US2289315A - Signal device - Google Patents

Description

July 7,1942.

J- R. M 'c AY SIGNALDEVICE Filed Oct. 16, 1959 4 S heets-S heet l A; ATTORNEY J- RLM cKAY SIGNALDEVICE July 7, 1942.

Filed Oct. 16, 1939 4 Sheets-Sheet 2 l\ g n NVENTOR BY 5 I l h; ATTbRNEY i ha..

July 7,1942. m. MaOKAY 2,289,315

SIGNAL DEVICE Filed Oct. 16, 1939 4 Sheets-Sheet 3 INVENTOR I I; ATTORNEY Patented July 7, 1942 cries 2,289,315 SIGNAL DEVICE John R. MacKay, West to Wallace & Tiernan Caldwell, N. 3., assignor Products, Inc., Belleville,

N. J a corporation of New Jersey Application October 16, 1939, Serial No. 292,693

(Cl. 24o-e7.1)

19 Elaims.

This invention relates to lamp changing apparatus for automatically replacing electric lamps which have failed. The invention has been made more especially with the idea of providing an apparatus of this kind for beacons, such as aviation and marine beacons, or other signal devices using comparatively high wattage lamps which are successively positioned in a fresnel type lens or other optical system of restricted dimensions.

The invention aims lamp-changing apparatus especially suitable for such use and which shall be of comparatively simple and rugged construction and very reliable in operation, shall, in the most approved form, have no relays or delicate electrical contacts or other parts liable to deterioration, shall operate to replace a failed lamp rapidly and to position the new lamp accurately, shall effect the replacement operation smoothly and without harmful jarring, and shall maintain the positioned lamp accurately in position regardless of vibration and inertia.

To these ends, lamp mounting and positioning means according to the invention comprises a lamp carrier, most desirably a rotary carrier, which moves the lamp into and out of position in the optical system in an arc of a circle or other suitably curved path, and on which each lamp is mounted on a support which is journalled on the carrier and which is caused, as the lamp is moved into or out of operative position, to turn on its pivotal axis so as to maintain its lamp in an upright position.

Being maintained upright, or in. positions of constant parallelism, as they move in their curved path to and from their operative position, the lamps require much less space horizontally in the plane of their movement'than is required by the lamps in lamp-changing apparatus as commonly made, in which the lamps extend at all times during their movement radially, or at right angles to the surface of the, carrier, thus requiring a much larger space within the lens in which to move in their curved path. In addition to other advantages, this has the important advantage especially in fresnel lens devices of largely reducing apparatus cost, since the cost of fresnel lenses increases very greatly as the size increases, so that it is very important to keep the size of the lens at a minimum.

To insure that the lamps shall be accurately positioned and maintained in position until the positioned lamp fails, the apparatus is provided with indexing means which include a fixed indexing; abutment and abutment engaging memhere or parts on the carrier positioned with respect to the several lamp supports.

Other objects, features and advantages of the invention will appear from the following description. While intended especially for aviation and to provide an improved marine beacons having fresnel lenses and using comparatively high power lamps, the invention is suitable for other lighting devices, whether of the fixed, or steady burning, light or of the flashing light type, and the feature of maintaining the lamps upright during their movement to and from operative position, while finding its greatest advantage in apparatus using lamps of comparatively high Wattage because of the size and especially the length of such lamps, is also suitable for and of advantage in apparatus using lamps of smaller wattage, and other motors and motor control means may, of course, be used with the lamp mounting and positioning means of the invention.

A full understanding of the invention can best be given by a detailed description of an apparatus embodying the various features of the invention in the form now considered best, and of certain modifications thereof, and such a description will now be given in connection with the accompanying drawings, in which:

Fig. 1 is a perspective view of a lamp changing apparatus according to the invention;

Fig. 2 is a side view of the apparatus partly in central vertical section;

Fig. 3 is a back view of the apparatus parts shown in section;

Fig. 4 is an enlarged detail view taken on line 4-4 of Fig. 2;

Fig. 5 is an enlarged detail View taken on line 5-5 of Fig. 3;

Fig. 6 is a detail sectional view taken on line 6-5 of Fig. 2;

Fig. 7 is an enlarged detail view partly in section on line 1-! of Fig. 2;

Fig. 8 is a perspective somewhat schematic view partly broken away of the support casting and certain parts of 'the apparatus, and showing diagrammatically the wiring connections;

9 is a diagrammatic view showing the driving motor and electrical connections;

Fig. 10 is a rear view, with parts omitted, showing an alternative means for maintaining the lamp supports in constant parallelism during the movement of the carrier; and

Figs. 11 and 12 are diagrammatic views illustrating alternative forms of driving motors.

