US1700705A - Interlocking system for railroads - Google Patents

Description

Jan. 29, 1929. 1,700,705 I J. c. LINDNER T INTERLOCKING SYSTEM FOR. RAILROADS Filed Feb. 23, 1926 2 Sheets-Sheet 1 X y INVENTOIIQ.

Jan. 29, 1929.

LYGOJQE J. C. LIND NER INTERLOCKING SYSTEM FOR RAILROADS Filed Feb. 23, 1926 2 Sheets-Sheet 2 JOHN G. Lrivioivnn, or noonnsr'nn, new YORK, Assrenon nAILwhv.

: t E'i SIGNAL COMPANY, or nocnnsrnn, new YORK.

rn'rnntoexme SYSTEM non RAInRoADs.

Application filed. February 23, 1926. Serial n6. 89,886.

This invention relates to an interlo'cking system for railroads, and more particularly to ci'ossprotec'tion means for electrically operated traffic controlling devices and to systems wherein two electrically operated traffic controlling devices may be'controlled by a single lever including such cross protection means. p p I The principle of cross-protection upon which the present invention is based, resides in the provision of an electro-responsive crossprotection device which is so connected in the circuit arrangement that, if current is improperly applied to the traffic controlling device such un authorized current will pass through the cross-protection device and in so doing will operate it and cut off all electrical energy. More specifically, in accordance with the present invention it is proposed to employ a control circuit in which the crossprotection device is contained, and'to provide means for shunting the cross-protection device at such times when current may flow which should not operate the cross-protection device. I

v In the installation of interlocking systems it is quite common for two traffic controlling devices, either switchesor signals, to be so located that they must always be operated at substantially the same time, and a large saving in interlocking equipment, as' well as lever space in the interlocking machine, may be taken advantage of, if such devices are operated from the same lever. For such cases, it; is proposed to provide a special arrangement of indication circuits and devices so that both traflic controlling devices must respond to the operation of the lever before the indication is effective. g

Other objects, purposes and characteristic features of the invention will appear as the description thereof progresses.

In describing the invention in detail refer- I enc-e will be made to the accompanying draw ings in which Fig. 1 shows a simple applicationof the cl'ossprotection' arrangement embodying-the present invention applied to a lever controlling alightsignal; and I Fig. 2 illustrates an interlocking system with a single lever controlling two switch machines at a cross-over, and employing the cross-protection. features of the present invention,

Referring to Fig. 1, the lever. L- of the usual construction is shown in a simplified and diagrammatic manner for controlling a two-indication light signal Z by governing its control relay K. The lever L is sh ow'nin its normal position, and the control relay K is ole-energized, lighting the redla-mp R from a source of current 2 by a circuit through a back contact of said relay. y

In order to clearly understand the manner in which the control relay K is protected against operation due to the flow of unauthorized currents, let'us consider the various circuit changes and operating functions .ivhich takeplace when the signal Z is cont-rolled by the lever L.- Let us first assumethat the lever L is moved from right to left from the normal position to the reverse position. .During the first portion of this stroke,.namely when the lever ismoved to the indicating position, an indicating circuit is completed through thecontacts 34 ofthelever and the back contact 5 of the control relay K). This 7 circuit is, however, unimportant at this time,

because the lever is beingmoved from right to left and the condition of the indication magnet TM is not important. f

When theleverhas reached hand orzreverse position, the contacts .6-.7

of the lever shunt the cross-protection relay CR; and the contacts 4t8 complete an energizing circuit forthe control relay K which may be traced as follows :beginning at the, battery 10, wires 11 and 12, contacts 4-8 of the lever L, wire 13,- wind-ing of thecontrol relay K, wires let and 15, contacts 67 of the lever, wires 16 and 17, contacts 18 of the cross-.

protection relay CR, and common return wire 19 leading to the other sidev of, the battery. 10.

