US2222218A - Synchronous selector apparatus - Google Patents

Description

Nov. 19, 1940. c. F. WALLACE S YNCHRONOUS SELECTOR APPARATUS Filed Dec. 18, 1936 3 Shets-Sheet 1 s Pia'o/vin/ce Ma'roe BY K INVENTQR F. waif! ATTORNEYS Nov. 19, 1940. c. F. WALLACE 2,222,218

SYNQHRQNOUS SELECTOR APPARATUS Filed Dec. 18, 1936 v 3 Sheets-Sheet 2 67 RADIO Pwamfi/vce RECEIVER Norm? EHVENTOR M F. wmwu can-min, KIA-A. LSMA/Wi 5 ATTORNEY-S Nov. 19, 1940. c. F. WALLACE 2,222,213

' SYNCHRONOUS SELECTOR APPARATUS Filed Dec. 18, 1956 3 Shets-Sheet 3 MFTUJQUML BY wru, KM-AMLM ATTORNEYS Patented Nov. 19, 1940 UNITED STATES PATENT OFFICE SYNCHRONOUS SELECTOR APPARATUS Application December 18, 1936, Serial No. 116,511

11 Claims.

This invention relates to synchronous selector apparatus, and more particularly to apparatus whereby operation of circuit-controlling or like elements at one station may be selectively effected in accordance with the operation of a controlled device at a remote station.

One object of the invention is to providea synchronous selector system, and indicator and selector mechanisms therein at the controlling and controlled stations, respectively, which are of superior efliciency, simple and fool-proof in operation, economical in construction, non-huntingand positive in synchronization, and adapted for a wide range of uses, particularly in the re mote control of electrically actuated or controlled apparatus. A further object is to provide synchronous selector apparatus whereby remote control by radio or the like may be readily eifected for stations such as marine light and fog signal s stations, so that the desired lights and signals at the remote station may be operated, and telemetering apparatus selected at the remote station for transmitting back by radio to the controlling or master station, any of a plurality of meter readings or like indications of the condition of the apparatus at the controlled station.

Another and important object of the invention is to provide an arrangement of the character described, wherein the'operator at the master or controlling station merely depresses a key or the like, whereupon an indicator is automatically set in operation and caused to stop at a desired dial position under the control of the operator, and wherein at the same time and in synchronization with the mechanism at the master station, a selector device is automatically operated at the remote station to select a control position at the remote station corresponding to the selected indicator position at the master station, and to 40 effect, when in the selected control position, a predetermined controlling operation, as by the closure of a set of electrical contacts.

A further object of the invention is to provide a selector arrangement, particularly having the operating characteristics Just described, wherein synchronization and re-setting of the apparatus may be effected automatically, and, so to speak,

simultaneously, upon the operation of a simple control at the master station, and wherein such synchronization of the selecting device at the remote station with the indicator device at the controlling station may be brought about or maintained simply by depressing the selector control key at the master station for a brief period of time; and a further object of the invention is to provide selector apparatus whe ein the functioning of the circuit controlling device at the remote station is positively controlled by electro-mechanical means, so as to insure against false or inadvertent operation and to provide a positive response to the selection efiected, for example, by the operator at the master station.

Further objects and advantages are such as will be apparent from the following description 01' what is now considered to be a preferred embodiment of'the invention, including such objects and advantages as may be inherent in such apparatus and mechanism, although not specifically adverted to herein.

Referring to the drawings, which illustrate the presently preferred embodiment:

Fig. 1 is a front elevation of the selector indicator at the master or controlling station;

Fig. 2 is a rear elevation of said mechanism;

Fig. 3 is a side elevation thereof Fig. 4 is a wiring diagram of the controlling and indicating apparatus at the master station;

Fig. 5 is a front elevation of the selector unit or switching device at the remote or controlled station;

Fig. 6 is a rear elevation of said mechanism;

Fig. 7 is a side elevation thereof;

Fig. 8 is a wiring diagram of the selector and switching apparatus at the controlled station;

Figs. 9 and 10 are side elevations, partly in section, of one set of the selector-controlled contacts of the mechanism shown in Figs. 5 to '7, inclusive, Fig. 9 showing the contacts in closed position, and Fig. 10 showing them in open position; and

Fig. 11 represents a modified contact arrangement similar to Fig. 10.

