US1897005A - Interlocking system for railroads - Google Patents

Description

Feb. 7, 1933. w ow 1,897,005

INTERLOCKING SYSTEM FOR RAILROADS Filed Sept. 12, 1929 2 Sheets-Sheet 1 BY zd7%%,

M MM

fly ATTORNEY Feb. 7, i933.

- 5&2.

W. K. HOWE INTERLOCKING SYSTEM FOR RAILROADS Filed Sept l2, l929 ATTORNEY 2 Sheets-Sheet 2 Patented Feb. 7, 1933 UNITED STATES PATENT oFFICE WINTHROP K. HOVE, OF ROCHESTER, YORK, ASSIGNOB TO GENERAL RAILWAY SIGNAL COMPANY, OF ROCHESTER, NEVJ YORK INTER-LOCKING SYSTEM FOR RAILROADS Application filed September 12, 1929. Serial No. 392,138.,

his invention relates to power interlocking systems, and more particularly pertains to indication means and devices for such systems.

In power interlocking systems, it is desirable, for reasons familiar to those skilled in the art, to provide indication latch mechanisms for the levers controlling the operation of switches and signals, and to provide suitable means for releasin such an indication latch mechanism for a particular lever when the switch or signal, controlled by that lever, has properly operated or responded. In one type of indication system, to which the present invention more particularly relates, current from a battery or other suitable source located at the switch machine, is controlled by contacts operated by the switch machine and is transmitted to the tower to doe employed for actuating the indication latch mechanism.

In the type of indication system above described, some times called a constant current or battery type of indication in contrastto "the dynamic type of indication, it may happen that an improper or false indication can be given under a certain combination of circumstances. For example, when the operator moves his control lever to a new position, 7 Of n I n there is a short interval of time, after power isapplied to the switch machine, during which the contacts of the switch machine controlling the indication relay remain closed and the indication relay is energized; and if 3a the operator should quickly return the control lever to its former position, the indication latch mechanism may be released, even though the operation of the switch machine from its former position has been initiated.

R n a Under such cond1t1ons, if provisions are made so that the switch machine will EtlltOlllEltl-r cally reverse and follow the movement of the control lever to its original pos1t1on, no particular y unsafe condition results; but, if the "switch mach ne should fail to reverse due to failure of parts, blowing of the fuse by exces- .sive current occurring by such quick reversal of the control lever, or the like, the inertia of the motor armature and the gearing of the switch machine might 'unlock the track switch proposed in accordance with the present in-;

vention, to provide a time element device which is set into operation upon each movement of the control lever to a new operating position to prevent the actuation of the indi-' cation latch mechanism for a limited time after each such lever movement, sufiicient to assure such operation of the switch machine as will deenergize the indication relay and avoid an improper indication under such conditions above explained.

It is a further object to provide such a time element device coacting with its asso ciated lever in a manner to leave the normal facility of operation unaffected. I

In describing the invention in detail, reference will be made to the accompanying drawings, in which like reference characters refer to like objects, and in which Fig. 1 is a diagrammatic view of one specific embodiment of the present invention as applied. to one type of an electrically operated switch machine having a constant current 7 type of indication system.

Fig. 2 is one modification of the present invention;

Various other objects, purposes and characteristic features of the present invention will be in part obvious and in part pointed out as the description of the invention progresses.

A still further object isto provide an economical control of the switch position repeating relay by the use of superimposed alternating current over the control wires of the switch machine.

With reference to Fig. 1 of the drawings,

a track switch TS is shown as operatedby a suitable. switch machine SM, which is preferably of the type described in my Patent. No. 1,466,903, dated September 4,1923. This i switch machine SM has the usual armature A and field winding F, and also associated therewith various groups of contacts.

ing contact between certain pairsof fixed,

contacts in either thenormal or reverse extreme pos1t1ons,be1ng operatedto such positions mechanically by theswitch machine at the completion of the corresponding operation; and are operated to an opposite position in midst-roke of the switch-.machine'by the 5 energization of a corresponding pair of two airs of poleichan'ging coils 7 and-8. "The contacts includedj withina dotted rectangle designate PCCareknown as pole" changer coil contacts and includea movable olcontact'block 9 of insulating material which furnishes a mounting-for the contacts '10 I and 11. -Tl'1e polechanger coil contacts PCG l "include two pairs-'oflfijxed contacts, one of when; the contact block'9 is in eithera nor mal'or reverse position, and both" of said pairs being electrically interconnected when i 1 the contact block'9'is in an intermediate'posi-f tion., Thls movable contact block 9 is oper- 91 ated' t'o'normal or reverse 1 extreme positions at the end of each'corresponding'operation of the switch machine fSM; and is caused to assume an intermediate position during the operation of 'the'switch machine or any other timethat it isunlocked; a

