US2156690A - Switch control system - Google Patents

Description

May 2, 1939. c:. M HINES SWITCH CONTROL- SYSTEM Filed Sept. 27, 1958 q u U u m F C IN NTOR la i Mflzinem. BY J HIS ATTORNEY Patented May 2, 1939 UNiTD s QFFICE SWITCH CONTROL SYSTEM Pa, a corporation of Pennsylvania Application September 27, 1938, Serial No. 231,885

8 Claims.

My invention relates to a control system for the motor for operating a railway track switch. It has heretofore been proposed to provide a switch control system for the motor for operating a railway track switch, the control system including an overload relay having a pick-up winding which is connected in series with the switch motor so that the overload relay is operated on excessive flow of current in the circuit of the switch motor to interrupt the circuit for energizing the motor and thusprevent injury to the motor.

It has also been proposed to provide the overload relay with a holding winding which is energized when the contacts of the relay become picked up to thereby maintain the relay contacts picked up until the switch control lever is changed from one position to the other.

It has also been proposed to provide means for 20 energizing the holding winding of the overload relay from a source in the vicinity of the switch,

such as the battery or other source from which current is supplied to operate the switch motor, and to provide means controlled by the polarized switch control relay for controlling the polarity of the current supplied to the holding winding of the overload relay so as to maintain the polarity of this current in correspondence with the direction of energization of the pick-up winding of the relay.

Relatively heavy currents are required to operate the motors which actuate railway track switches and it is advantageous to provide means other than the contacts of the polarized switch control relay or of the overload relay to interrupt the circuit of the switch motor in the event of an overload.

It is an object-of my invention to provide a switch control system of the type described and incorporating a relay separate from the polarized switch control relay and operative on picking up of the contacts of the overload relay to interrupt the circuit of the switch motor.

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

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

In the drawing the single figure is a diagram illustrating one embodiment of the improved switch control system provided by my invention.

Referring to the drawing, the reference character W designates a railway track switch which is operated by the Well-known dual selector type of mechanism. In the form here shown diagrammatically the mechanism includes a dual selector lever S which operates the link 3. When the lever S is in its normal position as shown in the drawing, link 3 connects the switch W with the motor M, while when the lever S is in its reverse position, link 3 no longer connects the switch W with the switch motor M, but instead connects the switch with a hand-throw lever H.

The switch W operates a motor cut-out contact 5 in accordance with the position of the switch. The contact 5 is arranged so that it engages a stationary contact 6 in all positions of the switch W except the normal position thereof, while the contact 5 engages a stationary contact I in all positions of the switch except the reverse position thereof.

The selector lever S operates contacts 9 and ill in accordance with the position occupied by the lever. When the lever S is in the normal position as shown in the drawing, contact 9 engages a contact I I, and contact Ill engages a contact 82, while when the lever S is in the handthrow position, the contacts 9 and Ill do not engage the contacts II and I2 and the contact 9 engages a contact I4.

The motor M is provided with an armature l5 and a field winding l6, while a polarized relay WR and a neutral relay WRP are provided for controlling the circuits for energizing the motor M. In addition, an overload relay OR is provided and is responsive to the current taken by the motor M.

The polarized switch control relay WR is controlled by a switch control lever L which is located at a point, such as an interlocking tower, remote from the switch. The lever L has associated therewith contacts l9 and to which are connected control wires 2| and 22. When the lever L is in the normal position as shown in the drawing, contact l9 connects control wire 2! to terminal 13* of a battery and contact 20 connects control wire 22 to terminal 0 of the battery 25. When the lever L is in the reverse position, contact l9 connects control wire 2| to terminal C of battery 25, while contact 20 connects control wire 22 to terminal B of battery 25.

Control wire 2! is connected to one terminal of the winding of polarized switch control relay WR, the other terminal of which is connected by wire 21 to a movable contact 28 of overload relay OR. A b-rnach of wire 21 is connected to one terminal of the winding of relay WRP, the other terminal of which is connected by wire 30 to contact 32 of overload relay OR. The contact 32 is engaged by a contact 33, when the contacts of relay OR are released, while the contact 33 is connected by Wire 34 to contact l2 which is engaged by contact it when the selector lever reverse polar contacts 31 and 38 of relay WR.

