US1978700A - Electrically operated driving device - Google Patents

Description

O 1934- F. DURING ET AL 1,978,700

: I ELBCTRICALLY OPERATED DRIVING DEVLCE I Filed Nov; 27. 19:51 5 Sheets-Sheet 1 Knmd. F5411- Oct. 30, 1934. F. DURING ET AL 1,973,700

ELECTRICALLY OPERATED DRIVING DEVICE Filed NOV. 27. 19551 5 Sheets-Sheet 2 0a. 30, 1934. D6R|NG ET AL 1,978,700

ELBGTRICALLY OPERATED DRIVING DEVICE Filed Nov. 27. 1931 5 Sheets-Sheet 3 Get. 30, 1934. k F. DURING ET AL 1,973,700

ELECTRICALLY OPERATED DRIVING DEVICE Filed Nov. 27, 1931 5 Sheets-Sheet 4 I 6' I I I Zu 17 @L5 7 4 all In fiT-LIETS Ff'fi'i During Konrad M111 1:1"

Oct. 30, 1934. FT. DURING El AL ELECTRICALLY OPERATED DRIVING DEVICE Filed NOV. 27, 1931 5 Sheets-Sheet 5 H H Q 13L U 1 H. n F J W 6 I.

Inuun nrs F171? During Konrad Muller impulse senders,

0 magnets Patented Oct.- 30, 1934 UNITED STATES PATENT OFFICE 1,978,700 ELECTRIOALLY OPERATED DRIVING DEVICE Application November 27,

1931, Serial No. 577,672

In Germany December 1, 1930 8 Claims.

The subject of the present invention relates to a device driven by an electric motor, particularly for instruments used in telephone systems, for example rotary switches, signalling devices,

remote repeaters of pointer positions, etc. and the object is mainly to improve the drive heretofore used in such instruments.

In most of the driving devices for instruments of the above named type heretofore used electroare generally employed to drive the armature which actuates toothed wheels by means of pawls, the toothed wheels being connected to the setting units (for example, switch wipers, pointers or the like). This type of drive, due to the hard knocks occurring, possesses various disadvantages, for example, heavy wear and tear of the driving members, weak or reduced setting speed, great vibration of the instrument members and a generally noisy operation. The elimination of these difliculties-generally known in the trade has been attempted in various manners and ways.

It has, for example, been suggested to replace the oscillating movement of the power transmitting means by a rotary movement, making use of a type of electric motor having a rotatable armature instead of electromagnets, stopping pawls and the like. The movement of the setting unit which, in many cases, is required to be step-like in nature has been achieved by the al-- ternative energization of two stator coils (for example by means of impulses from an impulse sender (causing the armature to execute a stepping movement), whereas an uninterrupted rotary movement was obtained by a type of relay interrupter bymeans of which a rapid sequence of impulses have been sent through the two stator coils. It will be readily appreciated that such a drive is comparatively expensive and unfavourable in technical regard due to the fact that a plurality of relays have to be used. In addition to these disadvantages it should be mentioned that in spite of using an almost continually operating drive it is possible to obtain only a slight increase in the setting speed by this type of drive.

In order to obtain a greater setting speed, other methods have already been suggested, including the method of replacing the forward motion of the setting units (for example the switch wipers) operated step by step by means of stop pawls, by a continuous movement which is obtained by a power storer, for example, a tensioned spring and not by an electromotor. This spring used, for example, in electric switching units runs with great speed over the contact laminations until the moved member is stopped by means of stopping units, such as for example, drop pawls, friction or the like when the required contact has been reached. The charging of the power storer, i.e. the tensioned spring is generally effected by means of an electromagnet. This type of drive also possesses certain disadvantages although great setting speeds are obtained thereby, the disadvantages mentioned being a great strain on the material and wear and tear and also the mechanical assembly of such switching units being too expensive and complicated.

