US1029728A - Railway-signal. - Google Patents

Description

J. D. TAYLOR.

RAILWAY SIGNAL.

APPLICATION FILED JULY 16, m0.

1,029,728, Patented June 18, 1912.

5 SHEETS-SHEET l.

J. D. TAYLOR.

I RAILWAY SIGNAL.

APPLICATION FILED JULY16, 1910. 1,029,728. Patented June 18, 1912.

5 SHEETS-SHEET 2.

WITNESSES. I |NVENTOR @176 W :LAZ W W BY? 2 COLUMBIA PLANOGRAPM 00., WASHINGTON, n. c.

J. D. TAYLOR.

RAILWAY SIGNAL.

APPLICATION FILED JULY 16, 1910.

1,029,728. Patented June 18,1912.

N 5 SILQBTS-SHEET 3. S

v j WITNESSES: INVENTOR COLUMBIA PLANOGRAPH 50.. WASHINGTON. D. c

J; D. TAYLOR.

RAILWAY SIGNAL.

APPLIOATION FILED JULY 16, 1910.

Patented June 18,1912.

5 SHEBTS-SHEET 4.

1 N E WEE I ATTORNEY J. D. TAYLOR.

RAILWAY SIGNAL.

APPLICATION FILED JULY 16, 1910.

1,029,728, Patented June 18,1912.

5 SHEETS-SHEET 5.

- WITNESSES: INVENTOR I fay (4v v84 ATTORNEY COLUMBIA PLANnnnAPH co.. WASHINGTON. n. c.

r the signal mechanism.

.nnrrnn STATESPATENT orrrcn JOHN D. TAYLOR, OF EDGEWOOD PARK, PENNSYLVANIA, ASSIGNOR TO THE UNION swr'rona SIGNAL COMPANY, OF SWISSVALE, PENNSYLVANIA, A CORPORATION or PENNSYLVANIA.

roaarse.

RAILWAY-SIGNAL.

Patented June 18, 1912.

Application filed July 16, 1910. Serial No. 572,231.

It all whom it may concern:

Be it known that I, JOHN D. TAYLOR, a citizen of the United States, and a resident of Edgewood Park, in the county of Allegheny and State of Pennsylvania, have invented certain new and useful Improvements in Railway-Signals, of which the following is a specification.

My invention relates to railway signal mechanisms, and particularly to that type of mechanism comprising a semaphore capable of a plurality of positions of indication, and an electric motor for moving the somaphore.

I will describe a railway signal mechanism embodying my invention, and then point out the novel features thereof in claims.

In the accompanying drawings, Figure 1 is a perspective view partly in section, showing a railway signal mechanism embodying my invention. Fig. 2 is a side elevation, partly sectioned, of the mechanism shown in Fig. 1. Fig. 3 is a sectional view on the line 3-3 of Fig. :2 looking in the direction of the arrows. Fig. 4: is a plan view, partly sectioned, of a portion of the mechanism shown in the preceding views. Fig. 5 is a sectional view showing a clutch N embodied in the signal mechanism shown in the preceding,

views. Fig. 6 is a sectional view on the line 6-6 of Fig. 5 looking in the direction of the arrows. Fig. 7 is a diagrammatic view showing an application of a signal mecha nism embodying my invention to an automatic railway signaling system.

Similar reference characters refer to similar parts throughout the several views.

A feature of my invention is a novel form of holding clear device comprising an electro-magnet which, in addition to the usual function of holding the signal in one or more of its oositions of indication, also performs the unction of controlling the circuits of the electric motor which operates By means of this feature of my invention I avoid the necessity of controlling the motor circuits through the contacts of a track relay when the signal mechanism is used in an automatic signaling system. The holding clear magnet, being much more powerful than a track relay, is capable of exerting a heavier pressure on the contacts of the circuit controller which it operates, and these contacts are therefore better adapted to carry the motor operating current. V V i In a signal mechanism embodying my invention, the semaphore is usually biased by gravity to the danger position of indication, and is moved to its other position or positions of indication by means of the electric motor. One feature of my invention is the use of t-hemotor to limit the speed of the return movement toward danger position under the influence of gravity, and if necessary, to assist the action of gravity in driving the semaphore back to its danger position.

