US1420030A - Signal system - Google Patents

Description

H. C. FORD.

SIGNAL SYSTEM- APPLICATION FILED OCT-10, 1917.

INVENTOR A TTORNEY Patented June 20, 1922,

' 5 SHEETS-SHEET l- A AA H. C. FORD.

SIGNAL SYSTEM.

APPLICATION FILED OCT- 10. 19!?- I 1,420,030. Patented June 20, 1922;

5 SHEETSSHEET Z.

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A TTUR/VE VS H. C. FORD.

SIGNAL SYSTEM.

APPLICATION FILED OCT-10M9l7.

1,420,030, Patented June 20, 1922,

i 5 SHEETSSHEET 3- INVENTOR M W M I ATTORNEYS H. C. FORD.

SIGNAL SYSTEM.

APPLICATION FILED OCT. I0, 1917.

1,4201) 30, I Patented June 20, 1922...

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ATTORNEY):

H. 0. FORD.

SIGNAL SYSTEM.

APPLICATION man ocr. m, 1912.

1,420,030, Patented June 20, 1922-1.

5 SHEETS-SHEET 5.

2 z -wy e e X a INVE/VTUR UNITED STATES PATENT ori-10E.

HANNIBAL 0. FORD, OF NEW YORK, N. Yi, ASSIGNOR TO FORD INSTRUMENT COMPANY, I

' INC., A CORPORATION OF NEW YORK.

SIGNAL SYSTEM.

Application filed OctoberIO, 1917. Serial No. 195,692.

Z '0 all whom it may concern;

Be it known that I, HANNIBAL C. Form, a citizen of the United States, residing at the city of New York, in the borough of Queens and State of New York, have invented certain new and useful Improvements in Signal Systems, of which the following is a full, clear,-and exact description.

This invention relates to signal systems and more particularly to systems by means of which intelligences are electrically transmitted' from a central to one or more substations. The invention has a particular adap tation to a signal system consisting of a transmitter and a receiver which are connected together by a plurality of circuits which are successively closed at the trans mitter to energize different poles of a multipole receiver at the substation and cause them to act upon a rotary armature to effect successive changes in its angular position.

One of the objects of the invention is to provide an improved form of transmitterfor a signal system of this type, which transmitter is so constructed that it is adapted to be continuously operated and yet the switches which control the circuits to the poles of the receiver are intermittent and quick acting in operation, to thereby prevent erroneous readings being obtained at the receiver when a plurality of receivers are combined together to give a single reading.

Another object of the invention is to provide a transmitter in which the parts are compactly arranged and the counter-wheels and switch operating mechanisms are directly connected together.

A further object of the invention is to i provide a transmitter having the switches and. mechanism for operating the same of a simple construction and positive in their operation. y

A still further object of the invention is to provide a receiver of the multipole type. in which the rotary armature can be moved successively to a plurality of intermediate positions between each pair of poles.

The invention also has for its object the provision of a receiver in which the pole pieces and the polarized rotary armature are both magnetically energized in such a manner that the attraction between parts of unlike polarity and the repulsion between parts of like polarity are utilized to cause the angular displacement of the armature.

With these and other objects in view the mvention consists of the constructions and combinations which will be hereinafter described .in detail in connection with the accompanying drawings, and will be par ticularly pointed out in the appended claims.

One embodiment of the invention is Specification of Letters Patent. Patented June 20, 1922.

shown, which embodiment is' especially adapted for transmitting ranges to one or more receiving stations, as for example, from a range finder to a plurality of gunners stations. I

In the drawings,

Figure 1 shows the transmitter, the casing of the same being partially broken away. F lgure 2 IS 'a recelvmg instrument,- which 'is adapted to be connected to the transmitter by a plurality of circuits, the casing of this instrument also being partially removed in order to more clearly show the parts.

Figu.re 3 is a central vertical section' through the transmitter.

' Figure 4-isan end view of the transmitter. I

Figure 5 is a section of the transmitter on the line 5-5 of Figure 3.