Another generally used type of drive for instruments of the above-mentioned type are electric motors which by means of a coupling (generally electromagnetically operated) are partly coupled to the setting units, with the result that a de-coupling of the driving motor is necessary to bring the setting units to rest. The use of couplings, however, has the disadvantage, be-

sides being expensive, that the exact setting of the setting units to the required positions is not always ensured due to the acceleration of mass and are also considered unfavourable from a technical point of view.

The stepping operation cannot even in this case be effected without stopping pawl mechanisms so that this combination of drive (electric motor and stopping pawls) is uneconomical and has the above mentioned disadvantages associated with stopping pawl drives.

For the purpose of eliminating the above men tioned difiiculties an electric motor according to the invention is used to operate instruments of the above mentioned type, the rotating member of the said electric motor actuating switching means for the control of the motor windings and bringing the switching means to rest by generating a static electromagnetic field. The motor can also be designed as a motor with an armature having no windings or as a motor with i by the rotating motor flux. The switching means for the control of the energizing winding are so designed. that an automatically controlled rotary movement 'is possible as well as a stepping movement of the armature (for example, caused by impulses). In such a case the stepping movement of the motor armature can either be controlled by impulses arriving from the outside or by means of impulses controlled by the motor.

The continuous or nearly continuous rotary of the armature can also be obtained, example, by means of movement by various means, for collectors, by means of cam contacts operated members which influence the magnet windings of the motor and by means of brush wipers operated by the movable motor member brushing stationary circular segments or in various other manners known per se.

According to the invention such switching means have been found particularly suitable in which the brush points are arranged separate from the contact known heretofore for the control of motor windings consist exclusively of brush wipers running over the collector laminations, brush carbons or the like, that is to say, consisting of arrangements in which in addition to the mechanical wear and tear at the brushed points, also the wear and tear caused by sparks is apparent as the brushed points at the same time serve as conductors for the current. For this reason the switching means for the control of the motor windings according to the invention are suitably designed in the form of a set of contact springs which are mechanically controlled by the rotating motor member. murder to avoid the sparks generated at the switching points which considerably reduce the efiect of the motor, suitable means for example, condensers, chokes or the like are provided.

; As a heavy starting and stopping moment is required for a static magnetic field to cause a stoppage for the-above mentioned purpose, the stationary as well as the rotating armature poles according to the invention are circular instead or square or rhombic. Such a construction of the poles is particularly advantageous in motors having armatures with no windings as, due to the faults in the winding, considerable power can be generated only if all possible means for the increase of power have been taken into consideration.

Further details of the driving device according to the invention are illustrated in the drawings and explained in the description below in conjunction with embodiments and particularly suitable circuit arrangements, especially for switching devices. Fig. 1 shows an embodiment of the invention for a rotary switch as used in telephone systems.

Fig. 2 shows a circuit example for the rotary switch shown in Fig. 1.

Fig. 3 shows an electric motor with an armature without windings constructed according to the invention.

Figs.- 4, 5 and 7 show an example of a motor armature having an auxiliary armature, while the circuit associated with this motor is shown in Fig. 6.

' Figs. 8 and 9 show an embodiment for a motor which operates as an alternating current motor during the uniform operation.

Fig. 16 shows a motor in which the uniform points. Switching means run as well as the stepping operation is effected over one and the same collector.

In Fig. 11 a circuit arrangement is shown in which the device driven by an electric motor according to the'invention is utilized to operate a switch for telephone systems.