The contact 35 when picked up engages a contact 40 which is connected by a wire 4! to terminal B of battery 42, while terminal N of this battery is connected by a wire 43 to one terminal of the motor field Winding [5, the other terminal of which is connected by a wire 44 to switch operated contact 5.

The relay WR has a polar contact 45 which is connected by a wire 46 to a brush of the motor armature [5. The contact 45 when in its normal position, as shown in the drawing, engages the stationary contact, 3?, while when the contact 45 is in its reverse position, it engages a stationary contact 48 which, is connected by a wire 49 to contact 1.

The relay WR has, in addition, a polar contact 50 which is connected by a wire 5| to one terminal of a resistor 52 and alsoto one terminalof the pick-up winding 53 of overloadrelay OR. The other terminals of the resistor 52 and of the relay winding 53 are connected by a wire 55to a brush of the motor armature l5.

The resistor 52 has a positivej therrnal coefiicient of resistance, that is, the resistance of the unit increases as the temperature increases. The

various parts of the system are arranged and proportioned so' that during normal operation of the motor M, most of the currenttaken by the motor flows through the resistor 52,,and so little current flows through the overload relay pick-up winding 53 that the relay contacts remain released. However, if movement of the switch W is obstructed so that the motor M takes abnormal current for an unusual period of time, the resistor 52 becomes heated, thereby increasing its resist ance and increasing the flow of current in the winding 53 to such a degree that the'contact's of the relay become picked up.

The relay W'R also has a polar, contact which i is connected by a wire 59 to one terrninal of the,

holding winding fit of overloadrelay OR. tThe wire 59 is also connected to a contact SI, which,

when the contacts of relay: OR. are released, is

engaged by a contact 52 which is connected by a wire 63 to contact I I associated with the selector lever contact 9 i The other terminal of'the holding winding to v of the overload relay OR is connected by awire 55 to selector lever contact 9, while wire 65 is also connected to movable contact 56" of relay, 0R.- Contact 55, when picked up, engages a star, r

, J9 and 2!! are, operated to establish circuits to "tionary contact 58 to which is connecteda branch of wire it leading from the center or common terminalC of the battery 42'. Another branch of the wire H3 is connected to stationary contact l4, which inthe handthrow position of the selec tor lever S is engaged by the contact 9. l

The equipment is shown inthe drawin-gin the M is interrupted.

winding of,the relay.

position which it assumes when the switch W,

the selector S and the control lever L are in their normal positions, and when the contacts of the overload relay OR are released.

As the control lever L is in the normal position, the contacts l5 and 25 establish circuits to supply current of one relative polarity, which may be considered'normal polarity, to the control wires 2! and 22. As the contacts of'overload relay OR are released, contact 33 engages contact 32, thereby establishing a circuit from control wire 22 to wire 38 leading to a terminal of the winding of the relay WRP. This circuit includes wire 22, selector lever contacts Ill-l2, wire 34, contacts 3332 of overload relay OR, and wire 30.

When contact 28 of relay OR, is released, it does not engage contact 33, and as a result the circuit from wire 22 to wire 21 leading to a terminal to thereby establisha circuit from wire 4! leading from terminal B ot battery 42 towire 36 leading'to stationary contacts 3l and 38 of relay WR.

As the winding of relay WR is energized with current of normal relative polarity, the polar [contacts of this relay are in their normalpositions as shown, and the polarcontact 45 engages contact 31, while the polar contact 50 engages contact 55.

