US2368762A - Light signal - Google Patents

Description

A. l- JEROME LIGHT SIGNAL Feb. 6, 1945.

Filed May 1, 1943 INVENTOR AmhzzpLJapome.

film HIS ATTORNEY Patented Feb. 6, 1945 LIGHT SIGNAL Arthur L. Jerome, Edgewood, Pal, assignor to The Union Switch & Signal Company, Swissva1e,.Pa., a corporation of Pennsylvania Application May 1, 1943, Serial No. 485,374

8 Claims. (Cl. 177337) My invention relates to a light signal, and particularly to a signal capable of selectively projecting a plurality of beams of light from a single light source. 4 i

More particularly my present invention relates to a Searchlight signal having a spectacle arm provided with red, yellow and green filters adapted to be selectively interposed in the signal beam to cause the signal to display stop, approach and clear indications.

An object of my invention is to provide novel means for operating the spectacle arm of a signal by two electromagnets so that the spectacle arm may be moved between itsapproach and its clear positions without passing through the stop position.

Another object of the invention is toprovide a signal employing a first and a second electromagnet which are energized from a polarized control circuit in such manner that the first magnet checks operation of the second magnet and will not respond unless the second magnet correctly responds to the energy supplied over the polarized control circuit.

an improved signal of the type described which is arranged so that the signal cannot display either its approach or its clear indication unless the first electromagnet responds to energy supplied over the control circuit to thereby insure that the signal will display its stop indication unless the signal is functioning asintended.

Another object of the invention is to provide a signal of the type described in which the first electromagnet is reversibly connected in series with the second electromagnet by means of continuity transfer contacts controlled by the second electromagnet so that the supply of energy to the second electromagnet is not interrupted during response of this magnet to energy supplied over the control circuit.

A further object of the invention is to provide an improved signal of the type described which is arranged so that thetwo electromagnets may both be energized from one polarized control circuit, or may be separately energized from different control circuits.

Another object of the invention is to provide improved means for energizing two electromagnets in series from a polarized control circuit.

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

According to my invention, a vane or spectacle arm carrying thecolor filters is biased by a counterweightor other means to one-extreme position in which a red filter is disposed in the path of the light beam, while the'vane is arranged to be moved from this position to the approach and clear positions by means of a floating lever con-- nected with the vane. One end of this floating lever is connected to the armature of the first electromagnet and the other end ;of this lever is connected to the armature of the secondelectromagnet. The vane is connected with the floating 'lever at an intermediate point on the lever which is nearer the point of connection of the lever with the armature of the first electromagnet than the point of connection 'of. the lever with the armature of the second electromagnet. The various elements of the signal are arrangecl so'that when the armature of the first electromagnet is released the vane isheld in a position in which a a red filter is disposedin the path of the light beam irrespective of the position of the armature of the second electromagnet. The various elements of the signal j are also'arranged so that when the armature, ,of the first electromagnet is picked up the vane is 'moved'to theposition in which'the yellow or the green filter is interposed in the path of the light beam according as the armature of the second electromagnet, is released or picked up.

I shall describe one, form of signal embodying my invention together with a modification .therei of which I may employ, and shall then pointout the novel features thereof in claims.

v In the drawing Fig. ,l is a diagram of-asignal embodying my invention, and I Fig. 2 is a view of a modification which I may employ. v .7 I I Referring to Fig.1 of the drawing the'signal comprises a vane or spectacle arm In which is supported on a suitable pivot l l, and is provided with four color filters or roundels. These include a green filter G, a yellow filter Y, and twored filters RI and R2, which are arranged to coop:- erate with a lamp l2. In the drawing the lamp i2 is shown above the filters for the purpose of illustration, but it is to be understood thatv in actual practice this lamp is located so that the filters are moved infront of the lamp as the spectacle arm is moved about the pivot II. In

, addition itis to be understood that the lamp l2 may have associated therewith means, not shown,

such as a reflector, for directing through the filter in front of the lamp the rays of light emitted by a the lamp. I

The spectacle arm I0 is connected by a pin M to the upper end of a link I5, while the lower. end

of the link I5 is connected by a pin I6 to a floating lever [8. One end of the lever I8 is connected by a pin and slot connection IS with the armature of the first magnet H, while the other end of the lever I8 is connected by a similar pin and slot connection 20 with the armature of the second magnet D.

