US2103378A - Time delay apparatus - Google Patents

Description

Dec- 28, 1937. v. L. oEsTNAEs ET AL 2,103,378

TIME DELAY APPARATUS Filed Aug. 24, 1933 2 Sheecs-Sheet l Dec. 28, 1937. v oEsTNAl-:s x-:r Al.

TIME DELAY APPARATUS Filed Aug. 24, 1933 2 Sheets-Sheet 2 C rl rwi'wmsmm,

Patented Dec. 28,l 1937 UNITED STATES PATENT oFFlcE f Swanstrom,

Irvington,

N. J., assignors to American Gasaccumulator Company, a corporation of New Jersey Application August 24,

20 Claims.

This invention relates to a time delay apparatus and involves an improvement in devices of this character wherein the delayed operation of a make and break device of an electrical circuit is controlled by means of a dash pot of the bellows type so constructed that the same air orA other gaseous medium is continuously utilized in the operation thereof, and the delaying operation is automatically discontinued after a predetermined time interval or a predetermined movement of the movable element of the make and break device.

As heretofore constructed, time delay apparatus of this general character has been so designed as to necessitate the use of a fresh charge of air for each successive operation thereof, and, as a consequence, such apparatus has not been uniform in its action by reason of the variations in the time required for operation due to changing atmospheric conditions and dust particles, etc., in the air. The time delay devices heretofore utilized have also been unsatisfactory in that they have not been so constructed as to effect the required quick make and break action which is usually essential to proper operation.

It is one of the primary objects of the present invention, therefore, to provide time delay apparatus for a make and break device of an electrical circuit wherein the 'controlling medium, such as air or other gaseous fluid, is confined within a container so that it may be continuously used. A further object of the invention is the provision of time delay apparatus for a make and break device of an electrical circuit wherein the controlling medium is rendered ineffectual for further delaying the movable element of the make and break device after a predetermined movement thereof. A still further object of the invention is the provision of time delay apparatus for a make and break device of an electrical circuit wherein the controlling medium is confined within ia container having oppositely arranged flexible diaphragm walls and a partition therebetween separating the container into two chambers which communicate with each other through 1933, serial No. 686,592

(Cl. 20o-97) ther object of the invention is the provision of diaphragm stop means for supporting one of the diaphragms of the improved device in its outermost or distended position in such a manner'that the diaphragm will notl adhere thereto in the operation of the apparatus, and to insure the utilization of a uniform volume of gas in the 'com- Still other rejects and'advantages of the invention will be apparent from the following description, taken with the accompanying drawings, wherein:

Fi'g. 1 is a vertical sectional view, partly in elevation, of the improved apparatus;

Fig. 2 is a transverse sectional view taken on the line 2-2 of Fig. 1, with the outer casing omitted;

Fig.. 3 is a transverse sectional view taken on the line 3-3 of Fig. 1, with the outer casing omitted andthelower diaphragm partly broken away;

Fig. 4 is a transverse sectional view, on a smaller scale, taken on the line 4 4 of Fig. 1;

Fig. 5 is an elevational view, partly in section,

of the bellows dash pot forming a part of the improved apparatus; and

Fig. 6 is a diagrammatic view of the electrical circuits utilized in the apparatus.

As disclosed herein, our circuit control device is enclosed within a casing I0 having its opposite side walls II and I2 and its top wall I3 formed from a strip of'sheet metal between the lower ends of which the bottom wall I4 of insulating material is secured by bolts I5 extending therethrough and having nuts I6 therein in engagement with brackets I'I riveted or otherwise secured to the lower vends of the side walls. Extending transversely between the sidewalls II and I2 are spaced partition lmembers I8 and I9 having the ends thereof bent transversely as shown at 20 for engagement with the walls IAI and I2, to which they are secured byrivets 2|.

'I'he opposite side edges-of each of the partition` members I8 and I9 have projecting portions 22 thereon likewise bent transversely to the body portions of the partitions and provided with perforations 23 to receive bolts 24 or other suitable means for securing the front and rear walls 25 ,ang Z5 @t the casing in position. The rear wall 1 CII 26 may have secured thereon belts 21 for mounting the assembled device upon a suitable support.

