US2838009A

US2838009A - Toy railroads

Info

Publication number: US2838009A
Application number: US188410A
Authority: US
Inventors: Joseph L Bonanno
Original assignee: Lionel Corp
Current assignee: Lionel Corp
Priority date: 1950-10-04
Filing date: 1950-10-04
Publication date: 1958-06-10
Anticipated expiration: 1975-06-10

Description

June 10, 1958 J. L. BQNANNO TOY RAILROAD-S 4 Sheets$heet 2 v Filed Oct. 4, 1950 MAGNETIZABLE M/EELS NON- MA GNETIC AXLES 40 \MA G/VET/ZABLE T/FA CK MA GA/ET/ZABLE WHEELS /VON'M4GNET/C MAGNET/ZED WHEELS MAGNET/2A ELE MAGNET/ZABLE INVENTOR. JOSEPH L. BONANNO BY 26 M a ATTORNEY.

June 10, 1958 J. L. BONANNO 2,838,009

v TOY RAILROADS Filed Oct. 4, 1950 4 Sheets-Sheet 3 NoN-MAgA/EM: FRAME AXLES INVENTOR.

M3567 .4. om/wo BY af K A TTORNE Y hired States Patent ce TOY RAILROADS Joseph L. Bonanno, Madison, N. 1., assignor to The Lionel Corporation, New York, N. Y., a corporation of New York Application October 4, 1950, Serial No. 188,410 3 Claims. (Cl. 105-77) The present invention relates to toy railroads and is more particularly directed toward toy railroads having means for securing tractive efforts greater than those normally available on toy railroads of customary construction.

Railroad operation, except in multiple unit trains for passenger traflic, or where pushers are needed, utilizes locomotives to haul the train of trailing cars. Similar toy locomotives are used for hauling toy trains. Draw bar pull of the locomotive, or of all the locomotives, when more than one is used, is the force which efiects the movement of the train and, in typical full sized locomo tives as well as in toy locomotives heretofore in use, draw bar pull is a direct function of the weight of the locomotive on the drivers and the coeflicient of friction (or adhesion) between the driving wheels andthe rails.

The coefiicient of adhesion, i. e., ratio of tractive effort to weight on the drivers, depends upon the condition of the rails, the composition of the wheels and rails and the uniformity of the torque. This coetlicient f r any set of particular conditions is constant and as it enters in the same way into calculations of tractive effort no matter how wheel-to-rail adhesion is achieved, its variation may be ignored in determining performance ratios.

The desire has long existed to more closely simulate in the toy or miniature railroad field the operation of full sized prototype railroads, particularly with respect to hauling longer trains, the climbing of grades, the rounding of curves at high speed, and quick starts with.- out slippage of drivers on the rails, but conditions heretofore existing in this art have handicapped the attainment of these objects. The adverse conditions arose on account of the high rolling frictional resistance of the car wheels on their axles, wheel flange resistance against the sides of the rails, the necessity of negotiating sharp curves, and track irregularities tending to derail the train of cars; also the low coeilicient of adhesion between the tread of the wheel and the surface of the sheet metal rail used on such railroads.

The only commonly used expedient to increase tractive effort has involved the adding of weight on the toy locomotive drivers. This requires the use of heavy metal locomotives often carrying metal parts of no functional value except to provide weight. Such weight loading, however, defeats the purpose when hill climbing is desired, for the weight must be lifted up the grade. It increases the cost of the locomotive, especially Where it provides no other functional purpose, as in locomotives with plastic bodies. Rubber tired toy locomotive wheels to increase the wheel-to-rail adhesion were tried and discarded many years ago.

In the early days of electric traction, many attempts were made to increase adhesion of rail-to-track by producing electromagnetically a phantom load. Direct current energized electromagnets on the locomotive or motor car were suggested for the purpose of magnetizing the wheels and supporting track so as to cause the wheels to press more forcibly on the rails. So far as I have been able to ascertain, these devices never went into practical use and, if they did, they were discarded long ago. They were necessarily costly, cumbersome devices and Patented June 10, 1958 occupied room on the locomotive which could well be used for something else, and to a substantial degree the added tractive effort which came from them was due to their own dead weight.