Referring to the drawings, and first to Figs. 1 to 9, the various parts of the apparatus are mounted on a support casting it which has a vertical front wall H and side walls 12 and I3 and a base M. A rotary lamp carrier I5 is mounted on a non-rotating stub shaft l6 which extends forward from the support wall II, the reduced inner end of the shaft extending through the wall and being secured by a lock nut I1 and held against turning, as by a pin I8. As shown, the carrier i5 is in the form of an arm which carries two lamps, one at each end at equal dis- With tances from its pivotal axis, one of the lamps, A, being the normal, or working, lamp and the other, B, the spare, or replacement, lamp. A carrier mounting only two lamps is shown for simplicity, but it will be understood that the carrier may mount more than two lamps and will be ofsuch form as is required according to the number of lamps to be carried, the only limitation to the number of lamps being the degree of interference that will be presented by the spare lamps intercepting the usable light rays emitted by the positioned lamp.

It will be understood that the apparatus shown is intended to be mounted in association with a fresnel lens or other optical system so that the positioned upper lamp will be properly located within the lens or other optical system. In one type of aviation beacon having a fresnel lens, th positioned lamp within the lens is reciprocated vertically at frequencies between 20 and. 60 times per minute in order. to produce a 360 cone of light of wide divergence. The lamp changing apparatus shown is especially suitable for such use, the support casting in such case being mounted on a vertically reciprocating support, one of the objects of the invention being to provide an apparatus which will withstand the vibration and inertia forces resulting from such reciprocation without danger of displacement of the positioned lamp with relation to the lens.

The rotary lamp carrier I is given its lamp changing movement by a driving motor 29 which together with a reduction gear unit 2| is mounted on the side wall I2 of the support. The motor, through the reduction gearing and through bevel gears 22, indicated by dotted lines in Fig. 2, and pinion 23, drives a gear 24 fast on the hub of the carrier l5. A ratchet gear 25 is fastened to the gear 24, and a pawl 26 pivoted on the front wall ll coacts with the ratchet gear to prevent backward rotation. The pawl 26 thus serves as a detent to prevent the lamp carrier being turned dexing means for determining the exact position of the positioned lamp and for maintaining the positioned lamp accurately in position. When to serve as the indexing detent, an eccentric carried by a stub adjustment of which the pawl may be adjusted to determine the exact position at which the carrier is stopped to position the lamp accurately in the optical system.

Each lamp is carried by a support casting 30 which is rotatably mounted on a stub shaft 3| extending horizontally forward from the carrier. Each of the stub shafts 3i is non-rotatably mounted near one end of the carrier arm by having its inner end extend through a hole in the the lamp are secured by means of thumb screws 36. The lamp carrier l5 and the lamp supports 30 are most desirably journalled on their shafts by means of bearing bushings 37 made of a suitable metal-impregnated graphite, as this mateand heat resistant and reother than that afforded by rial is very wear quires no lubricant the material itself.

The stationary stub shaft i 6 on which the lamp carrier arm I 5 is journalled carries in front of the carrier arm two spaced sprocket wheels 46 and 4| which are clamped on the shouldered end of the shaft by means of a lock nut 42 and secured against turning on the shaft, as by means of a pin 43 which extends into a thrust collar integral with the shaft. Each of the lamp supports 30 has fast on its inner end a sprocket 45, and these two sprockets are geared one with each of the stationary sprockets 45 and 4| by endless sprocket chains 46. The two sprockets 45 and the sprockets 40 and 4| are all of the same size. When, therefore, the carrier is turned on its axis the lamp supports are by the chains and sprockets given an angularly equal but opposite rotation, so that the lamp supports as they are moved by the carrier maintain a position of constant parallelism, the lamps being thus maintained in vertical position regardless of the an gular position of the carrier arm.