The contact bank 1 of the rotary switch shown in Fig. 1 is brushed by the switch wipers 3 arranged on the shaft 2. The drive of the switch wipers is eifected by means of the toothed wheels ;4, 5 and 6, by the armature '7 of the motor, the stationary stator armature 8 of which is energized by the winding 9. It will be seen from the circuit shown in Fig. 2 in which manner the motor is built to operate with a uniform or almost uniform as well as a stepping motion. For this purpose two relays are provided, namely, a reversing relay U and. an impulse relay J. The operation is as follows: closing the contacts 21!. and 4u'of the reversing relay U starts the motor as, due to a stopping arrangement not shown inFig. 2, corresponding to the stopping arrangement shown in Fig. 3, retaining the armature in such a position that a rotary moment can effect it. The motor runs uniformly or ahnost uniformly due to the collectors represented by the reference numeral 11. By switching over to the contacts lu and 3a the brushes allocated to the collector 11 are disconnected from battery and thus the brushes of the two brush rings 12 are connected up to which the ends of the armature winding are connected. The result is .that the armature will be permanently energized from abattery B and is stopped in position by means of the static field generated by the stationary portion of the motor. The current in this case extends from battery B over the closed contacts 6i and la, collector brush, brush ring 12, armature winding and back to the other brush ring 12, collector brush, contacts 3a, 82', and back to battery. The static field is generated by winding 9 and battery B due to the closing of contact 13. The batteries B and B, of course, may be one and the same source of current supply. A succeeding impulsive energization of relay J causes the current direction in the armature of the motor to be reversed, with the result that individual steps in tune with the energization of the J-relay.

The armature of the motor shown in Figure 3 has no For rotating in only one direction it is provided with projections 17. This motor operates continuously by the alternating energization of magnets '14 and 15. These magnets 14 and 15 have counter poles 31 and 32. The stopping arrangement consists of two flat springs 19 and 20 which rest against a square 18 disposed on the shaft of the armature. On the armature shaft are in addition two interrupters 21 and 24 the member 22 of which'is a metallic conductor for electric current and the member 23 of which is a non-conductor. The brushes 25, 26, 33 and 34 slide on these interrupters: During continual operation the current from the battery takes the following path: earth, battery 30, winding of magnet 15, interrupter segment 22, collector brush 33, contact 29, earth. The winding 15 is therefore energized,

and attracts the armature 16. After a revolu- 1 tion approaching 90 degrees the brush 33 leaves segment 22 while at the same time the brush 34 runs on to segment 35 of the interrupter below, thus energizing the winding of the magthis takes net 14 in the following circuit: earth, battery 30, winding of magnet 14, interrupter segment 35, brush 34, contact 29, back to earth. The current is fed to the interrupter segments 22 and 35 in known manner, for example, by means of a brush ring. The motor thus runs evenly or almost evenly as long as the contact 29 is closed. By the opening of contact 29 and the closing of contact 28, the one type of movement (continuous movement) is changed into the other type of movement (stepping movement). During the latter type of motion the collector brushes and 26 will function. These brushes 25 and 26 are set at such an angle relative to the brushes 33 and 34 that the connecting up of the second stator coil 14 to be energized cannot take place when the armature is located in front of the pole of the first stator coil 15. According to Fig. 3 the current, after closing contact 28, takes the following route: earth, battery 30, winding 15, interrupter segment 22, brush 25, contact 27, contact 28, back to earth, with the consequence that the stator coil 15. is energized and the armature 16 revolves until set in front of the pole of the coil 15. After the opening of contact 27 the coil 15 will be disconnected from battery, whereupon the armature, under the influence of the stopping arrangement 18, 19, 20 advances to such an angle that the segment 35 of the interrupter 24 will come into contact with the brush spring 26. Hereby a circuit for the coil 14 is prepared so that, at the closing of contact 27 the coil 14 is energized instead of the coil 15 and the armature will be drawn as far as in front of the pole of the coil 14. This operation is repeated as long as impulses are passing through the motor by contact 27 being actuated. To ensure that the armature 16 rotates in correct direction it is fitted with projections 17 in a manner known per se. Between these projections and the actual armature pole of the armature 16 portions 36- have been cut out in the iron in order to ensure that the armature is securely retained in front of the respectively energized pole.

