US2505804A - Piano construction with preassembled units - Google Patents

Description

May 2, 1950 c. F. STEIN 2,505,804

' PIANO CONSTRUCTION WITH PREASSEMBLED UNITS Filed Jan. 26. 1946 4 Sheets-Sheet l May 2, 1950 c. F. STEIN 2,505,804

PIANO CONSTRUCTION WITH PREASSEMBLED UNITS y Filed Jan. 26, 1946 4 sheets-shed 2 12d lz INVENTOR.

May 2, 1950 c. F. STEIN PIANO CONSTRUCTION WITH PREAssEMBLED UNITS Filed Jan. 2e, '1946 4 Sheets-Sheet 3 c. F. sTElN PIANOl CONSTRUCTION WITH PREASSEMBLED UNITS Filed Jan. 2e,` 194e May 2, 1950 4 Sheets-Sheet 4 BY. w

'is received in a store or in a home.

Patented May 2, 1950 PIANO CONSTRUCTION WITH PREASSEMBLED UNITS Charles Frederick Stein, Ivoryton, Conn., assignor to Pratt, Read and Company, Inc., Ivoryton, Conn., a corporation of Connecticut Application January 26, 1946, Serial No. 643,713

5 Claims.

1 This invention relates in general to pianos and more particularly to a piano structure including simple, rugged, and lightweight preassemblies which lend themselves to high speed production utilizing assembly-line methods which not only provide an improved piano construction with uniform parts, but also lprovide an improved piano construction with assemblies which can be put together and taken apart for greater ease in original manufacture, in shipping, and then in subsequent handling in a store and home.

Heretofore, it has been customary to manufacture pianos largely onv an individually customed basis. This has been due primarily to the nature of commercial piano construction and to the difficulty in producing-in such construction, the desired uniformity of tonal quality and performance. Different practices were introduced to speed up piano manufacture, but it still remained an operation wherein each piano was normally slightly or considerably different as a result of hand-fitting certain portions at least, and generally was characteristic of the individuals working upon it. Except in the most expensive pianos, there was often marked lack of uniformity among the pianos as far as playing quality, stability of tuning, and the like was concerned. The efforts which have been made prior to the present development as evidenced in this invention as well as those inventions of my copending application Serial No. 585,053 led on March 27, 1945 and my Patent No. 2,431,350 granted on November 25, 195i?, to provide a pianov construction lending itself to high speed uniform production have been notably unsuccessful. Furthermore, the efforts to construct a knock-down type piano in which the operating and playable parts ca n be manufactured entirely independently of the casing or housing unit have also been unsuccessful, and no such concept has heretofore been put into practice commercially. The present existing practice wherein the casing serves to assemble and retain many of the parts during the manufacture of a complete piano requires that special care be taken of the piano casing during manufacturing resulting in a less eilcient manufacturing procedure from the standpoint of labor and material costs. Not only is handling in manufacturing complicated but scratches and nicks must be repaired before shipme'ntand even after the piano Also, the requirements that vthe entire piano be assembled during manufacture in order to provide a satisfactory instrument has complicated shipment because of the bulk of the completed product.

In general, in prior commercialpiano construction, the string support of the instrument has comprised a frame, called a plate or harp of cast iron, and a pin block and sounding board which with pins on the block and plate altogether carry and stretch the strings. These parts are mounted on a stiff massive wood back. This is necessary in order to provide a back frame strong enough to resist the tremendous force exerted by the piano strings which on an average is 1'7 tons per piano. Also, it has been customary to utilize the piano case to maintain these parts in assembly and to support the keys and piano action so that a sturdy glued case was required. This rugged casing along with the heavy cast iron and wood back structure has contributed to the undesirable high over-all weight of the piano instrument.

Pianos in the past have represented an expensive instrument. The average family in a lifetime purchases no more than two pianos, and often just one. However, because of changing styles in the home over a long period of time, the case for a piano purchased in one era is not attractive in another era of style and decoration. The operating parts, except for the usual repairing, are often in good condition, but the case which has been in the past an integral part of the structure, spoils the appearance of the instrument and sometimes relegates it to a back room and disuse if the family is unable t0 afford a completely new piano. Even where a piano owner is willing to change casings because of a particularly high quality operating mechanism the cost of a new case is excessive both in removing the old case and hand fitting a new case to non-uniform operating structure.