With this circuit completed, the control relay K isenergized, thus closing an energizing circuit for the clear or proceed lamp G. It

should he noted, that the circuit just'traced its extreme left includes the connections leading; tot-he winds ing of the cross-protection relay GR but that thiswinding is shunted by shunting wires l5 and 16 and shunting contacts 67, so that the cross-protection relay is not operated. It should also be noted that a break anywhere in this circuit except in the coil of the crossprotection relay is on the side of safety;

Let us now assume that the operator desires to move the lever L to its normahpositidn, in order to unlock certain conflicting routes,

In accordance with interlocking practice there should be assurance that control relay K has assumed its ale-energized position before the lever L can be moved to the full normal po sition. As the operator moves the lever from left to right, hebreaks the energizing circuit for the control relay K, and also the shunt around the cross-protection relay CR. As the lever is moved from the left to right it cannot be moved beyond the indicating position because the indication magnet IM is de-energiz'ed and causes the plunger 22 to engage the projection 23 on the lever L, so that the lever cannot be moved to the normal position so long as the indication magnet IM is de-energized. In the indicating position of the lever 'L the contacts 3-4, however, complete an indication circuit including the indicationmagnet IM providing the control relay K has 2 reached its tile-energized position, which-indication circuit may be traced as follows :beginning at battery 10, wires 11 and 24:, back contact of the control relay K,wire 25, contacts 3- of the lever L, wire 26, winding of the indication magnet IM, wire 27, contact 18 of the cross-protection relay CR, common return wire 19 back to battery 10. With this circuit completed the lever is unlocked and the operator may move to its normal position, in which position the conflicting levers heretofore mentioned are unlocked.

In order to illustrate the manner in which the cross-protection relay CR prevents the flow of unauthorized current from energizing the control relay K, let us assume that the wire 13 is accidentally, due to a cross or the like, connected to the positive terminal of battery 10. Current to energize the control relay K must pass through the cross-protection relay CR in order to complete a circuit to the battery 10; and this current energizes the cross-protectionrelay, thereby lifting the latch 28 and opening of contacts 18, to cut oil the battery 10. The contacts 18 remain open until manually restored in some suitable manner. According to recognized practice, this restoring means, not shown, would be of such a type that it could not be used to keep the contacts 18 clcsed.

Fig. 1 thusillnstrates a simple embodiment of thexinvention, the principle of which re sides in llllG'lHClllSlOl'l of a cross-protection relay in a. proceed circuit and in preventing this cross-protection relay from being operated at a time when the lever is in a position to energize, such proceed circuit, by shunting the cross-protection device at the critical time it is desired to energize the proceed circuit. The cross-protection relay at other times is connect-ed in series with such proceed circuit, and if unauthorized energy is applied to the proceed circuit it"will 'cause actuation of the cross-protection device, and the main retin'n wireleadin to, such source of energy is entirelycut o Although Fig. 1 illustrates a two unit light signal controlled by a control relay K, it is of course to be understood that the control relay and signal merely represent an electro responsive device Which,if energized, indi= cates proceed, and that any suitable type of signal or other tratlic controlling device may I be used.

In Fig. 2 of the drawings has been shown a circuit arrangement in an interlocking system for controlling two switch machines by the same lever and for reliably receiving an indication only if bothswitch machines have responded to a change in the position of such lever. In order to simplify the description of the operation of the system shown in Fig. 2, the essential mechanismswill first be briefly described, after which the operation of the system will be considered in detail.

Referring to Fig, 2, the lever L illustrates one lever of an interlocking system in which a plurality of levers are mechanically or electro-mechanically interlocked, in a manner so that conflicting routes cannot be set up. This lever L is provided with an indication magnet lllvl 'which, if deenergized, will prevent the lever L from being moved from the-half normal to the full normal, or from the half re-.

verse to the full reverse positions respectively.

A look magnet LM, it deenergized, locksthe lever in the full normal or the full reverse position as the case may be. This lever L is also provided-with a double throw push button contact 30, whereby onlyone or the other, 7

either the indication magnet IM or lock mag-v net LM may be selected at a time, this contact being operated by the push button 31. This lever L has been shown in its normal position in which the switch machines SM and SM are inthe main line position. If the lever L is moved to the reverse aosition the switches S and o assume the cross-over position so that a train may cross from the lower east bound track to the upper west bound track, or vice versa. The apparatus in the tower, illustrated by the dotted rectangle 29, also includes a cross-protection relay CI an indication relay IR, and an indication selector IS.

