US2604581A - Switch control for trailable track switches - Google Patents

Description

2 SI'lEETS SHEET l Ihwcntor G. J. JOHANEK SWITCH CONTROL FOR TRAILABLE TRACK SWITCHES July 22, 1952 Filed. Aug. 10. 1949 wZEo Z JOMPZOU (Ittorneg G. J. JOHANEK SWITCH CONTROL FOR TRAILABLE TRACK SWITCHES July 22, 1952 2 SHEETS-SHEET 2 Filed Aug.

Zmventor Q n m at FI II uZIo Z JOmkzOu points by the car wheels.

Patented July 22, 1952 SWITCH CONTROL FOR-TRAILABLE TRACK SWITCHES George J. Johanek, Rochester, N. Y.,iassignor to General Railway Signal Company, Rochester, N. Y.

Application August 10, 1949, Serial No. 109,439

1 Claim.

This invention relates to control circuits, and more particularly pertains to the type of circuits used to control an electrically operated railway switch machine from a remote location.

Modern railway practice requires the-use of power operated switch machines and, in addition, the provision of some means for controlling the various switches in a given region from a single, remote location. It has also been found desirable to provide means for preventing damage to switch machines in the event that a trailing point train movement forcibly moves the switch points from their last actuated position. On someprior types of trailable switches, mechanical means, such as a spring connection with dash-pot, are provided tobias the switch points to their last actuated position, but which permit them to be temporarily forced to the opposite position by the wheels of passing cars. This type of switch machine operation has been found to cause a greater than normal amount of wear as the switch points are continually slammed to the trailed position by successive car wheels. In other types of trailable switches, the switch points are immediately moved to their full trailed positions independently of the switch operating mechanism by reason of a yieldable spring biased cam connection. With this type of operation, it generally is required that the switch machine control lever be manually operated to such trailed position after the passage of the train to bring the operating mechanism into correspondence with the switch points in order that the switch points can then be returned by power operation to their original position existing before the trailing point train movement.

The control circuit organization of the present invention avoids the disadvantages of the prior art by providing positive operation of the switch points by the switch operating mechanism immediately following the initial trailing of the switch This positive operation of the switch points prevents the slamming of the points against the stock rails upon the passage of successive car wheels, and also provides that the operating mechanism is in correspondence with the switch points at the termination-of the trailing point train movement.

Without attempting to describe the present invention in exact detail, it may be said that when the switch points are forcibly moved from either the full normal or full reverse position, the switch operating mechanism is immediately operated to a corresponding position, which position is of course opposite to that to which it was last actuated. This new position of the switch operating mechanism positively holds the switch points in the full operated position in which they are being trailed. Then when the associated track circuit becomes unoccupied, the switch.

points can immediately be restored by power operation to the'original position called for by a remotely located control lever without requiring any action on the part of the operator. -On .the other hand, if the operatorhas already operated the control lever to the new position in which-,the

switch points are being trailed, then the switch operating mechanism is in a correspondingposition and holding the switch points in that position. Thus, no operation is required on the part of the operator subsequent to the associated track section becoming unoccupied. V

The features of the present invention may be applied not only to conventional switch machines that are reversible in mid-stroke, but also to switches of the type disclosed in Patent No. 1,854,602 to C. W. Prescott, dated April 19,1932, which are ordinarily not so constructed as to be reversible in mid-stroke. Switch machines of this latter type employ a yieldable cam connection as shown in the above mentioned patent which not only permits movement of the switch points independently of the switch operating means, but also causes the switch points to be operated fully to the opposite positionupon their being moved from their last actuated position by a trailing point train movement. as above described. In order to demonstrate the applicability of the features of the present inventionto switches having switch machines of either type, two separate embodiments of this invention are herein disclosed but it should be understood that, although these specific embodiments have been employed in order to permit a specific and complete description of thisinvention, the features of this invention can readily be applied to Other types of switch machines. I

Other objects, purposes, and characteristic features of the present invention will be in part obvious from the accompanying drawing-and in part pointed out as the description-of this invention progresses. 3

In describing the invention in detail, reference will be made to the accompanying drawings.- In. these drawings, like reference characters have been used for corresponding parts in the two separate embodiments but distinctive reference characters are used for those parts which are associated with onlyone or the other of thetwo embodiments. In these drawings: a e

Fig. 1 illustrates the switch machine control circuit organization as applied to a switch machine of the type adaptedfor use in classification yards and having a yieldable cam connection; and

Fig. 2 illustrates the switch machine control circuit organization as applied to a switch machine having a yieldable connection and being reversible in mid-stroke.