The contacts includedfwithin adotted re'ctangle designated PD are known as point detector contacts and include amovable con- 40V tact block12 ofinsulating materialwhichis caused to'assume extreme normal and reverse positions when thetrack switchi'sf in corre sponding positions and locked; but it is,

, caused to assume an intermediate position when the track switchis being operated from "'one extreme position towalnother', .or at a ny such time that said track switcliis unlocked,

Mounted upon the movable contact block 12, there arecontacts 13 and ;1,4-,;,which ,make

', contact; between their respective pairs j Of fixed QOntactSjWhen in the normal or reverse. extreme positionsonly; a shunt contact 17. biased towarda contacting position, is actuated to anon-contacting position. only when.

the'movable contact block12 is in a normal position; a similarshunt contact-11 8 biased v toward a contacting position is actuated'toa non-contacting position only} when the mov-- b able'contaet block 12 an'extreine reverse position. example ofan operating mech anism of such point detector contacts 11sdis?v closed in, 'the patent to Bushnell, N01."

1,517,236,, dated November" 25, 1924." v Asmara w h the; H st. et ca said pairs being electrically interconnected" tacts PD, there is a local transformer T, the primary of'which is supplied with potential from a suitable alternating current source over va transmission line extending from the interlocking tower.

In the tower, acontrol lever L is provided being capable of assuming the usual full normal and full reverse positions indicated by the arrows N and B respectively as they ap- -.pear opposite an arrow A on the lev'erL.

These full positions of the lever L are supplemented by the normal and reverse indicating positionsfdesi'gnated by the arrows NI and RI respectively-,which indicating positions aredetermined by an indication latch mechanism IM including an indication magnet 19 and-plunger 20.; The movementof the lever-L froma full position to an indica-L- tion position operates a tappet bar 2lto a central positionby means of a cam slot 22 in the usual well known'manner.

a The leverL also governs the operations the switch machine SM over normal-and reverse operating wires N and B respectively in" con unct1on with a common return wire C,.the operating and indicating circuits -being completed over these wiresby movable contact members 27, and 29which make contact between certain pairs-of fixedcontacts -.whenthe lever Lis in the positions N and NI, and make contact between certain other pairs of'fixed' contacts when the leverL is in the position R and RI;

A lever lock2 3 is provided to lock the lever- L against movement from its full normal or full reverse position when the detector track i section associatedwith the track switch TS is shunted; The conditions of this detector track section is repeated by a track repeater relay TR which is controlled by a track relay T atlthe switch. 1

dissociated with the indication'latch mech' anism TM is anSS relay having a local phase winding 30 continuouslyenergized from a secondary ofalocal transformerT and havlng its linephase winding 32 energized over two line wires from the secondary of the local transformer T in accordance with the position and locked condition of the track switch TS. This SS relayhas' a contact 33 which assumes eitherof'two extreme posi,-

tion'sldependingupon the relative instantafneous' polarity ofthecurrents flowing in the 5 local phase winding BO anditheline phase winding 32, and"assumes a deenergiz'ed 'cen- 1 tral position when either'orboth phase wind-- 1 ings are deenergized. y

A'time element'device TE is operated by k the lever L each time the said lever is moved tea new operating position. This time ele- Two energy saving contacts 24 and 25" are provided which may be actuated to contacting'positionsby the control ofa 'lever latch ment device TE is diagrammatically shown as a tooth plunger 42 slidably attached to the frame of the interlocking machine represented by portions 43 and 44 and is biased to a contacting position with the surface of le ver L by a spring 45. Attached to this plunger 42 and insulated therefrom is a contact member 46 which electrically interconnects two fixed contacts conventionally shown as arrows. A roller is mounted upon the lower extremity of the plunger 42 to eliminate the contacting friction between the plunger 42 and the surface of the lever L. On the surface of the lever L over which the roller 47 travels, a projecting cam 48 is provided to force the plunger 42 in an upward direction when the lever is moved from a normal operating position to a reverse operating position. This motion is su'liicient to move the contact member to a non-contacting position which position is maintained for a predetermined desired period of time by means of an escapement mechanism including a gear 50 which engages with the teeth upon the plunger 42, a shaft 51 connecting the gear 50 with a ratchet gear 52. An escapement wheel 53 is supported upon the same axle 51 in a. manner that the ratchet gear 52 may rotate in a clockwise direction freely, but can not rotate in a counter clockwise direction due to the engagement of a spring biased detent 54 being biased by a spring 55. An escapement pawl 56 is provided to prevent the rotation of the escapement wheel 53 in either direction except at a predetermined rate.