Figs. 4, 5, 6 and 7 show an embodiment for a motor provided with a main and an auxiliary armature. Between the diagrammatically shown stator coils 33' and 34 the main armature 35 rotates and ismade of sheet metal having a cross section in the shape of a double T in order to reduce its mass to the greatest possible extent. This main armature 35 is also provided with projections 38. By means of the spring37 an auxiliary armature 36', likewise arranged'in the magnetic field of the poles 33' and 34', is provided on the armature shaft 45, the said auxiliary armature 36 being rotatably pivoted on the shaft 45 by means of the bearing sleeve 46. The mass of this auxiliary armature is kept exceedingly low compared to the mass of the main armature. The fibre disc 40 is rigidly connected to the shaft whereas the fibre disc 39 is rigidly connected to the bearing sleeve 46. The contact springs 41 and 42 are actuated by these fibre discs. A stopping arrangement similar to the type shown in Fig. 7 is also fitted on the shaft 45, the said stopping arrangement comprising an arresting spring engaging in the notches 46' of the arresting disc 49. Thenotches 46 are so arranged that they operate when the armature 35' is disposed immediately in front of the poles of the motor. The object of this stopping arrangement is to retain the main armature35' in its position in front of the poles when the auxiliary armature 36' is set to a dellnite angle under the action of the. spring 37 when the stator pole is disconnected from the' battery.

In conjunction with the circuit shown in Fig. L

6 the operation of the motor will be explained.

The motor shown in this figure has two stator coils, each provided with a pair of poles similar to the arrangement shown in Fig. 3. In the position of the contact U47, as shown in the illus- 1 tration, the motor runs uniformly or almost uniformly as, by means of the fibre disc 40 the stator coils 52 and 53 are alternatively disconnected from the battery by the separation of the contact springs 41a and 41b which have been displaced about If, for example, the fibre disc 40 is positioned between the pair of contact springs 411), the stator coil 52 will be energized over the following circuit: earth, U47, pair of contact springs 41a, coil 52, battery 51, earth.

ously connected up by this contact,-whereupon the motor is brought to rest by the generation of a static field. The two windings of the motor are connected to battery as follows: (1) earth, contacts U47, 41a, coil 52,. battery 51, earth. (2) earth, contacts U47, 41a, 11, coil 53, battery 51, earth.

In order to obtain a stepping movement of the armature the circuit for a not shown control relay U is closed which, for example, may be energized in conjunction with relay J. Relay U opens its contact U47 and closes U48. By the opening 'of contact U47 the earth potential is disconnected from the motor windings so that they receive no current. No" effect is obtained by connecting the earth potential overcontact U48 as a second contact 12 of the now re-energized relay J is opened.

The armature comprises a main and an auxiliary armature similar to that in the embodiment mentioned above. When the motor is brought to rest by the closing of contact i1 thearmature will be disposed in front of one of the pair of poles. The main armature in this case tends to pass the energized pole pair due to its mass. This, however, is of no consequence as the switching means 41a, 41b, which it actuates are disconnected. The auxiliary armature, on the other hand, is securely held in front of the pair of poles due to the smaller mass. The main armature after having overrun is positioned by the static field in front of the pair of poles. In this position of the main armature the spring 50 snaps into the notch 46 of the fibre disc 49 and thus retains the main armature in this position.

When the energizing circuit is disconnected which, as above mentioned, is caused by contacts U47 and ii, the auxiliary armature proceeds to such an angle under the influence of the helical spring 37 that one of the two sets of contacts, for example; 42b is opened. In this manner the winding 53 of the stator is preparatoriiy disconnected so that, at a closing of contact i2 the coil 52 only will function and thus cause the armato take one step. The circuit extendsoverzearth, U48, contact i2, set of contact springs 42a,

stator. coil 52, battery 51, earth. ,The 0011.52 is .disconnected from the battery at the opening of contact j2. The auxiliary armature, under the actionof the spring 37, revolves so tar-'thatrthe set ofjsprings 42a will be preparatorily separated.

