US2504687A - X-ray apparatus - Google Patents

Description

April 18, 0 o. c. HOLLSTEIN 2,504,687'

X-RAY APPARATUS Filed April 16, 1947 3 Sheets-Sheet l INVHENTOR 0. 6. #0145727. 5

ATTORNEY 0. C. HOLLSTEIN X-RAY APPARATUS April 18, 1950 3 Sheets-Sheet 2 Filed April 16, 1947 IINVENTOR 0. c. HULL 5/27/14 W mum ATTORN EY April 18, 1950 o. c. HOLLSTIEIN X-RAY APPARATUS 3 Sheets-Sheet 5 Filed April 16, 1947 iNV EN FOR a. 0. #0445229. BY (F Q (WM ZM ATTORNEY Patented Apr. 18, 1950 X-RAY APPARATUS Oswald Conrad Hollstein, Secaucus, N. J., as-

signor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsyl- Vania Application April 16, 1947, Serial No. 741,796

9 Claims. (Cl. 25058) The present invention relates to X-ray apparatus and more particularly to X-ray examination tables of the tilting type used by the roentgenologist for the making of radiographic and fluoroscopic examinations.

Tables of this type for enabling a patient, when reclining upon the table, to be moved to various angular positions from below the horizontal, or what is known as the Trendelenberg position, to a vertical position are known to the art. The most familiar type has been that with which two X-ray tubes are employed, with one of these tubes being disposed below the table top and used primarily for fiuoroscopy, and the other X-ray tube being carried by a tube column movable upon a rail longitudinally of the table, and suspended above the table top for the primary purpose of radiography.

In order to decrease the floor area formerly required as well as to eliminate the necessity for two X-ray tubes, the more modern design of X-ray examination tables provides for a single X-ray tube which is rotatable about an axis from its support, to positions above or below the table top as conditions require. This latter type apparatus presents many problems and has,;heretofore, possessed several disadvantages. For example, when used for fluoroscopy it is necessary that the X-ray tube which, during such examination is disposed below the table top, follow movement of the fluorescent screen with the latter in turn being movable toward and away from the table top. Moreover, it is essential for efiicient operation that the X-ray tube and screen be movable in unison substantially the full length of the table to enable the examination of a patient from one extremity to the other. Inasmuch as the various parts are of substantial weight, one of the greatest problems in this type of examination table has been that of counter-balancing the parts to facilitate ease of movement and protection of the patient, with most types counterbalancing the movable parts only when the table is moved to the vertical position.

During the making of a radiographic examination, when the X-ray tube is disposed above the table top, the fluorescent screen constitutes an obstruction which must be moved out of the field and retained safely in such position to prevent accidental contact with the X-ray tube or the patient. A further disadvantage heretofore existent in single tube X-ray examination tables has been the fact that movement of the X-ray tube relative to the table top, both longitudinally and perpendicular thereto, has been considerably restricted especially insofar as enabling the X-ray tube to be moved to as short a space as approximately six inches from the table top. I

It is accordingly the primary object of the present invention to provide an X-ray examina tion table of the tilting type wherein a single X-ray tube is employed which is movable to posltions both above and below the table top with certain movable parts being counter-balanced in all positions of the table to facilitate ease of movement thereof.

Another object of the present invention is the provision of an X-ray examination table in which the fluorescent screen and X-ray tube support are fully counter-balanced by the same counterweight thus decreasing the size of the equipment which would be otherwise required.

Another object of the present invention is the provision of an X-ray examination table wherein the X-ray tube can be moved to substantially any position above the table top and the fluorescent screen is so counter-balanced as to be automatically moved out of the X-ray field during the making of a radiographic examination.

A further object of the present invention is the provision of an X-ray examination table wherein all the moving parts are counter-bal anced by a single counter-weight which decreases the size and weight of the entire apparatus with such counter-weight selectively operating as each part is moved.