Thus, when the cam upon the lever L is moved under the roller 47, the motion of the plunger quickly rotates the ratchet gear 52 a clock-wise direction while the escapemcnt wheel does not appreciably rotate due to the detaining effect of the escapement pawl 56. However, the sp ing 45 tends to move the plunger 42 in a downward direction as soon as the cam 48 moves from the roller 47. but it can only do at a rate determined by the rate at which the escape me wl eel 53 rotate in a counter clockdirecton. as the gear 50, shaft 51 and are not allowed to rotate free caused to rotate synchronously with escapemcntwheel due to the engagement of detent 54.

Thus, the contact member 46 is raised to a no- -contacting positionoach time the lever of the operation of an interlocking system in which such a time element device is included.

Operation of the system the normal function.

.Vith the apparatus and circuits of the interlocking system in the normal condition as shown, tae contact 33 of the SS relay is in a ht hand energized position as the local f) is continuously energized and the ase winding 82 is energized over a al energizing circuit completed with t 1e track switch TS and switch machme SM 111 1101 al locked posltions.

i )rmal energizing circuit for the line phase winding 32 for the relay SS is traced as follows :from the right hand terminal of the secondary of transformer T, through wires 60 and 61,-contacts 62 13. wires 63, 64 and 65, winding 32 of relay SS, wires 66, 67 and 68, contacts 6914, wires 70 and 71, to the left hand terminal of the secondary of transformer T. p

Let us assume that the operator desires to reverse the track switch TS and to do so presses the lover latch 26 preparatory to moving the lever L in a left hand direction. This opera ion closes the energizing the lock 23 and the indication magnet 19 respectively.

The energizing circuit for the indication magnet 19 is traced as follows :--from a suit- Assuming the detector track section govern ng the relay T tobe unoccupied, the ener- ,q'izing circuit for the lock 23 is completed through a circuit traced as follows :from the positive terminal of a suitable source of potential indicated as 13+, through front contact 78, wire 79, closed contact 25, wire 80. winding of magnet 23, to the opposite terminal of the suitable source indicated as l With the electric lock 23 energized, its plunger is moved to such a position that the lever L may be moved in a lefthand direction. hen the lever L is moved beyond the normal indication position N1, the circuit for the in dication magnet 19 opened at contacts 76,

circuits through contacts 25 and 24 for energ1zmg,

permitting a forcedro p cam 81 to force the p1unger'20 downw'ard-into a locking position which prevents movement,,.of the lever L beyond the reverse indicating'position RI.

7 During the movementof the'lever L from the position NI to the position'RI the plunger 42 is actuatedto an upper extreme'position by the cam 48 which moves the contact mem-.' ber 46 .to a non-contacting position, as heretofore described. I

. With the lever L in thereverse indicating position RI, the reverse operating circuit for the switch machine SM is completed which causes the switch machine to unlock and operate the track switch to a reverse position and then again lock the switch. This operatingcircuit'for theswitch machine SM is traced as follows from theipositive terminal of a'suitable source of electrical potential indicated as 13+, through the fuse Y 49, wire 82,contacts 8327, wire 84, reverse.

operating wire R, wire 85, 7 contacts 866, 7 wires 87' and 88,'armature A, wire 89, contacts 905, wires 91 and 92, "field winding F, wire 25 93,'through the common wire CV to the oppo site terminal of the suitable source of elec trical potential indicated as.B.'

As soon as the switch machine armature AQhaSj completed acertainnumber of revolutions to unlock the switch-machine SM and track switch TS, the contact block12 assumes a central position, in which position the alternating current'suppliedto the line .phase windi ng 32 .over acircuit heretofore traced is opened at the vcontacts 6213 and 69- -14';"also the control wires 65 and 66 are cshunted bythelshuiit' contacts 17 and 18 through wires-94, shunt contact17,-fiXed con- ;tact memberj95, wire:96,';fshunt contact 18, fixed'coiitactf97, wires 98 and 67. Thus, the

;cbntac t 33 ,of the SS relay is assured ofbeing operated toa central deenergized'position, I

Also, with the switch machine SM unlockedandiin operation, the contact block 9 1s operated to a central position sothat' elther' the pole. changer coils 7 v ofthe pole changer coils 8may be energized accordingto whether the reverse operating wire R orfthe normal eratingwire'N is energized. with positive potentiaL' In other words, with the reverse operating wire Rf energized the coils 7 are energized'to hold the contact block 4 in its present position even though the switch ma- 5; chine SM is unlocked, through a circuit including wire 99, contacts 10010, wire 101,

coils 7, wire 102, through the wire to'negative potential. Also, withthe contact block 9 in a central "position should positive po-. coitentialbe applied tothe normal operating wire thev pole-changer coils-8 would be energized through wire 103, contacts '10411.'

wire 105, 'pole changer coils 8,-wire 106,

" QlVith the contact block 4 in sition, thus resulting in" the reversal of thei switch machine armature A.

Withthe switch machine SM and track to disengagethe lever L, andallowing the .op- .erator to control saidjlever. L to its full ree: ,verse position- R.