At repeated closing of contact i2 the coil 53 will.

. .1 thereby be energized. As will be seen it is therejiore possible to cause the motor armature to re-' volve each time to an angle of 90 after contact U48 has been closed by the intermittent operatlon contact i2.

8. and 9 show an embodiment in which.

the motor for continuous run is driven by alternating current, whereas the individual steps are be connected up to an alternating current source till of supply in the following circuit current source 01 supply, contact in, collector brush 3', armature winding 2', collector brush 4', contacttu' back to the current source of supply. The stator poles 6' and 7 are energized from battery'B by the stator winding 1' when contact 8 is closed, with,the consequence that the armature willmove continuously. When the U-relay is energized the contacts in and 3a are separated,

whereupon contacts 2a and 4a are closed and the direct current source of supply B will be applied to the armature winding over contacts 3i and it which causes the armature to be arrested. By the intermittent energization of the J-relay the current direction of the armature winding is changed by means of contacts 2i and at so that the armature is advancedhali a revolution at each energization. In order to ensure that this occurs without fail the stopping ar-- rangement shown in Fig. 9 is provided which consists of a flat spring 10' provided with a roller 11' and also an arresting disc 9' shaped:

like a double heart. I

Fig. 10 shows a further ent in which the polarization of the motor windings required for the arrest or for the stepp n operation which differs from the polarization which causes the continuous movement and is efiected by switching means which cause the motor to move uniformly or almost uniformly. These switching means comprise-an ordinary collector having two pairs of collector brushes, the second arrotbrushes being arranged at a certain angle'in relation to the first pair of brushes. The

brushes 13' and 14' operate during continuouswhereas the brushes 12' and 15' cause the motor to stop or run step by step. It contacts 111." and 3a" are closed the motor will run as an ordinary direct current motor with wound armature. 11 contacts 11!." and 3a" however are separated at the energization of relay U and thus contacts 2u"'and 4a" are closed, the pair of brushes 13' and 14. are disconnected from battery and thus connect up the brushes 12 and 15' which are arranged above the pole alternator laminations 16' and 17 in such a manner that a de-polarization of the armature 5' will not occur atthe right moment with the result that the armature remains stationary under the infiuence of the field of the stator poles 6 and '1'. In a similar manner, as already described in the above, the armature is disconnected from the battery at the opening of the J-contacts but advances, however, to a certain angle under the action of a not shown arresting arrangement, 1

rotating half a revolution at each closing of the J'-contact.

In Fig. 11 a circuit arrangement is shown in which the device driven by the electric motor 'necessarycomponents for theunderstanding of the invention are shown, whereas all devices having no connection with the invention. for

example, devices for the transmission of signals .(i-ree or busy signals, ringing, etc.) have been omitted. r

This case mainly relates toa so-called rotary switch (similarto that in Fig. 1) that is to say,

a switch having'a direction of movement at which the individual leads are readily reached by the rotary movement of the switch wipers. As such switches must operate with great speed,

the device driven by an electric motor-according.

'3a. After the preceding switches have completed their operations the impulse relay A will be energized over: earth, battery, resistance Ws'i, b-lead, loop in thepreceding switch, a-lead, winding of relay A, earth. Relay A opens its contact 3a whereby the above mentioned short circuit for relay C will be removed. This causes relay C to be energized, whereupon it opens its contact 1c and by closing oiits contact 2c prepares the energization oi relay ii. If new the calling subscriber sends out number impulses, thereby causing a periodic opening oi the loop extending over the a and b, relay A will be energized according to the. impulses sent out. At the first release of relay A, contact 3a is closed with the result that relay V is one in the following circuit: earth, contacts so, 2c,