Still further objects of the present invention will become obvious to those skilled in the art by reference to the accompanying drawings wherein:

Figure 1 is an end view of the X-ray examination table of the present invention in radiographic position,

Figure 2 is a view similar to Figure 1 but showing a position to which a part of the apparatus is moved for fluoroscopic examination,

Figure 3 is a side view of the X-ray examination table of the present invention as shown in Figure 1,

Figure 4 is a fragmentary top plan view of the table as shown in Figure 2,

Figure 5 is a detail view on an enlarged scale of a part of the apparatus for moving fluorescent screen in accordance with the present invention,

Figure 6 is a fragmentary perspective view of the fluorescent screen and the collapsible sup porting arrangement for moving the screen out of the X-ray field during a radiographic examination as shown in Figure 2,

Figure 7 is a schematic view somewhat similar w to Figure 2 and showing the position of the parts and the counter-weight therefore during the making of a fluoroscopic examination.

Figure 8 is a schematic view identical to Figure 7 but showing movement of the counterweight in response to movement of the fluorescent sc'reen to a new position relative to the table top,

Figure 9 is a schematic view similar to Figure 7 but showing the position of the various parts during the making of a radiographic examination.

Figure 10 is a View identical to Figure :9 but showing movement of the counter-weight in .response to movement of the X-ray tube and support relative to the table top during the making of a radiographic examination,

Figure 11 is a view similar to Figure '7 .and showing the fluorescent screen in its lowermost position relative to the table top, and

' Figure 12 is a schematic view showing movement "of the counter-weight in response to collapsing of the fluorescent screen to its'fixedpositi'on out of the iX-lray field preparatory "to the making of a radiographic examination.

Referring now to the drawings in 'detail the -X-ray examination table of the present invention tiltingthe tabletop, 'such'ifor exampleas an electric motor (not shown). This motor is operated :by aifoot switch-6 and rotates a shaft which car- :riesa gear I at each end meshing with arcuat'e rack-bars t welded or otherwise aiflxedto sect'ors 8 and constituting standards forthe table top ll). lhuswupon operation ofr th'e'motor, the'standards 9 are rotated by the rack bars 3 about an imaginary pivot as the sectors 9 slide over the base 5.

It willbe noted from Figure 3 that 'the'sectors :or uprights '19 :are provided with horizontal slots 12 and I3, and spaced tslightly beneath the table top are a pair of rails or the like 1'4, upon which a fluoroscopic carriage [5 provided with rollers '46, iswarranged to move longitudinally of the table top ID. The carriage 15' is also provided Withadditional rollers l1 '(Figures 1 and 2) engag-ing a horizontally disposed frame or the #like *8, which forms atelescopic connection with that portion "of the carriage 15 disposed below the table top I 8. Such frame H3 in turn supports a verticallypositione'd tower or column 19 'of channel shape on its front and rear surfaces to 'form tracks 20 and '22, as shown more clearly in Figure 6.

5A fluorescent screen carriage 23 is movable verticallytupon the tracks 20 on the frontfabe of the tower l9 while an X-ray tube carriage "2E likewise is vertically movable upon the tracks '22 formed on the rear surface of the'tower l9. Pivotally secured to the X-raytube carriage 24 at 25-:isan X-ray tube support assembly which comprises aflpivote'd member '26 carrying'a counter- Weight 21 at one end and a horizontally extending arm 28 at its other end. -As shown more clearly in Figure l, thisarm28 carries the X--ray tube'housing :29 at its free .end and in order to enable rotary motion of the X-ray tube and-housing29 the arm 28 is .rotatablysecured to the pivoted member 26. TheX-raytube disposed within the-housing '29 is supplied :with'high potential electrical energy throughinsulated cables 30 extending to 'a high tension transformer, in the customary manner.

.:B,y reference now :more particularly to Figure 6, it will be noted that the fluorescent screen carriage 23 is arranged to support a fluorescent screen frame 32, carrying a fluorescent screen'- 33, through a collapsible toggle connection. Sucharrangement comprises a pair of link members and 35 ,pivoted at 36 and-31 to the carriage 23 and to the fluorescent screen frame 32 at points 38 and 39, with one of these link mem.- bers 35 having an extension in the form of a] sector .40 as shown in Figure 5. A further pair of slightly curved toggle links 42 and 43 are piv-v oted at (it and 5 to the carriage 23 and at their opposite ends are pivotally connected to a pair of links it and i'i, respectively, with the pivot pin (18 being elongated and engageable by a catch "is operable by a lever 59 carried by the screen vframe '32. The opposite ends of these latter links are in turn pivotally connected to a pair of upstanding lugs 52 and .53 secured to the screen frame 32, with the pivot pin 54 passing through 1 In order to counter-balance both the 'fluorescent screen-and frame, as well a-s the *X-ray tube supporting assembly, .a counter-weight 55 is vertically movable interiorly of the tower or cob nmn ieupon suitable rollers 51 (Figure 3-). can be seen from Figure 3, as well as "from th'e schematic showing of Figures 7 to 12, a pair or.