Figure 6 is a section of a slightly modified construction. v Figure 6 is an end view of Figure 6. Figure 7 is a section on the line 7-7 of Figure 3.

Figure 8 is a section on the line 8 -8 of Figure 3.

{Figure 9 is a section on the line 9-9 of Figure 3.

Figure 10 is a transverse detail partially in section 'along the line 1010 of Fig. 1. showing the lost motion connection between the operating shaft and the cam shaft which actuates the switches.

Figure 11 is a central longitudinal section of the construction shown in Figure 10.

transmitter and receiving instrument which are shown in these views are adapted to transmit ranges from five thousand to twenty-five thousand yards. For this purpose the transmitter is provided with two counter-wheels and the receiving instrument with two receivers. The two counter-Wheels of the transmitter are connected together by intermittent gearing so that one complete turn of one Wheel will cause a small angular displacement of the other while the two receivers are independent of each other, but are connected to the switches of the transmitter by a series of electrical circuits, as will be hereinafter described.

The two counter-wheels of the transmitter are designated 1 and 2, which wheels have, for the specific embodiment of the invention illustrated, different numerals thereupon, the wheel 2 carrying the numbers 00, O5, 10, 15, etc., up to 95. and the wheel 1 carrying the numbers 5 to 24, inclusive. As ranges are usually indicated only to within 50 yards, a separate fixed cipher 3 is utilized, which is the digit column, the counterwheel 2 being the lOs and 100s column and the counter-wheel 1 being the thousandths and ten thousandths columns. The numbering upon the counter-wheels is duplicated upon the dials 5 and 6 of the receiver, which dials correspond to the counter-wheels 1 and 2, respectively, a fixed cipher. which is indicated at 7, being also utilized in the receiver for the same purpose as in the transmitter.

Referring now to the construction of the transmitter. any suitable casing 8 may be provided for it, in which it is housed. The transmitter comprises a base plate 9 having end standards 10 and 11 and intermediate standards 12 and 13 secured thereto. Mounted between the standards 11 and 13 is a shaft 14 and similarly mounted between the standards 10 and 12 is an axially aligned shaft 15, the counter-wheels 1 and 2 being respectively fastened to the inner ends .of these shafts so that these counter-wheels are in abutting relation, the numbers upon these counter-wheels appearing below an elongated opening in a plate 16, which is secured to the top of the standards 12 and 13.

Secured upon the top face of the base plate 9 and insulated therefrom, are a plurality of transversely extending bars which are inclicated 17, 1s, 19, 20, 21, 22, 23, 24, 25 and 2c.

Each of these bars carries two pairs of pivoted arms 27 and 27, which arms at their upper ends carry electrical contacts 28 and 29 each of which serve to connect the upper ends of a pair of arms together. These movable contacts are adapted to engage with and close the circuit through stationary con tacts, which are mounted upon bus bars. Four of these bus bars are shown in the specific embodiment illustrated, and are indicated 30, 31, 32 and 33. Each of these :1 ,aeo eo bus bars carries stationary adjustable contacts, and as is shown in Fig. 4"of the drawing. each contact comprises a terminal 34 and a threaded end 35 having a slotted head so that the contact may be turned in the bus bar to adjust its position relative to the movable contact with which it engages. Two sets of five pairs each of movable contacts are shown so that in all there are twenty pairs of fixed and movable contacts through which twenty different circuits may be closed to the receiver, as will be hereinafter described in connection with the diagram of the electrical circuits and the operation of the system.

The movements of the movable contacts are controlled by cam shafts 36 and 37, which are sleeves mounted upon the shafts 14 and 15, respectively, each cam shaft consisting of a cylinder of fiber or other suitable material having segmental cut-outs opposite each pair of pivoted contacts, which cut-outs are disposed in different angular positions for each respective pair of contacts. Each segmental slot is of a depth to permit a movable contact to move inwardly to close a circuit through its fixed contact when the slot comes opposite the arm carrying the contact. This inward movement of the contacts is obtained by providing a spring 38 between each pair of pivoted contacts. In order to eliminate the friction between the pivoted arms and the cam shafts rollers 39 'may also be provided, which rollers engage with the surface of the cam instead of having the arms engage directly with the cam shafts.