Irrespective of how the magneto-motive force is obtained, the maximum magnetic adhesion between wheel and rail would be achieved when the wheel material was magnetically saturated over the entire surface in close proximity. Owing to the shape of the full sized locomotive wheel and of the usual steel rail, this area is only about 5 square inches for each wheel. figures in the known formula- Magnetic attraction (P) of one wheel to rail:

72 lbs.

(Max.

On an eight driver locomotive, the total magnetic attraction would be 4500 lbs. or the equivalent of that additional weight on the drivers. This additional weight, whether real or magnetically produced, is insignificant when considered alongside total locomotive weight. Such a typical steam locomotive would weigh in the neighborhood of 440,000 lbs. and would have a weight on the drivers of 270,000 lbs. The added tractive effort produced magnetically is of the order of 1.7%.

The present invention contemplates the provision of toy railroads with locomotives of greatly increased trac tive effort when used on magnetizable trackage.

According to the present invention, trackage of the conventional type, either trackage with two steel, wheelbearing rails carried on steel cross-ties, or tracTrage having two steel, wheel-bearing rails electrically insulated from one another, may be employed; and the toy locomotive is provided with permanent magnet means and magnetizable parts so related to the drivers and track rails as to produce low reluctance paths each including two drivers and the rail means on which they bear. At the same time, the locomotive structure is provided with non-magnetizable structural parts in places where magnetizable structural parts would divert the magnetic flow from the wheel-to-rail-to-wheel circuit.

In practical applications of the present invention, it has been found that toy locomotives in general may be equipped with permanent magnet means, and, Without changing appearance or mode of operation to the casual observer, or prohibitively increasing cost of manufacture, thereupon be made capable of handling longer trains at higher speeds both on level track and on grades, with less tendency to jump the track and far improved overall operation.

Other and further objects of the invention will appearas the description proceeds.

The accompanying drawings show, 'llustrating the present invention, several embodiments in which the invention may take form, it being under stood that the drawings are illustrative of the invention rather than limiting the same.

In the accompanying drawings:

Figures 1 and la are schematic views showing on level Inserting these for purposes of Figure 4 is a diagrammatic perspective view illustrating a locomotive with magnetizable wheels opposite fixed permanent magnets, carried on non-magnetic ax es and bearing on magnetizable two-rail track;

Figure 5 is a view similar to Figure 3 illustrating a locomotive with pairs of magnetic axles with magnetizablwheels and on magnetizable two-rail track;

Figures 6 and 7 are fragmentary sectional views showing modified forms of magnetic axle locomotives;

Figure 8 is a diagrammatic top plan view of a locomotive with permanent magnets mounted adjacent the drivers at each side, the drivers and track-rails being magnetizable;

Figure 9 is a diagrammatic perspective view showing the locomotive having at each side a pair of drivers close to a block in the form of a bar magnet, and bearing on a magnetizable rail, the magnetizable rails and opposite pairs of drivers being in the same or in separate magnetic circuits;

Figure 10 is a view similar to Figure 9, except that the wheels are permanently magnetized and the block between wheels is magnetizable;

Figure 10a is a perspective view illustrating a pair of permanently magnetized locomotive driving wheels carried on a magnetizable axle and on magnetizable tworail track;

Figures 11a, 11b and 110 are fragmentary views illustrating the employment of flanged drivers magnetized in the direction of the driver axes;

Figure 12 is a vertical sectional view taken on the line 12-42 of Figure 13, showing a plastic locomotive chassis carrying permanent magnets adjacent opposite driving wheels;

Figure 13 is a side elevational view of the locomotive chassis of Figure 12,. the nearer wheels being omitted;

Figure 14 is a side elevational view of a locomotive having a metal chassis and carrying permanent magnet means between opposite drivers;

Figure 15 is an inverted plan view of the chassis of Figure 14;

Figure 16 is a vertical sectional view on the line 16-Zi6 of Figure 14;

Figure 17 is a top plan view partly in section of the truck portion of a diesel type, toy locomotive having permanent magnets acting on the dri ers;

Figure 18 is a side elevational view of such a locomotive truck with parts in section on line 18-1i of Figthe 17;

Figure 19 is a transverse section on line Figure 17;

Figure 20 is a transverse sectional view taken on the line 20-20 of Figure 17;

Figure 20a is a fragmentary view showing the truck of Figure 17 supplied with permanent magnet axles;

Figure 21 is a longitudinal sectional view through the truck portion of a still further modified form of construction in which the single permanent magnet through the medium of pole pieces magnetizes all the driving wheels; and

Figure 22 is a vertical sectional view taken on the line Z2-22 of Figure 21.