anda s'nn'lar pairof pulleys '63 and-64 are-disposed adjacent the bottom 0f the column 13. A chain or cable 65 extends from the counter-Weight 56 around the "pulley -64, thence around =p1-illey 59, to; pulley 15.3 :andaround the latter to the upperedge of the SECt0I '4Qit0 which one end-of the canes-5i is connected, as shown-in Figure 5. Another end of this cable '65 is connected to the lower edge of the sector 49 and passes upvvarcll-vover' the pulleytfi, around the latter 'to pulley =8, thence aroundithe .upper pulley 62, and downwardly "to the counter-weight 56.

,Byreferenc'e toIFigur-es"? and 8,'=Which1-shoW" the apparatus in position for the making-of 'afiuoroscopic examination with the X-ray 'tube'i29 dis posedibelow the tabletop, it will-'beseen that the fluorescent screen carriage 2-3 is 'connected'directly to :the counter-weight '56. Consequently, :as the carria'ge' zs is moved vertically of the column I! for atotal travel of approximatelyfifteen inches, the-countei weighttt" also moves a like distance in an opposite direction within the column ,llinasshown by the arrows inFigure 8.

Assuming 'IIOW the troentgenolqgi's't ,fiesires make a radiographic exposure, the 'X-ray tube support -26 is rotated about .the,,pivotl25 Tto move the X-ray tube '29 from below the table .top, shown'in Figures 2, 7, .andt8, 113.0 a positionpahdve the table top as shown in Figures 1, 3,39 andt-IO. lfn'order -to adjust the tube-to-obj ect distance, the roentgendlogist moves the tube relative to ilthe table-top whichcauses vertical movementpf .the X raytube carriage 24- riding .on the column 19.. As the tube-to-object distance is increased. as. shown by the upper arrow in "Figure I0, fthe' counter-weight 5'5 moves vertically within .Ithe column Win an opposite direction'but twice the distance "of vertica'lmovem'ent o'f the 'xerayitiihe 29 relative to the tabletop, as. shown byitheLlow'er arrow in Figure 10.

It can thus be seen that the counter-weight" 56 follows directly movement of the fluorescent screen carriage t3 and must be sumcient to counter-balance the latter because, during movement of the screen carriage 25, the X-ray tube carriage mi remains fixed which thus fixes the position of the pulleys t8 and as carried by the X-ray tube carnage 24. On the other hand, during movement or the X-ray tube carriage Hi the fluorescent screen carriage 23 remains fixed, as hereinafter pointed out, so that the pulleys 5t and 59 change their position which results in the counter-weight to moving twice the distance of movement of the Y-ray tube 25 relative to the table top. Moreover, due to such arrangement the X-ray tube carriage and associated parts may be twice as heavy as the fluorescent screen carriage, yet both are perfectly counter-balanced by the same counter-weight 5b.

Naturally, in order to make a radiographic examination, it is necessary that the fluorescent screen be out of the field of the X-rays from the X-ray tube 25 when positioned above the table top. Preparatory to rotating the X-ray tube 25 from below the table top, as shown in Figures 2 and 11, to its position above the table top as shown in Figures 1, 9 and and the roentgehologist first operates the lever to which thus disengages the catch 49 from elongated pivot pin 48. Upon such disengagement the fluorescent screen frame 32 carrying the fluorescent screen automatically moves to an angular position of about 30 with respect to the tower or column iii, as shown in Figures 2 and 12. Such automatic movement is due also to the counter-balancing by the unitary counter-weight 56 which moves downwardly, a distance such as shown by the shortest arrow in Figure 12. Since the ends of the cable 65 are, as hereinbefore mentioned, connected to opposite edges of the sector as, this takes up the slack in the cable 55 as the sector moves about its pivot 37, enabling the counter-weight 55 to balance the screen frame 32 in its 30 angular position, even though the fluorescent screen carriage 23 remains stationary on the column l9 due to the lock 66. 7