The motor is of the shunt wound type and is provided with two field windings reversely wound, one of which is connected with the armature when the semaphore is to be moved away from'the danger position and the other of which is connected with the armature when the semaphore is to move in the other direction. One characteristic of this type of motor is that its speed is limited. The motor therefore acts as a generator if external force is applied to drive it faster than the current would drive it, consequently when the semaphore is returning to danger position the motor acts as a bufl'er to prevent acceleration of the speed of the signal mechanism beyond the speed corresponding to the normal speed of the motor. When returning to the danger position, if the speed of the motor is below the normal speed, the current assists the action of gravity in moving the signal, but if the speed exceeds the normal speed the movement is retarded by the current.

Another feature of my invention is the use of the motor to act as a buffer to bring the parts of the mechanism quickly to rest when the operating current is cut oif. The motor acts in this capacity when the semaphore is moving ineither direction, due to the provision of the two reversely wound field windings, one for each direction of rotation.

Referring to the drawings, the semaphore comprises a blade 53 and a spectacle casting 54. The semaphore is suitably fixed on a sl1aft52, and when free to move, assumes a horizontal position under the influence of gravity on its blade 53 and the casting 54:. In the drawings I have shown the semaphore blade as being moved from its hori zontal position upwardly to its other positions of indication, but it may be arranged to move from its horizontal position clownwardly to its other positions of indication equally well. I have also shownthe semaphore blade as having two positions of indication besides the horizontal positionviz., an inclined position and a vertical position, but it may equally well be arranged to have any desired number of positions of indication. These arrangements of the sem aphore blade are understood by those skllled in the art and involve merely mechanical changes between the operating mechanism and the semaphore which need not be described herein.

E designates an electric motor by means of which the semaphore blade 53 is moved to its inclined and vertical positions, and by means of which the act-ion of gravity in returning the semaphore from these positions toward its horizontal position may be assisted.- The circuits for this electric motor are controlled by means of a circuit con-' troller D whlch 1s operated by an armature of an electro-magnet S. The semaphore blade is held in its inclined and vertical positions by means of a holding clear device H, which is also operated by the armature of the electro-magnet S. (l designates a circuit controller operatively connected with the semaphore blade, by means of which the motor circuit is opened when the semaphore reaches the proper positions, and by means of which the circuits for the operation of the holding clear magnet are controlled. Thes circuit controllers D and (Z, the electromagnet S, and the holding clear device H, as well as their modes of operation, will be more fully. described hereinafter.

A pinion 80 secured to the armature of the motor E drives a gear 76 which is con nected through the medium of a mechanical clutch device N (hereinafter to be described) with a pinion 86. The pinion 86 drives a gear 77 to which is secured a pinion 78 which latter in turn drives a segmental gear 7 9. This segmental gear 79 is mounted to rotate freely upon a collar 48 secured to a squared portion of section 51 of the semaphore shaft. The semaphore shaft is formed'in three sections, 50, 51 and 52, joined by tongue and groove coupling. The section 50 carries the sectors of the circuit controller (Z; the section 51 carries the segmental gear 79; and the section 52 is secured directly to the semaphore counterweight 54: which carries the semaphore blade 53. This construction permits of the removal of the circuit controller cZ without disturbing anyother part, and also permits of the removal of the entire mechanism leaving the semaphore in place.

The holding clear magnet S as shown in the accompanying drawings is of the iron clad type, comprising a central cylindrical core 55 of soft iron (see Fig. 2) surrounded by an energizing winding'58, and an iron shell 56 inclosing and protecting the winding. An armature 8 comprising a thin disk of soft iron is suspended below the poles of the magnet on a rod70. This armature, as well as the core 55, is provided with core pins, or non-magnetic studs 46,

for maintaining a minimum air gap be tween the armature and the core and shell. The energizing winding comprises two coils, one of comparatively 'low resistance for picking up the armature, the other of comparatively high resistance (for example 500 ohms or more) for holding the armature when up. The core 55 is bored longitudinally to permit the rod to pass through it. tremity two flanged nuts 98 by means of which it is operatively connected with the This rod 70 carries at-its upper ex circuit controller D, and at its lower extremity two similar flanged nuts 71 by means of which it is operatively connected with the holding clear device H.

