US2461625A - Telescopic structure - Google Patents

Description

Feb 15, 1949. a. o. BENSON TELESCOPIC STRUCTURE Filed July 26, 1945 2 Sheets-Sheet 1 INVENTOR.

Fe. 15, 1949; G. o. BENSON TELESCOPIC STRUCTURE Filed July 26; 1945 2 sheets-sheet 2 INVENTOR ATTORNES.

Patented Fel TELESCOPIC STRUCTURE George 0. Benson, Niagara Falls, N. Y. assignor to Chisholm-Ryder Company,

Incorporated,

Niagara Falls, N. Y.', a corporation of New York Application July 26, 1945, Serial No. 607,213

6 Claims.

This invention relates to a telescoplc'structure andmore particularly to such a structure, such as a portable radio antenna, composed of telescoping sections which .are nested together and which can rapidly be extended to provide a mast capable of being set up on any mobile or stationary support and used for sending or receiving radio messages. However, the invention is not confined to any particular use and can also be used as a telescopic support to carry signal lights or the like and for other like uses, such as tent poles.

One of the principal objects of the present invention is to provide such a telescopic structure in which the sections can be quickly extended and the several sections quickly latched in their extended positions so that the structure is re- .liably held in its extended position.

A further object of the invention is to provide :such a telescopic section in which the latching means holding the structure extended can be :readily released and the several sections nested :together without the use of tools.

Another object is to provide such a releasable latch for a telescopic structure in which there :ls no danger of the accidental'release of the latch between any of the sections, the release of the latch requiring an unusual manipulation of the sections which is not liable to occur accidentally.

A further object is to provide such a latch which is strong and reliably holds the sections in an extended position.

Another aim is to provide such a latch which "is not liable to be broken in setting up the structure, particularly if the operator uses excessive force in turning the sections relative to one another in effecting either the latching or release of the several sections. Another aim is to provide such a latch which does not require the addition of any parts to the telescopic structure, the latch being provided by stamping sections out of the ends of the tubes so that the latch is integral with the tubes.

Another 'aim'is to provide such a latch located ata point remote from the zone of greatest strain on the telescopic joint,'when the sections are extended, so as to impair the strength of the telescopic joint and structure to the least degree.

Another aim is to provide such a latch which does not require the use of tools to unlatch th telescopic sections. a

Another aim is to provide such a structure in which the form of the latch does not interfere with the complete nesting of the several sections completely inside thereby to insure that the nested structure is in its most compact form.

Another aim is to provide such a telescopic structure composed of metal tubes in which good electrical contact is insured between the several tubes so'that it can be employed as a radio antenna. v

Another purpose is to provide such a tubular telescopic structure in which the opposite ends of each section can be brought to the exact diameter required to fit the succeeding sections, thereby to permit of-the use of standard tubing in' which the tolerances are not maintained sufiiciently close to insure a good telescopic fit,

Another aim" is to provide such a telescopic structure which is simple and inexpensive in construction and which can be repeatedly extended and nested without Objectionable wear or de: te'rioration. I

Other objects will appear from the following description and drawings, in which Fig. 1 is a fragmentary longitudinal section through the base section and next succeeding section of a mast antenna embodying the present invention.

- Fig. 2 is a transverse 2--2, Fig. 1.

Fig. 3 is a. fragmentary side elevation viewed from line 3-3, Fig. 1.

Figs. 4 and 5 are fragmentary side elevations of the tube ends which are interfitted to form the structure shown in Fig. 3. a

Fig. 6 is an enlarged view similar to Fig. 3 and showing another position of the parts to illustrate the particular manipulation required to release the sections from one another.

Fig. 7 is a section, taken on line 1-1, Fig.5.

Fig. 8 is a view similar to Fig. 3 showing a modified form of the invention.

Fig. 9 is a fragmentary longitudinal section, taken on line 9-9, Fig. 8.

Fig. 10 is a view similar toFig. Sshowing the parts manipulated to release the latching tongue.

FigJ'll is a fragmentary longitudinal section, taken on line l 1-! i, Fig. 10. 1

Fig. 12 is an enlarged fragmentary cross section, taken on line I2! 2, Fig. 10.

Fig. 13 is a fragmentary enlarged side elevational view of the inner end of one of the telescopic sections, this view being taken on lin 13-43, Fig. 12.