The mechanism of the switch machine SM;

and switch machine SM is shown indotted rectangles. The block in which the switch machine SM of the west bound track is contained, includes a track relay T whereas the block oi the east bound track, in which the switch machine SM is located, is provided with a track relay T In order to simplify the specification, the mechanism associated this'block 42 is operated by snap action near the end of "the stroke of the switch machine. The block 43 ls' provided with segments @8 and 49 and connects one or the other ot the pole' changing coils 16 or an in multiple .with the switch machlne motor when the switch machine assumes a corresponding extreme position, but makes the necessary connection for both of these pole changing colls 1 when the switch machine is at any other than GlI'Culf/S' are ener ized the block 43 bein C 7 G operated intermittently to obtain this function.

' In other words, if the switch machine SM should assume an intermediate position and current should be applied to the normal wire 1H3, current would flow through the pole changer coil 47 thereby causing attraction of an armature (not shown) associated with the contact block 42 so as to move this block toward the left to effect a connection-between the armature 40 and field 41- ,,such as to cause the motor to operate the switch machine toward the normal position. In a similar way the application of current to the reverse wire 77 causes the pole changer coils 46 to establish the proper connections for the motor to cause it to operate the switch machine 8M toward the reverse position. For reasons already given, one of these pole changer coils is disconnected when the switch machine has reached an extreme position after operation trom a neutral positlon as ]L1St explalned. F or a more detailed description of these switch machines reference may be had to the patent to Howe #1,466,903 September 4, 1923.

Contained in the mechanism casing of the switch machine 8M or in a separate casing as is desired, are switch box contacts for completmg indication circults when both switch machines assume corresponding positions.

. These switch box contacts include a movable contact block 50 having contact segments 51 52 53 and 5& This contact block 50 is operated in accordance with the move- =ment oi the switch points and is shown in the normal main track position of the switch machine SM;

Operation O/Fg. 2.

* unoccupied, so that the track relays T and T are energized, and that the operator desires to set up the track for across-over move. In order to do so he operates the push button 3 1-, whereupon the look magnet is energized through the following ir'cuitF begi'nning at the terminal-B of a "suitable 'soureeof energy, push button contact 30 of the lever L contact 60, wire 61, winding of the lock mag net LlVL'wire 62, iront contact 63 of the trackrelay T wire 64, front contact 65 of the track relay T wire 66 and common return wire C connected to the other side of said source of energy. 1 I

With this circuit completed, the lock magnet LM assumes the energized position and the plunger 67 is raised out of engagement with the projecting portion of the lever D, so that the op'eratoris now free to move the lever to the half reverse position where it is stopped by engagement of the lock plunger 68 of the indication magnet 1M with the end of the notch cut in the bottom portion of the lever L i lVith the lever in this the half reversepo'sii tion, an energizing circuit for the motor is,

8 1-82 of the lever when the lever is in the 1 half reverse position, wires 83 and 84, con-, tacts 85 of the cross-protection relay CR}, wire 86 back to t-heother terminal of the secondary winding of transformer 70. j

With this circuit coml'jleted,jthe two i switch machines will beop'erated to the reverse position, thus causing the motor is versing contact blocks 42 and 42 to be;

moved to the opposite position by snap ac tion, thereby cutting energy ofi-ot the motors of these switch machines.

lVith the switch machines in the reverse position, all of the'various contact blocks 42, 43 50 42 48 and 50 will assume the letthand position; and with the lever in the half reverse or full reverse indicating position, an indication circuit for the indication relay IR is completed which may be traced as follows :beginning at the secondary winding of the transformer 90, wires 91 and 92, contacts 93 51 wires 94:, 95 and 96, contacts 98 51 ,wires 97 and 98, winding of the indication relay LR, wire 99, contacts 1O'0 5a wire 101, contacts 102 52 wires 103 and 104, contacts 10O?54 wires 106 and 107, contacts 1OL 52 wires'108 and 109, back to the secondary winding ofthe transformer 90. i

It should be noted that this circuit was I traced from left to right through the indication relay IR, which is a three-position alternating current relay having local winding 110 normally energized by current having the proper phase relation to cause this" relay w,

assume its left hand dotted position. With the 1nd1cat1on relay 1R energized to lts left hand position, an indication circuit through.

the indication magnet 1M is completed which may be traced as follows z beginning at the terminal B of a suitable source of energy, push button contact 30, stationary contact 32, wire 33, winding of the indication magnet 1M wire 34, contacts 35-3-37' of -were operated to the reverse position), wire 38,'contacts 3956 of the lever, wire 57, contact'58 of the indication relay IR when in the left hand position, wire 59 to common return wire C connected to the other sideof said source of energy.