From each lamp support 30, from each socket member 35 in the construction shown, extend two conducting strips 53 and 5|, one of which is electrically connected to each of the two socket contacts, and each of these strips carries a contact 52 of suitable non-corroding conducting material, such as silver. The upwardly facing contacts 52 of the positioned lamp engage downwardly facing stationary contacts 53 carried by forwardly extending conducting strips 54 and 55 which are mounted on rigid fixed conducting strips 56 and 51, respectively, by a hinge connection 58 which permits limited upward movement of the contact-carrying and 57, and by which springs the strips 54 and 55 are pressed downward to hold their contacts 53 pressed firmly against the contacts 52 of the positioned lamp. To avoid welding due to the momentary heavy inrush of current to the cold filament of a newly positioned lamp, the contacts 53 are made with a contact surface of a suitable non-welding material, such as the silverimpregnated graphite known as silver graphalloy. Obviously, the contacts 52 might be of the non-welding material and the contacts 53 of plain silver or other suitable metal. The lower portions of the fixed strips 56 and 5'! are secured to the support wall ll each by two bolts 62 and 63, the strips and bolts being insulated from the wall by panels 64 and 65 of insulating material. Electric connection to the contact strips 54 and 55 is made through the bolts 63 to the strips 56 and 51, flexible conductors 66 and 61 being most desirably provided between strips 54 and 55 and between strips 56 and 51.

For raising the contact-carrying strips 54 and 55 to permit the contacts 52 of the lamp socket member which is being moved into operative position to enter beneath the contacts 53, and for releasing the strips 54 and 55 when the lamp has reached its operative position so that the strips may move down under pressure of the springs 59 to press their contacts 53 against the positioned contacts 52, the carrier arm I 5 has at each end beyond the stub shaft 3| a cam plate 10 which engages shoes 12 and 13 on the strips 54 and 55, respectively, and forces them and the strips 54 and 55 upward as the carrier arm approaches its lamp positioning position, and then, when the lamp has reached its operative position releasesthe shoes abruptly. The shoes 12 and 13 then serve as indexing abutments coacting with the shoulders 14 and 15 of the cam to insure accurate positioningof the lamp and to maintain it exactly in position until the lamp fails, since when the cam releases the shoes and the contacts 53 drop into engagement with the contacts 52 to complete the circuit to the positioned lamp, the driving motor as hereinafter explained, is not only stopped suddenly but immediately rotates in the reverse direction sufficiently to move the carrier backward such short amount. as may be permitted by the indexing abutment, that is, such amount as will bring the cam shoulders firmly against the abutment shoes, or such amount as will bring the indexing tooth of the ratchet wheel firmly against the pawl 26 if the pawl is serving as the indexing abutment. The carrier is thus brought to a precise definite position, and thereafter, by its tendency to rotate backward, the motor holds the carrier in this position so long as current flows in the lamp circuit. The positioned lamp is thus accurately positioned and maintained in position until it fails, regardless of the vibration and inertia forces to which the apparatus is liable to be subjected. The strips 54 and 55, when the shoes 12 and 1.3 serve as indexing abutments, are horizontally rigid, and their mounting, including their hinged connections 58, is such that the shoes 12 and 13 are not horizontally movable and thus serve their purpose of acting as rigid abutments for the shoulders of the cam 1!]. Either the cam plates 1!) or the shoes 12 and 13 or their mounting on the conducting strips 54 and 55 must, in the construction shown, be made of suitable insulating material.

As will be understood from the foregoing description, the pawl 25, with properly positioned teeth on the ratchet wheel 25, may serve as the indexing abutment for insuring accurate positioning of the lamp by stopping backward movement of the carrier at the proper point and thereafter holding the carrier against the continued tendency of the motor to turn it backward so long as current flows in the lamp circuit. A construction providing an indexing abutment or abutments to be engaged by coacting parts at the outer ends of the carrier arm, or other peripheral portions of a carrier of other form has the advantage that the ooacting abutment-engaging parts for each lamp support may be adjustably positioned with relation to such support. To provide for such adjustment, the cam. plates 10 are adjustable on the carrier arm in the direction of the movement of the arm.

To provide for slight adjustment of the stub shafts 3| for adjusting the tension of the sprocket chains 46 to keep them sufficiently tight to avoid lost motion on the one hand and to keep friction at a minimum on the other hand, the end of each of the shafts 3| which extends through the arm I5 is made slightly smaller than the hole in the arm and two adjusting screws 86 and 8| are provided extending at an angle to each other and bearing against the under side of the shaft. By adjusting these screws when the lock nut 32 is loosened, the shaft and its sprocket may be adjusted so that when the lock nut is again tightened up the shaft will be held rigidly in its properly adjusted position. In order further to reduce the possibility of undesirable movement or play of the sprocket chains on the teeth of the sprockets 45 and the stationary sprockets 4B and 4|, and thereby further to insure accuracy in the positioning of the lamp supports, the cross-pins of the chains and the teeth of the sprockets are suitably conformed.