The shafts 14 and 15 carrying the counterwheels 2 and l and the cam shafts 36 and 37, respectively, are connected by intermittent gearing so' that acomplete rotation of the counter-wheel 2 will cause the angular advance of the counter-wheel 1 through onetenth of a revolution. This gearing will now be described.

A shaft 40 is rotatably mounted between the standards 12 and 18 beneath the two counter wheels. The shaft 40 carries a pinion. 41 at the righthand end thereof, as shown in Fig. 3. which pinion has its alternate teeth extending entirely across and half way across the pinion, respectively, so'that the right hand half of this pinion or 41 has a full number of teeth and the left hand half of the pinion, 41 has only half a full number of teeth (see Fig. 3). The right hand half 41 of the pinion 41 engages a mutilated gear 42 and the left hand half 41 a mutilated gear 43. The mutilated gear 42 is provided with two full teeth, which are shown clearly in Fig. 5. and are numbered 44 and 45, the remainder of this gear being cut away to the root circle, as at 46. The other mutilated gear 43 comprises a cylindrical surface which is provided with a recess 48 whose sides coincide with the inner adjacent sides of the two teeth 44 and 45 upon the gear 42. The relation between the recess and the teeth may also be seen from Fig. 10 which shows asimilar structure as will hereinafter appear. Two of the teeth of pinion 41 normally rest upon the surface of mutilated gear 43 and prevent the pinion 41 from turning inadvertently. The shaft carries at its other end a pinion 50 which meshes with a gear 51 carried by the counter-wheel 1. When the counter-whee1 2 makes a complete revolution the gear teeth 44 and will be brought into mesh with the pinion 41 and the tooth of pinion 4l will ride in the recess 48, which will cause a partial rotation of the shaft 40 and the counter-wheel 1. The pitch and diameter of the pinions and gears are so proportioned that one complete revolution of the counter-wheel 2 causes a tenth of a. revolution of the counterwheel 1. i

The shaft 14 which carries the counterwheel 2 is adapted to be rotated through the lost motion connection shown specifically in Figs. 10 and 11 for the purpose of imparting a quick. intermittent action to the cam shaft 36 for a continuous rotation of the operating member 59. Mounted upon the end of the shaft 14 is a gear wheel 54 which meshes with a pinion 55 of similar construction to the pinion 41. This pinion meshes with two mutilatedgears 56 and 57 similar in construction to gears 42 and 43, so that a complete revolution of these two gears will 1 advance the pinion 55 and gear 54 through inwardly by a spring 68.

a partial revolution. The gear wheels 56 and 57 are loosely mounted upon a sleeve 58, which is mounted upon an operating shaft 59, which is adapted to be rotated by a crank 59. The shaft 59 is provided with a head 60 at its inner end, to which the sleeve is secured bya set screw 61 carried by a collar 62. Mounted within a recessprovided between the sleeve 58 and the shaft 59 is a spring 63, which has its ends 63 bent up, as shown in Figure 10, to project through an opening in the sleeve 58 and to engage the walls of a sector shaped slot 64 provided in the gears 56 and 57. The shaft 14 carries adjacent to the counter-wheel 2 a ratchet wheel 65, which is clearly shown in Fig. 5 of the drawing. This ratchet wheel is engaged by a roller 66 carried upon an arm 67 pivoted to a bar 67 and is spring-pressed The'operation of this part of the transmitter is as follows: In the normal position of the transmitter, that is, while the shaft 59 is not being rotated, the ends 63 of the spring 63 engage the walls of the opening in the sleeve 58 so that there is no tendency for the gears 56 and 57 to rotate. When, however, the shaft 59 is rotated one wall of the opening in the sleeve 58 will engage one of the ends 63 wheel until the crank 59 this spring 63 is sufficient to overcome the tension of the spring 68 which holds the roller 66 in frictional engagement with the ratchet wheel 65. When this occurs the gears 56 and 57 will he suddenly partially rotated to cause, through the pinion 55 and the gear 54, a sudden partial rotation of the shaft 14, the roller 66 riding over one of the teeth of the ratchet wheel and then engaging the next tooth of the wheel 65 to prevent further rotation of the counterhas been further rotated. This feature of the invention is of importance because it permits the operating shaft 59 to be operated in a continuous manner and yet the shaft 14 which is connected thereto v will be operated intermittently with a quick acting step by step movement.