Figures 1 and la illustrate in full lines a typical locomotive and tender, together with single car outline for the number of cars X which the locomotive without magnetic augment will handle on the level or x which without magnetic augment will handle on a grade, and in dotted lines another single car outlinefor the number Y of additional cars which the same locomotive, with magnetic augment, will handle on the level or 3 which it will handle on the same grade.

In carrying the present invention into practice it is i9-l 9 of possible to have a locomotive which, instead of handling only one car on the level without magnetic augment can operate as many as 7 cars on the level, or to convert another form of locomotive which could handle 8 cars on the level without magnetic augment to one handling 15 cars on the level. Locomotives which cannot negotiate grades of over 3% to 5% with a train can be made to operate the same train on very substantial grades.

In Figure 2, the line OB represents the performance of a locomotive in which all the draw bar pull is due to real weight on the driving wheels. The draw bar pull increases in a straight line relation with the weight on the drivers. In the graph of Figure 2, the line CD r presents the performance due to an increase of driving wheel load irrespective of how it is produced. This line has the same slope as the other, but is displaced horizontally by a distance OC. The magnitude of this displacement is the direct indication of the efiectiveness of the added load on the drivers. According to the present invention this added load is produced by the magnetic augment resulting from the use of permanent magnet means on the locomotive.

In the diagrammatic view of Figure 3, the interrelation of the usual flanged toy wheel and the toy track rail is indicated. The wheel exerts on the track a gravity produced force proportionate to the weight and this is indicated by the heavy arrowed line, downwardly directed,

Due to the magnetic loading of the locomotive, there is an added magnetic attraction indicated by the lighter arrowed line F". These two forces add and increase the vertical loading imposed by the tread of the wheel on the rail. In view of the fact that the flange of the wheel is also magnetized, there is a third component which increases the adhesion of the wheel and rail. This component is indicated by the sloping arrow 5. While the magnetic component F is present for percent of the running time, the lateral component F' fluctuates between maximum and minimum due to the locomotive moving from side to side.

In the arrangement diagrammatically illustrated in Figure 4, the trackage is of the conventional type, having two magnetizable wheel bearing rails Zil-2fi interconnected by magnetizable ties 21. These ties carry the usual third rail 22 omitted, however, from the diagrammatic figures but shown in the detailed figures below. The driving wheels 23 are made of magnetizable material such as soft iron or a material containing powdered iron and are arranged in pairs on non-magnetic axles 24. Interposed between the pairs of wheels, and carried by the locomotive chassis (not shown here) are permanent mag nets 25, the ends of which are close to, but physically spaced from, the inner facesof the'driving wheels to magnetize the wheels without interfering with rotation. In this form of construction, the axles 24 as well as all other parts of the chassis which could be magnetized by the magnets 25 are made of non-magnetic material. When the wheeled axles are on the rails, a low reluctance magnetic circuit is provided through the permanent magnets, the magnetizable wheels and trackage.

In the form shown in Figure 5, the arrangement of rails'Zli and cross-ties 21 is the same as before. Here the wheels 26 are similarly made of magnetizable material, the axles 27 are permanent magnets, and adjacent locomotive parts are non-magnetic. V

The locomotive fragmentarily shown in Figure 6 has a non-magnetic tubular axle Z9 (Phosphor bronze, stainless steel, etc.) mounted on bearings 34 The tubular axle carries a permanent magnet 31 whose length is preferably twice its diameter, and shaft'extensions 32 of magnetizable material. These extensions are forced into the tube and are reduced to receive the magnetizable wheels 33. This arrangement conserves the expensive magnetic material and avoids the use of the brittle magnetic material for the axle proper.

V In the arrangementshown in Figure 7, the drivers 34 are carried on stub axles 35 of magnetizable material and a fixed permanent magnet 36 magnetizes the axles through a very narrow air gap. Such arrangement also ma es possible the use of a magnet of good diameter to length ratio.

Figure 8 diagrammatically illustrates an arrangement in which the drivers 37 are close to permanent bar ma nets 38. The drivers are made of magnetizable material so that a magnetic circuit is set up from each bar magnet to the adjacent drivers and the supporting track rail. With this arrangement, the locomotive chassis is otherwise made of non-magnetic material and the tracks may have magnetizable cross-ties, or not, as desired.