Referring first to Figs. 4 and 8, it may be explained that the system here shown is particularly adapted for the remote control or a plurality of switching stations by radio, Fig. 4 representing the wiring diagram at the master station, and Fig. 8 the wiring diagram at the remote or controlled station, the arrangement being such that when the operator at the master station depresses a key 20, an indicator arm 2| is set into clockwise rotation, and is stopped at the will of the operator upon his releasing the key 2|], presumably when the arm 2| has arrived at the desired position on the diali. e., the position which, identified (as are the other selectable positions) by an appropriate number, is known to correspond to the contacts or circuitcontrolling device that it is desired to operate at the remote station. At the same time, a selector member 22 (see Fig. 8) is automatically set into clockwise rotation at the controlled or remote station, and moving synchronously with the arm 2! at the master station, stops at the time that the arm 2| does, and at a position corresponding 5 to the selected control position in which the arm 2| (of the indicator) hasstopped. That is, the selector member 22 thus stops at the desired one of the several selectable switches or sets of contacts 23, and automatically brings about and maintains the desired circuit controlling operation of that particular switch or set of contacts.

Turning now to Figs..1 and 3, the indicator mechanism for the master station may be mounted upon a panel 24 of insulating material, such as Bakelite, having a series of numbers or other indicia on one face, to provide a dial for the indicator, (as shown in Fig. l). The indicating arm 2| is mounted on a shaft 28 passing through the plate 24 so that the arm 2| may be rotated by the shaft, and thus point to the successive numbers on the dial. The shaft 26 is connected, throughv a train of gears 21, 28, 23, 30, for drive from the shaft 3| of'a motor generally designated 32, the gearing being conveniently such as to reduce the driving speed, whereby the indicator arm 2| will be rotated slowly in relation to the speed of rotation of the motor shaft 3|. The motor 32 is preferably an alternating current motor of the I type described and claimed in United States Letters Patent No. 1,995,270, granted March 19, 1935, upon application filed by me, Charles F. Wallace, for Electric motor. This motor is a so-called resonance motor, has practically no inertia, and, therefore, can start and 35 stop almost instantly. That is, it is not only a motor which may require very little power for its operation, but is one which has practically no starting lag and does not coast" appreciably when the power is turned oil. It will be understood that although I prefer to employ the motor. of my patent just mentioned, other driving means may be used, such as other motors which have the characteristics Just stated or have starting and arresting attachments adapted to provide those characteristics.

An electro-magnet 35 is also conveniently mounted on the rear of the panel 24, and has an armature 36 at one end of which is pivoted a rod 31, siidably projecting through the face of the panel 24. The arrangement of the electro-magnet or solenoid 35 is such that when the magnet is energized and its armature 38 drawn down against its pole piece 38, the rod 31 is pushed through the panel a short distance into the path of a pin 39 on the under face of the indicator arm 2|. The rod 31 thus acts as a detent for the member 2|, the magnet and rod being conveniently so positioned, as shown in Figs. 1 to :3, that the arm or member 2| will be thereby arrested in its lowermost or "zero position.

Likewise conveniently mounted on the rear of the panel 24 are a transformer 40 which may be of the step-down type to provide, from an ordinary commercial alternating current line,

5 low-voltage alternating current for the operation of the motor 32; and a rectifier device 4|, comprising, for example, four units of the copper-oxide type connected in the usual bridge arrangement. A push button or key, 20, having normally open contacts 42, adapted to be operated by a manually depressible button 43 on the face of panel 24, is also provided, this push button or key being normally maintained in opencircuit position by the inherent resilience of the contact strips, or by other suitable means.