The driving motor 25 illustrated, and which is claimed in my continuation-impart application Serial No. 421,451, filed December 3, 1941, is a rotary armature alternating current induction motor of the shaded pole type. As illustrated best in Fig; 9, the motor has the usual field winding 85, and two shading coils 86 and 81 which when short circuited cause rotation of the mo-v tor in the direction to move the lamp carrier clockwise when viewed from the front, that is, from the left of Fig. l and counter-clockwise when viewed from the back as in Fig. 3. These shading coils are connected in a closed circuit which includes an impedance 90 which is also connected in the lamp circuit in series with the positioned lamp. Rather than a non-inductive resistance, the impedance is most desirably a reactance, as indicated in Fig. 9, and the impedance is of such value that when normal current is flowing through the lamp circuit there is ap-. plied to the shading coils an E. M. F. of greater value than the E. M. F. normally induced in the shading coils by the field winding of themotor, and the connections are such that this applied E. M. F. is of opposite phase from the E. M. F. induced in the coils by the field winding. This applied E. M. F. will therefore cause the motor to rotate in a reverse direction, or backward, or to tend to rotate backward against the restraint of the detent means. When, however, no current is flowing in the lamp circuit, the presence of the impedance in the shading coil circuit doesnot prevent normal forward rotation of the motor. By thus applying to the shading coils when normal current flows in the lamp circuit an E. M. F. of opposite phase from and of greater value than the E. M. F. normally induced in the shading coils by the field winding, the necessity of providing a motor of this kind with additional and oppositely placed shading coils to effect reverse rotation as shown in Patent No. 2,258,575 granted on my application Serial No. 190,565 is avoided.

In Figs. 2, 3 and 5 there is shown the special variable reactance device referred to in the introductory part of this specification and which for reasons there pointed out is most desirably used. This variable impedance device comprises a reactance coil 9i having comparatively few turns of heavy insulated wire carried on a tube 92, which may be made of insulating material or may be a metal cylinder with a longitudinal slot to reduce eddy current losses, and within the tube is a two-part core formed by an upper fixed part 95 and a lower part 94 which is movable within the tube in the manner of a solenoid core, both parts being made of soft or laminated iron. The movable lower core member 94 has a shading coil 95 set into its upper end for holding purposes when the device is energized by alternating current. The device is carried by a bracket 95 formed of two angle plates of soft or laminated iron connected together and to the side wall l2 against. a panel of insulating material 91 by screws 55. The arm of one of these angle plates extends over and is secured to the fixed core member 83, and the arm of, the other angle plate holds the lower end of the tube 92. The bracket thus forms a U-shaped magnetic return for the magnetic flux created by the coil 9|. A spring 99 tends to draw the core member 94 down away from the member 93 and against a stop plate I69, as shown in Fig. 3, thus opening an air gap I III between the two core members. The tension of the spring 99 is sufilcient to draw the core member 34 down to the position shown in Fig. 3 when only the normal shading coil current induced by the motor field flows through the reactance coil QI, but not sufficient to resist the upward pull on the core member 94 when normal lamp circuit current flows through coil SI, the core member 94 then being drawn upward by magnetic action to close the air gap IIlI.

As will be understood, the air gap Nil, formed wfhen the core member 9G is in its retracted position, increases the reluctance of the magnetic circuit formed by the U-shaped bracket 96 and the two core members 93 and 94, and the reactance of the coil BI is then less than when the core member 34 is in its upper position abutting the core member 93. When the core member 94 is in its upper position abutting the member 93, the magnetic circuit is improved and the reluctance of the flux path decreased, thus increasing the reactance of the coil.

The feed line from the source of alternating current is connected to binding posts H and III carried by a terminal panel II2 mounted on the side Wall I2. The Wiring connections are shown by Figs. 8 and 9. Current from one side of the source connected to the binding post IIO flows in a circuit including wire II5, reactor coil 9|, wire I I6, connector III, and conducting strip 54, from which connection is made through contacts 53 and 52 and conducting strip 56 to the positioned lamp, and from the lamp circuit is completed through conducting strip I, contacts 52 and 53, conducting strip 55, wire H8 and binding post III to the other side of the current source. The field winding of the motor 20 is, as shown, energized from the same current source, the circuit extending by wire I 20 to the motor binding post strip I2I and by wire I22 to one side of the field winding, the other side of the field winding being connected to the terminal post II I by wires I23 and I24 through a normally closed switch I25 hereinafter described. Shading coils 86 and 8! of the motor are connected to binding posts on the panel I2I and connected in parallel across the reactance coil Si by wires I26 and I26. A signal switch I30, which will be hereinafter described, is connected to binding posts I 3| and I32 on the panel II2 by wires I33 and I34.