winding I of relay V, battery, earth. Relay V remains energized during the whole impulse series as its contact 321: short-circuits its second winding causing the relay to be so retarded in its operation that it does not release during the short current interruptions at contact 3a. In consequence hereof the contact 201) and consequently also the starting circuit for the motor is closed during the impulse series over: earth, contacts 200. 19a, 6p2, contact at DL, motor winding M011, battery, earth. The devices DL and ES are only diagrammatically shown in this case. They correspond to the switching devices be applied. When relay A releases for the first (shown in Figs. 2 to 10 for the control of the motor windings in order to obtain a continuous time and contact 16a is closed, the following bridge is formed after relay V is energized, for the motor coils: motor coil MoI, d-wiper of the switch in normal position, O-contact, contacts 181, 16a, 1222, 811, motor coil No. II. The two motor coils are simultaneously energized in the following circuits: (1) earth, contacts 201;, 191:, 6:12, contact at DL, motor coil No. II, battery, earth, and (2) earth, contacts 200, 19a, 6 12, contact at DL, contacts 8a, 120, 16a, 181, O-contact, d-wiper of the switch in normal position, motor coil MoI, battery, earth. In this condition it is impossible for the motor to start but as soon as relay A is reenergized after the end of the first impulse the bridge at contact 16a. which is opened when relay A is energized is broken with the result that only one of the motor coils, connected up bya contact at DL, is energized (the motor coil No. II in the position shown) whereupon a starting moment is applied to the armature of the motor. The armature, as well as the switch wipers connected thereto are thus caused to advance. Prior to the opening of contact 16a, however, the contact 15a is closed (light contact). The motor, therefore, after the switch wipers have been set to the next contact, immediately comes to rest as the bridge is now reclosed over contact 150, the first main stop lHR and the first contact of the contact bank, switch wiper d, and the static field reproduced by the simultaneous energization of the two energizing windings of the motor. It will be assumed that a calling subscriber has sent out an impulse series consisting of two impulses. As already described in the above, after the end of the first impulse, the switch wipers are located on the first contact (d-wiperon contact 1BR). If the relay is now de-energized the-second time and contact 15a is opened the bridge of the motor windings is broken at contact 150 with the result that the motor starts, as mentioned above.

The switch wipers which are driven with great speed are brought to rest when the wiper :1 reaches contact lZR (first intermediate stop) and therefore the bridging of the motor windings has been completed over-this contact and contact 160.. As soon as relay Areturns to its operative position after the end of this impulse, the motor is restarted (bridge being broken at contact 16a) and the switch wipers are set on contact 2HR where the bridgeis reclosed over contact 150.. Relay V releases due to the impulse series now being ended and contact 3a remaining open for an extended period. It should be observed that the, device has been so arranged that the contact 250 is closed sooner than contact 111;. The motor is connected to battery over: earth, contact 2112, 22k, (closed when the switch wipers have left their original positions) key T3 in normal position, resistance Wi5, contact 6172, contact at DL, motor windings, battery,- earth. The resistance Wi5, connected up in this circuit, is provided for the purpose of weakening the current so that the speed of the motor is reduced during the succeeding hunting operations. The arrangement is so made that the switch wiper (1 leaves its position 2HR before contact 110 is closed. The hunting for a free line within the selected line group is effected over the c-wiper of the switch. The switch wipers are advanced until a free line has been found, such a line'being characterized by battery potential being applied thereto. The first test relay P1 is then energized in the following circuit: battery potential of the free line, c-wiper of the switch, contact 37122, winding of relay P1, key T2 in normal position, contacts 3112, 30!, 260, 287:, (closed when the switch wipers have left their normal positions), earth. Relay P1 is energized and immediately closes its contacts 9p1 and 10111. The two motor windings are bridged at contact 9p1. By the simultaneous energization -oi. the two windings a static field is generated in the manner fully described above which arrests the motor and also the switch wipers. The two motor windings are now energized as follows: (1) earth, contacts 210, 22k, key T3, resistance Wi5, contact 6p2, contact at DL, motor coil MoII, battery, earth, and (2) earth, contacts 211;, 22k, key T3, resistance Wi5, contact 6p2, contact at DL, contact 9p1, motor relay MoI, battery, earth.