. The'pin tfiiconnecting the link t5 with the leve I8 is locatedl'at moisten thelleverilil approximately twice as far from the point of connection of the lever IS with the armature of magnet D as it is from the point of connection of the lever IS with the armature of the magnet H. The

Various elements of the signal ar'earranged-and proportioned so that when ithe armatures "of the magnets H and D are both released -the:spectacle arm I!) is held in the position in which the red filter RI is located in front ofthelamp l2.

On picking up of the armature of magnetHthe picking up o'ffthearmaturedf the magnet H, the

spectacle'arm H! "is moved about thepivot H a distance equal to two filters or roundels. Accordingly, when fthearma'ture of magnetI-rpicks up when 'the-armature' of magnet D is released,

the spectacle arm l-Oj'ijs moved aroundthepivot I far enough to cause'the yellow filter Y'to be 'locatedin'front of-the lamp +2. I

On picking upof the armature of the magnet D'the lever 'l 8 pivots "about the =pin19 associated withthe armature offmagnetfi, while the pin l B islifted a distance substantially equal to 'onethirdof *the distance'that'the"pin 20 associated with thelmagn'et D is lifted. The various "elejments'o'f the signal are proportioned so that on 'pickingup'ofthe armature of magnet'D the specta'cle'arm'ismoved about the pivot H a distance equal'to'one filter or'roundel; Accordingly, when the armature "ofmagnet D picks up *when the armature of magnet H is picked up the spectacle arm "is moved from the position in which the yellow filter Y is "located "in front'of lamp H to "the,position inWhiCh"the green filter G is located in front of the. lamp 12, while when the armature ofmagnet Dpicks'up'whenth'e armatureof maghand to its right-hand terminal. The construction of the magnet D is not a part of this inven- 'tionand thismagnet may be constructed in any appropriate manner Well-known in the art. One

form of construction which may be employed is shownin-LetterszPatent of the United States No.

2303,4388; iss'uedflune 11, 1940, to H. E. Ashworth.

The windings of the magnets D and H are energized from a polarized control circuit over a circuit similar to that shown and claimed in application for Letters Patent of the United States, se n i'a'lf-tlo. 124,1151,"of A. Dodd. This circuit "includes make-before-break contacts "which 'are operated o me armature of the magnet D.

Eitherfor both 'o'f the magnets D and H may have contacts operated by the "armature of the magnetasshown in the drawing, andtheseco'ntacts may 'be employed inany appropriate manner; I

Energy is supplied from a source'of'direct current, the terminals of which are designated I and to the windings off-the magnets D and'H.

net H -isreleaseol. the spectacle arm is moved from the position in Whichthefilter'Rl is located in front of 'lamp "F2 to the position'in which filter R2 is located in frontoflampf-Z. I

In the drawing, the armatures of "the magnets are shown in their released positions, while the picked up pos'itionswof these armatures 'are indicated by broken lines. In addition, broken lines extend between the ends of the armatures 'in their picked up'and released positions to illus- "trate'theefiect of'movement of the armatures on 'the- 'pin F6, and therefore onthe spectacle arm l0.

For convenience, each position of the-pin I6 is designated'by the reference character ofthe'filter which is 'located'in front of the lamp 12 in that position of the pm. When the armatures of both magnetsare releasedfthe'pin It occupies its low 'ermostposition R1 in Wh iCh'fthe red filter BI is I located in "front of the'lamp [-2. When the' arms;-

ture'of magnet D' is picked up and the armature 7' "of magnet H is released the pm It is lifted one The polarity of the energy supplied from the 'source'is governed by'contactsHand 2'4 ofa pole changer PC which may be governed by any appropriate condition, as for example, trafiic'conditionsln-advance of the signal. The supply of energy to't'he control'wires'is governed by "a 'contact 2'5 which-maybe contro'lledin any desired 'manner; I

'The' equipment is shown in the condition which itassumes'when contact 25"is released so that the supply of 'energy'tothe windings of the magnets D and H is interrupted. As the windings ofthe 'magne'ts'D and E are not energized the armatures of these magnets are moved by gravity orothermeans to "their lowerflpositionsjas shown so'that force is exerted through the-floating lever 1'8 and-the link I5 to causethespe'cta'cle arm It to occupy the position in which the red filter Rl is located in front ofth'e lamp 12. Accordingly; the signal provides its red 'or stop indication. I I

' -'On picking up of "contact 25 when the pole changingcontact '23 and 2 3" are released energ of reverse 'polarity'is supplied to the control wires and flows through 'the'windin'gs of the magnets D and Hover the circuit which is traced from the "positive terminal of the source over contact D -from right to left, wire '30, and back contact '23 to the negative terminal of the source.

