US2156689A - Switch control system - Google Patents

Description

y 1939- c. M. HINES 2,156,689

SWITCH CONTROL SYSTEM Filed Sept. 29, 1958 HIS ATTORN EY Patented May 2, 1939 PATENT OFFICE SWITCH CONTROL SYSTEM Claude M. Hines, Pittsburgh, Pa., assignor to The Union Switch & Signal Company, Swissvale,

Pa., a corporation of Pennsylvania Application September 29, 1938, Serial No. 232,385

20 Claims.

My invention relates to railway switch controlling apparatus, and particularly to apparatus for the protection of a railway switch motor' against overload.

It has heretofore been proposed to providean overload relay having a winding which is energized in accordance with the current taken by the motor for operating a railway switch, the relay being operable to interrupt the circuit for energizing the motor if the current taken by the motor exceeds a predetermined value for a predetermined time interval.

It has also been proposed heretofore to provide means for effecting remote control of the motor for operating a railway switch, this means com prising a polarized relay which is supplied with current over a circuit which includes-a pair of control wires.

The overload relays employed in systems of .this type are provided with contacts which when picked up cause the energizing circuits for the switch motor to be interrupted. It is desirable that the overload relay be arranged so that once its cont-acts are picked up to interrupt the ener- 3 gizing circuit for the switch motor, these contacts will remain picked up until the polarityof the current supplied to the control wires is reversed to thereby cause the polarized switch control relay to eifcct operation of the motor in the opposite direction.

In order to maintain the overload relaycontacts picked uponce they are picked up, it has been proposed heretofore to provide the overload relay with a holding winding which is energized from the control wires. However, because of the structural characteristics of the overloadr-elays;

there is little space available in which to mount a holding winding, and this winding, therefore, is of limited size and accordingly of limited resistance. Because of the limited resistance of the Winding, it is impractical to attempt to energize the winding over control wires of substantial length.

It is an object of my invention to provide improved switch motor overload protection means including a holding winding effective when energized to maintain the switch motor circuit'interrupted, the holding winding being energized from the controlwires and having a high resistance so that it can be controlled over control wires extending for a substantial distance;

A further object of my invention is to provide overload protection means-of the type describedand incorporating a separate orholding relay in place of the holding winding forminga-part of the overload relay, whereby the size and the resistance of the winding employed is not restricted by the structural design and the physical characteristics of the overload relay.

Another object of my invention is to provide overload protection means of the type described and in which a circuit for energizing the winding of the separate or holding relay from the control wires is established when the contacts of the overload relay become picked up, this circuit being maintained when the contacts of the separate or holding relay become picked up.

A further object of my invention is to provide a system of the type described in which the sepa-' rate or holding relay and the overload relay jointly control the circuit for energizing the polarized switch control relay from the control wires, the system being arranged to insure that on picking up of the contacts of the overload relay the winding of the separate relaywill be energized and the contacts of that relay will become picked up.

Another object of my invention is to provide a system of the type described and incorporating means to prevent storage of switch control at times when the dual selector lever is in the position to condition the" switch for manual opera tion, or at times when the lock relay is released.

A further object of my invention is to provide a system of the type described and in which if the position of the switch control lever is changed at a time when the dual selector lever is in the hand-throw position, on subsequent return of the dual selector lever to the motor operating position, the motor will not be caused to move the switch without some further manipulation of the switch control lever.

Another object of my invention is to provide a switch control system incorporating improved means for preventing storage of switch control.

A further object of my invention is to provide an improved switch motor overload protection system.

Other objects of my invention and features of novelty will be apparent from the following description taken in connection with theaccompanying drawing.

In the drawing the single figure is a diagram of one system embodying my -invention'.

Referring to the drawing, the reference char- Q acter W designates a railway track switch which is operated by the well-known dual selector type of mechanism. In the form here shown diagrammatically'this mechanism comprises a dual'se-'-* lever S is in its normal position, as shown in the drawing, link 3 connects switch W with motor M, and when lever S is in its reverse or hand-throw position, link 3 disconnects theswitch W from the motor M and connects the switch with a hand-throw lever H.

The selector lever S also controls a contact 5v which is arranged to be closed only when the selector lever is in the normal position, and is open in all other positions of the selector lever so that the switch motor M can be energized only when the selector lever S is in its normal position. The selector lever S also operates a contact 65 in such manner that the contact is open in the normal position of the selector lever, and is closed in the hand-throw position of the selector lever.

The switch motor M is controlled by a polarized switch control relay WR and by an overload relay OR, while the relay WR is controlled by the overload relay OR by an overload repeating relay or holding relay ORP which is controlled by the overload relay OR.