By the closing of contact 10p a circuit for the second test relay P2 is completed over: earth, battery, motor coil Man or MoI, contact 10121, windings I and II of relay P2, key T2, contacts 311), 301, 260, 28k, earth. The relay P2 is energized and operates its contacts.

The circuit for the energizing windings of the motor is broken at contact 6122. The circuit for the first test relay P1 is opened at contact 37112 and the c-wiper of the switch is connected to the second test relay P2 at contact 361:2. By the closing of contact 25122 the high resistance winding II of relay P2 is short-circuited, whereby the switch is guarded against a further seizure. By the closing of contact 34122 the following circuit is completed: earth, contacts 28k, 260, 30!, 3122, key T2, contact 34122, winding I of relay L, battery, earth. Relay L is energized, closes a locking circuit for itself at contact 291 and is thus maintained energized during the duration of the connection in the following circuit: earth, battery, winding I of relay L, contacts 291, 260, 28k, earth. The final blocking circuit now extends over: battery potential on the c-lead, c-wiper of the switch, contact 36112, winding I of relay P2, contacts 35p2, 291, 26c, 28k, earth. Finally the speaking leads to a succeeding impulse receiver are switched through by the closing of contacts 38p2 and 391:2. 1

When the battery potential is cut of! from the c-lead at the end of the connection, whereby relay P2 is de-energized, a circuit for the motor winding is completed over: earth, contacts 51', 6112, contact at DL, motor winding, battery, earth. There being no special resistance located in this circuit the switch is rapidly advanced until it has reached its normal position. In this position the motor is immediately brought to rest as the bridge for the two motor coils is now again completed thus: MoI, d-wiper, o-contact of the contact bank, contact 171, (M011), and the armature of the motor is held in position by the permanent energization of the two windings. As soon as the normal position has been reached the off normal contacts 22k and 29k are opened. The earth potential is cut ofi at contact 211) by means of contact 22k while the circuit for relay L is opened at contact 28k. Hereby the earth potential required to return the switch to its original position is cut oil by the opening of contact 51. The switch now is set in its original position.

The case will now be considered if all the lines 15 of aselected group are busy and the switch cannot find a free line during its, hunting operation. It is again assumed that the impulse series sent out by the calling subscriber consists of two impulses. The d-wiper of the switch is then brought to rest on contact 2HR in the manner described above. The hunting operation is initiated by the release of relay V and the switch is advanced by the motor, thus hunting for a free line. After having passed through the selected line group, the 'd-wiper' finally reaches contact 3113. The bridge for the two energizing windings of the motor is again set up over this contact as well as over contacts 15a. and 1 31, winding II of relay L, contacts 11v, 8%, etc. with the result that the switch cannot advance farther. pleted: earth, contacts 21v, 22k, key T3 in normal position, resistance Wi5, contact 6p2, contact at DL, contacts 8a, 110, winding 11 of relay L, contact 13l, 15a, 3HR, d-wiper of the switch, motor coil MoI, battery, earth. Relay L is energized over its winding II in this circuit and operates its contacts. By the closing of contact 291 a locking circuit is formed for relay L over winding I of this relay: earth, contacts 28k, 260, 292, winding 1 of relay L, battery, earth. The above mentionedbridge for the motor coils is opened at contact 131, and the return of the switch to its original position is completed by means of the motor, the coils on which are now intermittently energized by the earth potential intermittently applied by means 'of contact 52 as already described. Obviously the calling subscriber in this case may be informed in any known manner by means of a signal that all the lines of the selected group are busy.