It is an object of this invention, therefore, to provide a new and improved knock-down type piano of high quality having uniform tonal and performance characteristics over large numbers of corresponding instruments.

Another object of my invention is to provide operating structure and a casing with parts and subassemblies of such construction as to lend themselves to precision machine-made manufacture.

It is another object of the invention to provide a piano construction having one preassembled portion comprising all of the operating parts which is entirely self-supporting and playable, and which has provisions thereon for connecting with a casing or cabinet in a manner such that the casing or cabinet can be used only to style the piano.

AIt is a further object of this invention to provide a new and .improved string chassis or sub- 3 assembly complete with sounding board and strings which is light enough to be readily handled by one person and completely self-supporting in an upright position so as to readily receive for assembly therewith the remaining operating parts of apiano.

It is also an object of my invention to provide a piano mechanism which lends itself to high speed assembly line manufacturing methods without sacriilcing tonal quality, stability of tuning, uniform key and action operation, .or any other essential feature of a high quality hand made piano.

A feature of my invention is the provision of a small number of precision-made subassemblies which fit together in a high speed productionline manner, and each contribute to the production of a lightweight piano in standard sizes, which is readily demountable into the subassemblies for shipping and handling.

Another feature is the provision of a preassembled operating portion lwhich is entirely capable of playing operation in a normal manner, and which may be combined with a housing or casing portion, each of which portions includes provisions for connecting the two portions together to style the operating portion in any one of a wide variety of interchangeable housing or casing portion designs.

An additional feature of my invention is the l provision of supports and connecting means for the light weight subassemb-lies and the housing such that one man can readily assemble or disassemble the entire piano, and similarly quickly change housings on the operating part of the piano to change the styling thereof to suit the changing desires of the owner` A further feature of the invention is the pro- Vision of a unitary string-chassis including a rigid self-supporting light metal frame member which together with a, sounding board and a pin block supported on the frame member, form the sole means for mounting and stretching the piano strings, and for resisting the tremendous forces caused by the tension of the strings. In a commercial embodiment of the invention the weight of `the complete assembly is less than one-half (1K2) of the weight of comparable structure heretofore universally used in the piano in dustry.

A still further feature of this invention is the provision of means on such unitary string-chassis or assembly to support the same in an upright position and which is manually operable and adjustable during the initial assembly of the chassis and while other sub-assemblies are being connected thereto.

It is also a feature of my invention to optionally provide means for securing to the lightweight metal frame member of the string chassis as a cross-support to permit the lightest possible weight thereof, and yet support such frame mem- 'ber in a, manner to withstand the tremendous tension exerted from corner to corner thereon when the playing strings are tightened to operating tension. On a small upright piano chassis, the tension is as much as 8,000 pounds, and

this will increase during playing.

For a, better understanding of the invention, together with further objects, features and advantages thereof, reference is had to the following description taken in connection with the appending drawings in which:

Fig. l is a perspective view of the self-supported piano operating structurein its final asi sembled condition and capable of being played in such condition.

Fig. 2 is a cross-sectional view approximately along the lines 2-2 of Fig. l but with the removable iront supporting leg omitted.

Fig. 3 is a partially exploded rear perspective view of a, complete Alow upright .piano using the operating unit of Fig. l.

Fig. 4. is a perspective View of the light weight metal frame member of the structure of Fig. l and illustrates the horizontal brace member therefor which is not visible in Fig. l.

Fig. 5 is a perspective View of the frame member having a modied form of cross bracing.

Fig. 6 is a front view of the frame member of Figs. l to 5 `showing the supporting feet secured thereto in a'projecting supporting position as contrasted to the folded position of Fig. l.

Fig. '7 is a sidc View of one of the feet of Fig. 6 and,

Fig. 8 is a perspective detail view of a foot.

For purposes of illustration, my invention will be described herein as applied to a low upright iano, but it is to be understood that the invention is not limited thereto. This pia-no includes an operating unit which comprises a string chassis including a unitary light weight metal frame member with a sounding board and pin block mounted thereon adapted to carry and stretch the full complement of strings for playing. The string-chassis hasl retractable feet for supporting it in an upright position as a sub-assembly and the sub-assembly is adapted to have mounted thereon a key bed supporting keys and an action in playing. position relative to the strings to in all make up the playing unit. The front portion of the playing unit is secured to the frame member by brackets removably mounted on the front side of the string-chassis. The pedals and mechanism therefor are supported from the frame member and key bed so that a complete playable piano is provided which can be completely and finally regulated during the manufacture of the entire playing or operating strucf ture.