The direction of 'flowof energy through the winding of magnet 'D'is such that the armature of this magnet will not pick up, but remains released, so contacts 28 'and2 9 maintain thecircuit traced above. The energy supplied through the winding of magnet'H causes the armature of this magnet to pick up and thereby lift the righthandend of the floating lever [8 so that force I is exertedthrough the lever 18, and the link It to move the spectacle arm about the pivotll' to the-position in which the yellow filter Y is 10- cated in front of the lamp [2. Accordingly, the signal now provides its yellow or'caution indication. 7

If the contacts 23' and 24 are now picked up,

the energy suppliedcto the control wires 21 and 30 is changed from reverse to normal polarity.

On the supply of energy of normal polarity to the wires 21 and 30, energy flows from the posi- When contact 32 engages contact 29 a circuit A is established to connect the winding of magnet D across the control wires 21 and'30 in series with the winding of magnet 1-1. ,This circuit is I traced from the right-hand terminalof the wind ing of magnet D over contacts. 29 and 32, winding of magnet H from left to right, and through asymmetric unit K2 to wire 21. 7

It will be seen, therefore, that on the supply of energy of normal polarity to the control wires 21 and 30 energy is supplied to the winding of magnet D over the circuit controlled by, contacts 29 and 28, While on picking up of the armaturev of the magnet contact 32 engages contact 29 to establish the circuit for energizing the winding of magnet D in series with the winding of magnet H before contact 29 is moved out of engagement with contact 28. Accordingly, there is no inter? ruption in the upply of energy to the winding of magnet D and the armature of this magnet is certain to complete its movement to its picked up position.

On the change in the energy supplied to the control wires from reverse to normal'polarity the supply of energy to the winding of magnet H is interrupted until the armature of magnet D picks up. However, during the period in which i the supply of energy to the winding of magnet H is interrupted the asymmetric units KI and K2 provide a snubbing circuit for the winding of magnet H to thereby render the magnet slow to release with the result that the armature remains picked up during the period in which the supply of energ to the winding of the magnet is interrupted. After the armature of magnet D picks up the windings of magnets D and H are energized in series'and the armatures of both of both magnets are picked up, contact 1 5 opened to cut off the supply of energy to the magnets D and H, the armatures of both magnet will release, while the spectacle arm It will be returned to the position in which it is shown in which the red filter RI is'located in front of the lamp I2. If while energy of normal polarity is supplied to the control wires 21 and and the armatures ofthelamp l2.

of the magnets D and H are both picked up, the contacts 23 and 24 are released to change the energy supplied to wires 21 and 30 from normal to reverse polarity, the 'supplyof 1 energy to the windings of magnets D and H in series will be interrupted, while energy will be supplied to the winding of magnet D over the circuit traced from the positive terminal of the source over contact 25, back contact 24, wire 21, asymmetric unit Kl, contact 32 and 29, winding of magnet D from right to left, wire 30,,and back contact. 23 to the negative terminal of the source. Energy flowing through ,the winding of magnet D from right to left reverses the fiux in the core of the magnet with the result that the armature of the magnet releases and thereafter remains released.

On movement of the armature of this magnet to its released position contact 32 is moved out of engagement with contact 29 to thereby interrupt the circuit just traced for energizing the winding of magnet D through the asymmetric unit Kl, while contact 29 is moved into. engagement with contact 28 to establish a circuit for energizing the magnet D in series'withthe winding of magnet H. This circuit is traced from the wire 21 through asyrmnetric unit Kl, winding of magnet H from left to right, contacts 28 and 29, and winding of magnet D from right to left to wire 30. Accordingly, energy continues to flow through the winding of magnet D-from right to left so the armature of this magnet remains released while energy isagain supplied through the winding'of magnet H from left to right to keep the armature of this magnet picked up. The winding of magnet H is snubbed by the circuit through the asymmetric units KI andKz during the period .in which the supply of energy to the winding is interrupted so that the armature of the magnet remains picked up until energy is again supplied to the, magnet winding.

On release of the armature of the magnet D while the armature of magnet H is picked up the left-hand end of the lever I8 is lowered so force is transmitted through the lever l8 and, the link l5 to move the spectacle arm It to the position in which the yellow filter Y is located in front If, while energy of reverse polarity is being supplied to wires 21 and 30 and the armature of magnet H is picked up to cause the signal to display its yellow or caution indication, the contact 25 is opened, the armature of magnet H will releaseand the spectacle arm II) will be moved to theposition in which red filter RI is located in front of the lamp l2. 1 v

This signal is arranged sothat if the armature of the magnet D picks up on the supply of energy of reverse polarity to the control wires 21 and 30 the signal will display it red or stop indication.