The overload relay OR is provided with a winding which is connected in series with the energizing circuit for the motor M, while a thermal resistance 6 is connected in parallel with the relay winding. Under normal conditions the resistance 6 carries the major portion of the current taken by the motor M and so little current flows in the winding of relay OR that the contacts of this relay do not become picked up. When the switch W is obstructed, the motor M draws increased current for an abnormal period of time which heats up the resistor 6, thereby increasing its resistance and causing such an increase in the flow of current in the winding of relay OR that the contacts of the relay become picked up. I

The polarized switch control relay WR is pro- Vided with a plurality of neutral contacts 8 which are picked up whenever the relay winding is energized, and which when picked up engage stationary contacts 9 which are connected by a wire II] to terminal B of a battery I2 The contacts 8 are connected by a wire M to a normal polar contact l5 and a reverse polar contact I6.

The relay WR has a polar contact I8 which is connected by a wire |9 to a brush 20 of the armature 22 of the motor M. The contact 8 when in the normal position engages contact l5, while in the reverse position it engages a contact 24 which is connected by a wire 25 to a stationary contact 26. A movable contact 21, which is actuated in accordance with the position of the switch W, engages contact 25 in all positions of the switch W except in the reverse position. The contact 27 has connected thereto one terminal of the motor field winding 28, the other terminal of which is connected to terminal C of battery l2 by a circuit controlled by tact 30, when in the reverse position, engages contact l6, while when the contact 30 is in the, normal position, as shown in the drawing, it engages a stationary contact 34 which is connected by a wire 35to contact 36 which is engaged by contact 5 which is operated by the selector lever switch operated contact 21 in all positions of the switch W except the normal position.

This systemincludes means for selectively supplying current of one or the other relative polarity to the winding of the relay WR to efiect movement of its polar contacts between their normal and reverse positions, and thereby efiect operation of the motor M to move the switch W between its two positions.

As shown in the drawing, there is a switch control lever L which is located at a point remote from the switch W, such as a control or interlocking tower, from which it is desired to control the switch W. The lever L has associated therewith contacts 40 and 4|. The contact 4|! has connected thereto control wire 43, while the contact 4| has connected thereto control wire 44.

The lever L is movable between a normal and a reverse position, and when the lever is in the normal position, as shown, the contact 40 engages a stationary contact to which is connected a wire 46 leading from terminal B of battery 41, while the contact 4| engages a stationary contact to which is connected a wire 48 leading from terminal C of battery 41. In the normal posi tion of the lever L, the contacts 40 and 4|, therefore, operate to supply current of one relative polarity, which may be considered as the normal polarity, from the battery 47 to the control wires 43 and 44.

In similar manner when the lever L is in the reverse position, the contact 40 engages a stationary contact to which is connected a branch of wire 48 leading from terminal C of battery 41, while contact 4| engages a stationary contact to which is connected a branch of wire 46 leading from terminal B of battery 41. In the reverse position of the lever L, therefore, the contacts 40 and 4| operate to supply current of reverse polarity from battery 41 to control wires 43 and 44.

The control wire 44 is connected to One terminal of the winding of polarized switch control relay WR, while a branch of this wire is connected to a terminal of the winding of holding or auxiliary relay ORP.

The control wire 43 is connected to contact of overload relay OR, while a branch of wire 43 is connected to contact 5| of, relay ORP. Contact 50. of relay OR, when released, engages a contact 53 which is connected by a wire 54 to a stationary contact 56 of relay ORP. The relay ORP has a contact 51 whichwhen released en- 43 to a terminal of the winding of relay WR,

, this circuit including contacts 50 and 53 of relay OR, wire 54, contacts and 51 of relay ,ORP, and Wire 58. When the contacts of relays OR and ORP are released, therefore, the winding of relay WR. may be supplied with currentof either polarity from the control Wires 43 and 44, and the relay WR may be controlled by the switch control Lever Lin the normal manner.

The relay OR is provided with a contact 60 which is connected by a wire 6| to a terminal of the Winding of the relay ORP. The contact 63' when picked ,up engagesthe contact 59 to which is connected control wire 43. 'W'hencontact 6|] ispicked up, therefore, a circuit is established from control wire 43 to wire 6| leading to a, terminal of the winding of relay ORP,

the other terminal of which has connected thereto a branch of control wire 44.

When the contact 60 is picked up, it engages contact 50 and moves contact 50 out of engagement with contact 53, thereby interrupting the circuit between control wire 43 and the winding of relay WR. It will be seen, however, that the circuit to the winding of relay WR is not interrupted until the circuit to the winding of relay ORP is established.

The contact 5| of relay ORP when picked up engages a stationary contact to which is connected a branch of wire 6|. Accordingly, contact 5| when picked up establishes a stick circuit from control wire 43 to wire 6| leading to a terminal of the winding of relay ORP.

The lock relay LR is provided with a contact 64 which when picked up establishes the circuit through wire 58 leading to a terminal of the winding of relay WR. The contact 64 when released interrupts the circuit through the wire 58.

