US2632469A

US2632469A - Gas valve

Info

Publication number: US2632469A
Application number: US709466A
Authority: US
Inventors: Charles C Lamar
Original assignee: Harris Trust and Savings Bank Corp
Current assignee: Harris Trust and Savings Bank Corp
Priority date: 1946-11-13
Filing date: 1946-11-13
Publication date: 1953-03-24
Anticipated expiration: 1970-03-24

Description

March 24, 1953 c. c. LAMAR 2,632,469

GAS VALVE Filed Nov. 15: 1946 5 Sheets-Sheet 1 J zwewa 290w Law/a aw March 24, 1953 5, C, LAMAR 2,632,469

GAS VALVE Filed Nov. 15, 1946 3 Sheets-Sheet 2 42 Z- OFF I 4 5mm? March 24, 1953 c. c. LAMAR 2,632,459

, GAS VALVE Filed Nov. 15, 1946 s Sheets-Sheet s ANDLL' Puszrlozv ISIMMER Patented Mar. 24, 1953 GAS VALVE Charles C. Lamar, Chicago, Ill., assignor of onefourth to Philip S. Harper and one-fourth to Carolyn L. Harper, both of Chicago, Ill., and one-fourth to Harris Trust and Savings Bank, an Illinois banking corporation, Chicago, 111., as trustee of the Philip S. Harper Trust, and one-fourth to said Harris Trust and Savings Bank as trustee of the Carolyn L. Harper Trust Application November 13, 1946, Serial No. 709,466

11 Claims.

The present invention relates to gas valves and particularly to gas valves for use with gas burners having I two burner sections. Burners of this character are commonly called double burners and thetwo burner sections are called the main and simmer burner sections.

Gas valves for double gas burners have heretofore been constructed and arranged to supply gas selectively to the two burner sections and also in selected quantities. For instance in a known type of valve, such as that disclosed in the Philip S. Harper Patent No. 2,299,624, granted October 20, 1942, the valve is operable into distinct operating positions, as follows:' (1) a full I on position, wherein gas is supplied to both the burner sections at maximum rates determined is toprovide anew and improved gas valve for a double gas burner, i. e., a new and improved double gas valve.

Another object of the present invention is to provide a new and improved double valve including asimplified arrangement enabling the supply of a predetermined and adjustable small quantityof gas to the simmer burner section, and more particularly, wherein said means includes an adjustment accessible through a hollow valve stem.

. A further object of the present invention is to provide a new and improved double valve which does not require any auxiliary drillings in the valve body, which in the past have been of a complicated and devious angular nature.

, A further object of the present invention is to provide a new and improved double gas valve operable into the various positions referred to heretofore with a minimum rotation of the valve plug and yethaving adequate sealing surfaces insuring against leakage of gas. 1 .A furtherobject ofthe present invention is to, provide a new and improved double gas valve of the character set forth above in which the main gas passageways in the valve body and plug can be drilled radially and simultaneously, thereby to insure accurate alignment of the passages in the full on position of the valve and also to acter It.

decrease the length of the arc subtended by the passageways in both the valve body and plug, thereby to provide good seals without increasing the overall length of the valve plug. a

A further object of the present invention is to provide a new and improved double gas valve including stem adjustment means for regulating the quantity of gas passed in the low simmer position which is so constructed and arranged that gas does not escape through it in a reverse direction.

Other objects and advantages of the present. invention will become apparent from the ensuing description of a preferred embodiment of the gas valve, in the course of which reference is had to the accompanying drawings, in which:

Fig. 1 is a fragmentary top plan view, partly: broken away, of a gas valve embodying the pres,- ent invention, the valve being illustrated in its off position;

Fig. 2 is a fragmentary enlarged axial crosssectional view taken along the line 2-2 of Fig. 1;

Fig. 3 is a transverse cross-sectional view taken. along the staggered line 33 of Fig. 1, and like-' wise illustrating the valve in its 011 position; I

Fig. 4 is a transverse cross-sectional view taken along the staggered line 44 of Fig. 1 and illus-l trating the valve in its simmer position; I

Fig. 5 is a view along the same section line as, Fig. 3, illustrating the valve in its full on position;

a Fig. 6 is a transverse cross-sectional view taken,

along the staggered line 6-6 of Fig. 1 and illus-' trating the valve in its low simmer position;

Fig. 7 is a fragmentary axial cross-sectional View taken along the line 'i'! of Fig. 6; and

Figs. 3A, 4A, 5A and 6A are flat developments of the valve body and valve plug surfaces in the positions corresponding to those in which these are shown in Figs. 3, 4,- 5 and 6. By flat developments are meant the surfaces developed by rolling the conical surfaces of the valve chamber and plug upon a plane surface. The plug surface is shaded and the body surface is unshaded.