As polar 'contact 4 5 engaaes contact 31, a circuit is established from wire 35, which is connected to terminal B of battery; to a brush of to contact '5. At this time, however, as the switch W is in its normal position, the switch operated contact 5 does not engage the stationary contact G and the energizing circuit of the switch motor In addition, 'as thecont acts 10f overload relay OR arereleased andas the selectdr lever S is in its normalposition, a shunt circuit is established which includes the holding winding 60 of the relay OR, ,This circuit includes winding 60, wire 55, selector lever contacts ,9 and I I, wire B3,,overload relaycontacts 525I,and wire 59 tothe other terminal of the overloadrelay; This circuit shunting the holding winding of theoverload relay serves to make the overloadrelay contacts slow in picking up onenergization of the pick-up If at this time, the bperator wishes to effect movementvof the switch W from the normal to the reverse position, ,he may do so by moving the switch controllever L from its normal to its -1reverse position; I i

it @011 this movement tim as nfthcontacts supply currentfof reverse, polarity tron-j the battery 25 to the control wires 2,! and 22, Onthis tact 35 of relayl WRPmbecomes released and on subsequent energization of the relay Winding,

with current of the. opposite polarity, contact 35 again becomes picked up. In addition, upon this change in the relative polarity of the current supplied to the control wires 2| and 22 the polar contacts ofrelay WR are shifted from their normal positions to their reverse positions.

As a result of this movement of the polar contacts- 45 and 50 of relay WR, a circuit is established: to energize the switch motor M and cause it to move the switch W from the normal to the reverse position, this circuit being traced from terminal B of battery 42 through wire 4!, con tacts 4il35of relay WRP. wire 36, reverse polar contacts 38-50 of .relay WR, wire 5!, resistor 52 and pick-up winding53 of relay OR in parallel, wire 55, motor armature I5, wire 46, reverse polar contacts 45-48 of relay WR, wire 49, contacts 1-5, wire 44, motor field winding l6, and wire 43 to terminal N of battery 42. The switch motor M being energized drives the switch W from the normal to the reverse position and when the switch W attains the reverse position, the contact 5, is moved out of engagement with contact 7, thereby interrupting the circuit for energizing motor "M with the result that the motor ceases to operate.

In similar manner, if when the switch W is in the reverse position the operator wishes to effect movement of the switch to the normal position, he may do so by moving the switch control lever from its reverse to its normal position, thereby again effecting the supply of current of normal relative polarity from battery 25 to control Wires 2! and 22, while the polar contacts of relay WR will be shifted from their reverse to their normal ment of the switch is prevented before the switch has completed its movement, the motor M will draw an excessively heavy current for an unusually long period of time. As a result of this heavy flow of current, the resistor 52 will become heated, thereby increasing its resistance and causing an increase in the flow of current in the pick-up winding of the overload relay ORsufficient to cause thecontacts of the relay to become picked up. On picking up of the contacts-of the relay OR. the circuit ofthe switch motor M will be interrupted in the manner hereinafter described in detail.

For purposes of illustration it will be assumed that the switch W is in the normal position, that it is desired to eii'ect movement of the switch to the reverse position, andthat movement of the switch is prevented before the switch has attainedthe reverse position.

lished to energize. the switch motor M and cause it .to drive the switch from the normal to the reverse position.

On obstruction of the switch, the motor M will draw an unusually-heavy current and the pick-up winding 53 of overload relay OR will be energized sufhciently to cause the relay contacts to become picked up as previously explained. Picking up of the contact of relay OR will be delayed, however, because of the shunt circuit established for the holding winding 60 of the relay. This delayed operation of the contacts of relay OR is desirable as it prevents interruption of the switch motor circuit in response to a momentary overload.

On picking up of the contacts of the overload relay OR, contact 28 first engages contact 33 to thereby establish a circuit from control wire 22 to wire 21 leading to a terminal of the polarized switch control relay WR. On further upward movement of the contact 28, contact 33 is moved out of engagement with contact 32 to thereby interrupt the circuit from control wire 22 to wire 30 leading to a terminal of the relay WRP. As a result, the relay WRP is deenergized.

and its contact 35 becomes released, thereby interrupting the energizing circuit for the switch motor M; The motor M, therefore, will cease to move the switch W, while the motor will not be injured because of continued energization at a time when movement of the switch is obstructed.