For the purpose of simplifying the illustration and facilitating in the explanation, the various parts and circuits; constituting.the embo'dimentof the invention have been shown diagrammatically and certain conventional illustrations have been employed, the drawings having been made more with the purpose of making it easy: to. understand the principles and mode of operation, than with the idea of illustrating the. specific construction and arrangement of parts that would be -em-:

ployed in practice. Thus, the various relaysand their contacts are illustrated in a conventional manner, and symbols are used ;to: indicate con nections to the terminals of batteries ,or, other.

"injanor mal position contacting the stationary 'contacts lt and H5 when the switch points are in correspondingful1-normal positions, and which 'j is caused tobe" in a reverseposition contacting stationary-contacts2l and --22 when the switch points are in--corresponding full reverse positi'ons'. =However when the switch points are out o iztheir-fullinormalaor reverse positions, as during their operation fromone position to another, thefmovablecontact- I 4 is in its mid-position --show n- 'by dotted lines.- Thissw-itch box SB may be pf the type-shown in the Patent No. 2,394,215 ton-J. stevenson dated February 5, 1946, or other su-itable-contacts capable of repeating the "position of the switchpoints can be incorporated -within-theswitch machine, if desired.

" -"A--switch machi'ne -lever SML located at the ---con;trol-ofiiceoperates the pole changing conta cts 3 'and4to-apply steady energy of either 'polarity fromthe battery B to the line wires 5 and 6; Thus, with the lever SML in the normal positi'on -N, it is evident-that the line wire -6- will be of positive polarity-with respect to the line wire l'as The energy thus transmitted over-the line wires is applied to-the= upper windings of the -eontactors'NWR*-and RWRi These contactors are of the polar-biased neutral type such as shown in the prior Patent No. 2,414,583 granted January 21, 1-947, to 'G. E. Duffy, Sr. -Each of thes'e contactors has two independent windings "either-on'e of which'will, when energized with the pi-openpolarity, pick -up-"its armature and cause the clo sure-of its various front contacts. However',- the-'energization of either one of these wind- -i'l'lgswith the opposite polarity will not cause an actuation of the contacts to their picked up positions: 'Thus,-energization of the line wires 5 ..anavs with'one polarity causes the actuation of -onecontactor while energizati'on of the line Wires off'the': opposite'polarity causes the actuation of the other contactor. This has been illustrated the simultaneous picking up of both contactors over the control line Wires 5 and 6. Thus, with the lever SML in the normal position N, as shown, the contactor NWR will be picked up because the direction of current flow through its upper winding-correspnds to the direction of the arrow included within the relay symbol. In order to pick up the contactor RWR, it is necessary to move the leverSML to its reverse position R, in which 'case'the'contactor NWR will drop away (because it can not respond to reverse current through itSiWlIldi'IlE) and close its back contact 1, thereby completing a circuit for the energization of the contactor RW'R.