Automatic movement of the fluorescent screen frame 32, in response to the counter-balancing as above described to a position of 30 relative to the column it, occurs by virtue of the rotation of the link members 34 and 35 (the latter including the sector 55) about their respective pivots 36 and 31. This causes a downward thrust on the pivots s8 and 39 which in turn causes rotation of the screen frame 32 about the pivots comprising the lugs 52 and 53. Such movement of the screen frame 32 causes the link arrangement to collapse with the toggle links 42 and "t3 moving toward each other about their respective pivots t4 and 35 and carrying with them the links 4'6 and All which are pivoted thereto and to the lugs 52 and 53. Once the frame 32 has automatically moved to its 30 angular position, the operator need then only apply a slight pressure to the frame pushing it into a position parallel to the column l9, where it is then held in such position by the elongated pivot pin 5 passing beneath the catch 55, as shown in Figure 1. In moving the screen frame from its angular position to that parallel with the column it, the sector 45 again makes the cable 55 taut and the counter-weight 55 moves downwardly a distance represented by the difference between that shown by the shortest and longest arrows in Figure 12.

When it is desired to again return the fluorescent screen frame in position for a fluoroscopic examination parallel to the table top, the operator need only release the latch 55 by raising a handle 57 which causes the latch 55 to slide away from above the pivot pin 55. The screen frame is then pulled away from the column iii until it again reaches its approximately 30 balanced position at which time the sector at will have again taken up the cable slack and raising the counter-weight 56 to a position where it again counter-balances the screen frame 32. From this 30 angular position to the horizontal above the table top, then requires very little force due to complete counter-balancing. Upon release of the lock 66 the carriage 23 is then free to move vertically of the column l9 under full counterbalancing of the counter weight 55 as before explained.

It can thus be seen from the foregoing that an X-ray examination table is herein provided, in which a single radiographic-fluoroscopic assembly is carried by the table with but one X-ray tube being employed, and such X-ray tube is readily movable from a fluoroscopic position below the table top to a radiographic position above the table top, and vice versa. Moreover, a unitary counter-weight is employed for counterbalancing vertical movement of the radiographic elements of the assembly and vertical movement of the ,fiuoroscopic elements thereof, as well as counter-balancing movement of the fluorescent screen frame in an angular position between the horizontal and vertical. Also the fluorescent screen frame carrying the fluorescent screen is supported by toggle link arrangement from the fluorescent screen carriage which facilitates the ease and rapidity with which the screen can be moved into a fixed position perpendicular to the table top and thus out of the field of X-radiations during a radiographic examination.

Although one embodiment of the present invention has been shown and described, it is to be understood that further modifications thereof may be made without departing from the spirit and scope of the appended claims.

I claim:

1. An X-ray examination table comprising "a base, a table top rotatable with respect to said base from a position below the horizontal to a vertical position, a carriage movable longitudinally of said table top, a column carried by said carriage and laterally adjustable with respect to said. table top, a radiographic assembly provided with an X-ray tube and movable longitudinally along said column to adjust said X-ray tube relative to said table top and including a pivoted member carrying said X-ray tube at one end for swinging said X-ray tube below said table top for a fluoroscopic examination and to a position above said table top for a radiographic examination, a fluoroscopic assembly movable longitudinally along said column independently of said radiographic assembly including a fluorescent screen and frame movable by the operator to a position parallel to said table top during a fluoroscopic examination and to a position perpendicular to said table top during a radiographic examination, and a unitary counter-weight movable longitudinally along said column and connected to said radiographic assembly and said fluoroscopic assembly for counter-balancing both of said assemblies in all longitudinal positions thereof as well as counter-balancing fiuorescent screen and frame in an angular position with respect to said table top. 5

. s'creen l 41 frame n graphic assembly and said fluoroscopic ass amass? nally of said table .top,.a column carried bysaid 5 carriage andlater'ally adjustable with respect 50.0

said table top, v a .radioe ragchic assembly provided with :an X-ray tube and movable longitudinally along said columnsto. adjust said X-rayltube [relative to said table tnp and including ,a pivoted @110 member carrying said tube vat oneaend. for swinging said tube-below said table top for a fluoroscopic examination .and .to a position .above said table topic-fa radiographic examination, a fluoroscopic assembly .movable longitu- 5 dinally. along said .columnrindependently of said radiographic -.ass'embly including a fluorescent screen and frame movable by the operatorto .a