When a live lamp is moved into operative position, that is, in the position of the lamp A in Fig. 1, it is connected in the lamp circuit, and the lamp circuit current then flows through the reactance coil SI, and, the core member 94 being by such flow raised to close the air gap IUI, produces a voltage drop across the coil, causing current flow in the shading coil circuit under an E. M. F. which is greater than the E. M. F. normally induced in the shading coils by the motor field winding 85 and is opposite in phase. A rotating magnetic field is thus produced by the shading coils in such direction as immediately to stop the motor and cause it to start rotating backward, that is, in the reverse direction from its normal direction of rotation. This backward rotation immediately forces the indexing members into engagement and the tendency of the motor to rotate backward then maintains the lamp in proper focal position at all times against the tendency of vibration to move the carrier and lamp out of position until the newly positioned lamp fails. On failure of the lamp, however, flow of lamp circuit current through the reactance coil 9| ceases, the core member 94 of the reactor is retracted, thereby re-establishing the air gap IUI and reducing the impedance of the coil, and current induced by the motor field winding then flows in the shading coil circuit, with the result that normal shading action takes place in the motor and the motor rotates in its normal forward direction, driving the lamp carrier forward, that is, in clockwise direction as viewed in Fig. 1. The motor continues to rotate, causing this forward movement of the lamp carrier, until a new lamp has been moved into focal position. Immediately on the positioning of the new lamp, there is a momentary heavy rush of current to the cold filament of the lamp, and the flow of this heavy current through the reactance coil 9I raises the core member 94 to close the air gap and increase the impedance of the coil, and the motor is immediately stopped and caused to rotate in the reverse direction sufficiently to move the carrier backward a short amount as may be permitted by the indexing means, thereby positively indexing the lamp; and thereafter, until the newly positioned lamp by the tendency maintained pointed out.

The signal switch I30 mounted on the side wall I3 is a normally open, enclosed plunger-type switch operated by a face cam I 35 on the rear side of the gear 24, shown in ating plunger of the cam extending through an opening in the support wall I I. This switch is connected, as before stated, to binding posts on the terminal panel I I2 from which circuit connection is made to a remotely located pilot light or other signal device, and the cam I35 is formed to close the switch on movement of the motor to rotate backward in accurate position, as before opening in the wall II to be operated by another face cam I36 on the rear side of gear 24. This limit switch is a normally closed switch, and its cam I36 is formed to operate the switch to open the motor circuit only after both lamp in the apparatus shown, have failed, that is,

tus were one fails, the carrier and lamp are bring the newly installed working lamp into operative position so that the apparatus will not be left in condition with no reserve lamp.

Fig. shows a gear train for maintaining the position of constant parallelism of the lamp supports as the carrier arm rotates, which may be used in place of the sprockets and chains of the apparatus of Figs. 1, 2 and 3. In this gear train construction, idler gears I40 and MI are mounted on the carrier arm I5, one on either side of and in engagement with a gear I42 fast on the nonrotating stub shaft It on which the carrier arm is journalled. The idler gear I40 engages a gear I43 fast on one of the lamp supports in place of the sprocket 45 of Figs. larly the idler gear I4l engages a gear I44 fast on the other lamp support 30 in place of its sprocket 45. The lamp supports will thus be turned by these gears on their stub shafts 3| in the same manner as by the sprocket chains of Figs. 1, 2 and 3 to maintain the lamps carried by the supports always in vertical position regardless of the angular position of the carrier arm.

The idler gears I and MI are most desirably split gears formed of two like gears set together flatwise against each other and rotatably tensioned for rotary movement with respect to each other, as by means of a spring I45 connected at one end to one gear part and at the other end to a stud I45 extending through an opening in such gear part from the other gear part. By use of such tensioned split gears, which are well known, all play is removed from the gear train and accurate positioning of the lamps obtained.

While I consider it most advantageous to oper ate the lamp-changing mechanism by means of an alternating current driving motor operated on the same current which supplies the lamp, and especially the motor and circuit of Fig. 9, it is sometimes desirable to use commercial alternating current for the normal operation of high power beacons or other lighting apparatus, and to operate the same from a standby direct current source in the event of power system failure. This condition may be'met by providing a motor and motor control means suitable for either alternating or direct current. Such a universal, or A. C.-D. C., motor and control means therefor suitable for use with the lamp-changing apparatus shown herein, and suitable also for other forms of lamp-changing apparatus, is shown diagrammatically by Fig. 11.