, Assuming that'the switch machine SM and track switch TS have operated to reverse positions and locked conditions, the contact blocks 4, 9 and 12 are also operated toree verse extreme positions. t a reverse posi-;- tion, a snubbing circuit for theswitcliymachine SM is completed which dynamically. brakes the momentum of. the armature A.

This dynamic snubbing circuit is traced as I follows from the upper terminal of armature A, through wires 89 and-113, contacts -1146, wires 115, normal operating wire. N, wire 116, contacts 11728, wirell'8, com-1 mon wireO, wire93, field winding F wires 1 92and '1l8, contacts 1195,,wire 88, to thelower terminal of armature c j With the contact block 12 in a reversepo-i sition, the shunt contact18 is actuated to a non-contacting position, so thatfwith -ithe' contacts 13 and 14'in=reversepositions, a 7

reverse energizing circuitiforthe line phase winding 32 for the relay. SS is completed, which. is traced as follows from the;.right hand terminalof thesecondary of transformer T, through wire 60, contacts 107: 14,

wire 66, line phase winding 32,wires 65,164

and108,contacts 109 -13, wire 71,-to the left fin handterminal of the: secondary of transformer T.; I 'Inasmuch as I polarity- 0f theline phase winding 32 has been reversed in respectto the instantaneous polarity in the local phase winding 30, the c contact 33 assumes a left-hand dotted lineposition." The contact 33'and the contact member 7 29 are in corresponding positions,

so when the operator'again presses the lever latch 26 closing the contact 24, the indication magnet 19 is energized inasmuch as the time element device TE is in a normal biased position. This energizing circuit for the indication magnet 19 is traced as follows from the positive terminal of suitable sourceof electrical. potential indicated as B through closedcontact 24, wire 72, closed contact 46, wire 73, coils ofindication magnet 19, wires the instantaneous relative,

; through the wire C'to negative "potential, to

V 74 and 110, contacts 111-29, wire 112, con 65 control the contact block 4 to areverse potaiiti'sgjiniai'lefi hand dotted line position,to

the opposite terminal of the suitable source indicated as B. The plunger 20 is now operated to a disengaging position in respect to lever L, so that the lever may be moved to its full reverse position B.

One operation of the specific interlocking system, including the time element device of the present invention, has been shown and described. It is obvious that the normal operation of the system is not in any manner retarded or hindered from completing its normal operating functions due to the in corporation of the time element device within the system. However, in order to make clear the usefulness of such a time element device, the case or combination of circumstances, in which such a device is made necessary, will now be considered.

Referring to the operation ofthe lever L from the normal position N to the reverse position R just described, let us assume that the lever L has been moved to the reverse indication position RI, and the operator changes his mind and tries to quickly change the lever L to its normal position N. Such a movement of the lever L can not be accomplished as the movement of the contact member 46 to a non-contacting position prevents the energization of the indication magnet 19, thus preventing the release of the indication latch mechanism IM which prevents the movement of the lever L from being moved to a full position.

Let us assume, that the time element contact 46 is not in place and the wires 7 2 and 7 3 are permanently connected together. Then the lever L upon being quickly returned to its normal indicating position NI will have given the armature A a chance to make several revolutions while said lever L was still in the reverse indicating position RI. Then, with energy now upon the normal control wire N, the pole changing coils 8 are energized moving the contact block 4 to a reverse position, so that the armature A will start revolving in an opposite direction if the fuse F does not blow out. However, due to the lack of a counter electromotive force within the motor, a sudden inrush of current occurs and is likely to blow the fuse F. Assuming that the fuse F does blow out and the armature A continues rotation due to its inertia and the momentum of the switch machine gearing, th n the contact 33 would still be in a normal energized position as the switch machine is not unlocked when the lever L is reversed. Thus, the normal energizing circuit for the indication magnet 19 is completed, allowing the lever L to be returned to its full normal position N, but the momentum of the motor continues to operate the switch machine SM to an unlocked condition. Should a train now pass over the track switch TS the vibration might be sufficient to cause the switch points to slightly open, so that a flange of-a car wheel might become engaged with the open point and cause the train to split the switch.

From the foregoing description, it is seen that the possibility of a false or hang over indication of an interlocking system without the time element device of the present invention, is due to a time interval during which the indication relay contacts indicate the true position of the switch, and during which an cause further operation for one-half unit of time after power is cut off. Then, if the operator returns the control lever to a former position when three-fourths of this first unit of time has elapsed and the fuse blow out, the

control lever may be returned to the full po sition although the switch machine. continues to move for one-half unit of time, thus unlocking the track switch. Obviously the SS relay cannot indicate the track switch as unlocked until the condition exists. I

Should a switch machine be so constructed as to be able to stop immediately as soon as its power supply is removed, the condition might arise in which the power cut-out might open the circuit ust as the track switch is unlocked with the control lever reaching its former position at the same instant. Such a condition would still be undesirable.