The manner in which the foregoing parts are electrically connected will be apparent from the wiring diagram (Fig. 4) and the following operative description of that diagram Upon depressing the key or push button 20, and main- 5 taining the same in depressed position, alternating current is supplied from a suitable source such as the ordinary -volt, (SO-cycle line, to the primary of transformer 40. The .motor 32, connected across the secondary of transformer 10 40 by means of conductors 45, 46, is thus set in operation and immediately commences to drive the indicator arm 2| in a clockwise direction as viewed in Figs. 1 and 4--it being assumed, for reasons hereinafter apparent, that the arm 2| has 15 been originally set at itslowermost or zero position. At the same time alternating current is also supplied from the secondary of transformer 40, to input terminals 41, 48, on the rectifier bridge 4|, whereby uni-directional E. M. F. is 20 set up at the output terminals 49, 60, of the bridge. The electro-magnet 35, being connected across the rectifier output 49, 50, is thus energized by the uni-directional current supplied therefrom, and attracts its armature 36, so as 2a to bring the detent 31 into position for arresting the arm 2| when and if it again arrives at the zero position.

There is also provided radio wave transmitting apparatus 5|, which may be of any type 30 adapted to transmit a carrier by reason of antenna 52 and ground 53, and which is adapted to impress modulation upon said carrier in accordance with, and at the frequency of, alternating current supplied as a modulating current 35 to the terminals 54 of the transmitting apparatus. A suitable transformer 55 is connected across the secondary of transformer 45, as by the conductors 45, 46 leading to the motor 32, and has its secondary connected to the terminals 40 54 of the transmitter. It will be understood that this transformer 55 is such as to provide, from the low voltage A. C. supplied by transformer 40, modulating alternating current at the appropriate voltage for modulation of the trans- 45 mitted carrier. Thus, so long as key 23 is depressed, not only is the motor 32 set in operation, and energizing uni-directional or direct current delivered to magnet 35, but the carrier transmitted by transmitter 5| is modulated at the 0 frequency of the alternating current delivered by the input line and transformer 4|]. I

Referring now to Figs. 5 to 10, inclusive, it will be seen that the selector apparatus at the remote station may comprise a'similar panel 64, 55 upon the face of which are mounted a plurality of contacts or switching devices generally desig nated 23, and arranged in circular formation, so as to be engaged, when and if desired, by rotatable member 22. As shown in Figs. 9 and 10, 60 each of the switches 23 may comprise a pair of normally open contacts 65, 66 mounted upon a suitable insulating support and normally open by virtue of their inherent resilience.

Mounted. on the rear of the panel is a motor 61, preferably and conveniently identical with, or of the same type as, the motor 32 employed in the indicator mechanism, as described hereinabove. 70

The shaft 68 of the motor 61 is connected by reducing gearing 69, 10, II and I2, conveniently providing a reduction in speed identical to that provided by the gearing in the indicator mechanism, to drive a hollow shaft 73, which 75 projects through the panel 64 and has mounted thereon, for rotation therewith, a member ll.

Member 22 is pivotally supported by a pair of upstanding arms l5, 15, on the member H, so that member 22 may be rocked about an axis which is in a plane perpendicular to, and is disposed laterally of, the axis of shaft 18, as shown in Fig. 5. Springs 18 are provided intermediate the member 22 and member 14 so as to bias member 22 in a counter-clock-wise direction, as seen in Figs. 9 and 10-1. e., so that the end of member 22 which is nearest shaft 18 is biased toward the panel 84. The outer end of member 22 is provided with a camming pf-ojection 18, conveniently of insulating material, which is adapted to pass below the contact strips 88 of the successive switching devices 22, and to engage the latter and close their contacts whenever memiber 22 is in the position to which it is biased by the springs 18, as shown in Fig. 9.

There is also provided an electro-magnet or solenoid 80, having an armature 8| and a. member 82 mounted on the armature and adapted. to push against a rod 83 which passes through the hollow interior of tubular shaft 18. The rod 88. longitudinally slidable within the shaft 18, thus abuts at one end the operating arm 82 of the armature 8|, and at the other end, where it has passed through the panel, the under side of the inner end of member 22. It will now be seen that by virtue of the manner in which member 22 is biased by its springs 18, and the manner in which the armature 8| is biased in retracted position, as by its spring 84, the member 22 normally occupies the position shown in Fig. 9; but that upon energization of the magnet 80, rod 83 is pushed to the right, as seen in Fig. 7, or upwardly as seen in Figs. 9 and 10, so as to rock the member 22 into the position shown in Fig. 10, in which position the member 22 does not operate, i. e. close, the contacts 23 by'urging together their arms 65, 66.