Fig. 11 shows a reversible universal series motor I with two field windings I5I and I52. A quick-acting relay I53 is connected in the lamp circuit in series with the positioned lamp and a source of current applied to the binding posts I Ill and III. This relay is preferably provided with a shading coil indicated at I54, although a direct current type of relay may be used with a rectifier unit such as shown in Fig. 12. When current flows in the lamp circuit, the armature I55 of the relay is maintained against its contact I55, thereby establishing a flow of current through the reverse field winding of the motor. This causes the motor to tend to run backward and thereby to maintain the positioned lamp accurately in position as before explained. A resistor I58 is most desirably provided between the contact I55 and the field winding I52 to prevent overheating of the field winding and armature windings during the time that the tendency of the motor to rotate backward is restrained by the detent means of the apparatus. When the positioned lamp burns out, the relay 1, 2 and 3, and simi-\ I52 and armature I51 armature I55 is released and swings out into engagement with contact I59, thereby completing the motor circuit through the forward running field winding I5I and the armature I5I. This causes forward rotation of the motor whereby the lamp carrier is moved to bring a new lamp into operative position, whereupon the relay armature is immediately drawn back into engagement with contact I56 to stop the motor and cause it to run momentarily in a reverse direction to properly index the lamp and thereafter to hold the lamp accurately in position. Lamp changinig apparatus equipped with this motor and control means will obviously operate on either alternating or direct current.

In Fig. 12 I have shown a different form of motor suitable for operationof the apparatus on either alternating or direct current. The motor shown in this figure is a vibratory armature motor of the kind shown and claimed in the pending application of Charles F. Wallace and John R. MacKay, Serial No. 281,356, filed June 2'7, 1939, as a division of an application filed October 6, 1936. Motors of this type operate in only one direction. This motor, as shown in Fig. 12, comprises an electromagnetic motor IE5 having a vibratory armature I6 I a quick-acting relay magnet I52 provided with a shading coil I52, and a current-interrupting switch I53 which is controlled both by the motor armature I6! and the relay magnet, the armature of the relay magnet serving as the movable member of the switch and being operated by the motor armature IEI to maintain the motor in operation so long as current is supplied to the motor and the relay magnet is not energized, and the relay when energized opening the switch to prevent operation of the motor and holding the switch open so long as it is energized. The vibratory armature IGI drives a shaft I64 by which the lamp carrier is turned through a pawl arm I55 acting on a ratchet wheel I56 on shaft I54, the pawl end of the arm I55 being pressed against the ratchet wheel by a spring I61. The relay magnet is connected in the lamp circuit in series with the positioned lamp and thus prevents operation of the motor so long as a live lamp is in operative position, and, by releasing its armature when the positioned lamp fails, causes the motor to operate to position a new lamp. This motor and its operation as the driving motor of a lamp-changing apparatus is more fully described in said Wallace and MacKay application. The motor is as described in said Wallace and MacKay application except that an adjustable abutment I68 is provided for limiting the movement of the pawl end of the pawl arm I65 away from the ratchet wheel, thereby preventing movement of the ratchet wheel except when the pawl arm is operated. Any possible continued movement of the lamp carrier after stopping of the motor, which might otherwise occur due to momentum of a heavy lamp carrier, is thereby prevented, and accurate indexing of the lamp is obtained.

In order to adapt this motor for universal operation, i. e., for operation on alternating current as well as on direct current, a full wave rectifier unit IIU is suitably connected as shown in the motor circuit. This rectifier unit may be of the copper oxide disc type or of other suitable type.

In a flashing light apparatus, that is, apparatus supplied with intermittent current resulting from the introduction of a current interrupter in one side of the supply line, it is desirable toprovide means whereby when, on failure of the positioned lamp, the carrier is first moved by the driving motor energized by the intermit tent current, the current interrupter is temporarily shunted to permit current to be supplied continuously to the driving motor from. the supply line until a new lamp has been moved into operative position, thereby avoiding the relatively slow lamp-changing operation that would result if the motor were dependent on the intermittent current. Means suitable for this purpose is shown and described in said Patent No. 2,258,575.

What is claimed is:

1. Lamp changing apparatus, comprising a rotary lamp carrier, a plurality of lamp supports pivotally mounted on the carrier at equal distances from the pivotal axis of the carrier, means for rotating the carrier and means for causing during rotation of the to position a new lamp,

carrier an angularly equal but opposite rotation of the lamp supports on their own pivotal axes.

2. Lamp changing apparatus, comprising a rotary lamp carrier, a plurality of lamp supports pivotally mounted on the carrier at equal distances from the pivotal axis of the carrier, means for rotating the carrier to position a new lamp, a stationary control member whose axis coincides with the pivotal axis of the carrier, and connections between said control member and each of the lamp supports whereby during rotation of the carrier the lamp supports are given an angularly equal but opposite rotation on their own pivotal axes.