However, the present invention provides a true compensation for such conditions, in

that a time element is used to counter-act an undesirable time element. i

It is obvious from the above description, that the time element device of the present invention may be varied to operate through a period of time 1n accordance w1th the conditions to be met in practice, which period of time for the. specific case stated above is pref erably sllghtly greater than the time required for the switch machine to unlock the trackswitch.

Other means have been proposed for use in battery type indication systems, such as a quick acting switch which selects the circuit for the opposite or next indication when the control lever is moved from the other or its last indicating position to its corresponding full position. Such a device prevents the returning of the control lever to its former position until after the originally intended'operation of the lever is completed. The interlocking system of the present invention gives no such undesirable results.

With reference to Fig. 2 of the drawings, a modification of the SS relay control is shown,

" i so which provides an economical means of ac- .Icomplishing such control. The. devices in Fig. 2 which are similar to devices in Fig. 1

-have been shown'nwith the same reference characters having distinctive exponents, 1 In other Words, the devices in Fig, 2 wh ch have 1 the same reference characters with distinctive exponents, are the same devices included in another circuit arrangement according to the invention and are operatively associated the supply of alternating current potential to the primaryc Winding of a transformer T,

' with the secondary of this transformer connected in series with the common Wire C.

."ThUS, with the line phase winding 32? of the V irelayfSS connected in series inthe wire 118' (see 1) which compl'e'tes the snubbing I flast snubbing circuit of the switch a hi *motor," r

' Movable contacts 13 and inthe same manner-as explained for'Fig. 1

in: 407 i r i v "When the track switch TS and switch ma A; resistance 120 provided in the primary circuit ofthe transformer T to limit the effectin the primary'winding' of the surge ofi the dynamic current flowing inthe secondary winding; i Acondenser 121*is shunted across the field Winding F. J

1 4 are controlled to make contact'between certain pairs offixed contacts in ,order to provide the reversal of instantaneous polarity upon the primary of thetransformerf T as is obvious fromthe drawings. Likewise, the pole changer contacts PC and the'polechanger coil contacts FCC are. controlled in a similar manner as heretofore explained.

chine SM are in their normal locked posi- .tions,contacts 13 and 1 F are inthe" position,

shown, thus energizing the transformer T :"With these conditions obtaining, alternating current is superimposedvuponthe snubbing II circuit of the switch machine, energizing the -line phase winding 32 of the relay SS field Winding F 'and condenser 1 21 in'm-ultis ,Iple, wires 151 and 152, 'c0ntacts'90 5, wire "153 armature A, wires 15 l'and'155', contacts "866, wire 156, reverse-operating wire R,

contacts 157*F- -28 ,-wires 15 8 and 159, winding 32 0f relay SS, wire 160,common wire C to the h ndterminal of; the secondary'of transformer-'1'.

During the operation of the switch machine SM, the contacts 18 and ll assume a central nonrcontacting' position, thus deenergizing the transformer'T -When the control lever L is moved to the reverse position the ener .g'izing circuit for the line phase winding 32* present invention ilowmg clann's.

rsozoozs a er contacts PC and the pole-changer coil contacts PCC 'toi their reverse positions in correspondence with: the controller contacts ofthe-co'ntrol lever At such time, a reverse energizing circuitfor the linephase' wind; ing-32 is completed, which is traced as fol lows from the right hand terminal of the secondary of transformer T through common WiI'e' C field windingF and condenser 119%5, wit-e154, armature A, wires 153. and 162, contacts H P-'6, wire 163-, normal oper- 121is multiple,wires '15land 161', contacts ating wireNt, wire 164, contacts 117 -28,

Wire 159, winding 32 0f relay SS, wire 160',

- common wire C, to theleft hand terminal of the secondary or transformer Tf. clrcuit, a circuit arrangement is provided. so I "that the SS'relay may be controlled over the A contact '33 is operated to its normal position; as shown, when the normal energizing 1 circuit for the line phase winding 32 is completed, 'andfis energized to a left hand dotted line position, when the reverseenergizingcircuit is completed thus 'heretoforeex'plained.

controllingcircuits as It "'s to' beinot'ed thatthe condensers 121 may heomitted in -suchcases where it is possible -t0-use a comparatively high; secondary voltage'on the transformer T "Thus,an interlocking'system of the 'constant current or battery typei'ndicati'on systern has been shown and'described as, provid- M 'in'g adequate indication control underthe va- "1 riou's exigencies 'of operating conditions.