With the switch points SW in the normal posi- -tion: shown inFig. 1, and the switch machine SM ina corresponding position, the movable con= 'tactsS and 9-ofthe'swi-tch machine are in their upper position-so that contact 8 engages-the stationary contacts l8 and 'l l, While the contact 9 engages stationary contacts [2 and it. Also, the movable contact M of the switch box SB is in-its u per position and provides an electrical connection-between the stationary contact l and IB. Q When the switch control lever SML is moved. to the reverse position'R so as to energize the contactor RWR and deenergize the contactor and if, at that time the switch points are iii-their normal-position as shown in the drawi'n'g, acircuitwill then be established to energize the switch machine motor and operate the switch points to the-reverse -position. This circuit may be traced as follows: from including front -*contact 25 of contactor RWR; back contact 26 of contactor NWR, line RW, stationary contact I3, movable contact 9' in a normal position, stationary contact 12, wire 21, motor armature A, wire zsfistationary contact H, movable contact 8 in a normalposition,stationary contact I9, field wind- 'ing'-'F,'c0ntro1- wire C, and front contact 28 of contactor RWR', to As-a result of this circuit' being: established, the switch machine motor isso energized as to drive the switch points to their reverse positions. As the switch points move from their normal positions, the movable contact Hiin the switch-box SB moves to its center position where it cannot make contact with-either-pair of stationary contacts, 1. e. contacts l5 and It or contacts 2| and 2.2. The contact i trem-ains in this mid-position until the end of the switch operating stroke when the switch points reach the reverse position, at which time -it is moved-to: a reverse position to make a connection between stationary contacts 2| and '22. The movable contacts8 and 9 of the switch machine, however, remain in the positions shown during the first part of the operating stroke and move-to their dotted line reverse positions only at theend of the operating stroke. When they 'move to these positions, the above described motor circuit is opened and the motor comes to rest, thereby stopping the switch operation.

If the lever SML is now returned to its normal position N, the contactor RWR Will be deener- 1 gized and the contactorNWR energized. As a result," a-circuit will then be established from ,through-front contact 26 of contactor NWR, backcontact 25 of contactor RWR, wire NW, stationary contact 26,;movable contact 9 in a I reverse position, stationar contact i8,wire 29, motor-armature A, wire '27, stationary contact l-fli movable contact 8 in a reverse position, stationary contact 1-0, field winding F, control wire 0, and front contact 3!] of contactor NWR, to The motor is thus energized and the direction of current flow through its armature A is such as to drive the switch points to their normal positions. It will be noted that in this case, as in the previously described circuit which 'causes'operation of the switch points to thereverse position, the unused control wire is shorted to the common wire C through a back contact of one of the contactors NWR or RWR." Thus, in this latter circuit the control wire RW is shorted to the common wire C through back contact 28 of contactor RWR. This arrangement tends to prevent the inadvertent application of energy to a control wire which might result in erroneous operation.

From the foregoing description, it can be seen that the operation of the switch machine motor shown in Fig. 1 is dependent upon the condition of the contactors NWR. and RWR. Thus, if the contactor NWR'is picked up and the contactor RWR dropped away, the switch points will be operated from the reverse to the normal position; whereas, if the contactor RWR is picked up and the contactor NWR. dropped away, the switch points will be operated from the normal to the reverse position.

As previously noted, the control circuit from the control lever SML to the contactors RWR and NWR. includes a front contact 3| of the track relay TR. For this reason, if a train should enter the detector track section DT and cause the track relay TR to drop away, the contactors NWR and RWR would then no longer be subject to control over the line wires 5 and 6. This circuit arrangement precludes the possibility of initiating an operation of the switch points after a train has entered the detector track section.

It is desired, however, that a switch movement, once begun, be completed even though the detector track section becomes occupied and causes the dropping away of the track relay TR. The control circuit of the present invention provides for this contingency by means of the stick circuits for the contactors NWR and RWR. More specifically, the movable contact I4 of the switch box SB does not engage either pair of stationary contacts when the switch points are in midstroke. Consequently, both repeater relays NWP and RWP will be dropped away under such circumstances. If the switch is being operated to its reverse position so that front contact -32 of the contactor RWR is closed, a stick circuit will then be completed through this'front contact 32 and also back contacts 33 and 34 of the repeater relays RWP and NWP respectively. In this way,

the condition of the contactors RWR and NWR as called for by the control lever SML will be maintained through this stick circuit even though the detector track section DT, becomes occupied and opens front contact 3|, thereby allowing completion of the operating stroke. If the switch machine SM is being operated to its normal position when the detector track circuit becomes occupied, a similar stick circuit is established including the front contact 35 of contactor NWR. g