The holding clear device H (see Figs. 1, 2 and 3) is constructed as follows: The flanged nuts 71 on the armature rod 70 engage the outer or free end of a lever 94 piv-' oted at 96 to the frame of the mechanism. A crank 72, also pivoted to the frame,has a horizontal arm carrying a stud 97 which projects through a hole in the lever 9 1 between the pivot 96 and the free end engaging with the flanged nuts 71. An upwardly projecting arm portion ofthe crank 72 carries a latch 7 3 which engages with a dog 7 5 se cured to wheel 88 for holding the semaphore in its inclined and vertical positions. The line perpendicular to the surfaces of contactbetween the latch 73 and the dog 75 makes an angle of approximately 30 with a line joining these surfacesand the pivot of the crank 72, hence there is a strong tendency due to the weight of the semaphore blade and counterweight to push the latch/73 out of the path of the dog 75 and release the signal. The latch 7 3 is pivoted to the crank 72 to permit of the former being pushed out of the path of the dog 75 when the semaphore is moving toward its clear positions, and is held in normal locking position by a spring 74. The motion of the latch 73' due to the action of the spring 74 is limited by a shoulder 61 on the crank 72, so that in performing its function of holding the signal in the positions of indication it acts as a rigid member of the crank 72. In order to reduce the shock on the latch 7 3 when the semaphore is brought to rest in its inclined or vertical position, the wheel 88 is connected withthe pinion 86 through the medium of a spring 90 (see Fig. 5) consisting of a single turn of heavy steel wire the ends of which are secured respectively to the wheel the motor s 88 at the point 67 and to a cup-shaped wheel 87 at the point 68, which latter wheel is secured to the pinion 86 as hereinafter explained. The ratio of the gearing is such that when the semaphore is in its inclined and vertical positions the dog is in the proper location to be engaged by the latch 73.

Referring now to Figs. 5 and 6, I have here shown in detail a form of clutch device N which I interpose between the motor and the semaphore to avoid breaking or straining any; part of the mechanism in case ould fail to retard the semaphore in its movement from clear toward the horizontal position, as might happen should the motor circuit he accidentally open during such movement. The pinion 86 is an integral part of the shaft which carries it. To this shaft is secured, as by means of a key 65, the cup-shaped wheel 87 which latter is connected with the wheel 88 by means of the spring 90 as hereinbefore explained. The wheel 88 is held in position by a flanged ring 89 which is secured to the wheel 88 by means of rivets 66 and fits over a shoulder on the cup-shaped wheel 87. A portion of the shaft 86 is threaded to receive two nuts 91 and 92, between which is clamped the gear wheels 76. The nut 92 is secured to the shaft 86, as by means of a key 47, and it is through the medium of the friction between the faces of this nut and the gear wheel 76 that the gear wheel 76 drives the pinion and shaft 86. The nut 91 is free to turn on the threaded portion of the shaft 86, and in turning it has a lateral movement toward or away from the nut 92 and the gear wheel 76, the direction of this lateral movement depending upon the direction of rotation of the nut. Secured to a face of the gear wheel 76 are two paw-ls 98, which are adapted to fit into notches cut in the circumference of the nut 91, by means of which this nut will be rotated when the gear wheel 76 rotates in one direction. The gear 76 is driven directly by the pinion on the motor armature shaft, and when it is being rotated in the direction to move the semaphore toward its clear position, the nut 91 is turned by means of the pawls 93 in the direction to clamp the gear wheel 7 6 between the two nuts 91 and 92, thus locking the gear wheel 76 to the shaft and pinion 86. When the gear wheel 76 is rotated in the opposite direction, that is, when the motor is rotating the gear wheel in the direction to move the semaphore toward its horizontal or danger position, it tends to unlock the clutch by turning the nut 91 in such a direction as to loosen the latter from the gear wheel 76; but the force required to release the clutch is about equal to that which tightened it, and since the semaphore is started witha slight jerk if the clutch happens to be loose at starting, the

force required to release the clutch is at least double that required to move the semaphore toward its clear position, but still far below that which would produce a strain upon the parts of the mechanism. It is therefore evident that this form of clutch device will hold with suiiicient strength to permit the motor to exert a considerable amount of force upon the semaphore while driving the latter toward its danger or horizontal position, but will release before the stress becomes great enough to produce a strain.