On the supply of energy of reverse polarity to the control wires when the armature of magnet D is released, energy flows from the positive terminal of the source over contact 25, back contact 24, wire 21, asymmetric unit Kl; winding of magnet H, contacts 28 and '29, windin of magnet D from right to left, and back contact 23 to the negative terminal of the source. On flow of energy through the winding of magnet D from right to left, thearmature of this magnet should not pick up, but if for any reason the armature does pick up and thereafter remains; picked up, the circuit just traced for energizing the windings of magnets D and H in series will be interrupted because of disengagement of contact 29 from concontrol wires.

21 through asymmetric unit Kl, contacts '32 and tact '28, and a circuit will be established to connect the winding of magnet D directlyaeross the This circuit is traced from wire 29, and winding of magnet .D from right to left, to wire 30. i

The energ-y'supplied to the winding :of magnet D may maintain .the armature of the magnet picked up, but as long as the armature remains picked up the winding of magnet His shunted by asymmetric unit K1 and its-armature releases and remains released..- When the armatureuof magnet D is picked up and the armature of magnet H is released, the left-hand :end of the lever I8 is lifted and force is exerted through the lever I8 and the link 15 to move the spectacle arm in to the position in which the red filter R2 is lo-.

cated in front of the lamp 12. Accordingly, when the armature of magnet D is improperlypicked up, the armature of magnet H is released and the signal operates to provide a red or stop indication. I I 4 When energy of reverse polarity is supplied to the control wires 21 and 3ll'th armature of the magnet D will normally be released and the armaa ch'eck on operation of magnet D and the armature ofmagnet H will be released if the armature of magnet D is picked up at a time where energy of reverse polarity is supplied to the control wires. When the armature of magnet H is released the signal displays ared or stop indication regardless of the position of the armature of'the-magnet D. The operation of the signal, therefore, is such as to provide the maximum degree of safety since the signal will provide its stop indication unless the signal is'function-ing to provide the proper indication.

As pointed 'out above, on a change in the polarity of the energy supplied to the control wires 21 and 313, whether this change is from normal to reverse polarity or from reverse to normal polarity, the supply of energy to the winding of magnet H is interrupted untilthe armature of magnet D moves to a position in correspondence with the polarity of the energy supplied to the winding of the device. On interruption of the supply of energy to the winding of magnet H armature of this magnet is maintained picked up for a short period because of the snubbing circuit which exists for the magnet winding through the asymmetric units KI and K2. This snubbing circuit for the magnet H serves to maintain the armature of the magnet picked up for a period long enough to enable the armature of the magnet D to respond to a change'in the polarity of the energy supplied to the winding of magnet D. Since the armature of magnet H ismaintained picked. up on a change in the polarity of the energy supplied to the control wires, the, spectacle arm i is moved between the yellow and "green ositions without moving to the red position as would occur if the armature of the magnet H shouldrelease. The operation of the signal, therefore, is such that changes between the yellow and green indications occur without momentary flashes of the red indication.

' armature of the second electromagnet is in its first a'eesyree "While the spectacle arm has been illustrated and described as being provided with two separate red filters, it is obvious that one filter large enough to extend'in front {of the lamp I2 in two positions of the spectacle arm, asshownin Fig. 2, might be employed instead.

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

I Having thus described my invention, what I claim is: v

1: In a light signal, in combination, a spectacle arm carrying a first and a second red filter, a yellow and a green filterwhic'h are adapted to be interposed in a beam 'of light-to cause the signal to provide'red, yellow and green indications, a first and a second electromagnet each having an armature movable between afirst and a second position, and means for operating saidspectacl'e arm by the armatures of said electromagn'et in such manner that when the armature of the first electromagnet is 'in i'ts'first position the first or the second red filter is interposed in the light beam according as the armature of the second electromagnet is in its first or its second position and so that when the armature of the first electromagne't is in its secondposition the yellow or the green filter is interposed in the light beam according as the armature of the second electro magnet is in its first or its second position.'