If the switch SW has been operated to the normal position as shown in the drawing, and is then trailed through by a train or car moving from the siding onto the main track, the switch points will be forced to the reverse position independently of the power operation of the switch -machine SM, as has been pointed out. This is because the switch machine SM includes the yieldable cam connection with biasing spring which acts to throw the switch points to their full reverse position when they are trailed reverse without the operation of the switch machine driving motor. As a result, the movable contact I4 in the switch box SB is then immediately moved to its lower dotted line position thereby causing the repeater relay NWP to drop away and the energizing instead of the repeater relay RWP. In making such a trailing point train movement, the track relay TR, is, of course, shunted and closes its back contact 36 while opening its front contact 3!. The opening of this'front contact 3| prevents manual control of the contactors NWR. and RWR over the line wires 5 and 6. However, with the front contact 31 of repeater relay RWP now closed, an alternate circuit is completed through this front contact 31 and back contact 36 of relay TR to energize the contactor RWR. The contactor NWR, on the other hand, cannot be held up through its upper winding because of the open front contact 3|, nor can it be held up through its lower winding because of the open back contact 33 in its stick circuit and the open front contact 38 of the relay NWP. Thus, with the contactor RWR energized and the contactor NWR dropped away, the switch machine motor will immediately be operated in the direction which will bring its operating mechanism into correspondence with its previously train actuated switch points.

When the train then moves out of the detector track section DT, and allows the track relay TR, again to be picked up, the opening of back contact 36 of this track relay opensthe alternate circuit to the lower winding of the contactor RVVR allowing it to drop away, while the closing of front contact 3! of relay TR restores the control of the contactors NWR. and RWR to the manually operable lever Sm as effected over the line wires 5 and 6. If the control lever SML has in the meanwhile been left in its normal by a train passing along the main track, the re peater relay NWP will be energized and a similar 'circuit established through front contact 38 of this relay NWP and back contact 36 of track relay TR to energize the'lower winding of the 1 contactor NWR. In a similar manner, the witch operating mechanism SM will then be operated to correspond with the trailed through switch points.

Modification of Fig. 2

The accompanying Fig. 2 shows a detector track section DT which is associated with the stretch of track adjacent the turn out switch SW and including the fouling section of this switch. The track relay TB is energized by a track battery I which has included in series therewith a current limiting resistor 2. The position of the switch points SW is shown diagrammatically as being controlled by the switch machine ZSM, and the position of the switch points SW, in turn, governs the operation of the switch repeater contacts included in th switch machine ZSM.

A switch machine lever SML located at the control office operates the pole changing contacts 3 and 4 to apply steady energy of either polarity from the battery B to the line wires 5 and 6. With the lever SML in the normal poare in either the mid-stroke or full reverse positions, respectively.

.When the switch machine control lever 'SML is moved to the reverse position R so as to energize the contactor RWR and deenergize the contactor NWR and if, at that time, the switch points are in their normal. position as shown'in thev drawing, a circuit will then be established to'ene'rgize the switch machine motor and operate the'switch points to the reverse position. This circuit may be traced as follows: from includingfront contact of contactor RWR, back contact 26 of contactor NWR, the line wire RW, stationary contact l3, movable contact 9, stationary contact l2, wire 21, motor armature A,wire' 29, stationary contact II, movable contact 8, stationary contact I0, field winding F, control wire C, and front contact 28 of contactor. RWR, to As a result ofthis circu'itbeing established, the switch machine motor is 'so energized as to drive the switch points to their reverse positions.

Ina'ddition to the above described circuit being-completed for the energization of Y the switchfmachine motor, a circuit is also completedithrough front contact 25 of contactor RWR, back contact 26 of contactor NWR, wire RW, magnet winding'54, stationary contact 44, movable contact' 40, stationary contact 43, .to thereby energizing the magnet 54. As indicated by the'dotted lines, this magnet 54, when energized, holds the movable contacts 8 and 9 in'ltheir upper positions. A similar magnet 55 is provided which, when energized, retains the movable contacts 8 and 9 in their lower positions. I As theswitch points SW move from the normal to-the reverse position, the movable contacts 8 'and'S remain in their upper positions to keep the motor energized but as the switch points finally'reach the full reverse position, the movablefcontacts 4D and 49 move to the positions 40b'and 491). With thesecontacts and 49 in this position, the above described circuit for the energiz ation of magnet winding 54- is interrupt ed a result, themovable contacts 8 and 9' are permitted to be mechanically moved to the positions .86 and 9b. When this action occurs, the circuitffor the energization of the switch machine motor is broken and the motor becomes deenergi 'ed, thereby stopping the switch operation'.