While the invention is not confined to any particular use, it is shown in the form of the invention illustrated in Figs. 1-7 as embodied in a metal antenna mast which has a tubular base c on. t n on ne a it or enclosing section I and which may have a dozen or more tubular metal sections II which telescope into one another and into the base section II) so that in the nested condition of the parts the entire mast is contained within the base section I0. The base section I0 is shown as having a plug I3 for mounting. it on any suitable support, this plug being fitted into an enlargement I4-of this basesection.

The construction of the joint and latch between each of the several sections i I is identical to the joint and latch shown between the first section I I and the base section it and hence the .description of the joint and latch shown willbc deemed to apply to the successive joints of'the mast. As shown in the drawings each of the sections II is provided with an enlarged end l5 and each of the sections it! and M is provided witha. reduced end It, the enlarged end of each section being fitted in the reduced end of the next succeeding section. By forming the several tubular members H *-with the 'enlargedand reduced-ends Hand 55, these ends can bebrought to theexact tolerances required for snug interfitting in the extended position of themast regardless of minorvariationsinthe original sizeof the tubing used. Thus, standard commercial tubing var.- ies in inside and outside diameter to an extent greater than the permissible tolerances for a telescopic mast.

- To overcome this-variation in the size ofa commercial tubing, the enlarged end I5 of each section is expanded-into a'surrounding die.to the exact outside diameter required and the opposite reducedend' 16 of each section is contracted around an internal die to provide the exact inside diameter required. The standard tubing used therefore vary substantially in inside or outside diameter but the opposite ends thereof are brought to the exact inside and outsidediameter required to secure :thenecessary snug fit between the several sections when the mast is 'extended'so as-to'interfit'the ends of the several sections, as illustrated in 'Fig. 1. In this figure, while the enlargements I 4, I5 must-besubstantially greater than the tubing from which they are formed-,Tor a purpose'which will presently appear, the contractions I6 at the opposite -en'ds of the-tubesare exaggerated and may not even be perceptible, the sole function of these contractions I'6 being to bring the-tubes to a definiteinside'diameter regardless of variations in.

the tube size.

' The outer extremity of the reduced end iBof "each-section it and is rolled over to provide an -inwardly extending head or flange I 8, this inwardly projecting bead or flange engaging the come accidentally released. the }r 4 ent invention is to provide a simple and sturdy latch at the joint between the several sections which holds the mast extended and which can readily be released so as to permit of nesting the several sections in transporting the mast to another place. A further feature of both forms of the invention resides in the latch being of such character. that the. sections cannot beeleas e-f of each latch requiringa special manipulation of the two connected sections which manipulation is not liable to occur accidentally. A further feature of both forms of the invention is to locate the latch of each telescopic joint remote from the zone of greatest strain where it does not mate- 7 rially reduce the strength of the telescopic joint.

For this purpose, in the form of the invention shown in Figs. 1-7, the enlarged end It of each annular'externalshoulder it between the body and enlargement I5 of the corresponding section II slidingly fitted thereinthereby to provide a .stopto limit the outward movement ofeach section relative to its enclosing section. :These stops I8, it further serve to accurately locate the latch in ,each section axially with reference to the ,openingproyided in the succeeding section so that no difficulty is experienced in interlatching of the sections H of the mast has a pair of 0pposed tongues 2:: out or stamped therein, these tongues bein bounded'at their sides by spaced slitsor slots 2-! which are -arranged. in planes at right angles to the'axis of the mast so-thatthe "tongues project circurni'erentially in opposed re-'- lation toeach other.- providcd with end-22 of less axial 'extentthan' of these tongues is the body portion of each tongue so that each tongue is provided with I a square shoulder 23ml;

each sideof its reducedend'22. Also,-'-the;reduced end 22 of each tongue is deio-rmed or-bent soas to curve outwardly, as best shown in Figs. a a e 7;

and thereby provide anoutwardlyiacing cam face opposing the outer tube.