The supply of current to the winding of the lock relay LR is controlled in the well-known manner by trafiic conditions in the vicinity of the switch W in such a manner that the winding is energized when and only when it is safe to change the position of the switch.

The dual selector lever S operates contact 65 to which is connected a branch of wire 6| leading to a terminal of the winding of the relay ORP. When the lever S is moved to the handthrow position, the contact 65 engages a stationary contact 65 to which is connected control wire 43.

The lock relay LR is provided with a movable contact 58 to which. is connected a branch of wire 6! leading from a terminal of the winding' At this time the contacts 40 and 4| associated with the control lever L operate to supply current of normal polarity to the control wires 43 and 44, while this current is supplied to the winding of relay WR. When the winding of relay WR is energized with current of normal polarity, the neutral contacts 8 of the relay are picked up, while the polar contacts I8 and of the relay are in their normal positions as shown. As the switch W is in the normal position, contact 21 does not engage contact 36 and the circuit for energizing the motor M, therefore, is interrupted.

If at this time it is desired to move the switch W from the normal to the reverse position, the operator may do so by moving the switch control lever L from the normal to the reverse position. As a result of this movement of the lever L, the contacts and 4| operate as previously explained to supply current of reverse polarity to the control wires 43 and 44.

On the supply of current of reverse polarity to the control wires there is a reversal in the direction of energization of the winding of relay WR., and the polar contacts I8 and 30 of this relay are shifted from their normal to their reverse positions and establish a circuit to energize the motor M to cause the motor to move the switch W from the normal to the reverse position. The circuit for energizing the motor M is traced from terminal B of battery |2 throughwire. l0, neu+ tral contacts 9-8 of relay-WR,, reverse polar contacts |6-3El of relay WR, wire 3| including re-- sistor 6 and winding of relay OR in series therewith, brush 32, motor armature 22, brush 20, wire l9, reverse polar contacts |B-24 of relay WR,

wire 25, contact 26, switch operatedcontact 21,

. supply of current of normal polarity to the control wires 43 and 44, while on the supply of current of this polarity to the winding of relay WR the polar contacts l8 and 3|] of the relay are shifted to their normal positions, and establish a circuit for energizing the motor M to cause it to move the switch W from the reverse to the normal position.

The circuit for energizing the motor M is traced from terminal B of battery l2, wire l0, neutral contacts 9-8 of relay WR, wire l4, normal polar contacts l5-l8 of relay WR, wire [9, brush 26, armature 22, brush 32, wire 3| including resistor & and winding of relay OR in series therewith, normal polar contacts 30-34 of relay WR, wire 35, contact 36, switch operated contact 2?, motor field winding 28, and selector lever contact 5 to terminal C of battery I2.

When the switch W attains its normal position, contact 21 is moved out of engagement with contact 36, thereby interrupting the energizing circuit for the switch motor M.

This control system is arranged so that in the event that movement of the switch W is obstructed, the polarized switch control relay WR will be deenergized' to thereby interrupt the supply a of current to the switch motor and thus prevent injury to the switch motor. This system is also arranged so that once the polarized switch control relay WR is deenergized it will be maintained deenergized until the polarity of the current supplied to the control wires is reversed, whereupon the polarized switch control relay will again be energized, but with current of the polarity opposite from that with which it was energized when the relay became deenergized,

and the relay will establish a circuit to the switch motor to cause the motor to move the switch away from the obstruction.

For purposes of illustration it will be assumed that the switch W is in the normal position, that it is desired to move it to the reverse position, and that further movement of the switch is prevented before the switch has been moved all of the way to the reverse position.

In order to effect movement of the switch from the normal to the reverse position the con-- mal resistance 6 and the winding of relay OR in series.

It is assumed that further movement of the switch W is prevented by an obstruction before the switch has completed its movement to the reverse position. As a result of this obstruction of the switch the motor M will draw increased current for an abnormal time interval with the result that the thermal resistance 6 will become heated, thereby increasing its resistance and causing increased flow of current in the winding of relay OR. On this increased current flow in the winding of relay OR the contacts of this relay become picked up.

When contact 60 is picked up, it first engages contact 59 to thereby establish a circuit from control wire 43 to wire 6| leading to a terminal of the winding of relay ORP. The operating characteristics of relay OR are such that once the contact 60 starts to pick up, the contact will quickly move all of the way to its picked up position and will move contact 50 out of engagement with contact 53, thereby interrupting the circuit from control wire 43 to the winding of relay WR with the result that the neutral contacts 8 of relay WR become released, thus interrupting the energizing circuit for the motor M. The motor M thereupon ceases to operate, while the circuit for energizing the winding of relay OR is also interrupted. The contacts of overload relay OR do not release instantaneously, however, but remain picked up for a time interval after the energizing circuit for the relay winding is interrupted with the result that the winding of relay 85 ORP will be energized long enough to effect picking up of its contacts.