The transmitter may, if desired, be provided with a device for obscuring the'numbers appearing before the opening in the plate 16 when the range is below 5,000 or above 25,000 yards. This device consists of a shutter 70 with an elongated opening 71 therein which is secured at one end to a disk 72 and at the other end to a hub 73, which hub is shown most clearly in Fig. 5 of the drawing. The disk 72 meshes with apinion 74, which is loosely mounted-uponthe shaft 40 (which pinion is of similar construction obscure the numbers upon the counterwheel.

The hub 73, which is secured to the other end of the shutter 70 is engaged by a roller 77 which, when the shutter is not before the opening, rests in a slot 78 in the hub 73, but upon a rotation of the shutter rides upon thecurved surfaces 79 or 80. The roller 77 is mounted between arms 81 which are connected to the arms 67 by a spring 68. The upper end of the arm 81 carries a contact 82 which, in the normal position, that is, when the roller 77 is resting in the recess 78, engages a fixed contact 83 carried by the bus bar 32. When, however, the roller rides upon either of the surfaces 79 or 80 this contact is moved to throw the contact 82 out of engagement with the contact 83 to break the signal or lamp circuit closed through these contacts, which circuit will be hereinafter referred to in the description of the electrical connections and the operation of the system. I

In F ig. 6 a modified construction of switch is shown. Here the two fixed contacts which are designated 85 and 86 are arranged adjacent each other and the circuit through these contacts is closed by a movable contact 87" the arms together so that their inner edges engage with a pin 99 carried by the bell crank 88 to hold the pin 99 normally in alignment with the pivots 90 and 91. When the bell crank 89 is actuated by the cam 36 the contact arm 87 will first have an upward or downward movement, depending upon the direction in which the bell crank 89 is moved, which will bring the contact 87 into engagement with one of the fixed contacts 85 or 86. Further movement of the bell crank will then cause the contact 87 carried by the arm 87' to slide on the contact with which it is in engagement, since the bell crank 88 is loosely mounted upon the bell crank 89. The pin 99 will, during such movement, move one of the centralizing arms 96 and 97 out of its normal position, exerting a tension on the parts to return them to normal position after the cam shaft has again been moved with respect to the bell crank 89. The sliding of the contact 87 over one of the fixed contacts 85 or 86 in this manner, will keep these contacts clean so that good contact is at all times assured. In Figure 2 of the drawing. two receivers are shown in the receiving instrument, which are provided with dials 5 and 6. These receivers are independent of each other and are of the same construction, which construction is clearly shown in Figs. 12 and 13 of the drawing. The receiver comprises two circular end plates 100 and 101, which are joined together by a plurality of iron cores 102, the irons cores being fastened to the end plates by means of screws 103.

Mounted upon each of the cores 102 are two magnetizing coils which have been designated 104 and 105. An annular plate 106 is interposed between the coils and fits against a curved face 102 on each of the cores 102, which rigidly hold the plate in position. Passing. through the central opening in the annular plate 106 is an armature shaft 107, which is mounted at its ends in suitable ball bearings in the end plates 100 and 101. The armature shaft 107 carries at its ends armatures 108 and 109, which have segment-shaped tops 110, from which projects a lateral segmental-shaped flange 111 of less width than the segment-shaped top. The cores 102 are enlarged at their ends to provide poles pieces 112 and 113, which pole pieces have curved inner faces so that the gap between the pole pieces and the armatures is relatively small. The annular plate 106 is provided with a hub 115, which sup ports two magnetizing coils 116 and 117 which coils serve to olarize the armatures 108 and 109. The 00118 116 and 117 are stationary and the armatures freely revolve with the shaft 107 so that the dial 5 which is mounted on the shaft 107 may be turned to different angular positions. To damp the oscillatory movement of the shaft 107, which would be caused by the successive energization and deenergizatio-n of the pole pieces, as described, a damping plate or fan 120 is 85 secured to the end of the shaft 107, which fan is enclosed by a suitable chamber 121 which may be filled with any suitable liquid.

