification shown in Fig.2 theeontact 3 L2 associated with each control lever establishes, connection between the associated reverse and common wires when the lever is inits, normal position, and establishes connection between, the associated normal and common wires when the levertisin its reverse position. a

' The equipmentis shownin the condition which I it 'assumeswhenthe control levers IL and IL,

and 2W. are in their normal and the switches vIW At this time relay ICR, is energized by current "supplied over its stick circuitwhich is traced "from the positive 'terminalgof, the battery II) through front contact 25 of, relay ICR, back, contact-.42 of, relay IXR, back, contact. 21 of relay IQR, and ,winding of relaygICRto the negative terminalof the battery. I0.

' The relay ZCRis energized by current supplied over its stick circuit which is similar to that As the control lever IL is in, its normal position, its contact LI establishes connection from the positive terminal of thebattery I to normal 7 wire I I. This connection includes in series there'- with the winding 40 of relay IXR. As the switch IW is in its normal position, switch operated contact I! interrupts thecircuit of, relay INC,

V while switch operated contact I8 interrupts'the contact 42 of this relay is released. V t a The equipment associated with control lever 2L operates in. the same manner as that ass0- ciated with lever IL and a detailed description thereof is unnecessary.

, On movement of the control leverqlLto-its reverse position energy is supplied to the reverse control relay IRC and to the switch motor ,IM

over the reverse wire I2 and the common wire I5, as explained in detatlin connection with As the Windin 40 of relay IXR is in series with the connection from the positive terim'nalof the battery II) to wireIZ, and the winding of relay IXRL'is in @series with the connection'from wire I5 tothe negative terminal of the battery, these windings jareenergized with current' of' equal value and fthe contact 42 of the relay IXIR. remains re-' leased, while when the switch IWIreachesits reverse position and contacts I1 and I8 cut-off "the supply of energy 'tothe switch'motor-JM and to the relay IRC, the. windings of "relay j IXR are'both deenergi'zed; I

: In like manner on movement of; the control As the windings of relay IXR are both-deenergized, the

lever ILfromiits reverse toitsnormal position when the switch IW is in its reverse position, energy is supplied over normal wireI I and com- ;mon wire I5. to the relay INC'and the switch :motor IM, while the two windings of relay IXR are energized with current of equal value so that the contact 42 of this, relay remains releasedand' maintains the circuit of relayfICR.

If movement of the switch IW is obstructed] so that the switch motor draws excessive current for an abnormal period, the contact 2] of relay IOR will be picked up, as explained in connection with the system shown in Fig. 1, and

:will interrupt the stick circuit of relay ICRso that contacts and of relay ICR release and. interrupt the supply of energy i-rom the battery ID to the switch motor IM and'th'e associated control relays. It will be observed, however, that release of the relay ICR does not affect the supply of energy from battery In to the equipment associated with switchZW; Sim

ilarly, release of the relay ZCR will not affect the supply of energy to the equipment assoor its reverse position and the switch; IW is; in

ciatedwith switch IW.

,If, while the lever ,IL is in'either its normal thecorrespond-ing position, across develops from V the positive terminal of the battery to thecommon wire I5 associated with switch IW, the

winding M of relay IXR will be energized and contact '42 of this relay will be picked up to interrupt the' circuit of relay ICR. Accordingly, relay ICR releases and its contact 25- interrupts connection from the positive terminal of. the battery E0 to the associated lever contact IL and also interrupts the circuit of its own," winding so that on release of relay IXR energy is not supplied to relay ICE and} the contacts of this relay remain released. In ad'- dition', on'release of relay I CR. contact 25 establishes the circuit oi the' lamp IK, while contact 30 interrupts connection from thexassociated'wire I5 to the negative terminal of the battery. I On release of relay ICR, therefore,

the supply 'of energy from the battery II] to the wires leading to switch IW is out 01f, while the circuits 'ofthe windings of relay IXR. are interrupted' so that neither 'of these windings can be energized and contact 42 of the relay IXR is rel-eased to permit the pick-up circuit of relay ICE to be established.