"position parallel toisaidi tabletop duringv a fillersoscopic examinationand to a .lposition perpen- ,go

dicular to c. said table ltgp fillrillg aradie rei hi examination, and, a unitary ..coun er-..weiah en mooted to said ceramic assembly and mavable longitndinallyalonc said ceillmn a d stanc equal to twice .t hefdistance of travel ,of said radio- 5 graphic ass mbly to counteielqalanee he l te i -a-l1its lon itudinal .nositions along said enlllmn, said, unitary flOllntfilf-flflfiightbein al o connect to said fluoroscopic assembly ,an imovabie n itudinally along said-column ,afiistailceedualto the distance of trayelioi said tli lresoop a s mblyio. countehhalaneei latte: nial i s .Yertical spe itiens alon saiccelum and aid uni ary -.counter -w.eieht bein ice illeq ied to s i fluore nba i n ih same a al au a 'eos l w res eet. to eai ta topa u tabl emra ti tine a -,be. e a t ble s e lei. ab e will; i eeee s to, Sai

fa'ffiuo'r'oscoyjic examination and to a positionjo abov'esaid tableltbzi for a- 'fadiographic examinatio'n,' a 'flnoroscopic asseml cily'hiovable longitu- .ani'any along said" column independently ofsaid radiograp hic I? if? 'fir' cludi'ng' fluorescent a to ,saijdltaliie top duringj "flun'atio'x'i anc'l provided with a toggle nt 7 collapsible in it l ie direction of position f oios'c'op'ic exa link arrange said commito be moved to "afgosition perpendicular to said li b e p dllr ae a rede ma x mi n a unitary counterrw eight movable lonaitudinally l e S 19 and ee n ili ai l aefoi nt rrbe ane ll lenti -p ei esteem. r a e t d lpe ilio l ilie ee s We a l e mo m n 3. 51 'iluo eee Sc een nd frame to a connter balanced ang ular position with respeot to sai d -tabl e top upon collapse of i'lo said toggle arrangement by an operator.

An Xr a ea m na e tab mpri i a base, a le to rot tabl w th res t sa bas o a ne liion e ew e h riz n a ,said tabletop, a radieerenhieas enibly .p.

the horizontal to a -40 jle by the'operator to 2.1.55

7.. s s i vem i ee etlen by ator to enable said fluorescent 'scre'en'and frame ,00

nally of said-table topha .eelumn earrieidzb i-said carriage andslaile allyladjlldi apl h see t m sled with an ray .tube and movable on lldinally along, said columntoadjuet aid Xfliay 1 3 5129 Q I've to said table top includi a lpiyeied member carry ng said X-r yillloe at eneend i32 swinging S3 Q.X-. .iy; lb b l saidta le teniq a fluoroscopic examination and 15.0 a pee en .aboiresaid table-stop fcra rad esraphicexa .tion, a fluoroscopic carriage movable lon itudi- .nally along .said col mn independently of ai .radiographic assembly, flu re cent screen an frame connect d tesai l flu *oscopie carria eb a iscggle arrangement includin a phirality ef piyoted linl-zs collapsible a p ane par llel said tabletop at 1 1 5351 11 .o an ppera er to. enabl said fluorescent vscreen. and frame .11 automatically m v to an an ular position and thenc meved joy thecpezater tea ees ti nrgerp nd 'cul .i-ov said tabletop .durinecairadie r nhicex inaa unitary canister-we ght movable leneitndina ly aion csaid column a d mated to .said .radioc ap e as embly .andsaidifl lloro cqpl base, .a table topvizotatable with respect to .sai base from apositionbslowsthe horizontalto, a. vertica eesition, a carriage .mcmbleleneitndina l ofsaidta le ep, avcolumn carriedlgy said carriage .and laterally adjustable with. respect to said table tone sradiogizaphic assemblylmevable lon i udisnallyvon saidcolumn and ineiudinga pivo ed member carryin anxeray-tuhe atsoneend for swin .ingfisaid Xr. lE '..I1lbfi.h19l said table v tqpiora fluoroscopic examination and ea nosi ien abov said table top. for ,a radiosraphic examination, fluoroscopic carriage ,mevame slengitudinally .Qf said column, a,filiorescentscreenland frame.-.piv -tgtallyuconnected .by .avrpair of brackets tosai fluoroscopic carria e, a collapsible to le arrangement connected to said fluoroscopic carriagecarid n aidfiuorescent screen frame comprisinga p of to l slinks izerticallyipivnted-to said carria e andmto a pair of linkmelnbers in turn vertically nei sa fiu s e w er en .i ramein an an ula e esltiq w th r spect i e..-se p1 tab e ten- 6. A rad o raphi .fluerQs Q -i a p a u co n s n e eelumn a .raei e'raphle ass mpl provided wi h a a tiiibe and mov b v ri y loncsaid eelumn to. a us s i X- ay i be r lative tosaid ta leio i l l pivo ed emhe s n qri c sa Xrre tu -le n M swie neealdr Xawfifllee to ex t on be ow he. elveieeiniqfeeid; ,i lemb r fe' l vertical position, ae rr a v bl eliud "w i-l on examieaiinane abeye 5 59b P 9 point for a radiographic "examination, a fluoroscopic assembly movable vertically along said column independentl of said'radiographic assembly including a fluorescent screen and frame movable by an operator to a horizontal position during a fluoroscopic examination and to a position parallel to said column during a radiographic examination, and a unitary counter-weight movable vertically along said column and connected to said radiographio assembly and said fluoroscopic assembly for counter-balancing both of said assemblies in all vertical positions thereof as well as counter-balancing said fluorescent screen and frame in an angular position between the horizontal and vertical.

