US2284755A - Coin collector apparatus - Google Patents

Description

June 2, 1942. J, MELICK COIN -GOLlZ-EKLTOR APPARATUS Original Filed Jan. 11, 1940 4 Sheets-Sheet 1 lNVE/VTOR J; M

ATTORNEY June 2, 1942. J. M. MELICK 2,234,755

COIN COLLECTOR APPARATUS Original Filed Jan. 11, 1940 4 Sheets-Sheet 2 FIG 4 INVENITOR V J M. MEL ICK Arrom/sy June 2, 1942. J. M. MELICK COIN COLLECTOR APPI RATUS Original Filed Jan. 11, 1940 4 Sheets-Sheet 3 ll/ENTOR J. M ME L /C/( Arrows/5k June 2, 1942. J. M. MELICK 2,284,755

COIN COLLECTOR APPARATUS Original Filed Jan. 11, 1940 4 Sheets-Sheet 4 INVENTOR J. M. MEL ICK ATTORNEY Patented June 2, 1942 1 COIN COLLECTOR APPARATUS John M. Melick, Cresskill, N. J., assignor to Bell Telephone Laboratories,

Incorporated, New

York, N. Y., a corporation of New York Original application January 11, 1940, Serial No.

313,329. Divided and this application September 24, 1940, Serial No. 358,063

6 Claims.

This invention relates to coin collection apparatus in which a coin or token is deposited for the use of an instrument; and this application constitutes a division of my application Serial No. 313,329, filed January 11, 1940, on Coin collector apparatus which issued on August 26, 1941 as Patent 2,253,863.

The invention is particularly suitable for use in a telephone pay station of the general type illustrated in the O. F. Forsberg U. S. Patent 1,043,219, issued November 5, 1912, wherein a deposited coin is temporarily held upon a coin trap after the coin has actuated a trigger to close electrical contacts for the purpose of signaling the central office and for the. additional purpose of establishing an energizing circuit for a coin relay. Thereafter, battery at the central office may be applied to the line to energize the relay whose armature serves to release the coin trap to direct the coin into a collect chute if the applied voltage is of one polarity, and to direct the coin into a refund chute if the applied voltage is of the opposite polarity. The operation of the relay also serves to restore the coin trigger to normal to reopen the electrical contacts controlled thereby.

An object of this invention is to provide an improved coin handling mechanism of efficient and positive operation. A further object is an improved electromagnet capable of being selectively operated in accordance with the polarity of the voltage applied thereto.

In' accordance with the preferred embodiment of the invention as applied to coin collectors, the

deposited coins are held in suspense on a coin trap comprising two downwardly inclined vanes pivoted at their upper ends, with the lower ends engaged to form a V-shaped coin supporting surface, with the junction of the two vanes lying immediately above a partition which separates a collect chute from a refund chute. Improved relay means are provided effective upon the application of collect current to move only that vane lying above the collect chute to a substantially vertical position whereby the deposite coins are directed into the collect chute; while upon the application of refund current the relay moves the vane above the refund chute to a substantially vertical position to permit the deposited coin to drop into the refund chute.

The preferred coin relay construction comprises a solenoidal winding having a pivoted armature at each end of the core. Mounted adjacent the winding is a rotatable member carrying a permanent magnet located between polar Y extensions of the core whereby the application of energizing current to the winding causes a rotation of said member in a direction dependent upon the polarity of the applied voltage. The said member is biased to a normal position where projections such as lugs on said member prevent the movement of both armatures to their attracted positions, but the rotation of said member in a given direction releases one of said armatures and prevents the operation of the other armature so that one armature is operated for applied voltage of one polarity and the other armature is operated for applied voltage of the opposite polarity. Each of the two above-mentioned vanes in the coin hopper is individually controlled by one of these armatures for permitting the collection of deposited coins when one armature is operated and for refunding the deposited ccins when the other armature is operated.

The energizing circuit for the coin relay just described is preferably established by electrical contacts which are closed by the operation of a coin trigger located in the coin hopper above the coin trap. If energizing current has been applied to the relay the operated armature also serves to restore the coin trigger to normal to insure the reopening of these contacts at the proper time.