When contact 60 of overload relay OR is picked up so as to engage contact 50 and thus establish a circuit from control wire 43 to wire 6| leading to a terminal of the winding of relay ORP, this winding is energized with current supplied from the control wires 43 and 44 and the contacts of relay ORP are thereupon picked up. On picking up of contact 5| a stick circuit is established from control wire 43 to wire 6| to maintain the winding of relay ORP energized after the released the contacts of relay OR, which will occur a short time interval after the energizing circuit for the switch motor M is interrupted by the polarized switch control relay WR.

On picking up of the contact 51 of relay ORP the energizing circuit for the winding of relay WR is interrupted, if it has not already been interrupted by movement of contact 50 of relay OR out of engagement with contact 53. The picking up of contact 51 also serves to maintain the circuit for the winding of relay WR interrupted after the contacts of relay OR are released.

It will be seen, therefore, that on the picking up 01" the contacts of the overload relay OR a circuit is established from the control wires 43 and 44 to energize the winding of relay ORP, while when the contacts of relay ORP become picked up a stick circuit is established from the control wires to maintain the winding of relay ORP energized after the release of the contacts of the overload relay OR. In addition it will be seen that on the picking up of the contacts of relays OR and ORP the energizing circuit for the switch control relay WR is interrupted, and that this circuit is maintained interrupted as long as the contacts of relay ORP are picked up.

It will be seen also that on the picking up of the contacts of overload relay OR not only is a circuit established to energize the winding of current from the control wires, thereby leaving all of the available current to energize the winding of relay ORP with the result that the contacts of this relay are more certain to become picked up.

When the contacts of relay ORP are picked up and the switch control relay WR is deenergized, the operator may effect the return of the switch W to the position from which it was being moved when its movement was obstructed, in the present case to the normal position. In order to effect this movement of the switch the switch control lever L is moved from the reverse to the normal position, thereby effecting a reversal in the polarity of the current supplied to the control wires 43 and 44.

On this reversal in the polarity of the current supplied to the control wires there is a reversal in the direction of energization of the winding of relay ORP with a consequent reversal in the flux in the core of the relay. When the flux reaches substantially the zero value, so little force is available to hold the relay contacts picked up that they become released and contact 5| interrupts the stick circuit for the winding of relay ORP with the result that when the contacts of relay ORP become released, they will not thereafter become picked up.

On the release of contact 51 of relay ORP, the circuit between control wire 43 and a terminal of the winding of relay WR is completed, this circuit including contact 50 of relay OR, which is released at this time, contact 53 of relay OR, wire 54, contacts 56- 51 of relay ORP, and wire 58. The winding of relay WR, therefore, will be energized with current supplied over the control wires 43 and 44, the polarity of the current being opposite from that with which the relay winding was last energized, and the polar contacts l8 and of the relay will be shifted from their reverse to their normal positions, while the neutral contacts 8 of the relay will become picked up to establish a circuit to energize the motor M to cause the motor to return the switch to the normal position. When the switch attains the normal position, the contact 21 interrupts the energizing circuit for the motor M and the equipment is again in the position in which it is shown in the drawing.

The operation of the overload relay OR and the relay ORP, as well as the other portions of the equipment, in the event movement of the switch W away from the reverse position is obstructed is substantially the same as has been described in detail in connection with movement of the switch from the normal position and need not be repeated.

It will be seen that the system provided by this invention has a holding relay separate from the overload relay which is energized from the control wires on picking up of the contacts of the overload relay, and that this separate or holding relay serves to maintain the switch control relay deenergized, and thus maintain the switch motor energizing circuit interrupted, until the polarity of the current supplied to the control wires is changed.

In addition, it will be seen that as the holding relay is separate from the overload relay, the winding of the holding relay may be made of any suitable resistance since its size is not restricted by the physical characteristics of the overload relayv as isthe case where the overload relay has a holding winding mounted directly thereon.

Since the winding of the holding relay may be of any suitable size, it can be made of sufficiently high resistance to enable the relay to be energized over control wires of considerable length.

Furthermore, as the holding relay is separate from the overload relay, it is unnecessary to provide means to control the polarityof the current supplied to the winding of the holding relay to keep it in correspondence with the direction of energization of the winding of the overload relay as is required where the holding winding is incorporated in the overload relay.

The system provided by this invention is arranged so that if the position of the control lever L is changed at a time when the dual selector lever S is in thehand-throw position, on subsequent return of the lever S to the normal or motor operating position, the switch-motor M will not be energized unless there is some subsequent manipulation of the control leverL.