If thelever SML is now returned to its normalfposition N, the 'Tco'ntaot'or' RWR willb e deenergized and the contactor NWR energized. As a' result, a circuit will then beestablished from ,,including front contact 26 of contactor NWR, back contact25 of contactor RWR, wire NWystationary contact 20, movable contact 917, stationary contact I9, wire 29, motor armature AQwire' 2'1, stationary contact l8, movable con tact 8b; stationary contact I0, field winding F, controlwlre C, and front contact 30 of contactor NWR,"to The switch machine motor is thus energized and the direction of current flow through its armature A is now of such a polarwas to drive the switch points from the reverse position to the normal position. It will be noted that-in this case, as in the previously described circuit for operation of the switch points to the reverse position, the unused control wire is shorted to the common wire C through a back'contact of one or'the other of the contactors NWR or RWR. Thus, in this latter circuit the control wire RW is shorted to the common wire C through back contact 28 of contactor RWR.

This arrangement tends" to prevent the mad vertent application of energy to a control wire which might result in erroneous operation From the foregoing description, itcan be seen that the operation of the switch machine motor shown in Fig. 2 is dependent upon the condition of the contactors NWR and RWR. Thus, if'the contactor NWR is picked up and the contactor RWR dropped away, the switch points SW will be operated from the reverse to the normal position; whereas, if the contactor RWR is picked up and the contactor NWR dropped away, the switch points will be operated from the normal to the reverse position.

As previously noted, the control'circuit from the control lever SML to the contactors RWR and NWR includes a front contact 3i of the track relay TR. For this reason, if a train should enter the detector track section DT and cause the track relay TR to drop away, the contactors NWR and RWR. will then no longer be subject to control over the line wires 5 and 6. This circuitarrangement precludes the possibility of initiating movement of the switch points when a train is in the detector track section.

It is desired, however, that, if operation of the switch points has been initiated, it will be com.-

pleted even though the detector track sectionDT becomes occupied and causes the dropping away of thetrack relay TR. The control circuit or-,

ganization of the present invention provides for this contingency by means of'the stick circuits for the contactors NWR and RWR governed by. contacts 4| and 50. For example, if the switch points are operated, as previously described, from the normal to the reverse position, the movable contacts 4| and 50 will assume the positions 411; and 56a respectively, as soon as the switch points move away from the full normal position and will remain in that position until the switchpoints have reached the full reverse position at which time the movable contacts 4| and 50 will assume the positions M2; and 50b. However, while these movable contacts are in the positions 4 la and 50a, a circuit is completed from including stationary contact 45, movable contact 4|, stationary contact 46, movable contact 500., stationary contact 52, wire 53, back contact 56 of contactor NWR, front contact 51 of contactor RWR, and the lower winding of contactor RWR, to By this means, the'contactor'RWR will remain energized even though a train has entered the detector track section DT, while the switch machine 2SM was in mid-stroke, and the switch points SW will continue to be operated to the reverse position.

If the detector track section DT becomes occupied when the switch points are being moved from the reverse to the normal position, a similar circuit will be established including the front contact 56 and the back contact 51; and this circuit will likewise maintain the contactor NWR in an energized condition until the switch points have reached the full normal position. In this way, the condition of the contactors RWR and NWR, as called for by the control lever SML, will scriptionjthat whenthe switch points are ope r ated from the normal to the reverse position, the

contactor NW3, is dropped away and the contactor RWRpicked up. ,If. howevenjthe' detftwri garter track" section D'I should become occupied while I 48 movable'c'ontact 42', stationary contact 31 and the lower winding of contactor NWR to, energize the'contactor NWR and pick up its front contacts; Also, the switch machine ZSM would then be -jinflmid-stroke so that" a stick circuit, similar to thatpreviouslydescribed, would be established to-maintain the contactor RWR, in an energized condition. Although both contactors RWR and NWR would thus be momentarily picked up, the opening of back contact 56 of contactor NWR would open the stick. circuit for contactor RWR so fithat only the contactor NWR would'remain pickedup.