Other features of the invention will be apparent from the following detailed description taken in connection with the accompanying drawings in which:

Fig. 1 is a side View of a telephone coin collector embodying the present invention;

Fig. 2 is a wiring diagram of a coin collector substation;

Fig. 3 is a view in perspective of the coin handling mechanism of this invention;

Fig. 4 is a front view of the coin relay and associated coin hopper of Fig. 3;

Fig. 5 is a top view of the apparatus of Fig. 4;

Fig. 6 is a rear View of the apparatus of Fig. 4;

Fig. 7 is a side view partly in section of the apparatus of Fig. 4;

Fig. 8 is a side view of a portion of the apparatus of Fig. '7 with the coin trigger in coin operated position;

Fig. 9 is a view of the apparatus corresponding to that of Fig. 4 except that one of the armatures of the relay is shown in attracted position;

Fig. 10 is a top view of the apparatus of Fig. 9 except for the omission of the electrical spring pile-up;

nism for the operated condition of Fig. 9;

Fig. 12 illustrates the position of the coin trap when one of the relay armatures is operated; and

Fig. 13 illustrates the position of the coin trap when the other relay armature is operated.

Mounted upon the upper housing l of the coin collector of Fig. 1 is a coin gauge |6 for receiving coins of various denominations and for direct-' ing them into individual channels of a multicoin chute l1 where they selectively actuate suitable sound signals before dropping into the mouth of a coin hopper 18. The first deposited coin upon reaching the coin hopper actuates a coin trigger 26 and then is temporarily held in suspense within the hopper for subsequent col lection or refund depending upon whether or not the desired telephone connection is established.

As shown particularly in Fig. 6, the coin hop-' per mechanism of this invention containstwo vanes 2|, 22 which together constitute a coin supporting means for all coins deposited in the hopper. Vane 2| is pivotally supported, from a pin 23 extending between the front and rear walls of the hopper adjacent hopper side wall 24, while vane 22 is pivotally supported from a pin 25 extending between the front and rear walls of the hopper adjacent the opposite side wall 26. spaced apertures 21 and 28 through which project formed extensions or arms 30, 3| of vanes The front wall of the hopper has two 2|, 22. Arms 36, 3| externally of the hopper are joined by a coiled spring 32 to maintain the two vanesin a normal position with their lower ends engaging each other. Preferably, and as shown in Fig. '7, the lower end'of vane 2| has spaced projections 33 which are adapted to fit into slots between the spaced projections 34 on the lower' Preferably, partition 35 lies in a vertical plane which alsocontains the contacting edges of the two vanes 2|, 22 as will be seen from Fig. 6. In order that a coin held by these vanes may be col.- lected, vane 22 should be held stationary and vane 2| moved downwardly substantially to the position of Fig. 13 to enable the coin to drop into collect channel 36; while in. order that the coins may be refunded, vane 2| should be held stationary and vane 22 moved downwardly substantially to the position shown in Fig. 12, to enable the coin to drop intothe refund channel 31.

The relay construction by means of which the two vanes 2|, 22 may be selectively actuated will now be described particularly with reference to Figs. 3, 4 and 5. The mechanism tray 40 forming the top for the lower housing 38 supports not only the coin hopper l8 but in front of the coin hopper supports the coin relay and associated mechanism. The bent-up lugs 4|, 42 from the bottom of the tray support a plate 43 upon which is mounted a non-magnetic frame structure comprising two vertical members 44, 45 joined at their upper ends by a horizontal plate 46. Suitably fastened within this framework is a solenoidal winding 41 surrounding a magnetic Fig. 11 is a sideview of the coin trigger mecha-v core 46v the ends of which project beyond the frame members 44, 45. Pivotally mounted from base plate 43 near the ends of core 48 .are two armatures, a refund armature 50 and a collect armature5l. Plate 46 of the framework extends beyond both ends of coil 41 and armature 50 works in a slot 52 of one of these extensions, the Walls of said slots serving as stops to determine the attracted and non-attracted positions of armature 56. Similarly, armature 5| works in a slot 56 in the other of these plate extensions and the walls of slot 56 serve as stops to determine the attracted and non-attracted positions of armature 5|. The upturned tab 53 of plate 46 and the armature extension 54 are connected by the armature restoring spring 55 to bias armature 56 against the outer edge of slot 52 in the nonoperated condition. Also, the upturned tab 51 of plate 46 and the armature extension 58 are connected by an armature restoring spring 60 to bias armature 5| against the outer edge of slot 56 in its non-operated condition.