Referring first more particularly to Figs. 1' and 2, the double gas valve of the present inven-' tion is indicated as a whole by reference char- It comprises a valve body l2 having a chamber with a conical inner surface [4 and within which is mounted a rotatable control mem-. ber illustrated as the tapered or conical plug 16.

The plug is provided with an axial passageway l8 providing communication between the interior;

of the valve plug and the valve chamber 20, which includes the earlier referred to conical surface [4. The plug is provided also with first and second

main passageways

22 and 24, which, in accordance with one of the important features of the present invention, are truly radial relative to the axis of the plug and the chamber 20 and which are readily drilled with the plug within the valve body when the plug is in its full on position'so that they register exactly with the gas inlet and outlet passageways 2B and 28, respectively, in the valve body, as best illustrated in Fig. 5.

The radial disposition not only enables the passageways to b drilled readily but the arrangement also reduces to a minimum th length of the arc at the intersections of the passageways with the inner surface M of the chamber 29 and the outer surface of the plug 16. This is an important factor in that the passagewayscan be spaced closer together both axially aswell as radially, thereby to decrease the angular movement of the. plug required to move it between its various positions as well as decreasing the overall length of the plug.

The valve plug, in accordance with another feature of the present invention, is provided with further passageway 30 through which a small and adjustable quantity of gas is supplied to the simmer burner section only in the low simmer position of the valve. The passageway has an enlarged radial portion 32 near the outer surface of the plug and an axially inclined inner portion 34 leading to the hollow 36 of the valve stem 33. The inner portion 34 of the auxiliary passageway communicates with an annular passageway 58 defined by the stem and an annular recess 42 in a stem adjustment auxiliary valve providing insert 44 which may take various forms and which is illustrated as being of the character disclosed and claimed in the copending application of Vincent 0. Peterson, Serial No. 600,795, filed June 21, 1945 (now Patent No. 2,590,569, granted March 25, 1952).

The stem adjustment insert includes a rotatably adjustable secondary valve member at having a slot 48 at its outer end whereby it is readily accessible for adjustment through the hollow of the stem by a suitable instrument such as a small screw driver. When the valve member at is rotated the quantity of gas flowing to the central axial passageway I 8 in the valve plug, and thus to the simmer section of the burner, is regulated by control of the effective size of an orifice including an aperture 52 in the insert 44 and a cooperating passageway 54 communicating with the interior of the valve plug through an axial passageway 58 at the inner end of the auxiliary valve 4'6.

The stemadjustment means is provided with a seal 58 at its outer end preventing escape of gas therethrough. The seal is comprised of an annular groove 60 in the valve member 36, which is filled with lubricant and an annular indentation 62 in the thin walled outer portion 6-! of the insert 44. The stem adjustment means is preferably preassembled in the form in which it is shown and then inserted into the enlarged portion 36A of the hollow 36 of the stem.

"The valve plug'includes an auxiliary passagewayfiihaving an enlarged outer end 66, for a purpose to be described hereinafter.

' The valve plug is rotatable by a handle 68 which is secured to the hollow valv stem 38 in suitable manner. The latter is preferably provided with a fiat side 10, giving the valve stem 2. generally D-shaped configuration fitting into an opening of similar configuration in the valve handle, whereby the two are readily assembled in operative relation with each other.

Gas is supplied to the valve through the inlet passageway 28, which is formed in an externally threaded transverse boss 12 adapted for attachment to the usual gas supply manifold (not shown). The valve body is also provided with a pair of longitudinally extending spaced apart exteriorly threaded'bosses 14 and 16, which are drilled to form gas outlet passageways l8 and 86 through which gas is supplied to the simmer and main burner sections, respectively, of a double gas burner. Passageway l8 communicates directly .with chamber 20 and the aXial passageway 58 in the valve plug, whereas passageway communicates with the previously referred to outlet passageway 28. The latter is, as already indicated, radial, and after drilling it is closed by a plug 82. Adjustably mounted

hoods

84 and 86, provided with orifices and cooperating with fixed needle valves secured to the valve body (not shown, but which may be of conventional construction) are secured to the outer ends of bosses l4 and is to provide nozzles through which gas is supplied to the burners at suitable velocities when the valve is in its full on position.