Likewise conveniently mounted on the rear of panel 64 are a rectifier 85, which may be of the same type as rectifier 4|, and a transformer 85 conveniently of the step-down type to be supplied with alternating or pulsating current from the output of a radio receiving apparatus, and adapted to provide a low voltage alternating current to operate the motor 61.

Referring now to the wiring diagram of Fig. 8, it will be seen that when the radio receiving apparatus 81, which is tuned to the carrier emitted by the transmitting apparatus picks up the modulated carrier from that apparatus, a pulsating or alternating current of frequency corresponding to that of the modulation, is delivered to the primary of transformer 86. It will be understood that the radio receiving apparatus may beof any suitable type, of which many types are known, including appropriate apparatus for amplifying at radio frequency, detecting, and amplifying at audio frequency, a modulated carrier. Thus assuming that the modulated carrier transmitted from the apparatus of Fig. 4 is picked up at the station of Fig. 8, the motor 61 connected across the secondary of transformer 88 by conductors 88, 89 is supplied with alternating current of the same frequency as that delivered to motor 82 at the master or controlling station. The motor 81 is thus immediately set into operation, and drives the member 22 in a clockwise direction as seen in Figs. 5 and 8-it being understood for reasons hereinafter apparent, that member 22 has been set to the starting or zero position indicated by the hereinafter-described pin 88 on the face of panel 84. At the same time, alternating current is delivered from the secondary of transformer 88 to the input of rectifier 88, having the same type of bridge arrangement previously described, and uni-directional current is thereby derived from the rectifier, for energizing the electro-magnet or solenoid 88. The armature of magnet 80 is attracted, shifting the rod 88 and rocking the member 22 out of switchoperating-i. e. contact closing-position. Thus as long as the motor 51 and consequently member 22 are driven by current supplied from transformer 86, the energization of magnet 88 keeps the member 22 from operating or closing any of the switching devices 28.

It will thus be seen that assuming the indicator member 2| of the indicator apparatus, and the switch-operating member 22 of the selector apparatus, have both started out in their zero positions, they will move simultaneously and in synchronism so long as key 20 is depressed. The operator at the master or controlling station (Fig. 4) watches the dial 24 while he depresses the key, and when the rotating arm 2| comes to the numbered position corresponding to the switch which he wishes to operate at the remote station, he releases the key. The member 2| stops at this position,.and at the same time, so does the member 22 stop at the corresponding position, and with its member 18 under the arm 65 of the corresponding switch, in the selector apparatus at the remote station. At the same time, since alternating current for modulation is then no longer delivered to the transmitter at the master station, a modulated carrier is no longer received at the remote station (Fig. 8) and no pulsating or alternating current is delivered to the primary of transformer 86. Thus no current is delivered by the secondary of the transformer and not only does the motor 6'! stop, but the magnet 88 is deeenergized, releasing its armature and the rod 83, and permitting the member 22 to rock (counter-clockwise as seen in Fig. 9) into switch operating (contact-closing) position. Thereafter, the switch thus selected will be maintained in the position into which it has been shifted by member 22, so that, for example, its contacts will be closed thereafter and as long as key 20 is not again depressed.

As previously stated, there is provided a pin 90, projecting from the face of the panel 64 (Fig. 5) of the selector apparatus and disposed at the "zero" position of the switch-operating member 22. A corresponding pin or abutment 9| (see Figs. 9 and projects from the lower surface of member 22 at the outer end of., .the latter, and the arrangement of pins 80 and 9| is such that when member 22 is kept in the position of Fig. 10 (for non-operation of the switching devices) by energization of magnet 88 and the associated instrumentalities, pin 9| will strike against pin 90 upon rotation of the member 22 to the "zero poistion-pin 80 thus operating as a detent for the member 22.