The frame member of the string-chassis comprises a wide peripheral flange with a web portion internally of the iiange and intermediate its edges from front to back. Provisions are made on the chassis and on the flange for positioning the sides and top of the piano case and removably retaining said members. The remaining parts of the piano case lare secured to the side members or operating structure to form a complete demountable case for the piano which is readily. interchangeable in various case and leg designs to style the piano to the owners taste.

Referring now to the drawings, Fig. l shows the operating structure comprising a string chassis I0, a key bed II secured thereto by brackets I2, and a playing unit I3 supported by said key bed and string chassis. As can be seen in Fig. 2, the string chassis includes a frame part I4 having a peripheral flange Ida and a web portion Idb. The peripheral flange extends completely around the frame portion as is clearly shown in Fig. i. The web portion is positioned substantially centrally of the peripheral flange. On the back of the frame are positioned a pin block I5 and a sounding board I6. The pin block I5 is positioned in a channel-like recess formed by the upper flange Ilia and a second fla-nge Mc secured to `the web portion of the frame and parallel to the upperflange. The .sounding board` I6 is positioned between the flange I4c and the lower peripheral flange IIIa to cover the remainder of the space on the back of frame I4. As shown in Fig. 3 the sounding board I6 is provided with ribs ISa for making the same more rigid over certain areas. For securing the sounding board to the web portion of frame I4, screws II or the like are provided.

Openings Md are formed in the web portion Mb of the fra-me, in the recess between flanges I4a and IIIc, to allow the string pins I3 in the pin block I5 to project through to the front of the web portion. The adjustable string pins I8 cooperate with xed string pins Ille on the web portion of the frame member (Fig. 1) to support the piano strings. Bridges Ib and Ic, for the base and treble strings respectively, are provided on the front face of the sounding board and project through openings in the web portion of the frame member to the front thereof to contact the strings.

The frame member I4 is preferably constructed of a high tensile strength, light metal alloy such as an aluminum-copper-magnesium alloy com mercially available as Duralumin, or an alloy of magnesium, aluminum, manganese and zinc commercially available as Dowmetal In any event the member I4 should be constructed of a material and with a cross sectional moment of inertia resulting in a resiliency for a given weight substantially higher than that of a compoiste cast iron frame and wooden back of the standard piano. Preferably the material of the frame member I4 should have a ratio oi Ycungs modulus to specific weight greater than 3x106 and preferably of the order of 3.75 106. This ratio may be termed the factor of merit and is an index of the rigidity per pound of metal of the chassis member for any given size and for any given cross-sectional conguration. In other Words, a string chassis of given dimensions made of a metal with a high ratio will have a higher rigidity for any given weight or will be lighter in Weight for any given rigidity than one made of a metal having a lower ratio. The mean value for laluminum alloy of the type mentioned is 3.89 /6 while a typical value for a magnesium alloy of the type mentioned is 3.5'7 101/6.

In one commercial embodiment of the inven tion, a frame member as shown in Fig. 6 for a 38 low upright piano weighs 8O pounds in a mag-4 150 pounds will result in the back structure alone.

This particular commercial embodiment corresponds in size to what is known in the industry as a 38" low upright piano.

Reference is now made to Fig. 4 which shows in detail the construction of the frame I4. As shown in this figure the web portion has a plurality ci -openings therein to lighten the weight of the frame member and a plurality of integral bracing struts I4f to provide strength at the points where it is needed. The tension of the strings on the frame causes a tremendous corner to corner force tending to twist or buckle the frame. The brac ing struts are positioned where they will be most effective in resisting thisi'orce.

An additional horizontal bracing rassembler- 39- fis may be positioned on the front side of the frame member and secured to the peripheral ange I4a and the bracing struts idf as shown in Fig. 4. This bracing member serves the dual function of reinforcing the frame member I4 and of cooperating with the brackets I2 to support the key bed and action of the piano. The bracing member is secured to the frame member in abutting relation with the struts idf so that a portion of the bracing member is positioned within the space defined by the peripheral flange la. This provides a maximum of reinforcement for the frame member. Clearance is provided between the frame and the bracing member in the space not occupied by the struts to permit the strings to extend from corner to corner as illustrated in Fig. 1,

Fig. 5 shows an alternative structure in which an X-shaped brace or member 3| is used to provide the same function as the horizontal brace member 3B. The member 3| is secured to the frame member at the flanges thereof, and at the reinforcing struts as shown. The reinforcing member is positioned at the lower part of the frame structure so that it does not interfere With he piano action and is also positioned so that a part thereof is within the space dened by the lange Iia to provide maximum support.