. 1 Like'wise, across from the positive terminal of the battery to reverse wire I2 at a time when f thelever 'lL is] in its normal positionjwill result in energization of thewindin-g M of relay IXR. Under these conditions, energy may be supplied to winding 4| over two paths, One

3 of these is traced from wirev I2 through lever contact L2, wire I5, front contact 30 of relayv ICE, and winding 4| of relay IXR, to the'negative terminal of the battery. The other path istraced from wire I2 through the winding of f relay IRCQcdntacts 20 and I'I, wire I5, front contact 3ilof relay ICE, and Winding II of relay y IXR to'the negative terminal of the battery.

As a result ofthe supply of energy to windmg, II; contact-42 of relay IXR. picks up and interrupts the circuit of relay ICE and the contacts of relay ICRrelease and prevent the V supply of energyfrom' the battery ID to the motor IM'or the associated control relays,;while contact. 30 of relay ICR interrupts the circuit of the winding 4| of relay IXR so that contact I 42 ofrelay IXR releases to permit the pick up circuit of relay ICE to be established on movement of the lever |L to its center position.

Similarly, a cross from the positiveterminal of the battery to normal wire I at a time when the lever VIL is in its reverse position will result in energization of the winding 4| of relay IXR. Under these conditions, energy may be supplied to winding 4! over the path which is traced from wire through contact L2, wire l5, front contact 30 of relay ICR, and winding 4| of relay IXR to the negative terminal of the battery in. Energy may also be supplied to the winding 4| over the path which is traced from wire through winding of relay INC,

contacts 2| and I1, wire I5, front contact 30 of I relay ICE, and winding 4| to the negative terminal of the battery. Contact 42 of relay IXR, will, therefore, be picked up to interrupt the circuit of relay ICR, as explained above.

The system shown in Fig. .2 of the draw ing is arranged so that if a cross dev'elopsbetween the common wires associated. with different switches, it will be detected by the relays XR as soon as an attempt is made to move either of these switches. a

If a cross develops between the common wire I 5 for switch IW and the common wire l5 for switch 2W at a time when the switch control levers and the switches are in correspondence, no energy is supplied over either wire and the cross will not cause picking up of either relay XR, but as soon as an attempt is made to move either switch, one or both of the relays R will be energized to thereby prevent movement of the switches.

If under these conditions the control lever IL is moved to its other position so that energy is supplied from the positive terminal of the battery l over the normal or reverse wire to one of the control relays and to the motor IM, all of the energy supplied from the battery will flow through the winding 40 of relay IXR. However, because of the cross which is assumed to exist between the common wires l only a portion of this energy flows through Winding 4| of relay IXR to the negative terminal of the battery. The remainder of the energy flows from wire l5 associated with switch IW through the assumed cross to the wire l5 associated with switch 2W and thence through winding 4| of relay ZXR to the negative terminal of the battery.

Since under these conditions all of the energy supplied from the battery flows through the winding'40 of relay |XR, and only a portion of this energy flows through the winding 4| of this relay, these windings do not offset each other and the contact 42 of relay |XR is picked up and interrupts the circuit of the relay ICR so that its contacts and release and cut off the supply of energy from the battery H] to the wires leading to the switch IW. In addition, contact 25 of relay ICR interrupts the supply of energy to this relay and establishes the circuit of the indication lamp IK.

On release of relay ICE and consequent interruption of the supply of energy from the battery to the wires associated with switch IW, the windings 40 and 4| of relay IXR are both deenergized and contact 42 of the relay releases, but relay ICR remains released and prevents the supply of energy from the battery to the wires associated with switch IW.