In the arrangement shown in Figure 9, a pair of wheels 39 are carried on each rail 20. In this case the ties may be magnetizable or not, as desired. The wheels 39 are made of magnetizable material and are close to a permanent bar magnet 46. The magnetic circuit now includes a pair of wheels, a supporting track rail and the permanent magnet. This arrangement is suitable for use where the track rails are insulated from one another to be used for the two sides of the track circuit instead of the third rail.

In the arrangement shown in Figure 10, the wheels 41 are made of highly coercive material and magnetized so that one wheel has the north pole at the tread and the south pole at the center, and the other wheel has the north pole at the center and the south pole at the tread. They are carried on non-magnetic axles and are close to soft iron bars 42. The magnetic circuit set up is similar to that of Figure 9.

In the form of construction illustrated in Figure a, the driving

wheels

43, 43 are similar to the wheels of Figure 10. They are arranged in pairs, each pair mounted on a soft iron axle 44 and when such a truck is carried on the track of rails 2 with cross-ties, the magnetic circuit is completed.

In the arrangement shown in Figure 11a, the driver 45 is of high coercive material with poles on opposite faces. The magnetic field traverses the rail 20.

In the arrangement shown in Figure 1115, the tread 46 of the driver and flange 47 are separately magnetized and have a non-magnetic spacer 48 which causes a portion of the field of each of magnets 46 and 47 to traverse the rail.

In the arrangement of Figure 110, the spacer 49 is a disk-shaped magnet with one face N, the other S, and the wheel body 49a and flange 4912 are magnetizable.

In the construction shown in Figures 12 and 13, the steel rails 20-20, the steel tie 21 and insulated third rail 22 are of conventional form. Here the locomotive chassis designated generally by the reference character 50 is made of two plastic halves Stla and 5%. These carry the motor and other parts as shown more in detail in copending applications of Joseph L. Bonanno and Richard E. Beger, Ser. Nos. 121,494 and 121,495, filed October 15, 1949, now Patents 2,659,317 and 2,581,166. The chassis 50 carries

magnetizahle driving wheels

51, 51 on non-magnetic axles 52, and also carries

permanent magnets

53, 54 between the wheels. These magnets terminate close to the faces of the wheels but do not contact with them. This type of magnetically loaded locomotive is diagrammatically illustrated above in Figure 4 and the magnetic loading is shown in Patent No. 2,659,317.

The locomotive of Figures 12 and 13 without magnetic load will handle tender and five 170 gram cars on a 3% grade, or will handle 12 cars on the level, or without any cars will climb an 18% grade. It can haul the tender and two cars up a 7% grade. When loaded with a single magnet, it can haul the tender and a 20-car train on the level, the tender and two cars up a 21% grade, and without tender can climb a 38% grade.

In the construction shown in Figures 14, and 16, the body of a steam type locomotive is shown at 66. The propulsion unit 61 is in general of the conventional type. It has

side plates

62, 62 made of non-magnetic material, such as aluminum, instead of steel, and non-magnetic spacers 63. The motor shaft is indicated at 64 and through the usual reduction gearing indicated at 65, 66, 67, 68, the drivers 70 are operated. This locomotive chassis may be the same as those heretofore in use, except for the use of the non-magnetic frames and axles 73 and for the use of

permanent magnets

71, 72 between the pairs of drivers 70. These magnets magnetize the drivers and set up a magnetic field as above described.

The type of locomotive shown in Figures 14 to 16 is similar to the full sized prototype locomotive discussed above where it was shown that the maximum magnetic augment obtainable in the full sized loco-motive was of the order of 1.7% of the tractive effort obtainable due to weight alone. The locomotive such as shown in Figures 14 to 16 has a total weight of approximately 1,880 grams with about 1,780 grams on the drivers. Inasmuch at it is easy to directly measure the added load on the drivers, due to magnetic loading, it is unnecessary to calculate such added load. The added driver load for the four drivers when using magnets of the comparative size indicated in the drawings is approximately 1,400 grams or nearly of the load due to weight alone. As a result, a locomotive such as Figures 14 to 16 supplied with the permanent magnet arrangement discussed will have an added tractive effort of approximately 80% above what is available with the same size and weight of toy locomotive of ordinary construction. The total weight of the two locomotives is very nearly the same. It will thus be seen that the magnetically loaded locomotive may have nearly 50 times as great increase in tractive effort due to magnetic loading as can theoretically be attained with magnetic loading of the full sized locomotive.