Secured to the bottom wall I4 of the casing Il! is a pair of stationary contacts each of which comprises a substantially rigid, upright portion 28 having its lower end angularly bent as shown at 29 for engagement with the inner face of the bottom wall and to which it is secured by means of a bolt 30 which also serves as a terminal for the electrical circuit controlled by our improved device. The upper end ofeach of the upright portions 28 is inclined inwardly as shown at 3l for engagement by the hooked upper end 32 of a flexible contact portion 33, the lower end of which is riveted or otherwise secured to the upright portion 28. 'I'he inclined upper end of the flexible contact portion 33 has secured to the under side thereof in any suitable manner a contact point 34. As will be seen from Fig. 1 of the drawings, the'hooked end 32 of the ilexible contact portion 33 is of such a size with respect to the free end of the inclined portion 3i of the upright member 28 as to permit a certain freedom of movement between the free end of the flexible portion 33 and the free end of the inclined portion 3i, for a purpose which will be clear from the structure hereinafter described. A movable contact 35 is supported on the lower end of a transmission rod 35. for movement into and out of engagement` with the stationary contact points 34 for the purpose of making and breaking the circuit in which the stationary con' tacts are connected and which our device is designed to control. As shown herein, the movable contact comprises a cone-shaped metallic member having a central opening 3l through the upper end thereof for looselyv engaging upon a shoulder-38 formed on the upper face of an insulating block 39 carried by the lower end of the transmission rod 36. The movable contact is retained in position on the shoulder 38 by another insulating block 40 carried by the transmission rod 36 andvresting upon the lowerinsulating block. With a mounting of this character the movable contact 35 is freely rotatable upon its support so that new contacting surfaces are brought into use from time to time during the operation of th'e device. The two insulating blocks 39 and 40 are arranged to be adjustably supported on the lower end of the transmission rod 36 between two nuts 4I and 42 threaded on the transmission rod.

Although it will be understood that other means may be employed for actuating the movable contact or bridge piece 35 into and out of engagement with the stationary contact points 34 for the purpose of making and breaking the electrical circuit controlled by the device, as disclosed herein we have shown a coiled compression spring 43 surrounding the transmission rod 36 and serving as the prime mover for making the electrical circuit. utilized for placing this .spring under compression such as clock-work, an electrical motor, or even manually operated means. Preferably, however, we employ a solenoid having a coil 44 supported between the transverse partitions I8 and I9 and provided with terminals 45 and 46as shown in Fig. 4, for connecting the same to an energizing circuit. y Mounted for longitudinal movement in the central opening of the solenoid coil 44 isa core 41 provided` with a longitudinal Various means may vbepression spring 43. The lower end of spring 43 engages against a shoulder 49 in an enlarged opening in the upper end of the core 4l, and the upper end of the spring 43 engages with a stop on the transmission rod, preferably in the form of a nut 50 threaded on the upper end thereof.`

1inv order to retard the action of the movable contact member in its movement toward circuit making position under the influence of spring 43, we have provided a novel form of bellows dash pot comprising an open-ended casing 5i having a partition wall 52 extending transversely thereof and substantially midway of the open ends. The upper end of the casing is closed by means of a flexible diaphragm 53Y which is preferably preformed in order to insure maximum. exibility. 'I'he edge of this diaphragm is supported upon a shoulder 54 formed on the upper end of the casing and is retaind in positionthereon by means of a clamping ring 55 having screws 53 passing therethrough into threaded engagement with suitable openings in the casing wall.

The lower end of the dash pot casing is closed by means of a exible diaphragm 3l having its outer edge supported upon a shoulder 53 on the lower end of the casing and secured thereon by means of a clamping plate 59 retained in position by means-of screws 6passing through suitable openings therein into threaded engagement with alined openings: in the wall of the casing. The clamping plate 59 is also constructed to operate as a stop for the diaphragm 51 when in its distended position as shown in Figs. 1 and 5. A plurality of concentrically arranged supporting ribs .60 are formed upon the inner face of the plate,

and, as disclosed inthe drawings, these ribs are preferably olf-set from each other transversely of the plane in which the edge of the diaphragm is mounted. By odsetting the ribs in this man-A y ner the diaphragm 51 is supported thereon in its.

vent the diaphragm from adhering to the platev and having a lock nut threaded thereon :into engagement with a washer BB contacting "with theA lower face of the diaphragm. An extension on the hub 62 is provided with a central threaded opening 61 to receive the upper threaded end of th'e transmission rod 36,l and the rod is secured" in adjusted position therein by'means of a lock nut 68. Y