2. In a light signal, in combination, a spectacle arm carrying a plurality of difierent filters which are adapted'to be interposedin abe'am of light to cause the signal to'provide a plurality of differentindications, said filters including a red and a green filter and a yellow filter disposed between said red and green filters to thereby permit the spectacle arm to be moved between the positions in which thegreen and yellow filters are interposed in the light beam without passing through the position in which a red filteris interposed in the light beam, a first electromagnet having an armature biased to a released position, a second electromagnet having an armature which is moved from a first to a, second position when and only when energyflows through the winding of the electromagnet in a particular clirection, a pair of control :wires, ,means for at times supplying energy of one polarity and at other times supplying energy of the other polarity to said control wires, means including a contact governed by the armature of said second electromagnet for'reversibly connecting the winding of said first electromagnet across said control wires in series with the winding of said second electromagnet, and means for operating said spectacle arm by the armatures of said electromagnets in such manner that when the armature of the first electromagnet is released a red filter is inter} posed in the light beam regardless of the position of the armature of the second electromagnet and so that when the armature of the first" electromagnet is picked up the yellow or the green'filte'r is'interposed in the light beam according as the or its second position. 3. In a light signal, in combination, a spectacle arm carrying a plurality of different filters which are adapted to be interposed in a beam of light to cause the signal to providea plurality of different indications, said filters including a red and 'a green filter and a yellow filter disposed between said red and green filters to thereby permit the spectacle arm to be moved between the positions in which the green and yellow filters are interposed inthe light beam without passing through the position in which a red filter is interposed in the light beam, a first electromagnet having an armature biased toareleased position, a second electromagnet having an armature which is moved from a first to a second position when and only when energy flows through the winding of the electromagnet in a particular direction, a pair of control wires, means for at times supplying energy of one polarity and at other times supplying energy of the other polarity to said control wires, means including make-before-break contacts governed by the armature of said second electromagnet for reversibly connecting the winding of said first electromagnet across said control wires in serieswith the winding of said second electromagnet, and means for operating said spectacle arm by the armatures of said electromagnets in such manner that when the armature of the first electromagnet is released a red filter is interposed in the light beam regardless of the position of the armature of the second electromagnet and so that when the armature of the first electromagnet is picked up the yellow or the green filter is interposed in the light beam according'as the armature of the second electromagnet is in its first or its second position.

4. In a. light signal, in combination, a spectacle arm carrying a plurality of difierent filters which are adapted to be interposed in a beam of light to cause the signal to provide a plurality'of different means for operating said spectacle arm by the armatures or said lectromagnets in such manner that when the armature oi':the first electromagnet is released a red filter is'interposed in the light beam regardless of the position of the armature of said second electromagnet and so that when the armature of said firstelectromagnet is pickedup the yellowor the green filter is interposed in the light beam according as the armature of the second electromagnet is in its first or its second position.

5. In a light signal, in combination, a spectacle arm carrying a plurality of difierent filters which are adapted to be interposed in a beam of'light to cause the signal to provide a plurality of different indications, said filters includinga red and a green filter and a. yellow filter vdisposed between said red and green filters to thereby permit the spectacle arm to be moved between the positions in which the green and yellow filtersare interposed in the light beam without passing through the position in which a red filter is interposed in the light beam, 3.

first and a second control conductorto which energy of normal polarity is supplied at times and to which energy of reverse polarityis supplied at other times, a first electromagnet having an armature biased toa, released position and movable therefrom to a picked up posi-' tion, asecond electromagnet having its winding connected .in series with one of said conductors and having an armature movable between a position when and only when energy flows ductor to which energy or normal polarity is supplied at times and to which energy of reverse polarity is supplied at other times, a first electromagnet having an armature biased to a released position and movable therefrom to a picked up position, a second electromagnet having its wind-, ing connected in series with one of said conductors and having an armature movable between a. first and a second position, said second electromagnet being of a type the armature of which when in its first position is moved to its second position when and only when energy flows through the Winding of said electromagnet from said first to said second conductor, means including make-beforebreak contacts governed by the armature of said second electromagnet and effective when said armature is released to connect said conductors together through an asymmetric unit poled to permit energy to flow from the second to the first conductor and to also connect said conductors together through the winding of said first electromagnet with the first conductor connected to a selected terminal of the winding of said first electromagnet and being-efiective when the armature of said second electromagnet is in its second position to connect said conductors together through an asymmetric unit poled to permit energy to flow through the winding of said electromagnet from saidcfirst to saidsecond conductor, means including make-before-break contacts governed by the armature of said second electromagnet and effective when said armature is released to connect said conductors together through an asymmetric unit poled to permit energy to fiow from the second to the first conductor and to also "connect saidconductors together through the winding of said first electromagnet with the first conductor connected to a selected termi-' nal of the winding of said first electromagnet andbeing efiective when the armature of said secondlelectromagnet is in its second position to connect said conductors together through an asymmetric unit poled to permit energy to 110W from'the first to the second conductor and to also connect said conductors together through thewinding ofthe first electromagnet with the second conductor connected to said selected terminalof the winding of said first electromagnet, and means for operating said spectacle arm by the armatures of said electromagnets so that when the armature of the first electromagnet is released and the armature of the second electromagnet is in its first position, the