The playing unit of the piano including the keys and action is supported on the key bed II. A split key bed is provided having a rear portion IIa and a front portion Hb. The rear portion i la, includes pins I 9, to support the action brackets 2li, which in turn carry the stationary and movable parts on the aetion itself. Except to refer to the whip 2l and the hammer 22 in each individual unit of the complete action, and like wise the pivoted hammer rest rail 23 and the stationary rail 2li, common to all units, there is no necessity for describing more in detail the action illustrated. Threaded pins or bolts 25 secured to the Amember receive and support the top of each of the plurality of action brackets Zt, all as shown in Fig. l. The front part of key bed lib supports a key frame 25 on which are pivotally mounted a purality of keys 2l. A capstan screw 28 is provided at the end of each key for engaging a whip when a key is depressed in playing and sets into motion the action of that unit including the hammer 22 which strikes the corresponding string. The vibration of the string is transmitted through the bridge IBb or IBC to the sounding board where the sound produced by the vibrating string is amplified.

As previously stated, the key bed is secured to the string chassis by brackets I2. As shown in Fig. l, the brackets include body portions I2a having integral right angle flanges I'Zb which are secured to the web portion of the frame member. Slot shaped openings I2C are provided in the flanged portion I2b for bolts 29 which enter the reinforced web portion Mg, as shown in Fig. l. The brackets i2 are adjustable on the bolts 29 for the proper vertical height relative to the string-chassis so that the keys and action are properly positioned relatively to the strings. The brackets include-an upper face or surface I2d -for supporting the'key bed, with an integral extension 32e extendingforwardly therefrom and offset inwardly of the key bed relative to the back and body portion i230; as is evidenced from Fig. l. The bracket may also include a notched portion 52j into which a horizontal supporting member 3i), which has been previouslyvdescribefd, is adapted to lit. It is evident that the-brackets I2 provide an adjustable connection between the string chassis and the playing unit of the piano operating structure as well as the support for the playing unit.

By use of the invention, the space within the flanges Illa and in front of the web portion l4b above the bracing member 30 (Figs. 1, 2, and 4) or 3| (Fig. 5) comprises a cavity into which the piano action may extend. This cavity is of depth equal to nearly one-half the over-all width of the frame member i4 and permits construction of a more shallow piano with the action and key bed extending into the frame member cavity. That is, it permits of a more shallow piano from front to back without sacrificing key length. This is a very important feature as it is desirable to keep the width of low upright type pianos to a minimum so that the piano will require a small amount of space in a room, may be taken through standard doorways, and in general is more easily handled in a small apartment, or any other home setting as a matter of fact. On the other hand by increasing the length of the keys, greater leverage is provided and an action which is unacceptably stiff and unnatural when operated by a short key might become entirely acceptable if the key length is increased to provide a greater leverage. This invention permits a longer key in comparison to that in a standard width conventional prior piano construction.

Considering specific typical dimensions, in a piano having a width of 23% inches, it is possible to increase the length of the key from 15 inches to 161/2 inches and retain the same overall width by utilizing the unitary string chassis of this invention instead of the standard composite frame. This increase in key length will greatly improve the operation of the piano action. Alternatively by utilizing the same key length it is possible to reduce the width of the piano by 1% inches which will result in a material saving in space.

As shown in Figs. 1, 6, '7, and 8, feet 32 are secured to the frame for supporting the stringchassis during the preliminary stages of assembly and for supporting the structure in an upright position when the housing or casing is being secured thereto. As shown clearly in Figs. 7, and 8 the feet 32 comprise upright angle members 33 secured to the frame I4 by bolts 33a, and having angle members 34 hinged thereto. The members 34 have bearing portions 34a thereon for resting on the floor on which the structure is supported and have latching members 35 secured thereto with top portions 35a adapted to t in the notches 33h on the upright members. As is shown in Fig. 1, the latching members may be released and the projecting members 34 hinged upwardly against members 32 so that the feet are positioned against the frame member I4. When in this position, the feet can be completely covered by the removable bottom frame, as it is called, of the casing of the piano and will be out of sight.