The valve may have and is shown as including a position determining and indicating mechanism Eli! which includes a plate 92 having a limited extent of angular movement with respect to the valve stem, a plate '94 secured to the valve body by the spaced apart screws 96, and a spring 93 bearing against the outer end of the valve plug and against the plate 92, thereby forcing the latter against the stationary plate 94. The spring thus holds the valve plug tightly in place and also biases the plate 92 against the plate 9%, thereby to provide the necessary movement of the latter for audibly indicating certain positions of the valve. The valve body is also provided with an axially extending portion I00 providing stop surfaces against which a part of the plate 92 moves to determine the closed and open positions of the valve. Only the full on stop surface 602 may be seen in the drawings and it is shown only in Fig. 1. The particular form of the position indicating and determining mechanism forms no part of the present invention and it may be of the character disclosed and claimed in the Turner et a1. Patent No. 2,299,666, gra'ntedOctober 20, 1942.

In order to provide a double gas valve capable of'being operated into the many positions required for adequate control of double gas burners with a minimum of angular movement and hav ing a minimum length and yet having the requisite valve plug sealing surfaces, certain of the passageways are displaced axially as well as angularly. For instance, the inlet and

outlet passageways

26 and 28 are axially displaced (about one-eighth inch) as are the passageways 22 and 2s, which as previously indicated are in the same planes as

passageways

26 and 28, respectively. They are also displaced angularly a distance of about 104 degrees. The auxiliary passageway 65, which constitutes a bypass-preventing extinction of the flames when the valve is operated between the full on and simmer positions, and the low adjustment passageway 39 are also displaced relative to the main passageways in the gas valve, as will be perhaps more apparent when reference is had to Figs. 3A to 6A in the following description. of the operation of the valve. The

auxiliary passageway

65, 66 is located angularly between the first and second radialpassageways 22 and 24, somewhat nearer the first, and its axis is displaced axially about one-sixteenth inch from the axis of the passageway 22 and three-sixteenths inch from passageway 24. The axis of the inlet portion 32 of further passageway 30 is angularly displaced about 150 degrees from the first passageway 22 and axially displaced about one-quarter inch from theaxis of the second passageway 24.

The axial location of the low adjustment passageway 30, in accordance withanother important feature of the invention, is such that it does register only with the inletpassageway 26 and never with the outlet passageway 28. Consequently, there is no undesired flow of gas to passageway 28 in any position of the valve. The closest approach of

passageways

28 and 30 is about one-sixteenth inch so that an adequate gas seal is provided.

, In the accompanying descriptionof the operation of the valve as a whole, reference will be had particularlyto Figs. 3 to 6 and 3A to 6A, both inclusive. v

Infthe off position of the valve illustrated in Figs; 3 and 3A the inlet passageway 26 is closed by the imperforate part of the valve plug l6. In this position of the valve, the valve handle extends downwardly, the fiat side 10 of the valve stem is at the bottom and the handle can be turned only in a counterclockwise direction as viewed from the right of Fig. 1, or in a clockwise direction as viewed in Figs. 3 to 6, also the solid line elements of Figs. 3A to 6A, inclusive, which represent the valve plug can only be moved counterclockwise as viewedin the latter figures.

Thedouble. gas valve is constructed and arranged to provide an audible indication when the valveis moved. to its simmer position, to which position it is usually turned for lighting purposes.

The valve is shown in the center of this position in Figs. 4 and 4A. In this position the inlet port 26 intersects the passageway 24 to the greatest extent and gas is supplied to .the simmer section of the burner through the axial passageway l8 in the valve plug and passageway 18. At this time the gas fiow to the simmer section is determined by the size of the orifice in the hood 84. Adjust-1 ment of the flow of gas to the simmersection alone may be efiected by movement of the valve plugto vary the extent of registry between the passageways 24 and 2B.