As will be noted fromv the drawings, the ar- 'rangement of the exible - dii'iphragms 53 and 51 75 with respectto the transverse partition 52 provides two fluid chambers 59 and 10 respectively, the chamber 10 serving as a compression chamber and the chamber 69 serving as an expansion chamber for the gaseous iluid utilized in the device. In order to provide for free, but throttled communication between the compression chamber 10 and the expansion chamber 69 a leak port 1| is provided through the partition wall 52. As shown in Fig. 510i the drawings, this port is provided with an enlargement 12 intermediate the two chambers to receive an adjustable throttling device. The improved device which we have pro.- vided for this purpose comprises a mass of compressible material 13, preferably in the form of shredded asbestos fibers, within which a coiled spring 14 is embedded. An adjustable plug 15 is threaded in the outer end of the enlargement 12 in the passageway so that when this plug is screwed inwardly it operates to compress the mass of asbestos fibers and thereby decrease the iiow of air or other gaseous fluid to and fro between the compression chamber and the expansion chamber. By unscrewing the plug 15 the coiled spring 14 embedded in the fibrous mass 13 operates to expand the mass and thereby permit an increased flow of air or other fluid. A suitable screen 16 may be employed at either or both ends of the mass of fibers for the purpose of properly retaining the fibers within the enlarged opening 12 provided therefor.

The partition wall 52 is also provided with a relatively large passageway or equalizing port 11 in communication with the compression chamber 'l0 and the expansion chamber 69. 'I'he end of the passageway 11 opening into the compression chamber 10 is enlarged to provide a shoulder '18 for receiving a suitable washer 19 which serves as a valve seat for the valve member 89. 'I'his valve member is provided with a marginal flange BI for engagement with the washer 19 and has a centrally arranged boss 82 cupped as shown at 83 to receive a cooperating projection 84 on one end of a valve lever 85, the valve 80 being secured thereto by means of a pin 86 extending centrally through the boss 82 and having a headed outer end 81 engaging within a socket 88 in the lower face of the lever. By this construction the valve 80 is permitted suilcient freedom of movement with respect to the lever 85 to enable the flange 9| to engage properly upon the valve seat. The valve lever 85 is supported intermediate its length upon a pivot pin 89 the opposite ends of which are secured in a groove 90 in the lower face of the partition wall 52, the edge of the groove being punched inwardly as indicated at 9| to retain the pivot pin in position.

The end of the valve' lever 85 opposite the valve 80 is provided with an opening therein to receive a cup-shaped retainer 92 for one end of a coiled spring 93, the opposite end of which is seated within a suitable recess 94 in the partition wall 52. The coiled spring 93 tends to retain the valve 80 in its closed position to thereby cut olf communication between the chambers 69 and l0 through clearly shown in Fig. 2. The outer end 99 of this lever is angularly bent and provided with an opening to receive a reduced portion 0| on the end of the valve lever 35. The opposite end of the valve lifting lever 95 extends into a position somewhat centrally over the lower diaphragm 51 and is provided with a curved portion |02 for engagement with the inner end of the hub 62 by which the transmission rod 35 is connected to the lower diaphragm. As will be clear from the dotted line position |03 of the hub and diaphragm as shown in Fig. 1, when the diaphragm 51 reaches this position in its upward movement, and the movable contact 35 reaches the dotted line position |04, hub BZengages with the free end |02 of the valve lifting lever to thereby lift the cut-off valve 80 from its seat and provide free communication between the compression chamber '10 and the expansion chamber 69, thus permitting the coiled spring 43 to move the contact 35 quickly into engagement with contact points 34. 'I'he manner in which the contactv points 34 are mounted is such as to provide a wiping action of these points upon the surface of contact 35 as the latter moves into and out of engagement therewith.

The dash pot device is supported in the upper end of the casing I0 by means of screws |05 passing through blocks |06 welded or otherwise secured to the top wall |3 of the casing l0 and threaded into suitable openings in the wall of the dash pot casing While we have shown the heads of the screws |05 supported by blocks upper wall of the casing I0.