Frame member 46 also supports two members 6|, 62 of magnetic material having spaced prongs 63, 64 and 65, 66 which form pole-pieces for the armature lock. Since these members 6|, 62 are in the magnetic field of winding 41 it follows that for a current applied to winding 41 these two members 6|, 62 will be magnetized with prongs 63, 64 of one polarity and prongs 65, 66 of the opposite polarity, their particular polarity. depending upon the direction of current flow through winding 41. Plate 46 also acts as a support for a stationary vertical pin having a cap 61 and rotatably mounted on this pin is a permanent bar magnet 68 one end of which is adjacent pole- pieces 63, 66 and the other end of which is adjacent pole- pieces 64, 65. Rigidly mounted on permanent magnet 68 for rotation therewith is a plate 10 of non-magnetic material having two laterally disposed arms or lugs 1|, 12 which normally form an armature lock. Magnet 68 is biased to a normal position (Fig. 3) by means of a spring 13 extending between the stationary cap 61 and upturned lug 14 on one end of plate 16,

As long as magnet 68 remains in its neutral position of Figs. 3 and 4 neither armature can,

be moved to its attracted position since armature 56 after only a small movement is stopped when its arm 54 engages lug 1|, and since armature 5| after only a small movement is stopped when its arm 58 engages lug 12. However, when a current traverses winding 41 prongs 63, 64 become of one polarity and prongs 65, 66 become of armature 5| to attracted position. Hence, with bar magnet 68 in the position of Fig. 10 only armature 56 can be moved to its fully attracted position. It is also obvious from Fig. 10 that with current flowing through winding 41in the opposite direction magnet. 68 would be rotated in a clockwise direction to an advanced position determined by the stop 16 in which position lug I2 would lie out of the path of armature extension 58 to permit the fully attracted movement of armature 5| while lug II would still be effective to hold armature 50 in its nonattracted position.

There has just been described the selective manner in which armature 50 will be fully actuated when voltage of one polarity is supplied to winding 41, while armature 5| will be fully actuated for an applied voltage of the opposite polarity. It will now be explained how this selective actuation of the two armatures is utilized to collect or refund any coin supported by the two vanes 2|, 22 within coin hopper I8.

Plate 45 adjacent coin hopper I8 has an upturned portion 'II which supports two spaced pivots I8, 88 for two angular levers or vane latches 8|, 82. The normal position of these levers is shown in Figs. 3 and 4 with both levers resting on a stop 83 formed out of plate portion TI. The lateral extension 84 of vane arm 3| normally engages a shoulder 85 on lever 8| to hold vane 2| in coin supporting engagement with vane 22 while the lateral extension 86 of vane arm 30 normally engages a shoulder 81 on lever 82 to hold vane 22 in coin supporting engagement wtih vane 2|. Therefore, as long as levers 531, 82 are in their normal positions the two vanes 12!, 22 are independently locked in coin supporting position, with each vane completely closing one of the lower coin channels 36, 31.

In order that each lever 8| or 82 may be in dependently actuated by one of the armatures, it will be noted that lever 8| has a downwardly inclined U-shaped portion 88 embracing a pin 98 on armature extension 9| and similarly lever 82 has a downwardly inclined U-shaped portion 82 embracing a pin 93 on armature extension 53. If we assume an applied voltage to winding 41 of such a polarity as to move bar magnet 68 to a position releasing armature 50, but not armature 5|, the resulting attraction of armature 58 will cause pin 80 to engage the inner arm of the U-shaped extension 88 to move lever 8| counter-clockwise as viewed in Fig. 3 to an advanced position shown in Fig. 9 whereby lever shoulder 85 is dropped below vane arm extension 84 to unlock vane 22 while the positive movement of vane 22 to its coin discharging psition of Fig. 12 is insured by reason of the fact that armature 58 in moving to its fully attracted position causes the horizontal arm 85 of armature 58 to positively engage vane arm 84 and force vane 22 from its normal position of Fig. 6 to its coin discharging position of Fig. 12. That is, the full actuation of armature 50 not only unlocks vane 22 but after unlocking supplies positive means for forcing vane 22 to a substantially vertical position where vane 22 remains as long as energizing current traverses the relay winding 47!. However the weight of the deposited coin or coins on vanes 2|, 22, will generally be suflicient to move the released vane 22 to coin discharging position, so that the coin discharging operation generally begins before arm 95 of armature has engaged vane arm 84. It is, therefore, obvious from Figs. 9 and 12 that any coin or coins held in suspense in the coin hopper i8 will be refunded whenever armature 50 is actuated since the consequent release of vane 22 allows the coins to drop in the refund channel 31 while the fact that vane 2| remains in its normal position insures that the entrance to collect channel 36 will remain closed under the assumed conditions illustrated in Fig. 12, where the position of vane 2| is the same as in Fig. 6. The path taken by a coin when vane 22 is unlocked is shown by the five-cent coin 98 of Fig. 12.