Also, an economical means of accomplishing such control has been included as onemodi- :fication ofthe interlocking systemiof the presin out invention.

a One specific construction of devices andarrangemen'tof circuits, designed for use; in rconnection with one particular type of inter- "locking system, has been shown; however, -it is to be understood that; the various devices and circuitarrangements selected are to {facilitatethe' disclosure" and nature of the invention rather than itsspecific form,and it is tobe further understoo'dthat various modi- 'fications and adaptations may'be made withoutdepartingfrom'the spirit orscope'of the Having described claim:,

sociated Withsaid control ilever', indication 'mean'srcapable of" actuating said indication as demanded by thefolmy invention, I now 1.1'In-an interlocking system of thetype shown. and-described, a control lever opera- "tively governing the movement of a switch machin'e, an "indication latch mechanism assaid switch machine are in correspondence,

-;and, a time element device operably prevents ing actuation of said indication latch mechanism by said indication means for a predetermined time after each governing operation of said control lever.

2. In an interlocking system of the type shown and described, a control lever operaively governing the movement of a switch machine, an indication latch mechanism associated with said control lever, indication means capable of actuating said indication latch mechanism when said control lever and said switch machine are in correspondence, and a time element device including, a normally closed contact operably actuated to a non-contacting position during each governing operation of said control lever, and means operably preventing the return of said contact to a normally closed position until a predetermined time after actuation, with said time element device preventing said indication means from actuating said indication latch mechanism for a certain time after each governing operation of said lever.

3. In an interlocking system of the type shown and described; a control lever operatively governing the movement of a switch machine; an indication latch mechanism associated with said control lever; indication means capable of actuating said indication latch mechanism when said control lever and said switch machine are in correspondence; and a time element device comprising, a contact normally biased to a contacting position, actuating means operably moving said contact to a non-contacting position upon each governing movement of said control lever,

and means actively preventing the return of said contact to a normally biased posi tion until after a predetermined lapse of time; whereby said indication latch mechanism is prevented from actuation for a pre determined time interval after each governing movement of control lever.

In an interlocking system of the type shown and described; a control lever operatively governing the movement of a switch machine; an indication latch mechanism as sociated with said control lever; indication means capable of actuating said indication latch mechanism when said control lever and said switch machine are in correspondence; and a time element device comprising, a contact normally biased to a contacting position, actuating means operably moving said contact to a non-contacting position upon each governing movement of said control lever;

and timing means including, an escapement wheel, a one way ratchet connecting said actuating means and said escapement wheel, and an escapement pawl regulating the rate of rotation of said cscapement wheel, whereby said timing means actively prevents the return of said contact to its normally biased position until after a predetermined time.

5. In an interlocking system for railroads, a control lever operably controlling a distant actuation of said indication latch mechanism after movement of said control lever from one operating position to another operating no ition until after the lapse of a predetermined time interval.

6. in an interloc ring system for railroads, 1

a lever controlling a distant switch machine and capable of assuming either a normal position, normal indication position, a re- 3 :e indication position or a reverse position, and means preventing manipulation of l lever no: either normal or reverse inn positions to normal or reverse positions respectively exceptupon indication that said switch machine is in a correspond position with said lever, said means inan indication magnet, a switch rerelay controlling said indication and time measuring means preventindication magnet'trom being con- V.-rematurely. In an interlocking system for railroads; a lever controlling a distant switch machine being capable of assuming either a norduos mal position, a normal indication position, a

reverse indication position or a reverse posi tion, and means for preventing manipnlaticn of said lever from either a normal or reverse indicating position to normal or reverse ms respectively except upon indication position with said lever, said means inan indication magnet, a switch reig relay; and time measuring means for iensating for the delay in response of itch repeating relay to the condition switch m achine.

n interlocking system for railroads, controlling a distant switch machine tively except upon indication that said machine is in a corresponding posiwith said lever, with said means including, a switch repeating relay, a time element contact opened by movement of said lever it said switch machine is in a correspoi'ida from either the normal or reverse indication positioin to the oppositejindication position and closed in a predetermined time thereafter, cont rollercontactsl controlled by said lever, said indication magnet being controlled by saidswitch repeating relay in 0on junction with said time element contact and said controller contacts; r v

9. In an interlocking system for railroads, a control lever capable of assuming any one of two extreme or two intermediate positions and controlling a distant switch machine, andmeans for preventing said control lever from being moved from a particular intermediate position to either extreme position except. when said-switch machine has completed its operation in correspondence with said particular intermediate position, said means vincluding, an indication magnet, a switchposition repeatingrelay, contacts controlled by said controljlever, and atime element contact opened by certain movements of said control lever andclosing apredetermined time thereafter, whereby said indicationmagnet cannot be energized after movement of said control lever untilsufiicient time has elapsed to allow saidtswitchmachine' to assume a position control lever. 1 a

10. In an interlocking system for rail -roads, a controllever capable of assuming any one of two extreme positions, or any one of two intermediate positions and controlling a" distant switch machine, an indication latch mechanism preventing movement of said control lever from a particular interme- I diate" position to either, extreme L position,