In the specific embodiment of the invention shown, five poles and pole pieces are provided and the armatures 108 and 109 are adapted to be held in three intermediate positions between each pair of poles. The dif-- ferent positions are shown by Figs. 13, 14. 15 and 16 and the polarity of the poles and armatures are designated by the letters N and S. The poles are of like polarity and the armatures always remain of unlike polarity, as will be later described.

In Figure 13 three )oles are energized, 100 that is, one N and two When this occurs, the flanged portion 111 of the S armature occupies a middle position directly beneath the N pole and the N armature is equally attracted by the two S poles.

In Figure 14, which is the first intermediate step from the one shown in Figure 13, only two of the oles are energized, that is, one N and one 5, in which instance the armatures move counter-clockwise until the 110 righthand end of the flange 111 of the S armature is coincident. with the'righthand edge of the north pole and the righth'and edge of the N armature is coincident with the righthand edge of the S pole.

The next step is shown by Figure 15, when two N poles and one S pole are energized, in which instance the flanged portion 111 of the N armature has its ends lying on the radii from the center of the two N poles and the The next step would bring the pole pieces so that the flange 111 of the S armature would again be medially disposed with respect to the pole piece marked \N, in Fig-1 ure 16.

. It will therefore be seen that the armatures, and hence the shaft carried thereby, may assume four angular positions in pass- -ing from one pole piece to another, and

where five poles or pole pieces are utilized, as in the present construction, this permits the rotary shaft to assume twenty independent sitions, which correspond to the twenty positions of the transmitter, as will be clear from the description of the connections, in which the various circuit connections are described for energizing the pole pieces.

In the diagram shown in Figure 17, the main supply Wires of the system are designated 1 and 1 and the two coils 116, 117 and 116 117*, which magnetize the armatures 108 and 109 of the two receivers, are shown as connected in parallel across the supply wires, so that as long asthe device is in use these armatures are permanently polarized. The coils 104 and 105 of three of the cores 102 have been designated 30 31 and 32, for convenience in describing the operation of the system. The bars which carry the movable switches of the transmitter are designated 17, 18, 19, 20, 21, 22, 23, 24, 25 and 26, corresponding to the reference characters utilized for these bars, as shown in Fig. 3 of the drawings. Each'bar is connected to one coil of the receiver, the bars 17 to 21 inclusive, being connected to the coils of one receiver actuating .dial 6 by wires 3?, 1 5 6 7 and the bars 22 to 26 are connected to the other receiver actuating the dial 5 by wires 8*, 9*, 10 11", 12*: As has been described, each pole has two coils or windings which are wound in opposite directions so that the pole pieces at the ends of the core are of the same polarity. The windings of each pole ar connected together, as