The valve may beoperated from the simmer position to the full on position by further counter clockwise movement of the valve plug as viewed in Figs. 3A to 6A. The full on position is shown in Figs. 5 and 5A from which it will be noted that the inlet passageway is fully aligned with the passageway 22 and that the passageway 24qis aligned with the outlet passageway 28 which communicates with the main burner outlet passageway 80. The axial passageway l8 of the valve plug remains. in communication with the simmerburner section through outlet passageway 18. In this position the

passageways

30 and 65 are closed. a

A turn down range of operation in which manually regulatable quantities of gas are supplied to both the main and simmer sections is located between the full on and simmer only sections. For instance, in movement of the valve from its full on to its simmer-only position, the extent of registry between the

passageways

22 and 26 and the

auxiliary passageway

65, 86 begins to register with the inlet passageway and is the only passageway registering with the inlet passageway fora time before the simmer only position is reached, at which time passageway 24 registers with the inlet passageway 26. The passageway 65 thus supplies a small quantity of gas to both the main and simmersections first and then to the simmer section only as the simmer only position is reached. It thus prevents the extinction of the flames and especially of the flame to the simmer burner section when the valve is operated from its full on to its simmer position. In order too-perate the valve to the low simme position, the valve is moved clockwise as viewed in Figs. 3A to 6A'from the-simmer position to bring the auxiliary passageway 30 into registry with the inlet passageway 26. Passageway 30 begins to register with the inlet passageway before the passageway 24 moves out of registrywith the inlet passageway sothat both supply gas to the simmer section for a time and finally gas is sup-- plied to the simmer section only through

theauxiliarypassageway

32, 34, as best illustrated'in Fig. 6A. i

The quantity of gas supplied to the simmer burner section in the low simmerposition may be adjusted readily by moving the handle 68 and turning the secondary valve member 46 to control the effective size of the opening or orifice defined by the openings 52 and in the insert 44 and valve member 46, respectively. a 4 From the foregoingdetailed description of the construction and operation of the double gas valve of the present invention, it may be noted that the valve may be constructed simply and economically and that it may be operated simply and, furthermore, the quantity of gas supplied to the simmer burner section may be regulated with a great degree of nicety by the stem adjustment means. Only a limited angular extent of movement is necessary to move the valve betweenits many positions, this movement being only about 195 degrees. The staggering of the ports in different axial planes also not only reduces the extent of angular movement but it also keeps down the overall length of the valve plugand, therefore, of the valve as a whole. Also, the nonregis-' trability of the stem adjustment passagewayand passageway 28 prevents undesired flow of gas to the main burner section. a

While the invention has been described in con- 'nection with the specific details of one embodiment, it should be understood that thesev details between 24an'd is reduced, thereby to reduce are intended to be illustrative and not limitative of the invention except in so far as set forth in the accompanying claims. a I j What I claim as new and desire to secure by United States Letters Patent is: I

1. A double gas valve for us with double ga burners of the type having main and simmer burner sections, including in combination, a valve body having a plug receiving chamber and a pair of outlet passageways adapted to supply gas to the simmer and main burner sections of the burner respectively, the simmer burner section outlet passageway communicating with said chamber and the main burner section outlet passageway Way, a valve 'plug ro-tatably' mounted'in said chamber, said plug having a valve stem, an axially 7 disposed passageway open to said chamber an a hollow portion extending through the valve Stem to said'axial' passageway, said plu having also first and-second radial passageways leading from the exterior of the said plug to said-axial passageway which are aligned with said inlet passageway and said radial portion of said main burner section outlet passageway in the full on position of the plug, said plug having also an auxiliary passageway located between said first and second passages which is axially displaced from both said first and second passageways and which provides communication between the inlet pa sa way and said axial plu passageway when the portion of the valve plug between-said first and second passageways is in the region of the inlet passageway, and said plug havin also a further passageway, the inlet end of which is axially and angularly displaced from all said other-passage-v ways and which extends to said hollow portion, and means including regulatable orifice defining structure in said hollow portion and accessible through the stem providing communication from said further passageway to said axial passageway. '2.=A double gas valve for use with double a burners of the type havin main and simmer burner sections, including in combination, a valve body having a plug receiving chamber and a pair of outlet passageways adapted to supply gas to the simmer and main burner sections of the burner respectively, the simmer burner section outlet passageway communicating with said chamber and the main burner section outlet passageway including a radial portion leading to said chamber, said body having also a radial inlet passageway leading to said chamber displaced both angularly and axially with respect to said radial portion of the main burner section outlet passageway, a valve plug rotatably mounted in said chamber, said plug having a valve stem, an axially disposed passageway open to said chamber and a hollow portion extending through the valve stem to said axial passageway, said plug having also first and second radial passageways leading from the exterior of said plug to said axial passageway which are aligned with said inlet passageway and said radial portion of said main burner section outlet passageway in the full on position of the plug, and said plug having also a further passageway, the inlet end of which is axially and angularly displaced from all said other passageways and which extends to said hollow portion, and means includin -orifice definingstructure in said hollow portion providing communication from said further passageway to said axial passageway. 3. -A double gas valve for double 'gas burners havingmain and simmer sections and operable to full on, simmer and low simmer positions in which positions gas is supplied to both burner sections, to the simmer only at a high rateand to the simmer only at a low rate, respectively, including in combination, a valve body having a, pai of angularly spaced apart passageways, a rotatable valve plug having an axial passageway, a pair of passageways leading from the surface of said plug to said axial passageway and which are aligned with said first pair of passageways in the full on position of the valve, the angular location of said passageways being such that in another position, the simmer position, one of said passages in the plug provides communication between the inlet and axial passageways in the body and plug, respectively, and said plug having a further passageway of adjustable restricted effective area leading from its surface to its axial passageway and angularly spaced from the others so that it provides communication between said inlet and axial passageways in the low simmer position of the valve, said aligned inlet. and one of said pair of plug passageways being axially spaced from said aligned outlet and the other of said pair o plug passageways and said further passageway being axially spaced from the other passageways.