-electro-responsive means for operating said latch when said switch machine and said *tant switch machine.

lever assume corresponding epositions, and means preventingactuation of said indication latch mechanism by said electro-responsive'means after movement of said control :lever from one intermediate position-to an 7 other intermediate position until after *the lapse of a certain predetermined time interval, whereby said control lever cannot be operated out of correspondencewith'said dis roads, a control lever capable of assuming anyone of two extreme positions, or anyone of two intermediate positlons for controlling it unless said-{control lever".and said distant a distant switchimachine,anindication latch mechanism for'preventing said control lever being moved from a particular intermediate 7 position to a corresponding extreme position switch, machine are in correspondence, and means preventing actuation of said indication latch mechanism after movement of said control lever from corresponding extreme or intermediate positions to opposite extreme or intermediate positions until'atter the lapse of a certain predetermined time interval,

incorrespondence with said V mechanism preventing said control lever from being moved from a particular intermediate position to a particular correspondmgextreme posltion except after being energized,

with said indication latch mechanism normal- 1y being capable of being energized when said controlelever and said distant switch machine arein correspondence, and means -;p'reventing energization or said indication latch mechanism aftermovement of said control lever from positions in correspondence I a with said switch machine to positionsoutfof correspondence with said switch machmeuntill after a certam predetermined lillIlGlIltGT- val, with said means including a time'element 7 contact, means for' instantaneously opening said time element contact operable by move- 7 ment ot' said lever, and means operable for slowly closing said time element contact ineluding an escapementlpawl.

a 13. "In an interlocking system for railroadsfa control levercapable'of assuming any one of twoeXti-eme positions or-any' one of two -intermediatelpositions and controlling a dist'ant switch machine, an indication latch mechanism preventing said control lever from being movedfrom a particular intermediate position to a corresponding extreme position except after being energized, with said'mechanism normally being capable of being ener- "gifted when said control lever and said dis-" tantfswitch machine are in correspondence, and means prevent ng energizatlon of sand. indicat on latch mechanism afterjmov-ement o'f'saidjcontrol lever from one intermediate positlon to another intermediate positlon until after a certainpredetermmed time lnter- .val,"with said means including, a timelelement contact, means for instantaneously openmg said time element contact including,are'

ciprocating' plunger, anda one-way ratchet, 3115 and means allowing said time elementcontact to close after a predetermmed time including an escap'ement pawl.;. v

14. Inan "interlocking system, a track switch operated by a switch machine, a control' lever governing the operations. of said '1 switch machine, anlindication latch mechanism preventing extreme movementslof said 7 control. lever except whentactuated, indication means including. point detector contacts operated by said track switchand saidswitch fn'iachine, an electro-responsive device indicatmg'the position of said track switch, two *l ue' wires over wlnch's'aid electro-respons1ve device is; controlled in Jaccordance with said ocking system for railroads; 70

point detector contacts, with said'indication means capable of actuating said indication latch mechanism when said track switch and said switch machine are in correspondence with said control lever and locked, and a time element mechanism operably preventing said indication means from actuating said indication latch mechanism during operation of said switch machine before said track switch is unlocked.

15. In an interlocking system, a track switch operated by a switch machine, a control lever governing the operations of said switch machine, an indication latch mechanism preventing extreme movements of said control lever ev'cept when actuated, indication means including, point detector contacts operated by said track switch and said switch machine, an electro-responsive device indicating the position of said track switch, means operably controlling said electro-responsive device over the control wires of said switch machine in accordance with said point detector contacts, with said indication means capable of actuating said indication latch mechanism when said track switch and said switch machine are in correspondence with said control lever and locked, and a time element mechanism operably preventing said indication means from actuating said indication latch mechanism during operation of said switch machine before said track switch is unlocked.

16. In an interlocking system for railroads, track swi ch, a s vitch machine for operatsaid track switch, a control lever, two control wires and a common return wire between said switch machine and said control lever providing normal and reverse operating circuits for said switch machine, and means for indicating the condition of said switch machine operable by alternating current flowing in reverse and normal indicating circuits respectively including said operating circuits of said switch machine.

17. In an interlocking system for railroads, a track switch, a switch machine for operating said track switch, a control lever, two control wires and a common return wire between said switch machine and said control lever providing normal and reverse operating circuits for said switch machine, an elec tro-responsive device in the tower indicating the position of said track switch and having normal and reverse energizing circuits including said operating circuits of said switch machine, means for energizing said electroresponsive device including, a secondary winding of a transformer in series with said common wire, a condenser for decreasing the reactance of said energizing circuits, and means for controlling the energization of the primary winding of said transformer in accordance with the condition of said track switch.