It will be seen that on picking up of the contacts of the overload relay OR, thecircuit for energizing the neutral relay WRP is interrupted. while a circuit is established to maintain the winding of relay WR energized from the control wires-2| and 22. As the winding ofrelay WRP is deenergized, the contact 35 becomes released and interrupts the circuit of the switch motor M, while the polar contacts of relay WR remain in the positions to which they have been operated. In addition, as the winding of relay WR is maintained connected to the control wire 22, the operator may reverse the direction of energization of the winding of the relay WR, and thereby eiTect movement of the switch W away from the obstruction.

In addition, upon picking up of the contacts of overload relay OR, the previously traced circuit shunting the holding winding fill is interrupted by picking up of contact 82, while a circuit is established to energize the holding winding. 60

with current supplied from battery 42, the direction of energization of the holding winding 60 corresponding to the direction of energization of the pick-up winding 53.

As previously stated, it is assumed that the obstruction to movement of the switch occurred at a time when the switch W was being moved to the reverse position. In order to effect movement of the switch to the reverse position, the relay WR is energized With current of reverse relative polarity and its contact 53 will be in engagement with reverse polar contact TI to which is connected a branch of wire 43 leading from terminal N of battery 42.

As contact as engages contact 1|, a circuit is established from wire 43, leading from terminal N of battery 42 to wire 59 leading to one terminal of pick-up winding 60, while on picking up of contact 66 of relay OR, wire 65 leading from the other terminal of the holding winding 60 is connected to wire It leading to the center or common terminal C of battery 42.

On picking up of the contacts of overload relay OR, therefore, a circuit is established to energize the holding winding 6|] with current supplied from the battery 42, and this current is of a polarity corresponding to the polarity of the current supplied to the pick-up Winding 53. As-

holding winding of relay OR, before contact 33 is moved out of engagement with contact 32 to interrupt the circuit to the winding of relay WRP and thus effect release of contact 35 and interruption of the switch motor circuit.

If following the occurrence of the obstruction to movement of the switch the operator wishes to return the switch W to the normal position, he

i may do'so by returning the control lever L to the normal position. On this movement of the control lever L, the contacts I9 and 2D establish circuits to supply current of normal relative polarity from battery 25 to control wires 2| and 22 with the result that the direction of energization of the winding of the polarized switch control relay WR is reversed and the polar contacts of this relay are shifted from their reverse to their nor mal positions. On this movement of the contact 58, it is moved out of engagement with contact thereby interrupting the previously traced circuit for energizing the holding winding 60 of overload relay OR. On movement of the contact 58 to its normalposition, it engages a contact 12 "to which is connected a branch of wire 4| leading from terminal B of battery 42, and a circuit is now established to energize the holding winding 6|] of relay OR with current of the opposite rela-,

tive polarity to that whichwas previously supplied to this winding; This circuit is traced from terminal B of battery 42. through wire 4|, normal polar contacts |2-58 of relay WR, wire 59, winding of relay OR, wire 65, contacts 66-58 of relay OR and wire 10 to terminal C of battery 42. On this change in thepolarity of the. current supplied to the holding winding 60, the contacts of the relay become released and contact 66 interrupts the previously traced circuit for enerwith contact 33, thereby interrupting the. circuit for establishing connection from control wire 22 i tacts of the overload relay OR, contact 33 moves into engagement with contact 32, thereby establishing the previously traced circuit for connecting control wire 22 to wire 30 leading to a terminal of the neutral relay WRP. Accordingly the windings of the relays WRP and WR are again connected in series and are energized from the control wires 2| and 22.

On energization of the winding of the neutral relay WRP, the contact 35 of this relay becomes picked up and engages contact 40 to again establish a circuit from wire 4| leading from terminal B of battery 42 to wire 36 leadingto a polar contact of the relay WR.

At this time as the winding of the relay WR is amaeeo mal position. When the switch W attains the normal position, contact 5 is moved out of engagement with contact 6 to thereby interrupt the energizing circuit for the switch motor.