Although the operation of our improved circuit control device will doubtless be clear from the above description of the structure thereof, it will be noted that whenl the solenoid coil is energized by the passage of an electrical current therethrough the core immediately responds to the action of the current and moves upwardly into contact with the stop 48, thereby placing -the coiled spring 43 under compression, and remains in this position until the circuit through the solenoid coil is broken. The tendency of coiled spring 49 to expand when placed under compression by the upward movement of the core causes the upper end of the spring to act against the stop nut 50, thereby tending to move thev transmission rod 36, together with the movable contact 35 carried on the lower end thereof, into circuit making position. The upward movement of the transmission rod and the movable contact is retarded by the action of the diaphragm 51 against the air or other gaseous fluid contained in the compression chamber 19. As the air in the compression chamber leaks through the throttling device into the expansion chamber 69, the diaphragm 51 is permitted to move upwardly and eventually the hub 52 contacts with the free end of .the valve lifting lever 95 which operates the valve 80, normally retained in closed position by the air pressure in the compression chamber.

'Ihe movable Contact 35 and the diaphragm hub 62 are preferably so adjusted on the transmission rod 36 that the movable contact is at such a distance from the stationary contacts as to avoid sparking of the contacts when the hub engages with the free end of the valve lifting lever. At the moment the hub 62 comes into contact with the valve lifting lever 95 in its upward movement the valve 850 is lifted from its seat to open the equalizing port 'il whereupon the diaphragm 51 and the transmission rod 36 continue their upward movement at a comparatively rapid rate to thereby produce a snap action of the movable contact member 35 into circuit making position. The movable contact member is retained in circuit making position as long as the solenoid coil is energized by the passage of current therethrough.

The rate of leakage of the air from the compression chamber l@ into the expansion chamber 69, and'consequently the delaying action of the diaphragm 571 upon the upward movement of the movable contact 35, may be regulated by means of the adjustable throttling valve in the leak port ii. The spacial movement of the diaphragm l and of the movable contact 35 is therefore xed, andthe time element of the delaying operation is determined by the rate of leakage of air through the leak port li.

When current is cut oi from the solenoid coil the core drops under force of gravity and carries the transmission rod 36, the diaphragm 5l and the movable contact member 35 along with it, thereby eecting a snap action of the movable contact member in breaking the circuit in which the stationary contacts are connected.

As we have disclosed the same herein, the stationary contacts and the movable contact are so arranged that the electrical circuit is made by the expansion of the coiled spring under the inuence of the solenoid core. -As will be understood, however, the parts may readily be rearranged so that the movable contact member operates to make the circuit through the stationary contacts at the end of the downward movement -of the movable contact member, and the circuit would thereupon be broken by the upward movement of the movable contact member undervthe expansion of the coiled spring. It will also be understood that the particular type of bellows dash pot disclosed herein may be utilized without the equalizing port and valve therefor where it is not essential to have a snap `action for the make and break device as the movable contact member moves in one direction under the influence of the coiled compression spring. It will be further understood that, al-

though we have disclosed communicating compression and expansion chambers in the device, the expansion chamber may be dispensed with undercertain circumstances where it is not desirable to utilize the same uid continuously. Still other changes in structure and arrangement of the parts of our device may be made Without departing from the invention as covered by the appended claims.

Having thus described our invention, what we claim and desire to secure by Letters Patent is:

1. In a time limit control device, the combination of a solenoid, a core movable therein, a transmission rod movable with said core and having a lost motion connection therewith, and delay means for said transmission rodcomprising a compression chamber having a diaphragm wall connected to said transmission rod, an expansion chamber associated with said compression chamber, a throttling valve between said chambers, an equalizing valve between said chambers, means for closing said equalizing valve, and means for opening said equalizing valve upon a predetermined spacial movement of said transmission rod.

2. In a time limit control device, the combination of an electromagnet, an energizing circuit therefor, a transmission rod having a, lost motion energy storage connection to said electromagnet, and delay means for said transmission rod comprising a compression chamber having a diaphragm wall connected to said transmission rod, an expansion chamber associated with said compression chamber and having a diaphragm wall therein, a throttling valve between said chambers, an equalizing valve between said chambers, means for closing said equalizing valve, and means for opening said equalizing valve upon a predetermined spacial movement of said transmission rod.