For purposes of illustration it will be assumed that with the switch W in the normal position, and with the other parts of the apparatus in the position shown in the drawing, that the dual selector lever S is moved to the hand-throw position. It will also be assumed that while the dual selector lever S is in the hand-throw position, the switch control lever L is moved from the normal to the reverse position, and that while the lever L is in the reverse position and the switch W is in the normal position, the dual selector lever S is returned to the motor operating position.

On movement of the dual selector lever S to the hand-throw position the contact is moved to a position to interrupt the energizing circuit for the switch motor M and thus prevent operation of the switch motor. In addition, on this movement of the dual selector lever S the contact 65 is moved into engagement with contact 66 to thereby complete a circuit from control wire 43 to wire 'filleading to the winding of relay ORP. The winding of relay ORP, therefore, is energized by current supplied from the control wires 43 and 44, and contact 51 of the relay is picked up to interrupt the circuit for energizing the winding of the switch control relay WR. As the winding of relay WR is deenergized, the neutral contacts 8 of the relay are released and interrupt'the motor circuit, which circuit is interrupted at another point by selector lever contact'5.

If, while the selector lever S is in the handthrow position, the control lever L is moved from the normal to the reverse position, the polarity of the current supplied to the control wires 43 and M will be changed. On'this change in the polarity of the current supplied to the winding of relay ORP, the contacts of the relay become released and then pick up again since the circuit for energizing the relay winding is maintained by the selector lever contact'65. As the contacts of relay ORP are picked up, contact 51 interrupts the circuit for-energizing the winding of relay WR, while contact5l establishes the stick circuit for energizing the winding of relay ORP after contact 65 is opened.

On subsequent return of the dual selector lever S to the normal position, contact 65 opens the circuit-which it'controls,'but the winding of relay ORP remains energized by current supplied through contact 5|. In addition, on thismovement of .selector lever S, contact 5 is moved'to the closed position, but at this time the circuit for energizing the switch motor M is interrupted by the neutral contacts 8 of the relay WR since the winding of relay W'R is deenergized because contact 51 of relay ORP is picked up. Accordingly, even if the switch W and the polar contacts of relay WR should be out of correspondence, the switch motor will not be operated.

The switch control relay WR will remain deenergized as long as relay ORP remains energized. After restoration of the dual selector lever S to the motor operating position, the relay ORP will remain energized until the position of the switch control lever L is changed. If the switch control lever L is now moved from the reverse to the normal position, the polarity of the current supplied to the control wires 43 and 44 will be changed and the contacts of relay ORP will'become released. When contact 5l'is released,the stick circuit for the winding of relay ORP is interrupted and this winding will not thereafter become energized since the contact 65 is now open.

On the release the contact 51 of relay ORP, the circuit from control wire 43 to wire 58 leading to the win-ding of relay WR is again complete and the neutral contacts of relay WR are picked up, while the polar contacts of relay 'WR willbe shifted to their normal positions if they are not already in those positions. On this energization of the winding of relay WR with current of normal polarity, the circuit for energizing the switch motor M to cause the motorto move the switch W to the normal position will be completed if the switch W is not already in the'normal position.

From the foregoing it is clear that this system is arranged so that when the duel selector lever S is in the hand-throw position, changes in the position of the control lever L will not efiect operation of the switch motor on subsequent return of the selector leverS to the normalposition. In order to effect operation ofthe switch motor M after the dual selector lever S has been in the hand-throw position, it is necessary to manipulate the control lever L to effect the release of the relay ORP.

The lock relay LR is incorporated in the system in such a manner that if the position of the control lever L changed whilethe lock relay'is released, on subsequent picking up of the contacts of the lock relay, the switch motor M will not be energized until there is further manipulation of the control lever.

On release of the lock relay LR, its contact 64 interrupts the circuit for energizing the Winding of relay WR. The neutral contacts 8 of relay WR will be rel-eased, therefore, and will interrupt the energizing circuit for the motor M as long as lock relay LR remains released.

In addition, on release of the contacts of lock relay LR, contact 68 engages back contact 69 to complete a circuit from control wire 43 to wire 6| leading to a terminal of the winding of relay ORP. On release of relay LR, therefore, a circuit is established from the control wires 33 and 44 to energize the winding of relay ORP, and this circuit is maintained as long as relay LR remains released. If, therefore, the position of the controllever L is changed at a time when the lock relay LR is released, the contacts of relay ORP will momentarily release due to the'reversal of the polarity of the current supplied to the windpick up since the winding'is energized by current supplied over the circuit which includes contact 68 of relay LR. 7

When the contacts of relay ORP are picked up, contact 5| establishes a stick circuit for the relay winding so that on picking up of the contacts of the relay LR the winding of relay ORP remains energized and the contacts of that relay remain picked up. As contact 51 of relay ORP is picked up, the circuit for energizing the relay WR from the control wires 43 and 44 is interrupted and the neutral contacts of relay WR remain released. As long as relay ORP is energized, therefore, the energizing circuit for the switch motor willbe interrupted.