' In similar manner, if when the switch W is being moved from the reverse to the normal position movement of the switch is obstructed before the switch has attained the normal position, the overload'relay. ORfwill operate in the manner previously described to interrupt the circuit for energizing the winding of the neutral relay WRP from the control wires 2| and 22, while maintaining the circuit for energizing the relay WR from these wires.

In addition, on picking up of the contacts of the overload relay OR at such time, a circuit is established to .energize the, holding winding 6|! of the relay OR with current of a polarity corresponding to that supplied to the pick-up winding 53 of the relay OR.

It will be seen that when the switch W is being moved from the reverse tothe normal position,

the polar contacts of the relay WR will be in their normal positions, as shown in the drawing, and the contact 53 will engage polar contact 12. .Ac-

'cordingly, on picking up of the contacts of the overload relay OR a circuit is established to energize the, holding winding 63 with current supplied froni'the battery 42, this circuit being traced from terminal B of battery 42 through wire 4|, normal. polar, contacts 12-58 ofrelay wire 59, winding 60, wire 65, contacts 63- 68 of relay OR, and wire '10 to terminal C of battery 42. It will be seen that the current supplied to energize the holding winding 6|] of relay OR is of a polarity opposite to that supplied at a time when the polar contacts of the relay WR are in their reverse positions. ls thepolarity of. the 7 current supplied t o energize the holding winds ing is in agreement with that supplied to the pick-up winding 53, thecontacts of the relay are held picked up as a'result of energization of the holding winding 60.

If following obstruction of theswitch during its movement to the normal position the operator wishes to return the switch to the reverse position, he may dosoby returning the control lever L to the reverse position, thereby reversing the polarity of the current supplied to the control wires 2| and 22, and thus reversing the direction of energization of the winding of the polarized relay WR with the result that the polar contacts of this relay are shifted from their normal to their reverse positions. On this movement of the polar contacts of the relay WR,.the previously traced circuit forenergizing the holding winding 60 of the relay OR is interrupted, and a circuit is established to energize this winding with cur-.

rent of the opposite relative polarity, this circuit battery 42, reverse polar contacts ||-58 of relay WR, wire 59 and the other portions of the circuit previously traced in detail leading to terminal C of battery 42.

including wire 43 leading from terminal N of l terrupted with the result that the contacts of the relaydo not thereafter become picked up again. On release of the contacts of the overload relay OR, contact 28 is disengaged from contact 33, thereby interrupting the circuit for establishing connection from control wire 22 to wire- 2'! leading to the terminal of the winding of the polarized relay WR, while contact 33 engages contact 32 to again establish the circuit forconnecting wire 22 to wire 30 leading to a terminal of thewinding of the neutral relay WRP. rhe winding of the relay WRP, therefore, will be energized and the contact 35 will be picked up to again establish the circuit for energizing the motor, while the polar contacts of the relay WR will establish circuits to energize the switch motor M in a direction to cause the motor to move the switch to the reverse position.

The control system provided by this invention is arranged so that when the selector lever S is in the hand-throw position, the circuits for energizing the windings of the relays WR and WRP are interrupted to thereby prevent operation of the motor as long as the selector lever S.

remains in the hand-throw position.

The system is also arranged so that on movement of the selector lever S to the hand-throw position, a circuit is established to energize the holding winding of the overload relay and so that when this winding is energized as a result of movement of the selector lever S to the handthrow position, the winding will be maintained energized after return of the selector lever S to the normal position until the position of the control lever L is changed. This is advantageous as it operates, on movement of the dual selector lever to the hand-throw position and return to the normal position, to remove the switch from the control of the switch control lever until there is some manipulation of the switch control lever after the dual selector lever has been returned to the hand-throw position.