3. Lamp changing apparatus, comprising a rotary lamp carrier, a plurality of lamp supports pivotally mounted on the carrier at equal distances from the pivotal axis of the carrier and means for rotating the carrier to position a new lamp, the lamp supports each having gear wheels fast thereon geared to a stationary gear wheel whose axis coincides with the pivotal axis of the carrier whereby during rotation of the carrier the lamp supports are given an angularly equal but opposite rotation on their own pivotal axes.

4. Lamp changing apparatus, comprising a rotary lamp carrier, a plurality of lamp supports pivotally mounted on the carrier at equal distances from the pivotal axis of the carrier, means for rotating the carrier to position a new lamp, and means for causing during rotation of the carrier an angularly equal but opposite rotation of the lamp supports on their own said means comprising for each lamp support a sprocket wheel fast thereon, a stationary sprocket wheel whose axis coincides with the pivotal axis of the carrier, and a sprocket chain running on said wheels.

5. Lamp changing apparatus, comprising a rotary lamp carrier, a plurality of lamp supports pivotally mounted on the carrier at equal distances from the pivotal axis of the carrier, means for rotating the carrier to position a new lamp, and means for causing during rotation of the carrier an angularly equal but opposite rotation of the lamp supports on their own pivotal axes, said means comprising for each lamp support a gear wheel fast on the lamp support, and an intermediate gear wheel mounted on the carrier in engagement with a stationary gear wheel whose axis coincides with the pivotal axis of the carrier.

6. Lamp changing apparatus, comprising a rotary lamp carrier, a plurality of lamp supports pivotally mounted on the carrier at equal distances from the pivotal axis of the carrier, means for rotating the carrierto position a new lamp, and means for causing during rotation of the carrier an angularly equal but opposite rotation of the lamp supports on their own pivotal axes, said means comprising for each lamp support a axis coincides with the pivotal axis of the carrier, the intermediate gear for each lamp support being a split gear provided with means tending to cause relative rotary movement of the two gear parts.

7. Lamp changing apparatus, comprising a rotary lamp carrier, a plurality of lamp supports mounted on the carrier, each lamp support being carrier parallel to the pivotal axis of the carrier, means for rotating the carrier to position a new lamp, a sprocket chain and wheel connection between each lamp support and a stationary member whose aXis coincides with the piveach of said stub shafts being adjustable for adjusting the tension of the sprocket.

8. Lamp changing apparatus, comprising a rotary lamp carrier, a plurality of lamp supports pivotally mounted on the carrier at equal disto engage the contact terminal of the positioned lamp sup-port, and means for moving said stationary contact terminal out of engaging position when a lamp is approaching operative position.

9. Lamp changing apparatus, comprising a rotary lamp carrier, a plurality of lamp supports pivotally mounted on the axis of the carrier, means for rotating the carrier to position a new means for causing during rotation of the carrier an angularly equal but opposite rotation of the lamp supports on their own pivotal axes, two contact terminals carried by each lamp support, two stationary contact terminals positioned to engage the two contact terminals of the powhen a lamp is approaching operative position.

10. Lamp changing apparatus, comprising a rotary lamp carrier, a plurality of lamp supports pivotally mounted on the carrier at equal distances from the pivotal axis of the carrier, means for rotating the carrier to position a new lamp, means for causing during rotation of the carrier an angularly equal but opposite rotation of the lamp supports on their own pivotal axes, two contact terminals carried by each lamp support, two stationary contact terminals positioned to engage the two contact terminals of the positioned lamp support, said stationary contact terminals being carried each by a contact arm tensioned to press said contact terminals against the contact terminals of the support, a cam member on the carrier adjacent each lamp support for moving said contact-carrying arms to move their contact terminals out of engaging position when a lamp is approaching operative position.

11. Lamp changing apparatus, comprising a rotary lamp carrier, a plurality of lamp supports pivotally mounted on the carrier at equal distances from the pivotal axis of the carrier, means for rotating the carrier to position a new lamp, means for causing during rotation of the carrier an angularly equal but opposite rotation of the lamp supports on their own pivotal axes, two contact terminals carried by each lamp support, two stationary contact terminals positioned to engage the two contact terminals of the positioned lamp support, said stationary contact terminals being carried each by a contact arm tensioned to press said contact terminals against the contact terminals of the positioned lamp support, a cam member on the carrier adjacent each lamp support for moving said contact-carrying arms to move their contact terminals out of engaging position when a lamp is approaching operative position, said cam being shouldered to serve in coaction with said contact-carrying arms as indexing means for determining accurately the operative position of the lamp.