4. A double gas valve for double gas burners of the type including main and simmer burner sections characterized in that it includes a valve body having gas inlet means and main and simmer burner outlets, and a rotatable valve element movab-ly mounted in the valve body and'controlling the connections between said inlet means and said outlets and having a hollow stem, said element having a first passageway between th gas inlet means and simmer burner outlet including adjustable gas flow limiting means accessible for adjustment through said stem for supplying a low quantity of gas to the simmer burner outlet in one position of the element, means including a second passageway in said element and between the gas inlet means and simmer burner outlet having a portion registrable with the gas inlet means for supplying a larger quantity of gas to said simmer burner outlet in another position of the element, and means including another passageway between the gas inlet means and bo burner outlets for-supplying gas to both outlets in a further position of said element, said p sageway including said portion in registry with said main burner outlet. I a

5. A double valve for double gas burners of the type including main and simmer burner sections, including in combination, a valve body with an inlet passageway and main and simmer burner outlet passageways, and a rotatable valve plug mounted in said body and controlling the connections between said inlet passageway and said outlet passageways, said valve plug including an axial passageway communicating with the simmer burner outlet passageway, a hollow stem communicating with said axial passageway, means including a first transverse passageway connecting the axial passageway to the exterior of said valve plug and including a portion registrable with the inlet passageway in one position of the plug, and auxiliary valve means controlling the flow of gas through said passageway and adjustable through the stem for connecting said inlet passageway to said simmer burner outlet passageway in said one position of the valveand supplying a low but regulat'able quantity of gas to the simmer burner section, means including said axial passageway and another transverse passageway in said plug angularly displaced from said first passageway and including a portion registrable with said inlet passageway in another position of the valve for connecting said inlet passageway to said axial passageway and simmer burner outlet passageway in said other position of the valve and supplying a larger quantity of gas to said simmer burner section, and said valve plu including also passageways extending from said axial passageway to the exterior of the plug for connecting said inlet passageway to both said simmer and main burner outlet passageways in a further position of the valve.

6. A double valve for double gas burners of the type including main and simmer burner sections, including in combination, a valve body with an inlet passageway and main and simmer burner Outlet p s a eway and a rotatable valve plug let passageways, said valve plug including a first system'of passageways including an axially extending passageway, a hollow stem and auxiliary valve. means controlling the flow of gas through said system of passageways and adjustable through the stem for connecting said inlet passageway to said simmer burner outlet passageway in one position of the valve and supplying a'low but regulatable quantity of gas to the simmer burner. section, a sec- .ond system of passageways in said pluginclud-- ing said axially extending passageway and effectively'angularly'displaced from said first system for connecting said inlet passageway to said simmer burner outlet passageway in another position of the valve and supplying a larger quantity of gas to said simmer burner section, and a third system of passageways including said axially extending passageway and effectively angularly displaced from said other systems for connecting said inlet passageway to both said simmer and main burner outlet passageways in a further po- 7 sition of the valve.