'1. A radiographic andl'fluoroscopic apparatus comprising a column, a'radiographic assembly provided with an X-ray tube and movable vertically along said column: to adjust said X-ray tube relative to said table top and including a pivoted member supporting said X-ray tube at one end for swinging said X-ray tube to a position below the pivot point of said member for a fluoroscopic examination and above such pivot point for a radiographic examination, a fluoroscopic assembly movable vertically along said column independently of said radiographic assembly including a fluorescent screen and frame supported by a collapsible toggle connection including a plurality of pivoted links to said fluoroscopic assembly to enable said fluorescent screen and frame to be moved at the will of an operator to ahorizontal position for a fluoroscopic examination and to a vertical position parallel with said column during a radiographic examination, and a unitary counter-weight movablevertically along said column and connected to said radiographic assembly and said fluoroscopic assembly for counterbalancing both said assemblies in all vertical positions thereof as well as counter-balancing said fluorescent screen and frame in an angular position between the horizontal and vertical.

8. A radiographic and fluoroscopic apparatus comprisin a column, a radiographic assembly provided with an X-ray tube and movable verscopic examination and above such pivot point for -fa radiographic examination, a fluoroscopic asseihbly movable vertically along said column independently of said radiographic assembly includmg" a fluorescent screen and frame supported by a.;collapsible toggle connection including a plur'ality of pivoted links to said fluoroscopic assembly to enable said fluorescent screen and frame to bej moved at the will of an operator to a horizontal position for a fluoroscopic examination and to a position parallel with said column during a 'radiographic examination.

.9. A radiographic and fluoroscopic apparatus comprising a column, a radiographic assembly movable vertically on said column including a pivoted member supporting an X-ray tube at one end for swinging said X-ray tube to a position below the pivot point of said member for a fluoroscopic examination and above such pivot point for a radiographic examination, a fluoroscopic assembly movable vertically on said column including a carriage, a fluorescent screen and frame pivotally connected by a pair of brackets to said carriage, a collapsible toggle arrangement connected to said fluorescent screen and frame and to said fluoroscopic carriage comprising a pair of toggle links vertically pivoted to said carriage and to a pair of link members in turn vertically pivoted to said fluorescent screen frame, with said pairs of links ."being collapsible in a horizontal plane about their respective vertical pivots to cause rotary movejment of said pair of brackets about their pivots,

tically along said column to adjust said X-ray tube relative to said table top and including a pivoted member supporting said X-ray tube at one end for swinging said X-ray tube to a position below the pivot point of said member for a. fluoroaccompanied by movement of said fluorescent screen and frame from a horizontal position for a "fluoroscopic examination to a vertical position parallel with said column during a radiographic examination.

OSWALD CONRAD HOLLSTEIN.

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

UNITED STATES PATENTS Number Name Date 1,623,043 Gro'be May 10, 1927 2,060,981 Fischer et a1 Nov. 17, 1936 2,311,581 Simmon Feb. 16, 1943 2,315,786 Grobe Apr. 6, 1943

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