If, on the other hand, it is assumed that the voltage applied to winding 41 is of the opposite polarity whereby armature 5| but not armature 5D is released for movement to attracted position, armature pin 93 will engage the inner arm of the U-shaped member 92 to move lever 82 clockwise as viewed in Fig. 3, to an advanced position corresponding to that shown for lever i in Fig. 9 whereby shoulder 81 is dropped below vane arm extension 86 to unlock vane 2|, after which armature extension 91 positively engages vane arm to force vane 2| from its normal position of Fig. 6 to its coin discharging position of Fig. 13, thereby permitting the suspended coin to fall into the collect channel 38, since it will be apparent under the assumed conditions that the other vane 22 will remain locked in its normal position completely closing the entrance to the refund channel 31.

In telephone collectors of the prepay type it is preferable to have the relay winding or windings in circuit with a pair of normally open electrical contacts which are closed upon coin deposit and reopened when the relay is operated due to either collect or refund current. The manner in which these operations are performed by the mechanism of this invention will now be described.

Vertical plate portion 1'! has an extension I00 supporting a pivoting pin IIII for the coin trigger 2h whose counterweight I82 normally maintains the trigger in a substantially horizontal position across the throat of the coin hopper I8 as shown in Fig. 7. Another extension of plate portion TI supports an electrical spring pile-up comprising a biasing spring IE3 and two electrical spring contacts I84, I85. Electrical contacts I84, I85 are normally biased to open position as shown in Fig. 2 but are adapted to be closed upon coin deposit. As shown in Fig. '7 the free end of biasing spring I83 normally engages the side edge of the trigger shoulder I08 to prevent spring I83 from closing the contacts. However, when a coin is deposited the coin operates the trigger from its normal position of Fig. '7 to its operated position of Fig. 8, thereby dropping shoulder I85 below the end of spring I83 to permit spring I03 to-force spring contacts I84, I85 together and against the vertical arm I81 of a trigger restoring lever I08 which is pivoted on the same pin IEI as'the coin trigger. It also may be noted that with the parts in the position of Fig. 8 and before the relay is energized the free end of spring 503 rests on the upper edge of trigger shoulder Ii G to temporarily prevent the restoration of trigger 28 by its counterweight I02. Trigger restoring lever I88 has a downwardly extending arm Iii) which normally rests on top of two studs III, II2 carried, respectively, by the two armature controlled levers SI, 82. Whenever relay winding 41 is energized to rotate either one of the levers 8|, 82 the consequent upward movement of either stud III or |I2 will cause an counter-clockwise rotation (as viewed in Fig. 8) of the trigger restoring lever N38 to cause vertical piece 8'! to engage the spring contact I85 and move the spring pile-up towards the coin hopper a distance suflicient to freetrigger shoulder I88 from the end of spring H13, in which position the spring pile-up will be maintained as long as relay winding 41 is energized. This advanced position of the spring pile-up as shown in Fig. ILtherefore, enables the coin tiiggerlfl to be restored to its normal position of Fig. 7 due to its counterweight I02, so that the subsequent deenergization of relay winding 4! in lowering the advanced stud III or II2 will permit the spring pile-up to assume its normal position of Fig. 3 with the end of spring Hi3 held by trigger shoulder I to allow contacts I04, I05 to reopen.