Referring now to Figs. 1, 2 and 1, I will describethe circuit controller D operated by the holding clear magnet S. This circuit controller comprises three contact fingers 10, 15, and 16 supported on a rocker shaft 59 of insulating material, which shaft has a lever engaging with the flanges of the nuts 98, and two sets of contacts with which the contact fingers mayengage. When the magnet S is deenergized and the ari'nature s and the rod 7 0 therefore at the lowest point of their stroke, the contact fingers 10, 15 and 16 are held at the highest point of their stroke and engage respectively with an upper set of contacts 11, 14; and 17; when the magnet S is energized and the armature s and the rod 70 therefore held at the highest point of their stroke, the contact fingers are moved downward to the lowest point of their stroke, the fingers 10' and 15 engaging respectively with a lower set of contacts 12 and 13, but the finger 16 engaging with no contact. This arrangement of the contact fingers and contacts is illus trated diagrammatically in Fig. 7, and will be more clearly understood in connection with the explanation of that figure hereinafter. It is sufficient to state here that the contact fingers 10 and 15 control the motor circuits; when the magnet S is energized, the circuits for moving the semaphore toward its clear position are closed; when the magnet S is deenergized the motor circuits for moving the semaphore toward its danger positions are closed. when the finger 16 touches the contact 17, it forms a shunt around the high resistance coil of the magnet S, thereby permitting a comparw tively large amount of current to flow through the low resistance coil or pick up coil of the magnet. Vi hen the armature s and the rod 70 have reached the highest point of their stroke, the finger 16 is separated from the contact 17, thus introducing the high resistance coil of magnet S into the circuit and reducing to a comparatively small amount the current required for holding the magnet S energized.

The circuit controller Z operated by the movement of the semaphore comprises (see Figs. 1 and 2) insulated sectors 18, 19, 20 and 21 carried by the semaphore shaft,

which sectors are arranged to make contact with contact springs 22, 23, 24, etc. supported on insulating bars 60 and 62 which are carried by the frame of the machine. The parts of this circuit controller are illustrated diagrammatically in Fig. 7 and the relations of these parts to one another and to the circuits controlled thereby will be understood from the explanation of that figure hereinafter.

A mechanical locking device may be employed, when desired, to prevent the semaphore being moved to its inclined or vertical position by hand fromthe outside of the mechanism. I will describe such a-locking device, referring to Figs. 1, 2, 3 and 4. The segmental gear 79, which is one extremity of the train of gearing connecting the motor with the semaphore, is mounted to rotate freely upon a collar 48 carried by the squared portion of sect-ion 51 of the semaphore shaft as hereinbefore explained. This segmental gear is connected by a set of links 82 and 83 with a pair of arms 81 which are secured to the section 51 of the semaphore shaft by virtue of the squared portion of that shaft which extends through square holes in the arms 81. The link 82 extends beyond the point of connection with the links 83 to form a latch 63 which is capable of en gaging with a dog 84L suspended from the frame of the mechanism. hen force is applied directly to the semaphore tending to move it toward its inclined or vertical position, the toggle formed by the links 82 and 83 is bent upwardly, which results in the latch 63 engaging with the dog 8%, thus pre venting movement of the semaphore. VYhen, however, a force is applied to the segmental gear 79 tending to rotate the latter, as when the motor is the agent, the toggle is straightened out and the latch 63 is pulled down SQ as to avoid engaging the dog 84:, thus permitting the semaphore to be moved toward its clear position. In order to prevent the toggle being pulled into a straight line, a stop 79 is provided on the segmental gear 7 9, which engages the arms 81 and prevents further relative movementof the segmental gear and the arms while there is still a considerable angle between the links of toggle. If it shoud happen that the motor is called upon to drive the semaphore toward its danger or horizontal position, the toggle joint would be bent by the reverse rotative force applied to the gear 7 9, and if the dog 84 were fixed to the frame of the mechanism it would interfere with the free movement of the apparatus. To prevent this interference, the dog 8 1 is pivoted so as to swing out of the path of the latch 63 while the movement toward horizontal is in progress.

Referring now to Fig. 7, I will explain an arrangement of circuits which may be employed for the operation of the railway signal mechanism which I have just de-.

scribed. The diagram Fig. 7 shows the application of the mechanism to railway signals operatedon the normal clear scheme, although it is to be understood that a signal mechanism embodying my invention may be applied equally well to railway signals operated on the normal danger scheme, the

changes which would be required being well.

understood by those skilled in the art. 1, 2 and 3 deslgnate block sections of a railway, these sections being governed respectively by railway signals, A, B, and G. Traffic is as-J sumed to be moving in the direction indicated by the arrow. Three positions of the mechanism controlling the circults are shown, correspond ng to the danger, caution and clear positions of the semaphore. it.

train represented by wheels and axle JV is in block sectlon 2,. and the signal 13 governing that block 1s therefore 1n danger position.