It will now be seen that by virtue of the arrangement just described, and by virtue of the arrangement of members 31 and 89 in the indicator mechanism, members 2| and 22 of the indicator and selector mechanisms, respectively, will be stopped at their respective "zero positions when they are being rotated by their respective motors under control of the key 28 at the master station. It will be understood that the construction of the motors 32 and G1 (motors, for example, of the type of the above-mentioned Wallace patent) is such that when members 2| and 22 are arrested and further rotation of the motor drive shafts thus prevented, no injury will be done to the corresponding motor. That is, although the energizing circuit for the motor may not have been interrupted, the shaft of the motor may be held against rotation, without harm to the motor itself.

It will now be seen that resetting and synchronization of both the indicator and selector mechanisms may be simultaneously and very easily accomplished. In order to do that-for instance, after the apparatus has been used for effecting control of one of the switching devices 23 at the remote stationthe operator at the master station need only depress his key 20 for the period of time, or preferably for slightly longer than the period of time, during which the respective members 2| and 22 would make a complete revolution under drive of their motors. In the apparatus here shown, the motors 32 and 61, with their associated gearing, may conveniently be adapted to effect a complete rotation of their corresponding members 2| and 22 in the predetermined period, for example, of 30 seconds (or in a shorter or longer period, as desired), and consequently if the operator wishes to set or reset the indicator and selector devices, so as to be ready for a controlling operation, he need merely depress the key 20 for a period slightly in excess of 30 seconds (or other predetermined time of rotation) A To explain that operation more fully: Suppose that the member 2| has previously been stopped opposite the number 5, on the dial of the indicator mechanism (Fig. 1). Presumably, the member 22 of the selector is stationed at the corresponding switching device 23 (particularly 40f identified as contacts 235 in Fig. 5), or it may be 45 either case.

that the members 2| and 22, as by an inadvertent manual displacement, are not stopped at corresponding positions in their respective paths of rotation; the resetting operation is the same in When the key 20 is now depressed, member 2| will be setin rotation by the motor 32, and magnet 35 will be energized so as to op erate member 31 and bring the latter into the path oi pin -39 on member 2| (see Figs. 1 and 3) As the operator continues to hold down the key 20, member l2 will rotate until the pin 39 strikes the detent 31, whereupon the member 2| will be positively stopped, in its zero position. At the same time, member 22 of the selector mechanism,

5 by virtue of the instrumentalities previously demagnet 80 is now energized, so as to keep mem ber 22 in its detent-engaging (and non-switchoperating) position.

It will thus be seen that if the key 20 is de pressed for a slightly longer time than that necessary for acomplete revolution of members 2| and 22 (for instance, in this case, slightly more than 30 seconds) each of these members will be certain to arrive at its zero position, and there be positively arrested-whether or not it previously occupied the same angular position as the other member.

Furthermore, upon release of the key 20, both the motors 32 and 81 stop, so that there can be no further rotation of either of the members 2| and 22, even though the concomitant deenergization of magnets 35 and 80 necessarily releases the respective stop pins at the two stations. Both the indicator and selector devices are thus at their zero positions, and their respective members 2| and 22 must then step out in unison or synchronism when key 20 is next depressed, as for the next desired controlling operation. It may be explained that the resonance motors 32 and 61 have no appreciable starting lag, and will consequently, on the next depression of key 20, start to drive the indicator and selector members 2| and 22 at once; on the other hand, the electromechanical control of pins 31 and 9| from the corresponding magnets 35 and 80, particularly by reason of the mechanical linkage involved, is such as to present a slight lag in the operation of the pins. In consequence, the motors will drive their rotating members away from the zero position before the detent action of the pins is there brought into play, i. e., before member or pin 31 is shifted (in the indicator mechanism) into the path of pin 39, and before member 22 (of the selector mechanism) is rocked so as to bring the path of its abutment 9| into intersection with pin 90. As explained, in the apparatus illustrated this delay is afforded by the practically instantaneous starting characteristics of the motors, together with the lag necessarily incidental to the electro-mechanical control of the stop pins, and is thus such as will allow sufficient rotation of the arms 2| and 22 to prevent their being held in the starting position by the stop pins. Consequently, the indicator and selector devices are started off in perfect synchronism; and that synchronism is maintained by the natural synchronism of the motors on currents of identical frequency or periodicity.