18. In an interlocking system for. railroads, a track switch, a switch machine for operating said track switch, a control lever, two control wires and a common return wire between said switch machine and said control lever providing normal and reverse operating circuits for said switch machine, a secondary winding of a transformer included in series with said common wire, contact means controlling the energization of the primary winding of said transformer in accordance with the conditions of said track switch and said switch machine. and a three position relay in the tower operably controlled by the energization of said secondary winding of said transformer over normal and reverse energizing circuits including said normal and reverse operating circuits of said switch machine, whereby the condition of said track switch is inoicated in the tower.

19. In an interlocking system for railroads, a control lever capable of assuming any one of two extreme positions or any one of two intermediate positions and controlling a distant switch machine, an indication latch mechanism when deenergized preventing said control lever from being moved from a particular intermediate position to a particular corresponding extreme position, said indication latch mechanism normally being capable of being energized when said control lever and said distant switch machine are in correspondence, and means preventing energization of said indication latch mechanism after movement of said control lever from positions in correspondence with said switch machine to positions out of correspondence with said switch machine until after the lapse of a certain predetermined time interval, said means including a time element contact, means for instantaneously opening said time element contact operable by movement of said lever, and means operable for slowly closing said time element contact including an escapement pawl.

20. In an interlocking system for railroads, a control lever capable of assuming any one of two extreme positions or any one of two intermediate positions and controlling a distant switch machine, an indication latch mechanism for, when energized, preventing said control lever from being moved from a particular intermediate position to a corresponding extreme position, said mechanism normally being capable of being energized when said control lever and said distant switch machine are in correspondence, and means for preventing energization of said indication latch mechanism after movement of said control lever from one intermediate position to another intermediate position until after the lapse of a certain predetermined time interval, said means includlng, a time element contact, means for tablished so long as said leverand' switch instantaneously opening said time element contact including, a reciprocating plunger, and a one-way ratchet, and means allowing said time element contact to close after a predetermined time including an escapement pawl.

21. In an interlocking system for railroads, the combination with a distant switch machine including an electric motor and a local lever, two control wires each used separately ina circuit with a common return wire for operating said switch machine in opposite directions each circuit of which is established solong as said lever and switch machine are out of correspondence, an indicating relay associated with said lever,itwo indicating circuits each including a different control wire and said common wire and completed only when said lever and sw tch machine assume corresponding positions, said indicating circuits including means for loy passing said motor to the flow of indicating current distinctive'in character from the current used for operating said motor, v I i a 22. In an interlocking system for railroads, the combination'with a distant switch machine including an electric motor and a local lever, two control wires each used separately in a circuit with a common return wire for operating said switch machine inopposite directions each circuit of which is es machine are out of correspondence, an indicating relay associated with said lever and responsive only to current distinctive from the current used for operating said motor, two indicating circuits each including a different control wire and said commonwire and completed only when said lever and switch machine assume corresponding positions, said indicating circuits including me ans for by-passing said motor to the flow of said distinctive indicating current, and means for impressing on said indicating circuits said distinctive, currents of distinctive instantaneous polarity corresponding .to the position of the switch machine. s

23. In an interlocking system for railroads, a trackswitch, a switch machine for operating said track switch, a control lever operable to normal and reverse governing positions for governing said switch machine to-normalcr reverse positions respectively,'

indicationmeansfor indicating the position of SaId'tIaCk switch, electrores'ponsive means governed by said indicationmeans, and time of said track's'witch, electroresponsive means governed sa d indication means, time measuring meansinitiated by each operation of said controllever for-preventing during a predetermined time thereafter the governingof said electroresponsive means by said indication means, said time measuring means including, a time element contact, means for instantaneouslyopening said time element contact including, a"reciprocating plunger, and a one-way ratchet, and means allowing said timeelement contact to close after-a predetermined time said means including-an escapement pawl 7 v 25. Inan interlocking system for railro'a'ds, a track'switch, a switch machine for operating said track switch, a controllever operableto normal and reverse'positionsfor governing said switch machine, a three-position relay for ind cating the position and locked condition ofsaid track switch, electroresponsive means having the energization of its windings governed by said three-position relay, and time measuring means initiated by movement of said control lever for preventing for a predetermined time thereafter the energization of said electroresponsive means by saidthree-position relay. 26.. In an interlocking system for railroads; a. switch machine; a lever for controlling s aid switch'machinmfsaid lever being capable of assuming either anormal extreme poistion, a normalindication position, a reverse indication position or a reverse extreme position, with said positions being progressively attained; and means allowing manipulation'of said lever from normal or reverse indication positions to corresponding normal or reverse extreme positions only whensaid lever hasbeen in a particular indication position for a predetermined period of time and measuring means initiated by each operationof said control lever forpreventing during a predetermined time thereafter the governingxof said electroresponsive means by said indication means.

24. In an interlocking system "for rail roads, a track switch, a switch machine for operating said track sWitch,a control lever operable to normal and reverse governingv

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