WVith this circuit completed, and with the indication magnet 1M energized, the operator is free to complete the movement of the lever to the full left hand or reverse position, in which position certain other levers are locked or unlocked as conditions require.

From the tracing of the circuit for the indication relay IR heretofore traced it readily appears that such indication circuit would not have been completed had one of the switch machines failed to respond to the change in the position of the lever, so that the lever could not have been moved to the full reverse position unless both of the switch machines had properly responded.

Let us now assume that a train has passed over the cross-over, and that the operator in the tower wishes to restore the switches S and S to their normal. position. .F or reasons heretofore given, this cannot be done until the blocks, in which the switches S and S are located, are unoccupied, because the lever L islocked by the lock magnet LM so long as either the track relay T or the track relay T is de-energized. If the track relays T and T are energized, depression of the push button 31 releases the lock magnet LM,

permitting the o aerator to move the handle from left to right until the end of the recess in the bottom of the lever L engages the plunger 68 of the indication magnet 1M in this the half normal position of the lever L an operating circuit for the two switch inachines is completed which may be traced. as follows.z-beginning at the second winding of the transformer 70, wires 71 and 120, the right hand winding of the indication selector IS, wire 121, contacts 75122 of the lever L in its half normal position, normal wire 123 through the two switch machine motors which now have their armatures and field connected to cause operation oi the switch machine toward the normal main track posi tion, wires 7 8, 7 9, and 124, contacts 82125' of the lever closed when the lever is in the hand or normal position shown.

half normal position, wires 126, 83 and 34', contacts 85 of the cross-protection relay CB wire 86 back to the secondary winding of the transformer 70.

With this circuit completed, the indication selector IS isoperated to its right hand posi-' tion (in which it has been shown), and also these switch machines will operate the switches and the contact blocks to the normal position (in which they are shown). Under this condition of the apparatus, an indication circuit for the indication relay IRis completed which may be traced as follow beginning at the secondary winding of the transformer 90, wires 91 and 130, contacts wires 106 and 132, contacts 131 52 wires 133 and 99, winding of the indication relay 1R, wire 98, contacts 53 134 wires 135, 101 and 136, contacts 51 137 wires 1 138' and 104, contacts 53 134 wire 95, contacts 51 137 wires 139 and 109 back to secondary winding of transformer 90.

It should be noted that the circuit through the indication relay 1R just traced was traced from right to left through thewinding of the relay IR but was started fromthesame terminal of the transformer as when the reverse indication circuit was traced heretofore, from which it readily appears that the indication magnet IR is energized to the op posite position from what it was when the switch machines were moved to their reverse position, and will, therefore, assume the right With the indication relay IR in the normal position, the indication selector in the normal posie tion, for reasons ust given, and with the lever L in the half normal position, a circuit for the 1nd1cat-1on magnet 1M is completed which may be tracedras follows: beginning at the terminal B of a suitable, source of encrgv, push button 30, stationary contact.

32, wire 33, winning of the indication magnet 1M wire 34, contacts the lever, wire 141, indication contacts 39 142, wire 143, contact 53 of the indication relay IR in its normal position, wire 59 to common return wire C connected to the other side of said source of energy.

With this circuit completed, the indication magnet 1M moves its arn'iaturc and plunger 63 to the lower poition against the force of CU-IllPl'QSSlOil spring 144, whereupon the op erator is free to complete the movement of his lever to its full right hand normalposition.

it should be noted that the circuit for the indication magnet 1M cannot be completed unless the lever is in a half normal or half reverse position, and the indication relay IR and the indication selector IS are in corresponding positions. This gives additional protection because the circuit for the indication magnet cannot be completed unless each of the various devices-have properly responded. Also, the indication magnet 1M is veryquick acting, sothat it will assume its locked. position before the operator,- by a quick move, can move the lever from one in.- dication to the other indication position. This precaution is taken to avoid accidental or malicious movement of the lever beyond a particular indication position without requiring both switch machines to first assume a corresponding position.