It will be seen that upon movement of the selector lever S to the hand-throw position, contact I is moved out of engagement with contact l2, thereby interrupting connection of control wire 22 with wire 34. Accordingly contact 33 is unable to establish a circuit from control wire 22 either to wire 2! leading to the winding of polarized relay WR, or to wire 38 leading to the windings of relays WRP and WR. The wind ings of relays WRP and WR, therefore, will be deenergized both while the contacts of relay OR are released and also when the contacts of this relay are picked up. As the contact 35 of relay WRP is released, the energizing circuit for the motor M is interrupted and the motor M cannot be operated.

In addition, upon movement of the selector lever S to the hand-throw position, contact 9 is moved out of engagement with contact I l, thereby interrupting the shunt circuit for the holding winding 60 of relay OR, while contact 9 is moved into engagement with contact H3, thereby establishing a circuit from wire 10, leading from terminal B of battery 42, to wire as leading to one terminal of the holding winding 68 of relay OR, The other terminal of the winding 60 is connected by wire 59 to polar contact 58 of relay WR. In one position of the polar contact 58 it engages contact 12 to which is connected wire ca leading from terminal B of battery 42, while in the other position of polar contact 58 it engages contact H to which is connected wire 63 leading from terminal N of battery 42. It will be seen, therefore,

that wire 59 leading from one terminal of the holding winding 66 of relay OR will be connected to terminal B or to terminal N of battery 42 depending upon the position occupied by polar contact 58 of relay WR, at the time the selector lever S is moved to the hand-throw position.

On energization of the winding 60, the contacts of relay OR become picked up and contact iii; engages contact 68 to establish a stick circuit from wire iii to Wire 65 to maintain the holding winding so of relay OR energized after movement of selector lever contact 9 out of engagement with contact Id.

It will be seen that when the contacts of relay OR become picked up, contact 62 interrupts the shunt circuit for the winding 60 so that on return of the selector lever S to the normal position and movement of contact 9 into engagement with contact I I, the shunt circuit for winding 58 is not restored, but remains interrupted by contact 52.

As long as the selector lever S remains in the hand-throw position, the contact if! interrupts the circuit from the control wire 22 to the Windings of relays WR and WRP as previously explained, while contact 9 maintains the circuit for energizing the holding winding 88 of relay OR.

Accordingly, if while the selector lever S is in the hand-throw position the posiiton of the control lever L is changed, thereby reversing the polarity of the current supplied to the control wires 2i and 22, the position of polar contacts of relay WR will not be changed, while contact 35 of relay WRP will remain released, with the result that the motor M will not be affected by such change in the position of the control lever L.

On subsequent return of the selector lever S to the normal position, contact 9 no longer engages contact l, but the winding BS of relay OR. is maintained energized by current supplied over the stick circuit established by contact 65 of relay OR. In addition, on return of the selector lever S to the normal position, contact it engages contact l2 and thereby connects wire 22 to wire 34. At this time, as the contacts of relay OR are picked up, contact 28 engages contact 33, while contact 33 is held out of engagement with contact 32. Accordingly a circuit is established from wire 34 to wire 21 so that when contact Hi is moved into engagement with contact l2 the winding of relay WR is connected to control wires 24 and 22, but the circuit to the winding of relay WRP remains interrupted with the result that contact 35 of relay WRP remains released.

If the operator in control of the switch control lever L now wishes to regain control of the switch W, he may be do by reversing the position of the switch control lever L. This reverses the po larity of the current supplied to the control wires 2| and 22, and as the winding of the relay W5. is connected to the control wires at this time, as previously explained, the polar contacts of the relay WR will be changed from one position to the other with the result that polar contact 58 is moved out of engagement with one of the stationary contacts associated therewith, and into engagement with the other of the stationary contacts associated therewith. As a result of this movement of the polar contact 58, there is a reversal in the direction of energization of the holding winding iii] of relay OR with the result that the contacts of this relay become released, and contact 66 thereupon interrupts the stick circuit for the winding 66 so that after release of the relay contacts the relay Winding is deenergized and the contacts of the relay do not thereafter again become picked up.