From the foregoing it is clear that on picking up of the contacts of relay LR, the switch control relay WR is maintained deenergi zed with the result that the energizing circuit for the switch motor is maintained interrupted and no operation of the motor will occur on picking up of the contacts of relay LR, even if at that time the switch W and the control lever L are out of correspondence.

If after picking up of the contacts of relay LR the operator wishes to effect movement of the switch W by the motor M, he may do so by moving the control lever L. On a change in the posi tion of the lever L there is a reversal in the polarity of the current supplied to the control wires 43 and 44, and therefrom to the winding of relay ORP, with the result that the contacts of relay ORP become released. On this release of the contacts of relay ORP, contact 5| interrupts the stick circuit for the relay winding with the result that the relay contacts when released remain released, while contact 51 of relay ORP completes the circuit from the control wire 43 to wire 58 leading to the winding of switch control relay WR, and the winding of relay WR may thereafter be energized with current of one polarity or the other in accordance with the position of the switch controllever L.

Although I have herein shown and described only one form of switch control system embodying my invention, it is understood that various changes and modifications may be made therein within the scope of,.the appended claims without departing iromthe spirit and scope of my invention. i

Having thus described my invention, whatI holding relay controlling a circuit for energizing said switch control relay from said conductors, and an overload relay controlled by the current supplied to said motor, said overload relay controlling a circuit for energizing the holding relay from said conductors.

2. In combination, a railway track switch, a motor for moving the switch between a normal and a reverse position, a pair of conductors, manually controlled means for supplying current to said conductors, a switch control relay controlling a circuit for energizing said motor, a holding relay controlling a circuit for energizing said switch control relay from said conductors, an overload relay controlled by the current supplied to said motor, said overload relay controlling a circuit ing of the relay, but the relay contacts will again for energizing the holding relay from said conductors, and a circuit controlled by said holding relay for energizing its own winding from said conductors.

3. In combination, a railway track switch, a motor for moving'the switch between a normal and a, reverse position, a pair of conductors, manually controlled means for supplying current to said conductors, a switch control relay controlling a circuit for energizing said motor, a holding relay, an overload relaycontrolled by the current supplied to said motor, a circuit controlled by the overload relay for energizing the holding relay from said conductors, and a circuit controlled by the overload relay and by the holding relay for energizing the switch control relay from said confrom said conductors,'a circuit'controlled by the overload relay and by the holding relay for energizing the switch control relay from said conductors, and a circuit controlled by said holding relay for energizing its own winding from said conductors.

5. In combination, a railway track switch, a motor for moving the switch between a normal and a reverse position, a pair of conductors, means for supplying to said conductors current of one polarity or the other, a polarized switch control relay controlling circuits for energizing said motor to cause it to move the switch to one position or the other, a holding relay controlling a circuit for energizing the switch control relay from said conductors, and an overload relay controlled by the current supplied to said motor, said overload relay controlling a circuit for energizing the holding relay from said conductors.

' 6. In combination, a railway track switch, a motor for moving the switch between a normal and a reverse position, a pair of conductors,

means forsupplying tdsaid conductors,currentat of one polarity or the other, a polarized switch control relay controlling tircuits for energizing said motor'to cause it to move the switch to one position or the other, a holding relay controlling a circuit for energizing the switch control relay from said conductors, an overload relay controlled by the current supplied to said motor, said overload relay controlling a circuit for energizing the holding relay from said conductors, and a circuit controlled by said holding relay for energizing its own winding from said conductors.

'7. In combination, a railway track switch, 'a motor for moving the switch between a normal and a reverse position, a pair of conductors, means for supplying to said conductors current of one polarity or the other, a polarized switch control relay controlling circuits for energizing said motor to cause it to move the switch to one position or the other, a holding relay, an overload relay controlled by the current supplied to said motor, a circuit controlled by the overload relay for energizing said holding relay from said conductors, and a circuit controlled by the overload relay and by the holding relay for energizing the switch control relay from said conductors.

8. In combination, a railway track switch, a

motor for moving the switch between a normal and a reverse position, a pair of conductors, means for supplying to said conductors current of one polarity or the other, a polarized switch control relay controlling circuits for energizing said motor to cause it to move the switch to one position or the other, a holding relay, an overload relay controlled by the current supplied to said motor, a circuit controlled by the overload relay for energizing said holding relay from said conductors, a circuit controlled by the overload relay and by the holding relay for energizing the switch control relay from said conductors, and a circuit controlled by said holding relay for energizing its own winding from said conductors.