at 13 and 14 Leading from the supply main 1 and 1 are wires 15 and 16*, which wires lead to the bus bars which carry the fixed contacts 35, the plus wires being connected to the fixed contacts at one side of the transmitter by a wire 1'? and to the minus side by a wire 18. A signal lamp 20 within the receiver casing is also connected across the plus and minus supply wires by a wire 21 leading from wire 17 connected to the plus side of the line, which wire 21 leads to the contacts 82 and 83, which are co-ntrolled by the shutter which obscures the numbers upon the counterwheels from view, as has been described. The fixed contact 83' is connected from a wire 22 to a push button 23 which leads by a wire 24 to the signal lamp. The other side of the signal lamp 'is connected to the minus side of the line by ment may b lighted when the receivers are actuated to call to the attention of the person at the receiving stations that the reading has been changed. When, however, the shutter is moved to a position in which its parts obscure the numbers on the counterwheels 1 and 2, the limit contacts 82 and 83 are opened as described, which will prevent any signal from being given in the receiver by the person operating the transmitter. \Vhen the transmitter isactuated the circuits through the receiver are therefore as follows. Assuming that the movable switches are closed, as shown in the diagrammatic view from the main supply wire 1 over the wires 15"* and 17 to the bus bar 30 through the closed contact which, in this instance, is connected to the transverse bar 2 1 and wire 10 through the two windings 30 of one pole of the receiver, then through the windings 31 of the other pole of th receiver and wire 8 to bar 32, through the closed contact connected to the bar 32 back to the negative side of the line through wires 18 and 16.

A parallel circuit will I also be closed through the windings 32 connected to the wire 12, to the transverse bar 26, to the negative bus bar 32 back to the negative side of the line, so that three poles are energized, and since the windings of each pair are in opposite directions the poles which are energized'will be similar to the poles energized in Fig. 13, that is, one north pole and two south poles.

Th circuit through the poles of the other receiver will be closed in the same manner, the circuit through the windings connected to the bars 19, 17 and 21 being closed so that the poles of this receiver will also be energized, as shown in Figure 13 of the drawing, so that the armatures-of each indicator will assume the position shown in Figure 13. As the transmitter is actuated, the cams which operate the movable cont-acts of the switches, as described, will successively close the circuits so that the poles of the two receivers will'be successively energized, as shown in Figs. 14, 15 and 16, and in this way the armature shaft will be intermittently rotated to successively give the proper readings upon the receiver.

As previously described, the two windings surrounding each core of the receiver which have been designated 30, 31 32", are wound in different directions so that the polepieces at the end of each core are of like polarity. The windings 116 and 117 which energize the armature of each receiver are wound in the same direction and are connected in series so that the segment-shaped ends of the armature are always of unlike polarity. The advantage of-this construction is that it insures that the armature will always change its angular position when the circuits through the poles of the receiver are varied, This is true because each segmentshaped end of the armature will be acted on by both an attractive and repulsive force.

two S poles at the' bottom of the receiver.

and repelled by the N pole at the top of the receiver.

It will be seen fromthe construction described that where the transmitter and receiver are utilized in connection with a range finder, the rotation of the crank 59, in accordance with the variation in the range, will cause a reading to apear in the transmitter for each change of fifty yards, which reading through the cam shaft and switches described will be transmitted to the receiver, which will have a corresponding reading. It will'also be seen that the continuous rotation of the crank 59 will cause the cam shaft 36 connected thereto to be actuated in a step by step manner, the changes in position of the cam shaft occurring suddenly and completely due to the lost motion connection and the ratchet wheel 65 and detent arm 67 which carry the roller 66 engaging the teeth of the ratchet wheel. The cam shaft 37 which is geared to the cam shaft 36 will therefore be moved one complete step each time the shaft 36 makes a complete revolution. This will preclude an erroneous reading of the receiver, since the contacts are controlled by the cam shafts and the circuits which are opened and closedto actuate the receivers are actuated practically simultaneously. As before referred to, the receivers are independent of each other and are controlled entirely by the circuits and therefore if the two cam shafts 36 and 37 did not move synchronously, the circuits to one receiver would be controlled prior to the circuits of the other receiver. This would occur when the counterwheel 2 is moving from its 95 to its 00 indication, for if the counter-wheel 1 which carries the thousands and tenthousands indication and its cam shaft did not then move in synchronism with the counter-wheel 2 and its cam shaft, for example, if the counter wheel 1 and its cam shaft lagged behind, the receiver actuating the dial 6 would be actuated first and the receiver actuating the dial 5 would remain unactuated. 'The thousands and ten thousands indication read from the dial 5 would not then give the proper indication, since its reading must be read in connection with the reading of the dial 6. In the construction described, this is avoided, since when the cam shafts of both transmitter switches move they move quickly together a complete step.