It will be appreciated that other or additional arrangements may be included to provide this delay or lag-for instance, the electro-magnetic device at each station may be of the delayed action type such as employed in delayed-action relays.

It will now be understood that when a radio system is employed, i. e., when the station of Fig. 8 is to be operated by radio from that of Fig. 4 as shown, it may be desirable to filter the output of the radio receiver 81, as in a well known manner--for example, by tuning or by a combination of high and low pass filters, so that. only the frequency to which the resonance motor 61 is tuned is allowed to pass with appreciable strength. In this way, extraneous impulses caused by static or interfering radio signals are effectively suppressed and will not have a tendency to operate the relay in the receiving selector apparatus.

The receiving apparatus 81 may also conveniently be equipped with an automatic volume control, such as one of the well known types, so that its output may remain fairly constant at all times. At the same time, or in lieu of such automatic volume control, some form of output limiting device, such as is well known in the art of radio communication, may be placed between the receiving apparatus 81 and the remainder of the circuit in Fig. 8 (i. e., on either side of transformer 86) to keep the input to the selector operating and control devices below a predetermined maximum.

It will now be seen that the arrangement hereinabove described affords a particularly simple, positive and efiicient system for remote control purposes. For example, if the apparatus of Figs. 6 to 11 is disposed at a marine light or fog signal station, the various switching devices 23 may be adapted for the control of various electrically actuated or controlled devices at that station. They may be connected to control the turning on and oil of the various light or fog signals, and to control the automatic transmission (for example, by radio) of telemetering signals to the master or shore station, i. e. to indicate there the state of the apparatus at the light or fog station (voltage of batteries, R. P. M. of generators, air pressure in storage tanks, and like data). It will be understood that the selector apparatus may, if desired, be operated by a land wire connection between the stations, either by the directconduction of the desired alternating current or by so-called wired wireless": but it should be apparent that the system is especially designed for, and particularly advantageous with, the employment of a carrier wave (wired" or free) to convey the controlling im- Pulses or alternations from the master station to the remote one.

As previously explained, the switching devices shown in Figs. 9 and 10, are, for purposes of illustration, merely a simple set of normally opened contacts; Fig. 11 shows a double set of normally opened contacts, to be operated by the member 22, and it will now be appreciated that many other different types of contact or switching devices, either normally open or normally closed or involving a combination of both types, may be substituted for one or more of the specific contact devices 23 shown in Fig. 5.

It will beunderstood that the invention is not limited to the apparatus and arrangements herein specifically illustrated and described, but may be embodied in other forms without departure from its spirit as defined by the following claims.

I claim:

1. Apparatus of the character described, comprising a plurality of selectable switching devices, a remotely located key, a switch-operating member movable to select one of the switching devices, means for concurrently effecting switch selecting movement of said member and upon movement of said member out of switch-operating position upon depression of the key and means controlled by the key for causing said member to operate only the selected switch and only upon release of the key.

2. Apparatus of the character described, comprising an indicator, a pluralityof switches, selecting means movable to select a switch to be operated and having a switch-operating member adapted to be shifted into non-operating position, means for moving said indicator and said selecting means in synchronism, said means including a substantially lag-free resonance motor for each of same and means for supplying alternating current of the same frequency to both of said motors, means settable to arrest said indicator and said selecting means at corresponding predetermined points and having electromagnetic actuating devices therefor, the electromagnetic actuating device for actuating the means settable to arrest the selecting means being adapted to shift the switch operating member to non-operating position, and the settable means having connections for receiving energizing current concurrently with the motors, whereby upon interruption of current supply a switch selected in accordance with movement of the indicator is operated, and whereby resetting and presynchronization of the indicator and selecting means may be effected by establishing current supply to the motors and electromagnetic devices until the indicator and selecting means are arrested at the predetermined points.

3. In apparatus of the character described, in combination, a movable member, a motor for moving said member, electrically actuated means concurrently energizable with said motor for shifting said member transversely of its path of movement, and a detent in the path of said member when shifted by the last-mentioned means.