Signal A ahead of .the train is in clear position; and signalC, the second in the rear of the train, is in the caution position. hen the train V leaves the block section 2, track relay T for that block section will be energized, lifting its armature a, and thereby closing a circuit through the low resistance or pick up coil of the magnet S for signal B as followsfrom battery G through wire 32, brush .27, sector 20,.brush 28, wire 35,.

contact 17, finger 16, low. resistance coil of magnet S, wire 4-2, armature e of track relay T to battery G. The currentfin this circuit energizes magnet S: causing thelatter to pick up its armature and the rod 70.which latter when it reaches the highest point of its stroke, separates the finger 16 from, contact 17, thereby inserting the high resistance coil of the magnet S into the circuit, and moves contact fingers 10 and 15 into engage ment with contacts 12 and 13 respectively.

The engagement of contact finger. 10 with 7 as followsfrom armature M through field coil F, wire 11, contact 13, contact finger 15, wire 39 to armature M. '7 The armature and clearing field, being energized by current in these circuits, the motor drives the sema phore nearly to its inclined or caution posil tion, at, whichpoint the sector 19 leavesthe brush 24 thereby opening the circuit between battery G andthe armature'and field of the motor. The armature and field F of the motor being stillconnected in shunt, .the

motor then acts as a buffer and the parts of themechanism are quickly brought to rest in the caution position. The brush 27 remains in contact with the sector 20, holding the circuit through the high resistance coil of the magnet S closed; the magnet S remaining energized holds the semaphore at caution position and keeps the shunt circuit around the armature M through the field coil F closed.

The signal B having reached its caution or inclined position, sector 21 connects brushes 30 and 31, thereby closing a circuit which includes the battery G at signal B and a line relay L at signal C as follows: from battery G- through wire 32, brush 30, sector 21, brush 31, wire 38, line relay L, wires 4-5 and 1 1 to battery G. Signal O has up to this point been in the inclined or caution position. The energizing of line relay L causes the armature contacts 6 and 8 of this relay to be lifted, thereby closing two new circuits for signal C; a new circuit through the high resistance coil of magnet S as follows: from battery G through armature 8, wire 37, brush 29, sector 20, brush 28, wire 35, high resistance coil of magnet S, wire 12, arma- -ture i, to battery G; and a new motor circuit as follows: from battery G through armature 6, wire 36, brush 26, sector 19, brush 25, wire 31, contact 12, contact finger 1.0, wire 39, armature M, wires 4-3 and 14 to battery G. The shunt circuit including the field coil F is held closed as before. The motor now drives the semaphore nearly to its vertical or clear position, at which point the motor circuit is again opened by the sector 19 leaving brush 25, and the motor then acts as a bufier bringing the parts quickly to rest in the clear position. The circuit through magnet S must be kept closed in order that this magnet may hold the semaphore in the vertical position, hence the sector 20 is so arranged as not to become disengaged from brush 28.

When the train W enters block sect-ion 1, it shunts track relay T at signal A for block 1, and the opening of armature 4c of this track relay opens the circuit through magnet S of signal A. The denergizing of magnet S allows its armature to drop, thereby releasing the semaphore and re-arranging the parts of the circuit controller operated by this magnet so that contact fingers 10 and 15 become engaged respectively with contacts 11 and 14. The engagement of contact finger 10 with contact 11 closes a circuit from battery G through armature M as follows: from battery G through wire 32, brush 22, sector, 18, brush 23, wire 33, contact 11, finger 10, wire 39, armature M, wires 43 and 44 to battery G. The engagement of the contact finger 15 with contact 141 connects field coil F in shunt with the armature M as follows: from armature M through field coil F wire 10, contact 14:, finger 15, wire 39 to armature M. Ourrent through the field coil F produces magnetism of the opposite polarity in the field of the motor to that produced by current in field coil F, and the motor therefore operates 1n the opposite direction, thereby acting as hereinbefore explained to retard the movement it the speed tends to exceed the normal speed of the motor, or to assist the weight of the semaphore in moving the parts if the speed is below the normal speed ofthe motor. Just before the semaphore reaches the horizontal position, the sector 18 and brush 23 become disengaged, breaking the motor operating circuit, and the current generated by the armature M flowing through the field coil F causes the motor to retard the movement of the parts sufliciently to bring the semaphore to rest gently against its stop.