The'reduced end I'Boi eachofthe-sectionsI0 and II isprovided wlth a generally-rectangular slot 25, this slot. having axiallyextending-parallel edges 26: and-circumferentially extendingparallel edges 28. The circumferentially extending-edges 28 are spaced from each other a-distance-slightly greater than the width of the reduced ends 22 of the tongues but are spacedcloser-than-dhe enlarged body-portions of these tongues. of these slots :2 5 is arranged to registerwith the tongue 29 of the next succeeding-inner section ii when the.corresponding stop bead I B- engages its companion shoulder l9. lt-willthereforebe seen that when any-pair of the-sections is fully extended sothat the-enlargedend I5 of one section is fitted inth'e reduceden d i6 #1; of the other section with its-shoulder IS-inengagement with-the. stop. bead l-d-ofthis other sec- .tion, the sections can be rotated relative-to each other until the reduced ends zz of thecorresp ondin pair. of opposed. tongues .20 snap out into the corresponding slot -.25,-.th-is.-pos ition of the parts beingillustrated in Figs. -l -3. W-he'n this occurs the parts are latched together. 1 Thus,

the. axial'inward movement of the-twosectionsis prevented by the engagement .of thercorresponding sides of the'reducedportions-22 of' the- -pair of opposed, tongues with the corresponding-circumferentially extending edge 28. of the slot-25, the axial outward movement being prevented by the stop bead 48. Further, if either section is turned in one direction relative to: the other section, the extremity of the outwardly-curved re-.

duced end'22 of one. of. the pair of tongues comes into engagement with the corresponding axially extending edge-260i the-s1ot25-so-astoprevent further turning of the parts relative to each other thatdireotion. 'If the two sections aretwisted relatives to: each other in the opposite --direction the outwardly curved reduced end 7&2 of theopposite tongue comes into engagement-with the opposite axially extending edge 26-of the slot 25 so as to prevent'further turning in that direction. It will therefore be seen that the several sections of the mast, when so latched by the presence of the outwardly curved ends 22 of the opposed tongues 20 in the slot 25, prevent axial movement of the sections inwardly relative to each other and also permit only a very limited rotative movement of the sections relative to each other so that the several sections are reliably latched together..

It will iurther be seen that the provision of the pair of shoulders 23 on each tongue by providing the ends 22 of less width than the bodies of the tongues permits the entry of only the reduced ends 22 of the pair of opposedtongues into the slot .25. By this means the operator is prevented from twisting the tongues off in applying too much force in rotating the sections relative to each other either when setting up the mast or when taking it down as hereinafter described. Thus, if the tongues 28 were of uniform width throughout their entire length the sections could be turned until the base of each tongue would engage the opposing axially extending edge 26 of the slot 25 and in this condition the tongue would be extended to a substantial degree and could readily be torn off if an excessive rotative pressure were exerted in the same direction against the tWo sections. Since only. the tips of the tongues are permitted to project into the slot 25, the danger of tearing the tongues off by the application of too great a rotative force is avoided.

As previously indicated, the several sections of the mast are capable of being unlatched and again nested. For this purpose the rectangular opening 25 is provided in one of its corners opposite the stop beadill with an axially extending notch 39. This notch can be in either of the corners remote from the stop bead l8 and is of comparatively slight depth and width, it being only necessary that it be capable of receiving the upturned extremity of that tongue 29 which is rotated toward the notch. In unlatching the several sections from the latched condition shown in Figs. 1-3, the operator rotates the two sections so that the outer section rotates in the direction of the arrow shown in Fig. 6 and the inner section rotates in the opposite direction.

Thisdraws the advanced tongue 22 out of the opening 25, the curved end of this advanced tongue being drawn into the outer section, as illustrated by dotted lines in Fig. 6, and the extremity of the other tongue 29 being brought against that axial edge 26 of, the slot 25 which bounds the notch 30. In this condition the latch is efiective, as previously described. However, it will be seen that the notch 33 now permits the two sections to be moved axially relative to each other to the extent permitted by the notch 30. The position of the parts with the outwardly curved extremity of one of the tongues 20 in the notch 38 is illustrated in Fig. 6. In the position of the parts illustrated in Fig. 6, it will be seen that uponrotating the two sections in the reverse direction the tongue extremity caught in the notch 38 will be drawn under the shoulder provided by this notch and hence into the outer section and out of latching engagement with the opening 25. At the same time a slight axial movement is imparted to the two sections so that the extremity of the other tongue does not enter the notch 30 when such rotation of the parts is eflected.

It will therefore be seen that the joint between each of the sections is readily unlatched but that this requires a special manipulation of the two sections, this comprising rotating the sections relative to each other so that one of the tongues is brought against that edge 26 of the opening 25 which bounds the notch 39; then moving the two sections axially so as to cause the extremity of the tongue so engaged to enter the notch 36; and then effecting a reverse rotation of the parts with a slight axial movement thereof, so that the tongue extremity so caught in the notch 30 is withdrawn into the outer section and out of latching engagement with the opening .25 therein.