9. In combination, a railway track switch, a motor for moving the switch between a normal and a reverse position, a pair of conductors, manually controlled means for supplying current to said conductors, a switch control relay controlling a circuit for energizing said motor, a circuit for energizing the switch control relay from said conductors, a holding relay, an overload relay controlled by the current supplied to said motor, said overload relay having a member movable from a normal position to an operated position when and only when the current supplied to the motor exceeds a predetermined value, said member being operable on movement towards the operated position to first establish a circuit to energize the holding relay from said conductors and to thereafter interrupt the circuit for energizing the switch control relay from said conductors, the holding relay being effective when energized to also interrupt the circuit for energizing the switch control relay from the said conductors.

10. In combination, a railway track switch, a motor for moving the switch between a normal and a reverse position, a pair of conductors, manually controlled means for supplying current to said conductors, a switch control relay controlling a circuit for energizing said motor, a circuit for energizing the switch control relay from said conductors, a holding relay, an overload relay controlled by the current supplied to said motor, said overload relay having a member movable from a normal position to an operated position when and only when the current supplied to the motor exceeds a predetermined value, said member being operable on movement towards the operated position to first establish a circuit to energize the holding relay from said conductors and to thereafter interrupt the circuit for energizing the switch control relay from said conductors, the holding relay being efiective when energized to also interrupt the circuit for energizing the switch control relay from the said conductors, the holding relay also being effective when energized to establish a circuit for energizing its own winding from said conductors.

11. In combination, a rail-way track switch, a motor for moving the switch between a normal and a reverse position, a pair of conductors, manually controlled means for supplying current to said conductors, a switch control relay controlling a circuit for energizing said motor, a circuit for energizing the switch control relay from said conductors, a holding relay, an overload relay controlled by the current supplied to the motor, said overload relay having means movable from a normal position to an operated position when and only when the current supplied to the motor exceeds a predetermined value, said means being operable on movement to the operated position to establish a circuit to energize the holding relay from said conductors and to interrupt the circuit for energizing the. switch control relay from said conductors, the holding relay being effective when energized to also interrupt the circuit for energizing the switch control relay from said conductors.

12. In combination, a railway track switch, a motor for moving the switch between a normal and a reverse position, a pair of conductors, manually controlled means for supplying current to said conductors, a switch control relay controlling a circuit for energizing said motor, a circuit for energizing the switch control relay from said conductors, a holding relay, an overload relay controlled by the current supplied to the motor, said overload relay having means movable from a normal position to an operated position when and only when the current supplied to the motor exceeds a predetermined value, said means be ng operable on movement to the operated position to establish a circuit to energize the holding relay from said conductors and to interrupt the circuit for energizing the switch control relay from said conductors, the holding relay being eiTective when energized to also interrupt the circuit for energizing the switch control relay from said conductors, the holding relay also being effective when energized to establish a circuit for energizing its own winding from said conductors.

13. In combination, a railway track switch. a motor for moving the switch between a normal and a reverse position, a pair of conductors. means for supplying to said conductors current of one polarity or the other, a polarized switch con trol relay controlling circuits for energizing said motor to cause it to move the switch to one position or the other, a circuit for energiz ng the switch control relay from said conductors, a holding relay, an overload relay controlled by the current supplied to the motor, said overload relay having means movable from a normal position to an operated position when and only when the current supplied to the motor exceeds a predetermined value, said means being operable on movement to the operated position to establish a circuit to energize the holding relay from said conductors and to interrupt the circuit for energizing the switch control relay from said conductors, the holding relay being effective when energized to also interrupt the circuit for energizing the switch control relay from said conductors.

14. In combination, a railway track switch, a motor for moving the switch between a normal and a reverse position, a pair of conductors, means for supplying to said conductors current of one polarity or the other, a polarized switch control relay controlling circuits for energizing said motor to cause it to move the switch to one position or the other, a circuit for energizing the switch control relay from said conductors, a holding relay, an overload relay controlled by the current supplied to the motor, said overload relay having means movable from a normal position to an operated position when and only when the current supplied to the motor exceeds a predetermined value, said means being operable on movement to the operated-position to establish a circuit to energize the holding relay from said conductors and to interrupt the circuit for energizing the switch control relay from said eonductors,'the holding relay being efiective when energized to also interrupt the circuit for energizing the switch control relay from said conductors, the holding relay also being effective when energized to establish a circuit for energizing its own winding from said conductors.

15. In combination, a railway track switch, a motor for moving the switch between a normal and a reverse position, a pair of conductors, manually controlled means for supplying current to said conductors, a switch control relay control ling a circuit for energizing said motor, a circuit for energizing the switch control relay from said conductors, a holding relay, an overload relay controlled by the current supplied to the motor, said overload relay having a contact movable from a normal to an operated position when and only when the current supplied to the motor exceeds a predetermined value, said contact being operable on movement to the operated position to establish a circuit to energize the holding relay from said conductors, the holding relay being operable when energized to interrupt the circuit for energizing the switch control relay from said conductors and to also establish a circuit to energize its own winding from said conductors.