On release of the contacts of relay OR, contact 28 moves out of engagement with contact 33, while contact 33 is moved into engagement with contact 32 to again connect the winding of relay WRP in series with the winding of relay WR, while contact 35 of relay WRP becomes picked up to again establish the circuit for the switch motor M. The switch motor M, therefore, will be energized in a direction determined by the position of the polar contacts &5 and 5d of relay WR.

From the foregoing, it will be seen that the improved switch control system provided by this invention incorporates a neutral relay in addition to the usual polarized switch control relay, and that the system is arranged so that the con tacts of the polarized relay are not required to interrupt the energizing circuit for the switch motor.

During normal operation of the switch W, at the completion of the movement of the switch, the energizing circuit for the switch motor M is interrupted by the switch operated contact 5. In the event movement of the switch W is obstructed and the contacts of the overload relay OR become picked up, the winding of neutral relay WRP is deenergized with the result that its contact 35 is released and interrupts the energizing circuit for the switch motor.

In addition, on picking up of the contacts of the overload relay OR, the winding of relay WR remains connected to the control wires 23 and 22. Furthermore, at this time the degree of errergization of this winding is increased because of the removal of the Winding of the relay WRP from the circuit of the control wires 2! and 22. Accordingly at the time the contact 35 of relay WRP is released, the polar contacts of relay WR are held closed with more than usual force and no arcing occurs at the contacts of relay WR, While subsequent response of relay WR to a change in the polarity of the current supplied to the control wires 2! and 22 is made more certain.

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

Having thus described my invention, what I claim is:

1. In a switch control system, in combination, a railway track switch movable between a normal and a reverse position, a motor for operating said switch, a pair of conductors, means for supplying to said conductors current of one relative polarity or the other, a neutral relay controlling a supply circuit for energizing the switch motor, a polarized relay controlling the direction of energization of the motor by current supplied by said supply circuit, an overload relay controlled by the magnitude of the current in the motor supply circuit, a control circuit for energizing the windings of the neutral and polarized relays from said pair of conductors, and means controlled by the overload relay for interrupting said control circuit and for establishing a circuit for energizing only the winding of the polarized relay from said conductors.

2. In a switch control system, in combination, a railway track switch movable between a normal and a reverse position, a motor for opcrating said switch, a pair of conductors, means for supplying to said conductors current of one relative polarity or the other, a neutral relay controlling a supply circuit for energizing the switch motor, a polarized relay controlling the direction of energization of the motor by current supplied by said supply circuit, an overload relay controlled by the magnitude of the current in the motor supply circuit, a control circuit for energizing the windings of the neutral and polarized relays in series from said pair of conductors, and means controlled by the overload relay for interrupting said control circuit and for establishing a circuit for energizing only the winding of the polarized relay from said conductors.

3. In a switch control system, in combination, a railway track switch movable between a normal and a reverse position, a motor for operating said switch, a pair of conductors, means for supplying to said conductors current of one rela tive polarity or the other, a neutral relay controlling a supply circuit for energizing the switch motor, a polarized relay controlling the direction of energization of the motor by current supplied by said supply circuit, an overload relay controlled by the magnitude of the current in the motor supply circuit, the overload relay having contacts which when released establish a control circuit for energizing the windings of the neutral and polarized relays from the said pair of conductors, said contacts being operative on energization of the overload relay winding to first establish a circuit to energize only the winding of the polarized relay from said conductors and to thereafter interrupt the said control circuit.

l. In a switch control system, in combination, a railway track switch movable between a normal and a reverse position, a motor for operating said switch, a pair of conductors, means for supplying to said conductors current of one relative polarity or the other, a neutral relay controlling a supply circuit for energizing the switch motor, a polarized relay controlling the direction of energization of the motor by current supplied by said supply circuit, an overload relay controlled by the magnitude of the current in the motor supply circuit, the overload relay having contacts which are normally released and which become picked up on a predetermined incuit being controlled by a contact of the overload relay and being interrupted on picking up of said overload relay contacts, and means for energizing the winding of the switch control relay from said conductors both when the overload relay contacts are picked up and when they are released.