The form shown in Figures 17 to 20 is one more particularly adapted for use with locomotives such as diesel type toy locomotives having the motor axis vertical and using a worm gear reduction drive to the drivers. Here the motor frame is fragmentarily shown at 88. It has a downwardly extending cylindrical boss 81 below which projects the worm shaft 82. It also carries a downwardly extending stud 83 passing through an apertured plate 84 carried by the locomotive chassis. The truck body, a die casting designated generally by 85, has an upwardly facing cylindrical recess 86 to receive the boss 81 and a bearing sleeve 87 to receive the stud 83. A screw 83 passing up from the bottom of the truck body is threaded into the lower end of the boss 81, to the rear of the worm 82, so as to fixedly secure the motor unit to the truck. The truck and motor can swing as a unit about the axis to the stud 83.

The worm 82 meshes with a worm wheel anon-magnetic axle 90 mounted in bearings 91 in the chassis body 85. The axle 90 is secured to two

magnetizable driving wheels

93 and 94, the wheel 94 having a gear 95. At the other end of the body casting a similar set of bearings 91, 91' support a similar nonmagnetic axle 90, which carries magnetizaole wheels 33' and 94'. The body casting is cut back at 96 to accommodate two flat bar magnets 97 held in place by cement.

The gear teeth 99 on wheel 94 and gear teeth on wheel 94 are interconnected by idler gears 1th} mounted on studs itll extending out from the side of the body 85. The idlers 100 are held on the studs by side piece 182 having flange 193 overlying a bracket formed in the die casting body 85. A screw 104 secures the side bracket in place. This bracket simulates the side frame of a locomotive truck. A similar side bracket is secured in place at the other side of the truck by a screw 18-5. The axles are lubricated by lubricant placed in the well which receives the Worm and Worm wheel and in a secend well 197 above the axle 96.

In this construction, the magnetizable wheels and track complete the magnet circuit from the permanent magnets and the magnetic adhesion caused thereby is added to the adhesion due to the weight on the drivers. This construction is particularly well suited for single motor diesel type locomotives. Without magnetic augment, such a 89 carried on locomotive can handle, under varying conditions, from one to seven cars on the level in addition to its tender. Under the same conditions with magnetic augment, it can operate seven additional cars. Without augment, its load is three cars one 3.4% grade, while with augment, it handles these cars on a 10% grade.

The arrangement shown in Figure a has a magnetic axle 1113 for the

wheels

93, 94, 93, 94 of the diesel type truck.

In the arrangements shown in Figures 21 and 22 a locomotive truck is fragmentarily shown at 110. This truck is of the type used on worm drive steam type toy locomotives. The worm drive from the motor is indicated at 111. The truck has four pairs of

drivers

112, 113, 114 and 115 connected together by gears, not shown. In this construction the truck body 110 and the axles are made of non-magnetic material. A bar magnet 116 is secured in the truck frame as indicated. This bar magnet is in good contact with

pole pieces

117, 117 which extend down below the axles and are apertured to receive the axles, the pole pieces are close to the drives 112 to 115 so that the pole pieces 117 magnetize the drivers 112 to 115.

The non-magnetic axle type of locomotives such as in Figures 4, 8, 9, 10 and 12 to 20, with magnets carried by the motor frame so as to have their faces close to the highly permeable wheels to produce magnetic flux through them and the rails and crossties, or the rails alone, is capable of wide application and the most important of the three types of those shown. The construction is simple and the short air gaps necessary for clearance do not impair the efiectiveness of the magnetic loading. The type with a single magnet and pole pieces (Figures 21 and 22) is also adaptable for wide application and is equally effective for the purposes. The types with term-magnetic wheels and magnetized axles, Figures 4-6 and 20a, are excellent where the propulsion motor and driver design will accommodate the same.

The employment of magnetic loading makes it possible, in the design of locomotives, to eliminate the customary top heavy cabs and replace them with light weight, thin walled structures with lower centers of gravity. The design also makes available under the locomotive body space for a larger propulsion unit and additional accessories. The effective weight is right at the rails.