12. Lamp-changing apparatus, comprising a lamp carrier, a plurality of lamp supports mounted on the carrier, said carrier being movable for positioning the lamps successively, a lamp circuit having terminals for connecting the positioned lamp in the circuit, an indexing abutment, a plurality of abutment-engaging memhere on the carrier one adjacent to each lamp support for co-acting with said abutment, motor means for moving the carrier forward on failure of the positioned lamp to position another lamp, and means for causing the motor means to urge the carrier backward when normal current flows in the lamp circuit, whereby when a new lamp is positioned its abutmentengaging member is forced back into engagement with the indexing abutment to accurately position the lamp and is thereafter held in such engagement to maintain the lamp in position.

13. Lamp-changing apparatus, comprising a lamp carrier, a plurality of lamp supports mounted on the carrier, said carrier being movable for positioning the lamps successively, a lamp circuit having terminals for connecting the positioned lamp in the circuit, an indexing abutment, a plurality of abutment engaging members on the carrier one adjacent to each lamp support for co-acting with said abutment, said members being independently adjustable, motor means for moving the carrier forward on failure of the positioned lamp to position another lamp, and means for causing the motor means to urge the carrier backward when normal current flows in the lamp circuit, whereby when a new lamp is positioned its abutment-engaging member is forced back into engagement with the indexing abutment to accurately position the lamp and is thereafter held in such engagement to maintain the lamp in position.

14:. Lamp-changing apparatus, comprising a carrier for a plurality of lamps movable for positioning the lamps successively, a lamp circuit having terminals for connecting the positioned lamp in the circuit, an indexing abutment, an abutment-engaging member moving with the carrier, motor means for moving the carrier forward on failure of the positioned lamp to position another lamp, and means for causing the motor means to urge the carrier backward when normal current flows in the lamp circuit, whereby when a new lamp is positioned the abutment-engaging member is forced back into engagement with the indexing abutment to accurately position the lamp and is thereafter held in such engagement to maintain the lamp in position.

15. Lamp-changing apparatus, comprising a rotary lamp carrier, a plurality of lamp supports pivotally mounted on the carrier at equal distances from the pivotal axis of the carrier, electric motor means for rotating the carrier on failure of the positioned lamp to position another lamp, means for causing during rotation of the carrier an angularly equal but opposite rotation of the lamp supports on their own pivotal axes, and a limit switch for opening the motor circuit to prevent continued operation of the motor after failure of the last lamp on the carrier.

16. Lamp-changing apparatus, comprising a rotary lamp carrier, a plurality of lamp supports pivotally mounted on the carrier at equal distances from the pivotal axis of the carrier, electric motor means for rotating the carrier on failure of the positioned lamp to position another lamp, means for causing during rotation of the carrier an angularly equal but opposite rotation of the lamp supports on their own pivotal axes, a normally open switch in said circuit, and means for closing said switch on movement of the carrier following the failure of a positioned lamp.

17. Lamp-changing apparatus, comprising a rotary lamp carrier, a plurality of lamp supports pivotally mounted on the carrier at equal distances from the pivotal axis of the carrier, electric motor means for rotating the carrier on failure of the positioned lamp to position another lamp, means for causing during rotation of the carrier an angularly equal but opposite rotation of the lamp supports on their own pivotal axes, a normally open switch in said circuit, and means for closing said switch when the carrier moves to position the last lamp.

18. Lamp-changing apparatus, comprising a plurality of lamp supports, means for moving the lamp supports successively in a curved path to and from operative position, means for maintaining the lamp supports in parallelism as they are moved into and out of operative position whereby the lamps during such movement are maintained in vertical position, a contact terminal carried by each lamp support, a stationary contact terminal positioned to engage said contact terminal of the positioned lamp support, and means for moving said stationary contact terminal out of, engaging position when a lamp is approaching operative position.

19. Lamp-changing apparatus, comprising a plurality of lamp supports, means for moving the lamp supports successively in a curved path to and from operative position, means for maintaining the lamp supports in parallelism as they are moved into and out of operative position whereby the lamps during such movement are maintained in vertical position, two contact terminals carried by each lamp support, two stationary contact terminals positioned to engage the two contact terminals of the positioned lamp support and under tension to press thereagainst, and means on the carrier adjacent each lamp support for moving said stationary contact terminals out of engaging position when a lamp is approaching operative position.

JOHN R. MACKAY.

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