As previously stated, the feet secured to the frame member may be used to support the string chassis during the preliminary stages of assembly of the operating structure. After assembly of the brackets I2 on the preassembled string chassis of the operating structure and thereafter the assembly of the key board and associated elements or units including the action itself on the brackets, legs 48 are connected to the front part of the playing portion to support the coming' manufacturing steps.

In the disassembly of a complete piano for shipment or moving, when the casing is removed from the operating structure of Fig. l, then as the operating structure is taken apart the feet are dropped down to the position of Fig. 7 with the arm 35 in a notch such that with legs 48 removed and the string-chassis I4 standing alone, it leans forward very slightly to prevent the string-chassis from being tipped over backward. The angle at which the string chassis rests is exaggerated in Fig. 7 for the purpose of illustration.

In Fig. 3 is shown the assembly of the cabinet on the operating structure of the piano. As previously stated, the feet secured to the frame member are used to support the operating structure while the casing is being secured thereto. The cabinet includes side members 36, a top member 31, and a front frame 38 which includes a music shelf. rIhe fall board which pivots out of the top frame and down over the keys is not visible in the illustration. Key blocks 4'! are provided at each side of the keys while a key slip 4!0. extends across the front of the keys. Included in the demountable casing is a removable bottom frame below the key bed and over the face of the bottom of the string-chassis. A toe rail 45 supports the pedals 46 and associated mechanism as shown in Fig. 1.

The side members 35 are provided with dowels 36aJ which are adapted to t in openings I4h in the flange of the frame member I4 for positioning the members with respect to the frame as shown in Fig. l. Corresponding hinge- like members 39 and 40 are secured to the side members 36 and the pin block and sounding board with removable pins 4I for securing the members together. Similar members are provided for securing the front of the side members, the exact position of which depending on the style of the cabinet. The top member or frame 31 is secured to the top of the frame member I4 by hinges 42 shown in Figs. 1 and 3. The front parts of the piano casing as previously identified are secured to the side members by readily disconnectible means to provide a casing structure which can be easily assembled or disassembled.

From the foregoing description, it can be seen that a knock-down type piano is provided In which the various operating parts and the cabinet parts may be prefabricated and shipped in 'a knock-down'condition for assembly by unskilled labor at a sales room or even the home of the user. In a fully representative operation a cabinet as illustrated in Fig. 3 was removed from the operating structure of that iigure, and a Victorian style cabinet substituted thereon in approximately 15 minutes and skilled help can do it in less. The various components are arranged for production-line manufacture in such a manner that a uniform and high quality instrument will be provided. The string-chassis is so constructed that the weight thereof is reduced to a minimum to facilitate manufacture, and also assembling of the unit after being shipped to the seller or user. The provision of the self-contained feet for supporting the string chassis while assembling the subassemblies into the complete operating structures, makes for a great ease and simplicity in manufacturing and assembly or disassembly. Although the frame structure is of simple construction and light in weight, it is sufficiently rugged with the integral struts, and optionally with the bracing member to resist the great strain thereon due to the tension of the piano strings.

Although the description has been limited to what lis at present considered the preferred embodiment of the invention, it will be apparent to those skilled in the art that various changes and modiiications may be made therein and the scope of the invention should be limited only as defined bythe appended claims.

I claim:

1. A unitary string chassis for a piano including a rigid metal frame having continuouswide peripheral flanges and a web portion, said web portion throughout its entire extent being disposed in a single plane approximately centrally of said peripheral flanges and integral therewith, a sounding board, means supporting said sounding board on said frame on one side of said web portion within the space dened by said peripheral flanges on said one side, piano strings, meanssupporting said piano strings on said frame on the side of said web portion opposite to said one side, brace means on said opposite side of said web portion spaced from said piano strings, means securing said brace means to the flanges on opposite sides of said frame and to said web poi'tion, said strings being positioned between said web portion and said brace means, at least a portion of said brace means being positioned within the Space defined by said peripheral ilanges on said opposite side of said web portion.