The maximum additional tractive etiort available in the heavier locomotives maltes it possible to load such a locomotive with so heavy a train as to require an extremely large track lay-out and many cars. it exceed the propulsion capacity of the motor which would otherwise be used. The comes a compromise in design so as to avoid motor burnouts.

It will thus be seen that very substantial increase in tractive effort can be had so as to greatly alter the operational characteristics of the locomotive and train. Not only can entire trains be hauled on level track, but they can be handled on grades so that far more spectacular train operation may be had. The added magnetic adhesion coming from the permanent magnets is uniform at starting and when at speed. There is no variation due to any fluctuating voltage in .the track supply circuit and no heating or coil losses are involved. The additional cost is small and the permanent magnets may be incorporated into the restricted spaces available in the toy locomotives. in all cases there is marked improvement in train operation with respect to avoidance of derailment. The adhesion of the drivers to the track keeps the locomotive on the trackmuch better than in similar locomotives without the magnetic loading. The avoidance of derailment is even more pronounced in rounding curves at high speeds where centrifugal force tends to produce derailment.

Since it is obvious that the invention may be embodied in other forms and constructions within the scope of the extent of the magnetic loading then beclaims, I wish it to be understood that the particular forms shown are but several of these forms, and various modifications and changes being possible, 1 do not otherwise limit myself in any way with respect thereto.

What is claimed is:

1. in combination, magnetizable wheel supporting rail means including two parallel magnetizable rails and magnetiza'ole cross ties connected between said rails, a selfpropelled wheeled toy vehicle for running on said rail means, means on said vehicle providing a magnetic path of low reluctance through at least one pair of opposite wheels of said vehicle and through portions of the rails with which said wheels are in contact and the cross ties adjacent thereto, said magnetic path including a permanent magnet positioned between said pair of wheels so that one wheel is a north pole and the other is a south pole, said vehicle being so constructed of non-magnetic material that the portions of the vehicle adjacent said magnetic path will not shunt the low reluctance path and the passage of the magnetic flux through the wheels and the rails results in increased traction.

2. In combination, magnetizable wheel supporting rail means including two parallel magnetizable rails and magnetizable. cross ties connected between said rails, a selfpropelled wheeled toy vehicle for running on said rail means, means on said vehicle providing a magnetic path of low reluctance through at least one pair of opposite wheels of said vehicle and through portions of the rails with which said wheels are in contact and the cross ties adjacent thereto, said magnetic path including axle means for said pair of wheels having a permanent magnet positioned therebetween so that one wheel is a north pole and the other is a south pole, said vehicle being so constructed of non-magnetic material that the portions of the vehicle adjacent said magnetic path will not shunt the low reluctance path and the passage of the magnetic flux through the wheels and the rails results in increased traction.

3. In combination, magnetizable wheel supporting rail means including two parallel magnetizable rails and mag netizable cross ties connected between said rails, a selfpropelled wheeled toy vehicle for running on said rail means, means on said vehicle'providing a magnetic path of low reluctance through at least one pair of opposite wheels of said vehicle and through a portion of the rails with which said wheel is in contact and the cross ties adjacent thereto, said magnetic path including axle means for said pair of wheels comprising a magnetic pole piece adjacent each wheel and a permanent magnet positioned between said pole pieces so that said pair of wheels are oppositely magnetized, said vehicle being so constructed of non-magnetic material that the portions of the vehicle adjacent said magnetic path will not shunt the low reluctance path and the passage of the magnetic flux through the wheels and the rails results in increased traction.

References Cited in the file of this patent UNlTEDSTATES PATENTS 647,454 Moore Apr. 10, 1900 671,482 Herkner Apr. 9, 1901 775,837 Lowry Nov. 22, 1904 794,871 Lowry July 18, 1905 824,812 Plimlcton July 3, 1906 1,730,944 Peterson et al Oct. 8, 1929 1,894,513 Grondahl Jan. 17, 1933 2,046,310 Billner July 7, 1936 2,226,287 Miller Dec. 24, 1940 2,307,197 Bonanno Jan. 5,1943 2,486,273 Gibson Oct. 25, 1949 2,493,755 Ferrill Jan. 10, 1950 2,500,180 Hubbell Mar. 14, 1950 2,596,322 Zumwalt May 13 1952 FOREIGN PATENTS 12,295 Great Britain Oct. 26, 1848' of 1848