The operation of applicants mechanism has been described in connection with each component part but it seems advisable to briefly describe the operation in a more chronological manner. hopper I8 operates coin trigger to release spring I03 to close contacts I04, I65 (Fig. 8) to signal the central ofiice by closing a circuit to ground through the winding of relay 41. After actuating coin trigger 20 the coin is held suspended on the two-part coin trap 2I, 22 of Fig. 6. Assuming the desired telephone connection is obtained, thereby requiring the collection of the deposited coin, equipment at the central office supplies collect current to relay winding 4! to rotate permanent magnet 68 clockwise as viewed in Fig. 3 to permit armature 5I to be fully attracted. Armature 5| in pulling up will rotate lever 82 clockwise to unlock vane 2| from lever shoulder 81 to permit vane 2| under the coin load to move from its position of Fig. 6 to its position of Fig. 13 to discharge the coin into collect channel 36. The attraction of armature 5I in moving upwardly stud II2 on lever 82, rotates the trigger restoring lever I08 to cause the spring pile-up to be moved as a unit towards the coin hopper from its position of Fig. 8 to its position of Fig. 11, thereby freeing coin trigger 2i) from the retraining action of spring I03 to permit the trigger to be restored to normal. Hence, when relay 4! is deenergized all parts are restored to normal as in Fig. 3 with the contacts I54, I05 in open condition.

In the event that it is desired to refund the deposited coin, refund current is applied to relay winding 41 with the applied voltage of such polarity that permanent magnet 68 is rotated counter-clockwise to permit armature to be moved to its fully attracted position. Armature 50 in pulling up will rotate lever 8| counterclockwise to unlock vane 22 from lever shoulder 85 to permit vane 22 to move from its position of Fig. 6 to its position of Fig. 12 to enable the coin to be discharged into the refund channel 31.

The attraction of armature 50 in moving up- J wardly stud III on lever 8| rotates the trigger restoring lever I08 in the same manner as described above to restore the coin trigger to normal and reopen contacts I04, I05.

The above-described mechanism presents several advantages, particularly in giving protection against attempted fraudulent operation of the collector. Normally, the armature lock II, I2 prevents both armatures 50, 5I from moving to their fully attracted positions and the vanes H, 22 in the coin hopper are likewise held locked by the vane latches 8'5, 81. It is a customary condition for telephone coin collector relays of the type disclosed in the above-mentioned Forsberg patent that they should not operate for an applied voltage of 40 volts or less, and in the mechanism of the present invention the armature restoring springs and are designed to prevent the armatures from starting to operate for an applied voltage of 40 volts although permitting A deposited coin upon entering coin operation on a somewhat higher voltage. For example, in-one embodiment of this invention where the restoring springs 55 and 60 were tensioned so that the relay would not operate on 41 milliamperes the relay would operate at 44 milliamperes with any load on the coin vanes 2I, 22 from zero to eleven nickels, would release on 33 milliamaperes in the collect direction and 36 milliamaperes in the refund direction. In applicants invention the spread between the operate and release values is kept small because only one armature operates at a time and there always remains the air-gap between the armature and the pole-piece on the other side. This results in less difference in the total reluctance of the magnetic circuit in the normal and operated positions so that there is not as much counteraction to the effect of any change in ampere turns with changes in amplitude of operating current applied to the relay. The difference between the operate and release values is also made less by the use of the two springs I I4, I I5 (Fig; 4) which are compressednear the end of armature travel, adding to the tension of springs 55, 60 at the very end of the armature stroke when the airgap is a minimum. It should be noted that preferably small clearances are provided between the armature. parts 54, 58 and the armature looking lugs 1|, 12 so that upon the application of collect or refund current these locking lugs II, I2 which are of non-magnetic material are free to swing to their fully operated position before the flux in either armature is built up sufiiciently to overcome the tension of the armature restoring springs. V

The biasing spring I3 serves to center the bar magnet 68 when no current is flowing through the coil 41 and also tends to resist rotation of magnet 68 so that the locking lugs II, I2 do not get completely out of the way of either armature until the current through coil i! is greater than the usual talking and signaling current encountered in the field, which is normally less than 15 milliamperes.

. It should be noted that with the armatures in their non-operated positions each'vane latch 88, 92 curves around the armature pins 90, 93 so that each vane latch 88 or 92 cannot move downwardly until its armature has been moved inwardly towards the relay winding. This prevents the coin vanes 2|, 22 from operating due to the weight of the coins and also prevents either vane latch from being jarred open by any blows on the collector housing. Since each armature is normaly prevented from moving by the armature lock II, I2 it is obvious that the vanes2I, 22 in the hopper, the vane latches 88, 92 and the armatures 50, 5I are all looked up and cannot be moved until operating current is applied to the relay winding 41 to release the lock for one of the armatures.