'7. A double gas valve of the type operable to one position to supply a first quantity of gas to the main and simmer burner sections of a double gas burner and to a second position to supply a smaller predetermined quantity of gas to the simmer section only characterized in that it includes a'valve body having a gas inlet passageway and main and simmer burner outlet passageways, and a rotatable valve plug mounted in said valve body and controlling the connections between said inlet and outlet passageways and including an axially extending passageway and a hollow stem, said body and plug each having a pair of angularly spaced apart and interconnected passageways which are aligned in said one position, said passageways in said valve body being the gas inlet passageway and the main burner section outlet passageway and the passageways in said plug communicating with said axially extending passageway, and said axially extending passageway communicating with said simmer burner section outlet passageway, and means including said axially extending passageway and a further passageway in said plug effectively angularly spaced from the other passageways in said plug and adapted to connect said gas inlet only to the simmer burner section in said second position, and means in said further passageway adjustable through said hollow stem controlling the flow of gas through said further passageway for supplying said smaller predetermined quantity of gas in said second position. 7

8. A double gas valve for double gas burners of the type including main and simmer burner sections characterized in that it includes a valve body having gas inlet means and main and simmer burner outlets, and a rotatable valve element movably mounted in the valve body and controlling the connections between said inlet means and said outlets, said movable valve element having a first passageway between the gas inlet means and simmer burner outlet including flow limiting means for supplying a low quantity of gas to the simmer burner outlet in one position of the element, means including a second passageway in said element between the gas inlet means and simmer burner outlet for supplying a larger quantity of gas to said simmer burner outlet in another position of the element, and means including passageways other than said first passageway in said element between the gas inlet means and bothburner outlets for supplying gas to both said simmer and main burner outlets in a further position of the movable. element and in a range between said other and furtherpositions.

9. A double gas valve, including'in combination, a valve'bodyha'ving a pair of radial an.- gularly and axially spaced apart passageways, one of which constitutes an inlet and the other a first burner outlet passageway, anda rotatable valve plug mounted in'said body in cooperative relation to said inlet and outlet passageways and controlling ;theqfiow of gas between them, said plug having an axial passageway adapted to communicate with a second burner outlet passageway, a pair of radial passageways communicating with said axial passageway and of which the first is aligned with said inlet passageway and said second is aligned with said outlet passageway in one position of the valve, said second passageway also being aligned with said inlet passageway in a second position of the valve plug, and a further passageway including flow predetermining means in said valve plug and angularly and axially spaced from the others and extending from the exterior of the valve plug to said axial passageway and adapted in a third position of said valve to connect said inlet and axial passageways, the axial spacing of said further passageway at the exterior of the valve plug being such that it cannot register with the first burner outlet passageway in any position of said plug. 7

10. A gas valve having a valve body with axially and angularly spaced apart inlet and outlet passageways, and a rotatable valve plug mounted in said body for controlling connections between said inlet and outlet passageways, said plug including first and second axially and angularly spaced apart passageways which are substantially aligned with said inlet and outlet passageways, respectively, in one position of said plug, the axial spacing being such that in another position of said plug said second passageway is registrable with said inlet passageway, and said plug including a further passageway having an inlet end at the exterior of the plug which is angularly displaced from the others and which is also axially displaced from said inlet and first passageways in a direction opposite to the displacement of said outlet and second passageways, the axial displacement of said further passageway being such that it is registrable with said inlet passageway in a further position of said plug but such that it does not register with said outlet passageway in any position of said plug.

11. A gas valve having a valve body with axially and angularly spaced apart inlet and outlet passageways, and a rotatable valve plug mounted in said body for controlling connections between said inlet and outlet passageways, said plug including an axial passageway and first and second axially and angularly spaced but.

passageways in a direction opposite to the displacement of said outlet and second passageways,

the axial displacement of said further passageway being such that it is registrable with said inlet passageway in a further position of said plug but such that it does not register with said outlet passageway in any position of said 'plu CHARLES C. LAMAR.

REFERENCES CITED UNITED STATES PATENTS Number Name Date 471,799 Leibman Mar. 29, 1892 1,763,305 Heidbrink Jan. 10, 1930 2,249,982 Rutherford July 22, 1941 2,252,134 Mueller Aug. 12, 1941 2,257,886 Mueller Oct. ,7, 1941 2,299,624 Harper Oct. 20, 1942 2,299,666

Turner Oct. 20, 1942