It will be seen that the notch 30 permits of unlatching the sections without the use of tools, this being an important feature of the invention. However, it will be seen that the unlatching could be effected without the notch 30 by pressing that tongue 2:: Which is eiTective as a latch inwardly by hand or by a tool such as a knife or screw driver so as to release it from the opening 25. Further, it will be seen that the latch would be effective with only one tongue 20 in which case the sections would be latched against axial movement but could be released by turning the sec.- tions relative to each other in one direction but not in the other.

When used as an antenna mast, it is essential that there be good electrical contact between the several sections. To this end the enlarged end i5 of each of the sections I i can be provided with a pair of parallel slits 3| which form between them a strip 32. This strip is preferably deformed so as to bulge outwardly to a slight extent and it will therefore be seen that when the sections are extended each of the strips presses against the adjacent section to provide good electrical contact between the sections. At the same time this electrical contact strip does not interfere with the manipulation of the sections in erecting or nesting the telescopic structure as previously described. This strip could also, of course, be provided in each contracted end Hi to bulge inwardly and establish electrical contact,

The outwardly curved ends 22 of each pair of tongues 29 project beyond the outside circumference of the tube from which they are formed, and the space provided by the end enlargement of the next succeeding larger tube accommodates this projection of these tongues. This space is provided by the enlargement Id of the base section it and by the enlargements lb of the other sections ll. When the sections are nested, the curved ends of all of the tongues 20 are arranged in these enlargements l4 and I5 which are sumciently oversize, as compared with the diameter of the tube sections, to accommodate the same. Hence the provision of the enlargements l4 and i5 in the sections serves the definite function of accommodating the tongues when nested, whereas the contractions IB' provided at the opposite ends of these sections are merely provided so that each section can be brought to the exact inside diameter required for proper interfit with the next succeeding section. '--It will also be noted that each latch provided by the tongues 26 and opening 25 is approximately at the axial center of the telescopic joint, that is, at the approximate axial centers of the enlargements l 5 and contractions It. This centered arrangement weakens the telescopic joints to the least degree since the points of greatest bending stress on the telescopic joint are at theends a e-teas th'ereot where; weakening the wallsof the tubes'by the removal of metal to pr vi heon 23 and openings would materially reduce the strength of the telescopic joint as a whole. 7 V

In. the form of. the invention shown: in Figs. 8-13,. the-larger. of. the two. tubular telescopic sections-illustrated is designated atS'Ei and the smaller at 35. Each of the sections. is. proxidedswith an. enlarged end, 38 similar to the enlarged ends in the form of the invention shown in; Figs. .1;-.-7:, and the opposite ends 39. canbe: reduced, zsimilar. to the reduced ends. 5.6 in the form. of the invention shown in Figs. 1-! so. thatthe; opposite ends of the several sections. can be brought to the exact tolerances, required, for snug inter- ;fittingin the extended position, of the. mast rezgardless of minor variations. in the original size of the tubing used, aspreviously' described.

as. with the form of the inyention shown in Rig th outer rem of he re uc d end 39; of each section is rolled over to provide t w d i n ins he or flan e 411, this inwardly extending bead or flange engaging the annular external shoulder 's-l between thebody {and enlargement. 38 of each section thereby to provide stops to limit the outward movement of the sections relative to one another. These stops 4%" and M are located to facilitate: the latching :and unlatching of the sections as hereinafter described.

In the form of the invention shown in Figs. j

8 -13, the latch between each pair of the sections and 35 includes a tongue 4; which is formed Iby providing a pair of spaced slits or notches 46 extending inwardly from the inner. or enlargd end38 of each of the tubular sections with the exception of the base section. At the -free end of the tongue 45 and along its longitudinal sides, it is provided with a pair of ears 48 which project radially outward and extend axially a short distance along the sides of the; tongue. These ears are formed from the metal dis}- placed'from the outer ends of the notches 46. Each of the tongues #55 can also be strengthened by a central axially extending corrugation 4 9 if desired. 7