16. In combination, a railway track switch, a

" motor for moving the switch between a normal and a reverse position, a pair of conductors, means for supplying to said conductors current of one polarity or the other, a polarized switch control relay controlling circuits for energizing said motor to cause it to move the switch to one position or the other, a circuit for energizing the switch control relay from said conductors, a holding relay, an overload relay controlled by the current supplied to the motor, said overload relay having a contact movable from a normal to an operated position when and only when the current supplied to the motor exceeds a predetermined value, said contact being operable on movement to the operated position to establish a circuit to energize the holding relay from said conductors, the holding relay being operable when energized to interrupt the circuit for energizing the switch control relay from said conductors and to also establish a circuit to energize its ownwinding from said conductors.

17. In combination, a railroad track switch, a motor for moving the switch between a normal and a reverse position, a pair of conductors, means for selectively supplying to said conductors current of one polarity or the other, means selectively responsive to the polarity of the current supplied to said conductors for establishing circuits for effecting operation of the motor to produce movement of the switch to one position or the other, an overload relay controlled in accordanoe with the value of the current supplied to said motor, said relay having a contact which is picked up when and only when the current supplied to the motor exceeds a predetermined value, an auxiliary relay operative when energized to effect interruption of the motor energizing circuits, and a circuit for energizing said auxiliary relay from said conductors, said circuit being established when the contact of the overload relay is picked up, the auxiliary relay having a contact which becomes pickedup when the relay is energized and which when picked up establishes a circuit for energizing the relay winding from said conductors. V

18. In combination, a railroad track switch, a motor for moving the switch between a normal and a reverse position, a pair of conductors, means for selectively supplying to said conductors current of one polarity or the other, means selectively responsive to the polarity of the'current supplied to said conductors for establishing circuits for effecting operation of the motor to produce movement of the switch to one position or the other, an overload relay controlled in accordance with the value of the current supplied to said motor, said relay having a contact which is picked up when and only when the current supplied to the motor exceeds a predetermined value, an auxiliary relay having a contact which is operative when the relay is energized to effect interruption of the motor energizing circuits, and a circuit for energizing said auxiliary relay from said conductors, said circuit being established when the contact of the overload relay is picked up, the auxiliary relay having a contact which becomes picked up when the relay is energized and which when picked up establishes a circuit for energizing the relay from said conductors, the contact of the auxiliary relay being released on a change in the polarity of the current supplied thereto from said conductors.

19. In combination, a railway track switch, a motor for effecting movement of said switch between a normal and a reverse position, a pair of conductors, manually controlled means for supplying current of one or the other relative polarity to said conductors, a switch control relay controlling said motor, said relay obeing operative on the supply of current of one relative polarity thereto to condition the motor to effect movement of the switch to one position, said relay being operative on the supply of current of the other relative polarity thereto to condition the motor to effect movement of the switch to the other position, a control circuit for energizing said control relay from said conductors, an auxiliary relay controlling said control circuit, said auxiliary relay being operative when and only when deenergized to permit supply of current through said control circuit, said auxiliary relay being operative when energized to interrupt said control circuit and to establish a circuit for energizing its own winding from said conductors, and a lock relay governed by tramc conditons in the vicinity of said switch, said lock relay being 0perative when energized to permit supply of current throughsaid control circuit, said lock relay being operative when deenergized to interrupt saidcontrol circuit andto establish a circuit for energizing said auxiliary relay from said conductors. I I

20. In combination, a railway track switch, an electric motor for effecting movement of said switch between a normal and a reverse position, a pair of conductors, manually controlled means for supplying current of one or the other relative polarity to said conductors, a switch control relay controlling said motor, said relay being operative on the supply of current of one relative polarity thereto to condition the motor to efiect movement of the switch to one position, said relay being operative on the supply of current of the other relative polarity thereto tocondition the motor to efiect movement of the switch to the other position, a control circuit for energizing said control relay from said conductors, an auxiliary relay controlling said control circuit, said auxiliary relay being operative when and only when deenergized to permit supply of current through said control circuit, said auxiliary relay being operative when energized to interrupt said control circuit and to establish a circuit for energizing its own winding from said conductors, a lock relay governed by traffic conditions in the vicinity of said switch, said lock relay being 0perative when energized to permit supply of current through said control circuit, said lock relay being operative when deenergized to interrupt said control circuit and to establish a circuit'for energizing said auxiliary relay from said conductors, and an overload relay responsive to the magnitude of the current taken by said motor, said relay being operative on a predetermined increase in the magnitude of the motor current to establish a circuit for energizing the auxiliary relay from said conductors.

CLAUDE M. HINES.

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