5. In a switch control system, in combination, a railway track switch movable between a normal and a reverse position, a motor for operating said switch, a pair of conductors, means for supplying to said conductors current of one relative polarity or the other, a neutral relay controlling a supply circuit for energizing the switch motor, a polarized relay controlling the direction of energization of the motor by current supplied by said supply circuit, an overload relay having a pick-up winding and a holding winding, means for energizing the relay pickup winding in accordance with the magnitude of the current in the motor supply circuit, the

overload relay having contacts which become picked up on a predetermined increase in the magnitude of the current in the motor supply circuit, the overload relay contacts being operative when picked up to establish a circuit to supply current to the holding winding of such relay, means controlled by the polarized relay for controlling the polarity of the current supplied to the circuit of the holding winding, a circuit controlled by a contact of the overload relay for energizing the winding of the neutral relay, and means for energizing the winding of the polarized relay from said pair of conductors.

6. In a switch control system, in combination, a railway track switch movable between a normal and a reverse position, a motor for operating said switch, a pair of conductors, means for supplying to said conductors current of one relative polarity or the other, a neutral relay controlling a supply circuit for energizing the switch motor, a polarized relay controlling the direction of energization of the motor by current supplied by said supply circuit, means for energizing the winding of the polarized relay from said pair of conductors, an overload relay having a pickup winding and a holding winding, means for energizing the relay pick-up winding in accordance with the magnitude of the current in the motor supply circuit, the overload relay having contacts which become picked up on a predetermined increase in the magnitude of the current in the motor supply circuit or when the holding winding is energized, a circuit controlled by a contact of the overload relay for energizing the winding of the neutral relay, and a selector lever having a normal position in which it conditions the switch for operation by the motor and a hand-throw position in which it conditions the switch for manual operation, the selector lever being operative in the hand-throw position to establish a circuit to supply energy to the overload relay holding winding, the polarized relay controlling the polarity of the current supplied to the holding winding through such circuit.

7. In a switch control system, in combination, a railway track switch movable between a normal and a reverse position, a motor for operating said switch, a pair of conductors, means for supplying to said conductors current of one relative polarity or the other, a neutral relay controlling a supply circuit for energizing the switch motor, a polarized relay controlling the direction of energization of the motor by current supplied by said supply circuit, means for energizing the winding of the polarized relay from said pair of conductors, an overload relay having a pickup winding and a holding winding, means for energizing the relay pick-up winding in accordance with the magnitude of the current in the motor supply circuit, the overload relay having contacts which become picked up on a predetermined increase in the magnitude of the current in the motor supply circuit, a circuit controlled by a contact of the overload relay for energizing the winding of the neutral relay, and a selector lever having a normal position in which it conditions the switch for operation by the motor and a hand-throw position in which it conditions the switch for manual operation, the selector lever being operative when and only when in the handthrow position to establish a circuit to supply energy to the overload relay holding winding, a contact of the overload relay being operative when picked up to also establish a circuit to supply energy to the overload relay holding winding, the polarized relay controlling the polarity of the current supplied to the holding winding by the circuits established by the selector lever and the overload relay contact.

8. In a switch control system, in combination, a railway track switch movable between a normal and a reverse position, a motor for operating said switch, a pair of conductors, means for supplying to said conductors current of one relative polarity or the other, a polarized relay having a winding energized from said pair of conductors, said relay controlling normal and reverse circuits for energizing said motor to cause it to operate in one direction or the other, an overload relay having a pick-up winding and a holding winding, means for energizing the relay pick-up winding in accordance with the magnitude of the current supplied to the switch motor through either said normal or reverse circuits, the overload relay having contacts which become picked up on a predetermined increase in the magnitude of the current in the pick-up winding, a contact of the overload relay controlling a holding circuit for supplying current to said holding winding, means controlled by the polarized relay for controlling the polarity of the current supplied to said holding circuit, and a neutral relay operative on picking up of the overload relay contacts to interrupt the normal and reverse circuits for energizing the switch motor.

CLAUDE M. I-HNES

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