Another desirable feature of applicants invention relates to the prevention of fraudulent operation of the electrical spring contacts. .As shown in Fig. 8 it is evident that the cam surface of trigger shoulder I06 facing the coin hopper has a rising contour to prevent the trigger 20 from being accidentally jarred down. In the above mechanism there is also little chance that theoperating voltage supplied from the central I office to relay winding 41 could be'for such a duration as to permit the trigger 22 to be restored to normal without disposing of the coins in the coin hopper, this being due to the fact that each coin vane is released at the beginning of armature travel, the coin trigger is restored at the end of armature travel and the coin vanes present a steeply inclined supporting surface from which the coins will be discharged quickly.

While the preferred embodiment of applicant's invention has been described above, it is to be understood that alternative arrangements are contemplated commensurate with the scope of the appended claims.

What is claimed is:

1. An electromagnet comprising a winding, a core for said winding, a rotatable member comprising a permanent magnet lying in the field of said electromagnet and adapted to rotate to an advanced position in a clockwise or counterclockwise direction determined by the polarity of the voltage applied to said Winding, means for biasing said member to a neutral position in the absence of applied voltage, a pair of independently movable armatures for said electromagnet, and means carried by said member normally acting as a mechanical barrier to the movement of each armature from its non-operated position to its attracted position, said means when said rotatable member is in one of its advanced positions releasing one of said armatures while maintaining the other armature locked in its non-operated position, said means when said rotatable member is in the other of its advanced positions releasing the second armature while maintaining the first armature locked in its non-operated position.

2. An electromagnet comprising winding, a core for said winding, a rotatable member comprising a permanent magnet lying in the field of said electromagnet and adapted to rotate to an advanced position in a clockwise or counterclockwise direction determined by the polarity of the voltage applied to said Winding, means for biasing said member to a neutral position in the absence of applied voltage, a pair of independently movable armatures for said electromagnet, and means carried by said member and comprising a mechanical barrier normally lying in the path of movement of each armature for locking both armatures in their non-operated position when said member is in its neutral position and for selectively releasing one of said armatures in accordance with the polarity of the applied voltage when said member has assumed an advanced position.

3. An electromagnet comprising a winding, a core for said winding, a rotatable member comprising a permanent magnet lying in the field of said electromagnet and adapted to rotate in a direction determined by the polarity of the voltage applied to said winding, stops for determining the extent of clockwise or counterclockwise rotation of said member, a pair of independently movable armatures for said electromagnet, means carried by said member effective when said member is in neutral position to interpose a mechanical barrier in the path of movement of each armature for locking both armatures in their non-operated positions, effective when said member is in its maximum clockwise position to release one of said armatures and to hold the second of said armatures, and eiiective when said member is in its maximum counter-clockwise position to release said second armature and to hold said first armature.

4. An electromagnet comprising a winding, a core for said winding, a pair of independently movable armatures for said winding, and means comprising a permanent magnet rotatably mounted in the field of said electromagnet for interposing a mechanical barrier in the path of movement of each armature for normally locking both of said armatures in their non-operated positions for zero current in said winding, for unlocking one of said armatures for a voltage of one polarity applied to said winding, and for unlocking the second of said armatures for a voltage of the opposite polarity applied to said winding.

5. An electromagnet comprising a solenoidal winding, a core within said winding, an armature pivoted adjacent one end of said winding, a second armature pivoted adjacent the opposite end of said winding, and means comprising a permanent magnet rotatably mounted in the field of electromagnet for interposing a mechanical barrier in the path of movement of each armature for normally locking both of said armatures in their non-operated positions for zero current in said winding, for unlocking one of said armatures for a voltage of one polarity applied to said winding, and for unlocking the second of said armatures for a voltage of the oposite polarity applied to said winding.

6. An electromagnet comprising a winding. a core for said winding, a pair of independently movable armatures pivoted adjacent the opposite ends of said winding for movement towards said winding when a voltage is applied-to said winding, a rotatable member biased to a normal position and having a lug normally occupying a position to be engaged by said first armature to prevent movement of said armature to its fully attracted position, said member having a second lug normally occupying a position to be engaged bv said second armature to prevent movement of said second armature to its fully attracted position, said member in one advanced position freeing said first armature of said first lug while maintaining said second lug in armature restraining position, said member in a second advanced position freeing said second armature of said second lug while maintaining said first lug in armature restraining position, and means selectively controlled by the polarity of the voltage applied to said winding for moving said member to one of said advanced positions.

JOHN M. MELICK.

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