If, while the signal A is in the clear or vertical position, a train should enter the second block section ahead, as for example from a side track connected with that block section, the track relay T at signal A would remain energized; but the line relay L at signal A would be deenergized on account of the movement of the next signal ahead to danger position,.this movement opening the circuit for line relay L at brushes 30 and 31 on that signal. The consequent opening of the armature contacts 6 and 8 of line relay L at signal A opens the circuit through magnet S, and the deenergizing of this magnet results in the closing of the motor circuit for driving the semaphore toward its horizontal position as above traced. Current continues through this circuit until a notch 6A in sector 18 reaches brush 22, when the circuit is interrupted. Just before the circuit is reestablished by the brush 22 again touching sector 18, and after allowing time for the current generated by armature M to efi'ect suflicient retardation of the moving parts, the sector 20 touches brush 27 and re establishes the circuit as hereinbefore traced through magnet S. This energization of magnet S causes it to pick up its armature, thereby opening the motor operating circuit and holding the semaphore in its caution or inclined position.

The field coil F is preferably constructed to have less resistance than field coil F. This is to permit a greater generated current for purposes of retardation to flow while the semaphore is moving toward its horizontal or danger position than while moving toward its clear position, because while moving toward the clear position the weight of the semaphore blade and spectacle casting assist the motor in its stopping action, whereas while moving toward the damn ger position the weight of these parts is added to the load to be overcome by the motor.

I Having thus described my inventiomwhat I claim is:

1. In combination, a signal device biased to danger position of indication, a motor operatively connected with the signal device and comprising two independent field windings one of which is connected in shunt with the armature for moving the signal device from its biased position to another position of indication and the other of which is connected in shunt with the armature for moving the signal device toward its biased position when necessary, and electro-magnetic means for holding'the signal device in the said other position to which it is moved by the'motor.

2. In combination, a signal device biased to danger position of indication, a motor operatively connected with the signal device and comprising two independent field windings one of which is connected in shunt with the armature for moving the signal device from its biased position to other positions of indication and the other of which is connected in shunt with the armature for moving the signal device from said other positions toward the biased position when necessary, and electromagnetic means for holding the signal device in the said other positions to which it is moved.

3. In combination, a signal device biased to one position of indication, a motor for moving it to another position of indication and for cushioning its return movement toward the biased position; and mechanism interposed between the motor and the signal device, said mechanism comprising a threaded shaft operatively connected with one of said members, a collar rigidly secured to said shaft, a nut free to travel on r the threads of the shaft, a rotatable disk operatively connected with the other of said members and having a portion located between the nut and the collar, a shoulder on the nut and a pawl pivoted to the disk and adapted to engage the shoulder to rotate the nut toward the collar, whereby the disk is rigidly clamped between the nut and the collar when the motor rotates in the direction to move the signal device away fromits biased position, and whereby 'the'disk may be disengaged from between the nut and the collar'by a shock when the signal device is moving toward its biased position in case 1 the motor fails to cushion such last-menmeans for connecting one of said windings in shunt with the armature for moving the signal from its biased position to another position of indication, and for connecting the other winding in shunt with the armature to act as a bufier throughout the return movement of the signal toward its biased position.

5. In combination, a signal device biased to danger position of indication, a motor operatively connected therewith and comprising two independent and reversely wound field windings, means for connecting one of the windings in shunt with the armature for moving the signal away from its biased position and for connecting the other winding in shunt with the armature to act as a butter throughout the re-.

turn movement of the signal toward its biased position and to drive the signal toward its biased position if necessary.

6. In a railway signal, a signal device biased to danger position of indication, a motor operatively connected therewith and comprising two independent and reversely wound field windings,'means for connecting one of said windings in shunt with the armature when the signal device is to be moved from its biased position to another position and for connecting the other winding in shunt with the armature when the signal device is to return to its'biased position, a source of current, and means for connecting the sourcev with the motor during the greater part of the movement in each Copies of this patent may be obtained for five cents each, by addressing the Commissioner of latents, Washington, D. G.

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