2. Operating structure for a piano comprising a string chassis and a playing unit, said string chassis including a rigid metal frame member having continuous wide peripheral flanges and a web portion, said web portion throughout its entire extent being disposed in a single plane approximately centrally of said anges and integral therewith, a sounding board and a pin block, means for supporting said sounding board and pin block on said frame on one side of said web i portion within the space dened by said peripheral flanges on said one side of said web portion, a horizontal brace member on the side of said web portion opposite to said one side, means for securing said brace member to said fianges and said Web portion, piano strings, means supporting said strings on said frame with said strings being positioned between said brace member and said web portion, and means including said brace member for supporting said playing unit on said string chassis on said opposite side of said web portion,

the casing, said operating structure including a string chassis having a rigid metal frame member, a sounding board, piano strings, and means for supporting said sounding board and strings on said frame member, a playing unit, means for removably securing said playing unit to said string chassis, retractable feet members having iirst stationary portions and second portions pivotally connected to said first portions, said rst portions including notches therein and said second portions including members adapted to selectively engage said notches for adjustably positioning said second portions with respect to said first portions, and means for securing said rst portions to said frame member with said second portions being pivotable away from said frame member to support said string chassis in an upright position while said playing unit is secured thereto, and to support said entire operating structure in an upright position while said casing is being assembled thereto, said flange and casing including registering provisions for positioning said casing with respect to said operating structure, and means for removably connecting said casing and operating structure.

4. A knock-down type piano comprising a casing and an operating structure capable of standing upright in assembled condition independently of the casing, said operating structure including a string chassis having a rigid metal frame member, a pin block, a sounding board, piano strings, and means for supporting said pin block, sounding board and strings on said frame member, a. playing unit including a key bed, means for removably securing said playing unit to said string chassis, legs for said operating structure, means for removably securing said legs to said key bed, retractable feet, means for securing said retractable feet to said frame member with said feet being adapted when in extended position to hold said string chassis in upright position while said playing unit and legs are assembled thereto, said operating structure including said legs being entirely self-supporting and being adapted to be entirely regulated and played in a normal fashion independently of said casing, said casing including end members and horizontal members, said flange and said end members including registering provisions for positioning said end members with respect to said ilange and for securing said end members to said flange, said end members having provisions for supporting said horizontal members thereto, said feet being retracted prior to assembly of said horizontal members to said end members and being enclosed by said horizontal members.

5. A piano structure for use in an enclosing case, said piano structure comprising a rigid metal frame having peripheral ilanges with a web structure integrally connecting the saine and substantially in a single plane centrally of said flanges, string supports on said frame, piano strings secured to said supports, a sounding board, means for securing said sounding board to said frame, a key bed having keys supported thereon, means for supporting said key bed including brackets secured to said frame and eX- tending forwardly thereof, a piano action, means for supporting said piano action on said frame in cooperative position with respect to said keys and in operative playing engagement with said strings, supporting means in front of said frame including a fixed portion and a bipart retractable portion, means for securing said xed portion to said rigid metal frame, and means on said rigid metal frame and on said keybed for detachably securing a case thereto, said retractable portion having an operative position for supporting said piano structure and a retracted position within the space enclosed by the case.

CHARLES FREDERICK STEIN.

REFERENCES CITED UNITED STATES PATENTS Name Date McCammon May 23, 1882 Number (Other references on following page) l 1 UNTTED STATES PATENTS Numbei` Name Date Brackett Oct. 20, 1885 Dow Nov. 24, 1885 Wing Oct. 12, 1886 Mahling Oct. 25, 1887 Smith May 26, 1896 Conover Jan. 5, 1897 Knutz June 2, 1903 Arnold Apr. 19, 1904 Bless Apr. 2, 1907 Hopphan Jan. 13, 1914 Lunde et a1 Mar. 17, 1914. Avisus Jan. 4, 1916 Schwemberger Jan. 11, 1916 Meiklejohn July 17, 1917 Munafo Apr. 15, 1924 Brey Sept. 13, 1927 Collen Jan. 22, 1929 Number Number Name Date Coiien Oct. 8, 1929 Collen Mar. 25, 1930 Pressiey May 20, 1930 Clark Nov'. 11, 1930 Haddorff Oct. 6, 1936 Heller May 25, 1937 Sauerland Nov. 2, 1937 Huseby Dec. 21, 1937 Stein Nov. 25, 1947 FOREIGN PATENTS Country Date Great Britain Aug. 3, 1855 Great Britain May 12, 1885 Great Britain May 10, 1893 Great Britain Sept. 10, 1925 Great Britain Mar. 8, 1828

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