3. In a time control device, the combination of an electromagnet, an energizing circuit therefor, and delay means for said electromagnet comprising a compression chamber having a diaphragm wall actuated by the movement of said electromagnet, an expansion chamber associated with said compression chamber and having a diaphragm wall therein, a throttling valve between said chambers, an equalizing valve between said chambers, means for closing said equalizing valve, means for opening said equalizing valve upon a predetermined spacial movement of the diaphragm wall of said compression chamber, and energy storage means interposed between said electromagnet and the diaphragm wall of said compression chamber.

4. In a time limit control device, the combination of an electromagnet, an energizing coil therefor, and delay means for said electromagnet comprising a compression chamber having a movable wall therein, an expansion chamber associated with said compression chamber and having a movable wall therein, a throttling valve between said chambers, an equalizing valve between said chambers, means for closing said equalizing valve, means for opening said equalizing valve upon a predetermined spacial movement of the movable wall of said compression chamber, and a compression spring interposed between said'electromagnetand the movable wall of said compression chamber.

5. In a time limit control device, the combination of an electromagnet core having an openingr extending lengthwise therein, an energizing coil for said core, and delay means for said core comprising a compression chamber having a movable wall therein, an expansionhamber associated with said compression chamber and having a movable wall' therein, a throttling valve between said chambers, an equalizing valve between said chambers, means for closing said equalizing valve, means for opening said equalizing valve\.upon a predetermined spacial movement of the movable wall of said compression chamber, a transmission rod secured to the movable wall of said compression chamber and extending into the opening in said core, and a coiled compression spring surrounding said transmission rod between said core and the movable wall of said compression chamber.

6. In a time limit circuit control device, the combination of an electromagnet core, an energizing coil therefor, a stationary contact in said circuit, a movable contact for making and breaking said circuit, and means responsive to the movement of said core under the action of said coil for actuating said movable contact comprising a compression chamber having a diaphragm wall therein. an expansion chamber associated with said compression chamber and having a diaphragm wall therein, a throttling valve between said chambers, an equalizing valve between said chambers, means for closing said equalizing valve, means for opening said equalizing valve upon a predetermined spacial movement of the diaphragm wall of said compression chamber, a transmission rod extending freely through said core and having one end connected to said movable contact and the opposite end connected to the diaphragm wall of said compression chamber, and a compression spring lost motion connection between said core and the diaphragm wall of said compression chamber.

'7. In a circuit control device, the combination of an electromagnet core, an energizing coil therefor, a stationary contact in said circuit, a movable contact for making and breaking said circuit, and means for actuating said movable contact in response to the movement of said core under the action of vsaid coil comprising a uid container having a pair of movable walls and a partition dividing said container into a compression chamber and an expansion chamber, said partition having a throttled passageway therethrough communicating with said chambers and an equalizing passageway therethrough, a normally closed valve for said equalizing passageway, a transmission rod connected to the movable wall of said compression chamber and extending freely into said core, a compression spring interposed between said transmission rod and said core, means foropening said valve upon a predetermined movement of said transmission rod, and meansfor mounting said movable contact upon said transmission rod.

8. In a circuit control device, a stationary contact, a movable contact cooperating therewith to make and break said circuit, power means for actuating said movable contact, and fluid controlled means for retarding the action Iof said movable contact by said power means comprising a compression chamber having a diaphragm wall con-A nected to said movable contact vfor movement therewith, an expansion chamber associated with said compression chamber, a throttling valve between said chambers, an equalizing valve between said chambers, means for closing said equalizing valve, and means for opening said equalizing valve upon a predetermined movement of said movable contact.

9. In a circuit control device, a stationary contact, a movable contact cooperating therewith to make and break said circuit, a compression spring arranged to actuate said movable contact when under compression, means for placing said spring under compression, and iluid controlled means for retarding the action of said movable contact by said spring comprising a compression chamber having a diaphragm wall operatively connected to said movable contact for movement therewith, an expansion chamber associated with said compression chamber, a throttling valve between said chambers, an equal'izing valve between said chambers, means for closing said equalizing valve, and

means for opening said equalizing valve upon a predetermined movement of said movable contact.

l0. In a circuit control device, a stationary contact, a movable contact cooperating therewith to make and break said circuit, actuating means for said movable contact, and fluid controlled means for retarding the action of said actuating means comprising a compression chamber having a diaphragm wall therein operatively connected to said movable contact, an expansion chamber having a diaphragm wall therein and communicating with said compression chamber through a leak port and an equalizing port, a throttling valve for said leak port, an equalizing valve for said equalizing port, means for closing said equalizing valve, and means for opening said equalizing valve upon a predetermined movement of said actuating means.