4. In apparatus of the character described, in combination, an indicator, a substantially lagfree resonance motor for driving said indicator, means settable to arrest the indicator at a predetermined point and having an electro-magnetlc actuating device therefor, said actuating device having an operative lag relative to said motor,

and means for concurrently supplying energizing current to said motor and said actuating device.

5. In apparatus of the character described, in combination, a plurality of switches, switch operating means movable to select a switch and having a substantially lag-free resonance motor for effecting selecting movement thereof, means settable to arrest selecting movement of said lastmentioned means at a predetermined point and having an electro-magnetic actuating device therefor, said actuating device having an operative lag relative to said motor, and means for concurrently supplying energizing current to said motor and said actuating device.

6. The combination of claim 13 in which the switch operating means is adapted to be positively maintained out of switch operating position by the electro-magnetic actuating device, whereby interruption of current supply by the currentsupplying means arrests the motor and effects operation of the selected switch.

7. In apparatus of the character described, in combination, a rotatable member, a detent member, a key, driving means for the rotatable member, including a motor and adapted in response to operation of said key to initiate rotation of said rotatable member substantially free of lag, and electromagnetic means energizable in response to operation of said key for displacing one of the aforesaid members with respect to the other whereby the detent member will be adapted to arrest the rotatable member at a predetermined position in the path of rotation of the latter, said last-mentioned mean-s having an operative lag whereby upon depressing the key when the rotatable member is in the said predetermined position, the driving means will drive the rotatable member away from said position before member-displacing operation of the electromagnetic means occurs.

8. In apparatus of the character described, in combination, a rotatable member, electrical driving means therefor adapted to initiate rotation of said member substantially free of lag, and cooperating means for effecting the arrest of said member at a predetermined position, said cooperating means including an electromagnetic actuating device energlzable concurrently with the electrical driving means, and said cooperating means having an operative lag relative to said driving means.

9. In apparatus of the character described, in combination, a plurality of switches independently shiftable for operation, selecting means movable past the switches in succession to select a switch to be operated and having a switch operating member which is adapted to engage and shift the switches and is mounted to rock into and out of switch shifting position, said member being biased to switch-shifting position, a motor for moving the selecting means, electromagnetic means for rocking and holding the aforesaid member out of switch-shifting position, means for concurrently supplying current to said motor and electromagnetic means whereby upon interruption of said current supply the aforesaid member is caused to operate the selected switch, and a detent at a predetermined point in the path of the aforesaid member past the switches, said detent being there disposed to engage the member when the latter is out of switch-operating position, for arresting movement of the member at said point.

10. In apparatus of the character described, in combination, switch means comprising a plurality of selectable switches, switch selecting and operating means therefor including means responsive to an electrical impulse of selected duration for driving said second-mentioned means to select a switch, means normally biasing one of said first and second mentioned means into switch-operating position relative to the other, and means operated substantially simultaneously with the durationof the drive-controlling impulse for maintaining the aforesaid first and second mentioned meansout of switch operating position relative to each other, whereby upon termination of the impulse the selected switch is operated in response to the biasing means.

11. In apparatus of the character described, in combination, selectable switches, a switch selector normally in switch-abutting position, means for moving the switch selector to select a switch, means brought into play when the switch selector is moving, for maintaining the' selector out of abutment with any of said switches, means for shifting the selector to effect operation of the selected switch upon arrest of the selector adjacent said switch, and means operable when the selector is out of switch-abutting position, to arrest the moving selector at a predetermined point in its path.

, CHARLES F. WALLACE.

CERTIFICATE OF CORRECTION. Patent-No. 2,222,218. November 19, 191m.

J cBARLEs F. WALLACE.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 5, second column, line 611., for "poietion" reed --poeition-; page L first column, line 51,. for "member 12" read "member 2l--; page 5, first column, line h, claim 1, strike out the word "open" and second column, line 53, claim 6, for the claim reference numeral "13" read. --5--; and that the said Letter: .Patent should be read with this correction therein that the some may conform to the record of the case in the Patent Office.

Signed And sealed this 28th day of January, A. 1). 19in.

Henry Van Arsdale, (Seal) Acting Commissioner of Patents.

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