According to the previous description; the magnet 54 is" energized when the switch machine is being operated to the reverse position. However, with the switch machine in mid-stroke the movable contacts ifi andv 49 are in the positions ita andASa, respectively, so that'eith'er magnet 54 or 55 can then be energized, provided only that its-associated wire RW or NW, respectively, is at that time energized. In the case now under consideration, the reversal of conditionswith respect to the contactors RWR and NWR caused by the entrance of a train into the detector track section DT when the switch'points are only partially opera-ted will result in the removal of energy from wire'RW and at the same'time apply energy to the wire NW. As a result, the magnet 54 will become deenergized and the magnet 55' energized; Thus,-although the; movable contacts 8 and 9 would ordinarily remain their upper positions until the switch points have reached the full reverse position, the energizationof' this magnet 55 causes the movable contacts 8 and'9 to be quickly moved to their positions 812 and so. For this reason, the previously described circuit for the energization of the switch machine motor which causesthe switch points to be operated to the normal position'is now completed and the switch points are immediately returned to that position.

This operation occurs because the movable contact 42 follows the switch points as they are moved between their extreme positions. The fixed contact 4'! is preferably constructed toallow the movable contact 42 to make connection be tween it and the fixed contact 48 for'abcut onethird of the operating travel of the switch points adjacent their normal position; whereas, the fixed contact GU-is adjusted to allow the movable contact 42 to make connection between'itand the fixedcontact 48 for"about'one-third of the operating'travel'of the'switch points adjacent their reverse'position. Thus, the movable contact 42 doesnot make any connection during about onethird of' the intermediate'portion of an operating stroke. It is of course to be understood that these proportions of the operating' strcke are selected for convenience inthe disclosure and other applied to the lower winding 'of either. contactor NWR or RWR so that the contactor RW'R which has been picked up' for the feverse'operation' of theswitch'machine, will remain picked 12 up through its stick circuitincludingmovable contact 50 in its position 50a. This causes. the pole changing magnet54 to continue to be energized'and the contacts 8 and 9 to be maintained in their positions to effect the continued reverse operation of the switch machine in spite of the occupancy of the detector track section. It should be noted, however, that if the track switch has operated sufficientlyreverse so as to close a circuit to supply energy through the back con-- tact 62 of the track relay TR, and through movable contact 42 in its position b, then the lower winding of contactor RWR is merely supplied with an auxiliary energizing circuit in multiple with its stick circuit already energized. This circuit continues to remain closed, even after the switch machine 2SM has completed its operating stroke'and has opened the stick circuit, until the detector track section DT becomes unoccupied allowing the track relay TR to pick up and open back contact 62. v

A similar operation will occur if the switch machine ZSM is operating the switch points of thetrack switch SW to their normal positions when the detector track section DT becomes occupied. In brief, it may be said that the entrance of a train into the detector track section DT while the switch SW is being operated, causes the switch machine to continue operation so 'asto move the switch points to a full normal or reverse locked position, but if such occupancy occurs before the points have been moved more than one-third of the distance to the new position, theywill be returned to their original positions.

Inother words, the entrance of a train into the detector track section while the switch machine is operating the switch points, results in the switch points being returned to their original positions if they have been moved something less than one-third of the distance to the opposite position, but their movement will be continued to the opposite position if they have moved more than one-third of the operating stroke. In this way the switch points are assured of being operated -to a full normal or reverse position for the passage of a car. In this connection, will be understood that the detector track sectionex+ tends sufliciently in advance of the switch'S W to allow such a completion of the operating stroke for the usual speeds at which cars approach the switch.