The ears 48' are specially shaped to coact in holding the sectoins 35, 36 extended and. to per mit the release or unlatching of the sections when it is desired to nest the same. 'Ioithis end the end edge 59 of each ear is in the form of a square shoulder extending parallel with the extremity of the tubular section from which the ear is formed. The opposite extremity 5! of each ear is of curved form to provide a cam surface for a purpose which will presently appear. Each of the tongues 45 fits into a generally rectangular slot 55 provided in the reduced end 39 ofthe next larger section of themast. Thisgenerally rectangular slot has circumferentially' extending parallel sides 56 and 58 and has axially extending parallel edges 59 and fiilf which are spaced frozn'eaeh other a distance slightly greater than the. width of the tongue 45 received by this slot. Each of these slots 55 isarranged to register with the tongue 55 of the next succeeding smaller section immediately preceding the en'- gagement of the stop shoulders and M of these sections. It will therefore be seen that when any pair of the sections is extended just short of the engagement between its stop shoulders it and M, the sections can be rotated relative to eachother so that the ears 48 'oijthe tongue snap outwardly into the slot55'. When thisoccurs thesection's are latched in theirexlatch s, p o sea t.

8" tended position. Thus; as -best sh'oyvnin-Figf 9, the engagementof the squa *o each can 28- with the' edge 58-- of the slotprev nts axial eonassaea the "sections'- rla'ti'vetd 'eaoh other. Rotation of the section relative to: each otherisperrnit'ted only-to the'extent allowed-*by' the circumferential Width brine $16555?Axial. outward --'n'-.0vemepe "of" t-he' 'sec'tions rlativ toeach" other is limiteddoyengagement Qff'the stop wardrelative toeach other,- this movemenwbeihg permitted: by theeclea-ran-celleftsbetvieen the stop shoulders Amend M'Ioflthetwo sections. Imso drawing the. two. sections axially apart with the corresponding; car 48 .in the; nptclrfilthe curvnapr ami edge 51.01 ear-.48; ridesunderthe ed of. the -notch; so tha "this. ear. is. pressed inner dis th by to depressthatongue and more it out of the generally rectiangulgaropeningvor lo The tw -se ions canthen; bes-rotatedso he ma n t-,5 complet l 'ireextromthe e hihevor lot fi- -f .cwlnsx.z wh ch e Qnscan he telesqoeecitoeeih rr his nfla n re -"bringing th e r 4.8 to the no 6i. pulling. the sections. axially apart to depress the tongtraikqtating the segtions to. bring,

theton ue away from: the-' at hipappg ne. an t s-o l p s these-s igma .is epeated er each ioin-t and with. littlelpjracticecan. .be. per-termed Yerf qu kly.

" Int 1 mm h inren en sh wn ni iss. 5-1

'eextremity of each lfro'm. the shoulder 4, This hezloneoitmgreateststrain 1 i z c e' a d hence lay-p. 2 ding thefton Ipjrlatch. 4,5,.rmotjrom this so e, the..mast-i's not materially weakened hythe pr sioiniofithe latchingtongue; Further it will be seenthaft the tongue vissftiirdy andlwillreliably hold the inastjflin its fcxtendedjposition. seem, the f oregoi'n'g' 'it'i'will e seen that. both terms ,oi the present inventionlproyide an extr melxsirome d rugeedtaesc m tru tu in wlo xih; iferalj c on 'are relcasably interlatched by means which are" erely cut for stamped out of the sections thern'se e's so as to notlappre section and re 'ciebly ds to ,thefjcost of the striicturef .Further,

' outer slidablyand vrotate;,bly 'interfitte'd t mes, a

toh'gue' inithel ecsdyor'qn qr's dtubes and having a 'sinall proi ection on its 'free end projecting radially'to'wardtheother of said tubesand ,jha vin a cam face and an abrupt face each opposing:

said other of said tubes, said other of said tubes having an opening through one side, said opening receiving said projection and having one edge arranged to engage said abrupt face and latch said tubes in their extended position, and means for releasing said tongue from said opening, comprising a small notch in one of the sides of said opening which extends lengthwise of said tongue, said notch receiving said projection and cooperating with said cam face, upon a corresponding manipulation of said tubes, to retract said tongue and projection from said opening and notch to permit nesting of said tubes.

2. A telescopic structure comprising a cylindrical outer tube, an inner tube having an enlarged cylindrical end slidably and rotatably fitted in said outer tube, and a tongue integral with said enlarged cylindrical end of said inner tube and having an end ofiset radially outwardly from said enlarged cylindrical end of said inner tube, said outer tube having an opening through one side receiving the outwardly offset end of said tongue to limit the movement of said tubes relative to each other, and said enlarged end of said inner tube providing space for the reception of said tongue when said tubes are nested together.