ll. In time delay apparatus for a circuit make f and break device comprising a stationary contact, a movable contact and actuating means for operating the movable contact in one direction, a uid container having oppositely arranged diaphragm walls therein, a partition extending across said container between said diaphragm walls and dividing the container into a compression chamber and an expansion chamber, a leak port connecting said chambers, a throttling device for said leak port, an equalizing port between said chambers, 'a cut-off valve for said equalizing port, means normally retaining said cut-off valve in closed position, lifting means for opening said cut-off valve, connecting means between said movable contact and the diaphragm wall in said compression chamber, and means for actuating said lifting means upon a predetermined movement of said movable contact.

12. In fluid controlled time delay apparatus, a compression chamber having a diaphragm wall therein, an expansion chamber associated with said compression chamber and having a leak port and an equalizing port leading thereto from said compression chamber, a throttling device in said leak port, a out-off valve in said equalizing port, means tending to retain said cut-off valve in closed position, and means to open said cut-off valve upon a predetermined movement of the diaphragm wall of said compression chamber.

13. In time delay apparatus, a uid container having a pair of oppositely arranged diaphragm walls therein, a 'partition extending across said container between said walls and dividing the same into a compression chamber and an expansion chamberand having a leak port and an equalizing port connecting said chambers there- Y through, a throttling valve for said leak port, a

cut-orf valve for said equalizing port, means tending to retain said cut-off valve in closed position, operating means in said compression chamber for opening said cut-oil' valve, and means connected to the diaphragm wall of said compression chamber for actuating said operating means upon a predetermined movement thereof.

14. In time delay apparatus'and the like, a fluid container having a pair of oppositely arranged diaphragm walls therein, a partition extending across said container between said walls and dividing the same into a compression chamber and an expansion chamber and having a leak port and an equalizing port connecting said chambers therethrough, a throttling valve for said leak port, a cut-off valve for said equalizing port supported within said compression chamber, spring meansA for normally retaining said cut-off valve in closed position', a valve opening lever having one end connected to said cut-oftvalve and the opposite end projecting centrally over the diaphragm wall of said compression chamber, and actuating means on said last mentioned diaphragm wall for contacting with said lever to open said cut-oir valve upon a predetermined inward movement of said actuating means.

15. In a circuit control device, a stationary contact, a movable contact cooperating therewith to make and break said circuit, power means for actuating said movable contact, and fluid controlled means for retarding the action of said movable contact by said power means comprising a compression chamber having a diaphragm wall connected to said movable `contact for movement therewith and a leak port and an equalizing port opening therefrom, a throttling valve in said leak port, a normally closed cut-off valve for said equalizing port, and means for opening said cutoff valve upon a predetermined spacial movement of said movable contact.

16. In a circuit control device, a stationary contact, a movable contact cooperating therewith to make and break said circuit, actuating means for said movable contact, andA fluid controlled 17. In a circuit control device, a stationary contact, a movable contact cooperating therewith to make and break said circuit, actuating means for said movablecontact, and fluid controlled means for retarding the action of said actuating means comprising a compression chamber having a diaphragm Wall therein operatively connected to said movable contact, an expansion chamber having a passageway communicating with said compression chamber, an adjustable throttling valve for aioasvc phragm wall in its distended position -comprising a plurality of radially spaced, rigid supporting members concentrically arranged with respect to said diaphragm.

19. In time delay apparatus and the like having an enclosed fluid chamber and a flexible dia.

phragm wall therein, stop means for' said diaphragm wall in its distended position comprising a plurality of radially spaced, rigid supporting members concentrically arranged with respect to said diaphragm wall and offset from each other transversely of the plane of the diaphragm wall mounting.

20. In time. delay apparatus and the like, an open-ended fluid chamber of rigid material, a eXible diaphragm covering the open end of said chamber, and stop means for said diaphragm in its distended Vposition comprising a rigid plate mounted on said casing outside of said diaphragm and having a plurality of spaced, annular ribs projecting from the inner face thereof and a plurality of openings extending therethrough between said ribs, said ribs being progressively offset from each other. transversely of the plane of the diaphragm mounting.

' VICTOR L. OES'I'NAES.

CARL ARTHUR SWANSTROM.

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