If the switch SW is in the normal position" as shown in-Fig. 2 and is then trailed through'b'y a train or car moving from the siding onto the main track, the switch points will be forced out of the full normal position regardless of the locked condition of the switch machine 28M. which is permitted by reason of the conventional spring switch arrangement associated with the front tie rod and operating bar 64. Thisyieldable connection has beenshown diagrammatically in Fig.2 by the springs 59. Althougha trailing point train-movement of this type which forces the'switch points from their-last actuated position may not necessarilyforce theswi-tclr points fully over to the opposite position, such;-a' trainmovem'ent is certain to move the switch points'at least more than two thirds of the way,

toflthe trailed through position. As has been pointed out, movable contact 42 substantially follows the position of the switch points so-that when the switch points are forcibly moved fromthe normal position to approach the reverse posi tion by a trailing point train movement,1the mov-' able contact 42 will be operated to a position.

tact 48, movable contact 42, stationary contact 60, Wire 63, and lower winding of contactor RWR, V

to As a result, the contactor RWR will become energized.

Since the entrance of the train into the detector track section DT which is now assumed to be trailing the switch points, caused the opening of front contact 3| of track relay TR immediately upon such entrance, the normal contactor NWR is deenergized at the time the reverse contactor RWR is picked up. Thus, the switch machine 25M is caused to immediately operate to its full reverse locked position which causes the switchpoints to be held in their reverse positions for continued passage of the train. It can thus be seen that such operation obviates any intermittent movement of the switch points during the trailing point movement of the train after the initial movement of the points by the leading initiated after the detector track section becomes occupied.

Having described two forms of a switch machine control circuit organization as specific Bll'h' bodiments of the present invention, it is desired to be understood that these forms are selected to facilitate in the disclosure of the invention rather than to limit the number of forms which it may assume: and, it is to be further understood that various modifications, adaptations, and alterations may be applied to the specific forms shown to meet the requirements of practice, without in any manner departing from the spirit or scope of the present invention.

What I claim is:

A switch control system for the power operation of a track switch comprising in combination,

a detector track circuit, manually operable means for designating respective normal and reverse positions for the control of said track switch, an electric switch machine for the power operation of said track switch having a reversible electric wheels of the train. This saves considerable wear track Section the track relay TR will again 23-5;- tively energizing a particular one of the windbe picked up and front contact 3i will become closed while back contact 62 will be opened. The circuit just described for the energization of the lower winding of contactor RWR will then be interrupted and the control of the contactors RWR and NWR, will then revert to the polar control transmitted over line wires 5 and 6.

If the lever SML has, in the meanwhile been left in the normal position N, the switch machine will then be immediately operated to return the switch points to the normal position.

Obviously, if the switch points are-forced out of their full reverse position by a train making a trailing point move along the main track, a

similar circuit will be established through back By using a control circuit of this type, it becomes unnecessary to operate the switch machine control lever to bring the switch operating means into correspondence with the trailed through switch points prior to returning the points to their original position. By means of the present invention not only is the operating mechanism 1 brought into correspondence with the switch points and the switch points instantly brought to the full trailed through position, but the switch points are immediately returned to their last actuated position when the train making the trailing move leaves the associated detector track section. In addition, switch operation is prevented from being motor drive and having a yieldable connection between its driving mechanismv and said track switch, whereby said track switch can be operated by the passage of a train when trailed independent of the electric driving mechanism, double Wound respective normal and reverse switch ma chine control contactors, circuit means for selecings of said normal and reverse switch control contactors, the contactor selected for energization being in accordance with the normal or reverse switch position designated by said manually operable means, said circuit means being effective only provided that the switch control contactor for the other switch position is dropped away, normal and reverse switch position repeaterrelays' having circuit control means ef-' fective to energize each of these relays when in correspondence with the respective 'full-normal or full-reverse position of the track switch, stick circuit means acting upon the other of said windings of said normal and reverse switch control contactors to maintain the associated contactor energized whenever said normal and reverse switch position repeater relays are both dropped away, auxiliary circuit control means for energizing said other winding of either of said contactors when said switch position repeater relay for the opposite switch position has been picked up by reason of the forcing of the switch points REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,706,851 Howe Mar. 26, 1929 1,854,602 Prescott Apr. 19, 1932 2,082,933 Young et a1 June 8, 1937 2,183,694 Rees Dec. 19, 1939

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