In connection with the circuits for the indication relay IR'heretofore't-raced it should be noted that the winding of the indication relay IR is short circuit'ed, or. shunted, through shunting contacts.5 i 1OO and contacts 53 134 in series when the switch 1nachine SM is in an intermediate position; and further that the wires 96and 108, through which the-indication circuit was traced when the switch machines were moved to the reverse position, are shunted by shunting contacts 53 -134 and that the wires 132 and 138, through which the indication circuitwas traced when the switch" machines were moved to their normal position, are shunted by con,-

' tacts 54 -100 when the switch machines S .point in its stroke; noted that the presence and proper function ing of stationary shunting contacts 1OO 1'34 1'O0?-184- a-re'all checked each time the switch machine is-movedto the reverse position and is moved back to its normal position, because-an essent1alport1oni of the nu:- dication circuit ll'lClll'dGS-tllQSG contacts. at

onetime or the other; Hence, if these shuntcertaintimes, are'brokembent up. orareburnt away due: to arc1ng,.no11ndicat 1on can be re-. ceived, and such contacts must be replaced before further operation of; the switch is" possible, so that-it is assured that theseshuntingcontacts are in proper workingcondition at all times. Further, the; cross-protection relay CR iscontainedin, but shunted, in each of the operating circuits for switch machines SMF-and: SM? under operation thereof in either direction, that is, when thelever is in one or the other indication POS1t10lflIlCl this cross-protection relay CR is left unshunted in such-Icircnits-when the lever is ,eitherofthe two extreme positions. Hence, if energy should be applie'd to the normal wire mg contacts, which. arevessential. to assure proper. shunting; of the lndication relay IR. at

while-the lever is-in the reverse position, or to the reverse wire while the lever is in the: normal positlon, this current will; also traverse the cross-protection relay CR and cause its operation, thus cutting off allv available invention havebeen shown applied,;it should be understood that the particular embodiments of the invention'selected are not in- ,tended to illustrate all of the constructions preferably employed in practice, nor the scope of the invention, and that various additions,

changes and modifications may be made to' adapt the construction to the problems and systems encountered in practice, without departing fromthe' scope. of the invention, or

the idea ofmeans .underlyingthe same; What I claim as new is g 1. In an.interlockingsystem, thecombina tion with two switch machine's, an indication relay, a source of energy, andfioftwo circuit, controlling devices each controlled separately by one of said switch machines tor connecting said: source. of energy to said relay to indicate when. both switchmachines assume corresponding positions, sjaid circuit controlling."devices being so; connected'in a circuit'arrangement. that the partial circuit leading to said indication. device is shunted by shunting contacts. when either of. said switch machines assume anintermediate position and when one switch machine, assumes oneextre'meposition; and the otherswitch machine assumes theother extreme position,- said shuntingcontacts forming-part. of the indicatien' circuits, whereby the working, condition as well asthe presence of said shuntingcontacts is checked each time the switch .machines are operated t'o-the reverse position and backto normal. p v p 2. In an interlocking: system, the combination. with alever of an.interlockingiinachine, of an electrically operated traffic controlling device, a circuit controlled by contacts; on

said lever. closedwhensa-idlever is inlthc'half or indicating position for operating? said traffic controlling device to certainipositlon,

said circuit includingacross protectiong de- V vicewhich iitcopcratedi cuts energyoft of said system but which cross protection= device is shunted by. contacts on said lever closed onl-y when said lever is in said half or indicating position, whereby if saidlevertismoveditoathe full position said; cross-protection deviceis left unshunted 1n said circu t. Y

3, An interlocking system comp'rising a leverinterlocked with a plurality ofother levers so-that certain of said other leverslcam not be operated unless. said lever assumes acertain position, a trafiiccontrolling device, a source of electrical energy, a cross-protection device which if operated disconnects said source ofenergy from the system, contacts on said lever closed when said lever is in the indicating position for operating said trafiic controlling device by energy derived from said source through a circuit including said cross-protection device, and other contacts for shunting said cross-protection relay on said lever and closed when said lever is in said I indicating position, whereby said cross-proing, atraflic controlling device controllable tec'tion device is left unshunted in the circuit of said traflic controlling device when said lever is ineither extreme position, so that the application of unauthorized current thereto effects operation of said crossprotection device before said traiiic controlled device responds to such unauthorized current.