After release of the relay ICR, whether caused by picking up of relay IXR or overload relay IOR, the operator may regain control of the switch by'moving the control lever |L to its center or intermediate position C. In this position of the lever, contact L3 establishes the pick-up circuit for relay ICR; This circuit is traced from the positive terminal of the battery through contact L3, backcontact 42 of relay IXR, back contact 2'! of relay ICE, and winding of relay |CR to the negative terminal of the battery. On picking up of the relay lCR its contact 25 interrupts the circuit of the lamp |L and establishes the stick circuit for relay ICR to keep the relay energized after movement of the lever IL from its center position, while contact 39 of relay ICR. establishes connection from wire i5 to the negative terminal of the'battery.

The operator may now move the lever |L to 'eitherits normal or its reverse position to move the switch, but if the overload or defective wiring condition which caused release of the relay ICE is still present, this relay will again release and prevent movement of the switch, while inability of the operator to move the switch will inform him that there is a defect in the apparatus which must be corrected.

As pointed out above, if there is a cross between the common wires I5 for the switches W and 2W, and an attempt is made to move switch IW, energy will be supplied to the winding 4| of relay 213%. This energy may pick up the contact 42 of this relay so that the circuit of relay 20B is interrupted and this relay releases and prevents the supply of energy to switch motor 2M. If the relay ZCR releases, it may be picked up by moving the lever 2L to its intermediate position, but if the cross between the common wires for switches |W and 2W is still present when the attempt is made to move switch 2W, contact 42 of relay 223?, will pick up and interrupt the circuit of relay 20R, while contact 42 of relay IXR may also be picked up to interrupt the circuit of relay ICR.

From the foregoing it will be seen that the systems provided by this invention are arranged so that an overload relay of standard design may be employed to detect abnormal flow of current from the source, and on such an occurrence to cut off further supply of energy from the source.

The systems are arranged so that after an overload the operator may regain control of the switch by moving the control lever to its intermediate position. This permits the operator to move the switch away from an obstruction which caused the overload.

In each of the systems provided by this invention the overload relay operates through a contactor to control the supply of energy from the source, and this contactor when released interrupts connection from both terminals of the source so that the source is completely isolated from the circuits in which the overload occurred.

In addition, each form of the invention employs a cross detecting relay which controls the contactor, while the system shown in Fig. 2' employs an improved form of cross detecting relay which responds to certain additional defects. These systems are arranged so that the cross protection relays do not directly control the supply of energy from the source, butdo so through the contactor so that these relays do not need to be of sufiicient capacity to control the circuits of the switch motors.

Although the apparatus embodying my invention is shown applied to cross and overload protection of railway track switch motors, it will be apparent that this apparatus has broader utility and may be used to protect any suitable electrical apparatus which may be subject to an overload and to undesired operation due to a cross in its control or operating circuits.

Although I have herein shown and described only two forms of control systems embodying my invention, it is understood that various changes and modifications may be made therein within" the scope of the appended claim without departing from the spirit and scope of my invention. Having thus described my'invention, what I claim is; 7 V

In combination, a track switch, a motor for moving said switch, a source of current located 1 at a control point, a normal, a' reverse and a common wire extending from said control point'to terminal of its winding connected to said comsaid switch and over which energy may be sup plied fromsaid source to said motor, said common wire being connected to'one terminal of 'said source, manually controlled means for at times establishing connection from the, other terminalof said source to said normal wire and wire, a normal circuitincluding said normal and 1 common wires for'operating said motor, areverse circuit including saidreverse and common wires foroperating said motor, a-conta'ctor having'a'contact which when released interrupts the supply of energy from said source to saidmon wire and having the, other terminal of its winding connected tothe normal or reverse wire according, as said "manually controlled means establishes connection from said source to said reverse. or said-normal wire, said cross detecting relay having a normally closed contact which'is opened on flow of energy through the relay winding and which whenopened. remains open when flow of energy through the relay winding ceases,

a stick circuit for said contactor including its i own front contact, saidcross detecting relay con- 7 for at other, times establishing connection from the other terminal of said source to said reverse ,;said cross detecting relay tact and a back contact of said overload relay,

and a pick-up circuit for said contactor includin contact. HENRY S YOUNG.

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