from the first to the second conductor and to also connect said conductors together through the winding of the first electromagnet with the second conductor connected to said selected terminal of the winding of said first electromagnet, and

,rality of difierent indications, said filters including a red and a green filter and a yellow filter disposed between said red and green filters to thereby' permitth'e spectacle armto': be moved betweenthe positions-in; which the green: and yellow filtersare interposedinthe light beam without passing through the". position in which a redfilter is interposed in the light beam, :1. first and a second control conductor to which energy of normal polarity is supplied at times and to. which energy of reverse polarity is supplied. at other times afirst electromagnet having an armature biased to.a..released position and movable therefrom to a picked up position, a second electromagnet having its. winding connected in series with one of said conductors and having an armature movable between afirst and asecond position, said second electromagnet being. of a type thearmature of which when in its first position is moved to its second position when and: only. :whenenergy flows through the winding of said electromagnetfrom said first to said second. conductor, an asymmetric unit said armature .is .in its. firstorits second posi:

tion to connect theother control conductor to the first or thesecond terminalof said. asymmetric 'a-gecerzea electromagnet andijfsupportedi at a second point by the armature of: the second electnomag net, ."and means: connected. with, saida lever: for

moving said: spectacle: arm, saidamean's being, ar range-dso that when the-armatureof. the: first electromagnet is in its: first positionmovement of thearmatureof. the second electromagnet I between its two positions causes the spectacle arm t'obe moved between the position in which the first red filteris interposed in; the, light beam. and the position which the second red filter .isi nterpos'edin the; light beam" and also being arranged so that; when/[the armature of; the first electromagnet is; in itsgsecond' position movement oftho; armature: of the second electromaghet from itsfirst togits second position causes the spectacle arm to be moved from the: positioninwhich the yellow filter: is'i-nterr posed the light beamto' the position in which the green. filter isinterposedginrthe light beam.

8'. Ina light signalin. combination, a,,fi-rst and a second electrcmagnet each having an armature biasedv to a released position and; movable therefrom to a piokedup position, a floating lever supported at a firstp'ointby the armature of the first electromagnet and; supported at a second point by the armature of the second electrom-agnet, a spectacle arm biased to a posi-tio-n in which'itcauses the signal to provide a stopindication and movable therefrom. through a caution position inwhich it causesthe signal unit,;and means foroperating; said spectacle arm manner that aredfilter-is interposed in the light beam when, the-armature of said first electro magnet .is'. released regardlessof'the position of the armature of the second electromagnet and by the armatures. of said electromagnets insuch sothat when the armature of the first electro.:

magnet is picked up theyellow .or .thexgreen filter is interposed the lightjbeam according as the armature of the second ,electromagnet is in its firstor. itsv secondpositiom '7..,In a light signal, in combination, a spectacle arm carrying a first and a second red filter, a yellow and a green filter which are adapted .to. be interposed. in a. beam of light toicause the.

' signal to provide. red, yellow and green indications, a first and a second electromagneteach having an armature movable between a firstand a second position, a floatingv lever. supported at a first point by the. armature of the first to, provide a caution indication. to a clearposition in which it causes" the signal toprovide a clear indication, saidspec-tacle arm:- beingoperatively connectedwith said lever in such'manner that when the armaturesofboth of said e1ectromagnets are released the spectacle armoccupies its ,stop position, the point of connection of the spectacle arm with said lever, the amount of movement of the leverby the armatures of said electromagnets and the distance between the different positionsof the spectacle arm being arranged and proportioned so that picking up of the armature of thefirst electromagnet will move the spectacle arm from the stop to the caution position and so that picking up of the armaturebf the second eleotromagnet will not move-the spectacle arm from the stop to the caution position if the armatureof the first electromagnetis released but will move the spectacle arm f rom the caution to the clear position if the armature of the first electromagnet is picked p I v H 1 i

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