The switch shown in the embodiment can also operate as a final selector. To this end it will be necessary to operatethe keys represented by T1-T3. The setting to the required line group is effected in the same manner as when the switch is used as a group selector as described in a previous paragraph. When relay V releases,

after the end of the last impulse of the first impulse series and contact 23c is closed at the transmission of the first impulse of the second impulse series the following circuit is'completed: earth, contacts 211), 22k, key T3 inoperative position, contacts 23a, 25a, winding of relay U, battery, earth." RelayUis energized in this circuit. At contact 2414, (light contact) it closes a locking circuit for itself over: earth, battery, winding of relay U, contacts 2411., 260, 28k, earth. The device ES which is so arranged that, at the transmission of the impulses for the setting of the switch to a required individual line the motor advances its armature so far that the switch wipers connected thereto step from contact'to contact, is connected up at contact 411., over key T1 in operative position. This device is only diagrammatically shown'in Fig. 1 1 similarly to the device DL. A complete description of these devices and their operations is furnished in connection with Figs. 2 to 10 andthe specification associated therewith, The transmission of impulses to ES is effected in the following circuit:

earth, contacts 3a, 20, resistance Wi3, contact 411., key T1 in operative position, contact at ES, contact 711, motor coil MoII' or contact at ES (the ofiice contact closed) motor coil M01, battery, earth.

Parallel to the two windings of the motor the devices shown on the drawings and represented I by C'Oand Wi4, i.e. condensers and resistances,

The following circuit is then comare provided in order to prevent sparks with their harmful efiects during the run of the motor.

. What we claim as new and desire to secure by Letters Patent is: v

1. In combination with an electric motor of the type in which equipment is rotated consequent to the alternate energization of a pair of field windings, operating circuits for the field windings including contacts operable consequent to the rotation of said equipment, a control relay effective when energized to energize the field windings of the motor alternately under control of certain ones of said contacts tothereby ro-' tate the equipment substantially continuously until said relay again becomes deenergized, and a second relay cooperative with other of said contacts when the first relay is deenergized to rotate said equipment in a step-by-step manner.

2. In combination, an electric motor of the type in which an armature is rotated consequent to the alternate energization of a pair of field windings, a pair of commutating members rotatable with the armature and each having a pair of brushes cooperative with one of the field 0 windings, and circuit switching means which.- when in one position causes one brush of each of said pairs to cooperate with said commutating means to rotate the armature of said motor substantially continuously and when in an alter- 5 native position causes the other brush set of said pairs to cooperate with said commutating means to rotate the armature in steps.

3. In a control arrangement for an electric motor of the type wherein a pair of field coils are alternately energized to produce a rotary movement of the motor armature, the provision of a pair of contact sets controlled by the armature and included in alternative energizing circuits of the field windings, the circuits and contact sets being so arranged with respect to said armature that when one set is employed the armature may be caused to rotate in a step-bystep manner whereas when the other set is employed the armature will be rotated substantially continuously, and means for making either contact set efiective. V

4. In an electric motor, a pair offield windings, a rotatable member rotated thereby, switching means operated by said member to alter nately energize said windings to rotate the member, and means for energizing-both said windings in such a manner as to set up a static magnetic field to bring the member to rest in a specific position relative to said windings.

5. In an electric motor, a rotatable-membena pair of field windings, means for alternatelylenergizing said windings to rotate said member, means for-always stopping the member'by ener-' gizing both field windings togenerate a static operated position. 1

6. In an electric motor, an armature, field windings for operating the armature, means for energizing said windings to cause either a con-' tinuous rotary movement of the armature or a step by step rotary movement thereof, an auxiliary armature, said auxiliary armature operated to cause a change from continuous to step by step movement of the armature. r

'7. In an electric motor, an armature, field windings for rotating said armature, means for energizing said windings alternately to rotate the armature, an auxiliary armature, said auxilfield to therebymaintain themember in its last tating the auxiliary armature independent of the main armature, and circuit connections controlled by the auxiliary armature for contro the energization of the field windings.

mrrz BORING. KONRAD minim.

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