It is to be understood that one specific counter-wheel mounted on said shaft, and

means including a lost motion connection for rotating said shaft.

- 3. In a signal system, a transmitter cornprising a rotary cam shaft, a plurality of switches actuated by said cam shaft, a counter wheel mounted on said shaft, said cam shaft being arranged to close one or more of said switches in each different position thereof.

i. In a signal system, a transmitter comprising a cam shaft, a counter wheel mounted on said shaft, aplurality of pairs of switches actuated by said cam shaft, and means for rotating said shaft.

5. In a signal system, a t-ransmltter comprising a rotary cam shaft, a counter wheel carried on said cam shaft, a plurality of switches actuated by said cam shaft each comprising a fixed contact and a pivoted contact actuated to engage said cam shaft.

6. In a signal system, a transmitter comprising a rotary cam shaft, a switch actuated by said cam shaft, comprising a fixed contact and a bell crank actuated by said cam shaft, and a pivotedcontact carried by said bell crank.

7. In a signal system, a plurality of switches, a plurality of cam shafts for actuating said switches, a counter wheel on each of said shafts, said counter wheels being arranged adjacent each other, and means for rotating said shafts.

8. In a signal system, a plurality of switches, a plurality of cam shafts for actuating said switches, intermittent gearing connecting said shafts, counter-wheels mounted on saidshafts, said counter-wheels being arranged adjacent each other, resilient means acting on one of said shafts to cause its quick actuation, and means for rotating one of said shafts including a lost motion connection.

9. In a signal system, a transmitter comprising a driving member adapted to be continuously rotated, a plurality of switches, a cam shaft adapted to be intermittently operated for actuating said switches, gearing connecting said driving member to said cam shaft including a art positively driven from said driving mem r, a loosely mounted part resiliently connected to said positively driven part, and means for causing said cam shaft to move step by step.

10. In a signal system, a transmitter comprising a driving member adapted to be continuously rotated, a plurality of switches, a

cam shaft adapted to be intermittently operated for actuating said switches, gearing connecting said driving member to said cam shaft including a part positively driven from said driving member, a loosely mounted part resiliently connected to said positively driven part, a ratchet wheel carried by said cam shaft, and a resiliently mounted member cooperating with said ratchet wheel to cause said cam shaft to move step by step.

11. In a signal system, apair of independent juxtaposed electric step by step receivers carrying indicia which, when combined, give a single reading, a rotary transmitter switch for each receiver, circuits connecting each switch to its respective receiver, a driving member for said switches adapted to be continuously rotated, a transfer mechanism connecting said switches, and means for causing both switches to move together a complete step when the transfer mechanism is actuated.

12. In a signal system, a pair of independent juxtaposed electric step by step receivers carrying indicia which, when combined, give a single reading, a rotary transmitter switch for each receiver, circuits connecting each switch to its respective receiver, a driving member for said switch adapted to be continuously actuated, a transfer mechanism between said switches, and means for'moving said switches step b step for a continuous rotation of said driving member.

13. In a single system, a pair of'independent juxtaposed electric step by step receivers carrying indicia which, when combined, give a single reading, a rotary transmitter switch for each receiver, circuits connecting each switch to its respective receiver, a driving member for said switches adapted to be continuously rotated, a transfer mechanism, a lost motion connection interposed between said driving member and said switches, an energy-storing device associated with said lost motion connection and a step by step device associated with said switches.

14. In a signal system, a pair of independent juxtaposed electric step by step receivers carrying indicia which, when combined, give a single reading, a rotary transmitter switch for each receiver, circuitsv connecting each switch to its respective receivers, a driving member for said switches adapted to be continuously rotated, a transfer mechanism be tween the switches, a lost motion connection bet-ween the driving member and the switches, and an energy-storing member connected to the parts of said lost motion connection and associated with said switches normally holding them stationary but permitting them to be moved step by step by said energy-storing member.

, In witness whereof, I subscribe iny signature.

HANNIBAL 0. FORD.

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