4. An interlocking system comprising, a lever interlocked with a plurality of other levers so that certain of said levers cannot be moved unless said lever assumes a predetermined position, an electrically operated traific controlling device, an electrically operated cross-protection device connected in series with said trafiic controlling device, a source of energy connected to said system through contacts of said cross-protection device which contacts are open if said cross-protection device is in its operated position, contacts associated with said lever for applying current to said trafiic controlling device when the lever is in a certain position, and other contacts associated with said lever for shunting said cross-protection device when the lever is in said certain position, whereby said cross-protection device is not operated upon the ap'pli'- cation of current to saidtrafiic controlling device by said lever but is left unshunted in series with said trafiic controlling device at other times and is operated if unauthorized current'is applied to said trailic controlling device at times when said lever is not in position to operate said traflic controlling device.

5. Traific controlling apparatus comprisfrom a source of energy, a cross-protection device having its operating coilconnected in series with said trafiic'controlling device and which if operated prevents said traffic controlling device from beingoperated by current from said source of energy, and a lever for simultaneously applying currentfrom said source to said trafiic controlling device and shunting the coil of said cross-protection I device.

6. In a control system for controlling two switch machines by the same lever, the com} bination with a lever having a normal and a reverse position, two switch machines connected in multiple to normal and reverse wires respectively leading to said lever, an

. indication selector operated to one position when current flows in said normal wire and to the other position when current flows in said reverse wire, a three-position indication relay in a circuit including a. source 01 energy and circuit controls operated by said switch machines in a manner to cause said relay to assume one energized position only if both switch machines assume one extreme position and cause it to assume the other ener gized position only if both switch machines assume the other extreme position, an indication magnet for said lever which if energized permits said lever to be moved to the normal or to the reverse position, and a circuit for energizing said indication magnet closed only if said lever, said indication selector and said indication relay all'assume corresponding positions.

'Z. In a control system for controlling two switch machines with the same lever, the combination with a lever. having a normal and a reverse position, a source of energy, two switch machines each having a normal and a reverse wire and connected in multiple and to said lever in a manner so as to connect the normal wires to said source of energy when the lever is normal and connect the reverse wires to said source of energy when the lever is reversed, an indication selector operated to one position when current flows in said normal. wire and to the other position when current flows in said reverse wire and which remains in its last operated position, an indication magnet for said lever preventing said lever from being moved to either the normal or. the reverse position whende-energized, and means for energizing said indication magnet efi'ective only if said'lever, said indication selector and both of said switch machines assume corresponding posit-ions.

8. The methodof protecting by cross-protection relay an interlocking system for railways of the type wherein a' distant trallic controlling device'is at times operated from a local source of current which has one terminal thereof connected directly to a line wire returning to such traffiocontrollingdevice, which consists in connecting the winding and a normally closed contact of such cross-protection relay in said line wire, and in shunting said winding only when current should be flowing in said line wire, whereby if current from said sourceis caused to flow in said line wire through an unauthorized partial circuit when no current should flow therein said cross-protectionrelay is operated and said line wire is disconnected fromsaid source of current.

9. In an interlocking system comprising;

an electrically operated traffic controlling device; acircuit' for operating said device in-.

eluding a source of current, the winding and i a normally closed contact of a cross-protec, tion relay, and a normally open contact of a manually operable interlocking lever; a contact on said lever for shunting the winding of said cross-protection relay closed when manually operable interlocking lever; and a contact on said lever for shunting the wind ing of said cross-protection relay closed when said normally open contact is closed.

11. In a control system for controlling two switch machines by the same lever, the combination with a lever having a normal and a reverse position, a source of energy, two swltch machines each having a normal and a reverse wire connected in multiple and to said lever in a manner so as to connect the normal wires to said source of energy when the lever is normal and connect the reverse wires to said source of energy when the lever, is reversed, a cross-protect1on relay at all times having its winding connected in a circuit portion in series with said source of energy, and means for shunting said winding when current is caused to flow in either said normal or said reverse wires due to'operation of said lever. r

12. In an interlocking system for railways,

the combination with a lever interlocked with other levers of such System, a lock magnet havlng its energization controlled 1n accordance with trafic conditions; for locking said lever in either of its extreme positions, an indication magnet controlled by indication current flowing when the trafiic controlling device controlled by'Sitld lever has responded to a change in they position'of said lever for locking said lever against movement from an intermediate to such extreme position, and manually operable means assoclated with said lever which if in one posltlon opens the circuit for said lock magnet and in the other position opens the circuit for said indication magnet, whereby a quick stroke of said lever from one extreme position to'the other extreme position cannot be made.

In testimony whereof I afiixmy signature.

, JOHN o. LIN NER,

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