3. A telescopic structure including inner and outer slidably and rotatably interfitted. tubes, and a pair of circumferentially extending tongues integral with the body of one of said tubes and arranged in opposed relation to each other and having ends ofiset radially toward the other of said tubes, said other of said tubes having an opening through one side receiving the outwardly offset ends of said pair of tongues to limit the axial and circumferential movement of said tubes relative to each other.

4. A telescopic structure including inner and outer slidably and rotatably interfitted tubes, and a circumferentially extending tongue in the body of one of said tubes, the outer end of said tongue having parallel sides and being of reduced Width as compared with the body of the tongue and said body of said tongue thereby having circumferentially facing shoulders on opposite sides of said tongue and said reduced outer end of said tongue being offset radially toward the other of said tubes, said other of said tubes havin an opening through one side, said opening having parallel edges extending circumferentially of said other of said tubes and spaced from each other a distance greater than the width of the reduced outer end of said tongue but less than the width of the body portion of said tongue, said opening receiving the outwardly offset reduced end of said tongue with said parallel edges engaging said parallel sides of said reduced end of said tongue to prevent axial movement of said tubes relative to each other, the other edges of said opening engagin said shoulders of said tongue to limit the rotative movement of said tubes relative to each other in a corresponding direction.

5. A telescopic structure including inner and outer slidably and rotatably interfitted tubes, a

pair of circumferentially extending tongues in the body of said inner tube in opposed relation to each other and each having its extremity curved to extend radially outwardly from the body of said inner tube, said outer tube having a generally rectangular opening through one side, said generally rectangular opening having generally parallel edges extending, respectively, axially and circumferentially of said outer tube and said opening receiving the outwardly curved extremities of said pair of tongues in which relation said parallel circumferentially extending edges of said opening limit the axial movement of said tubes relative to each other and each of said axially extending edges of said opening permits the curved extremity of the adjacent tongue to be drawn thereunder but forms a'stop for the curved extremity of the opposing tongue when said tubes are rotated relative one-another in a corresponding direction, and means for releasing said tongues fro .1 said opening, comprising a small notch in one of the said circumferentially extending edges of said opening adjacent one of said axially extending edges thereof, said notch being adapted to receive the curved extremity stopped by said one of said axially extending edges when said tubes are moved axially relative to each other in a corresponding direction.

6. A telescopic structure including inner and outer slidably and rotatably interfitted tubes, a pair of circumferentially extending tongues in the body of said inner tubeand arranged in opposed relation to each other, the outer end of each tongue having parallel sides and being of reduced width as compared with the body of the tongue and said body of said tongue thereby having circumferentially facing shoulders on opposite sides ofsaid tongue, and said reduced outer end of each tongue curving to extend radially outwardlyfrom the body of said inner tube, said outer tube havinga generally rectangular opening through one side, said generally rectangular opening having generally parallel edges extending, respectively, axially and circumferentially of said outer tube, said circumferentially ex tending parallel edges of said opening being spaced from each other a distance greater than the width of the reduced outer ends of said tongues but less than the width of the body portions thereof, said opening receiving the outwardly curving reduced ends of said pair of tongues with said parallel edges engaging said parallel sides of said reduced ends to prevent axial movement of said tubes relative to each other, each of the axially extending edges of said opening permittingthe curving reduced end of the adjacent tongue to be drawn thereunder but forming a stop for said shoulders of the opposing tongue when said tubes are rotated relative to each other in a corresponding direction, and means for releasing said tongues from said opening, comprising a small notch in one of the said circumferentially extending edges of said opening adjacent one of said axially extending edges thereof, said notch being adapted to receive the curving reduced end of that tongue stopped by said one of said axially extending edges when said tubes are moved axially relativev to each other in a corresponding direction.

GEORGE O. BENSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,312,485 Krauth Aug. 5, 1919 1,394,636 Murray Oct. 25, 1921 2,240,330 Flagg et al. Apr. 29, 1941 2,243,190 Capaldo May 27, 1941 2,354,806 Fletcher Aug. 1, 1944 V FOREIGN PATENTS Number Country Date 500,888 Great Britain Feb. 17, 1939

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