US2482925A - Method for repairing cracked hollow metallic bodies - Google Patents

Description

Sept. 27, 1949. MERCER 2,482,925

METHOD FOR REPAIRING CRACKED HOLLQW METALLIC BODIE$ Filed June 16, 1945 2 Sheets-Sheet 1 n w m m M M n M ww. 4 I\3 H Mm W.

Sept. 27, 1949.

D. A. MERCER METHOD FOR REPAIRING CRACKED HOLLOW METALLIC BODIES 2 Sheets-Sheet 2 Filed June 16, 1945 .m y R mm 5 N M N E V 2 WM 0 w r A Y E 4 m .0

Patented Sept. 27, 1949 METHOD FOR REPAIRING CRACKED HOLLOW METALLIC BODIES Dudley Anson Mercer, Bloomington, Ind., assignor to Moguloid Company 01' America, Chicago, III., a copartnership Application June 16, 1945, Serial No. 599,908

5. Claims.

This invention relates to a method for repairins cracked hollow metallic bodies.

It is the primary object of the invention to provide a method of the character described for effecting repairs quickly, economically and simply, and in such manner that the same will not reopen when subjected to severe stresses, sudden or large temperature changes, or vibration.

Other objects of the invention will in part be obvious and in part hereinafter pointed out.

The invention accordingly consists in the features 01' construction; combinations of elements, and arrangement of parts which will be exemplified in the construction hereinafter de-- scribed, and of which the scope of application will be indicated in the appended claims.

In the accompanying drawing, in which is shown one of the various possible embodiments of this invention,

Fig. 1 is a sectional view through a crack in an automobile engine block between a valve port and a cylinder;

Figs. 2, 3 and 4 are similar views of said block at successive stages in the repair of the crack;

Fig. 4a is a sectional view taken substantially along the line lit-4a of Fig. 4;

Fig. is a side view of the block with a plate mounted thereon to block of! openings in the water jacket preparatory to introducing into the block a fluent pore-sealing material;

Fi'g. 6 is a top plan view of said block and plate; and

Fig. '1 is an enlarged sectional view taken substantially along the line 1-1 of Fig. 6.

In general, the invention is carried out by practicing the following steps: (1) locating the crack, (2) isolating the crack from the sound portion of cracked body, (3) inserting pins to prevent relative movement of the walls of the crack in the direction of the crack, (4) channeling out the exposed side of the crack, (5) depositing sufllcient metal in the resulting groove by electric bonding to restore the original surface, and (6) sealing the pores in the deposited metal and the fine crevices around the pins.

Locating the crack The position and course of the crack conveniently may be ascertained by cooling the cracked body, thus causing the same to contract and increasing the space between the walls of the crack. Under some circumstances, the crack may be so situated that the application of cold tends to close the crack and in these cases the 2 crack can be found by heating the body. The body may be heated or chilled in any suitable manner, and the way in which heating or cooling is performed will, to a considerable extent, de-

pend upon the type of the body which is being v repaired. Thus, if the body is an engine block such as is illustrated herein, or a cylinder head, the same is most easily heated or cooled by introducing a heating or cooling medium in the water jacket. For example, to chill an engine block, cool or even ice water can be circulated through the water jacket. To heat the block, hot water or steam can be introduced into said jacket.

In Fig. 1 there is shown a crack II! which has been located in the block l2 of an automobile engine. The course of said crack is from a valve seat and port M to a cylinder I6. A part of the crack runs across the top surface of the block. Said block has the customary circulating passageways I8, 20 which form a water jacket surrounding the cylinders and valves. As is usual, the crack extends from the outside surface of the block to the hollow interior thereof.

Isolating the crack The next step in the practice of the invention is to fix the position of the crack by separating the intracrystalline or crystalline lines of cleavage, that present themselves at the time of fracture, from the normal structure of the sound metal. crack in the body is prevented and the damaged area is isolated from th remaining sound portion of the body. Such isolation is accomplished, according to the invention, byproviding fixing pins 22, 24, one at each end of the crack Ill. Preferably these pins are applied by first boring terminal holes 23 in the crack at the ends thereof. Said holes are so positioned that the ends of the crack terminate in directions approximately normalto the walls of the holes, whereby the ends of the crack appear to be diametrically disposed with respect to the holes and the walls of each hole are cracked at only one place. If desired, the terminal holes may be smooth and smooth fixing pins driven therein. In such case the pins should be large enough so that they have to be force-fitted. This is accomplished by having the pins made slightly larger in diameter than the holes and, since blocks are usually cast and therefore relatively fragile, making the pins of metal soft enough to be forced into the hole without further cracking th block. A pin of low carbon annealed steel is satisfactory for this In this manner, the progression of the purpose. The pins also may be slightly tapered.

Alternatively, the holes 23 may be tapped and the fixing pins 22, 24 have threads provided thereon so that said pins can be screwed tightly into the holes and firmly held in place. In this latter case, the pins or the holes may be slightly tapered to make sure that when the pins are tightened, they are rigidly secured in place.

Preventing relative movement of the ioallsiol the crack in the direction of the crack Either before or after the fixing pins 22, 24 are inserted, limit pins 26, 28 are applied. The function of these latter pins is to prevent relative movement in the direction of the crack between the portions of the metal body at the two sides of the crack. Said limit pins take up any stresses which may be induced into the body in the region of the repair. Accordingly, limit pins are placed wherever stress in tension, compression or shear, which might cause relative movement of the walls of the crack, could arise in the body after repair, regardless of the nature of the force giving rise to the stress. Such stresses usually are caused by thermal expansion or contraction, vibration or direct application of a strain. Such stresses also are created by applying a strain to a bend, and particularly to an abrupt bend. Places where stresses of this nature occur are well known to the automobile mechanic. For example, such stresses arise at and near the point of application of a load, resulting, for example, from an explosion in the cylinder or tightening the cylinder head on the engine block. Such stresses also might arise where the crack runs along an unsupported span for about one inch or more or extends around a corner connecting two walls, e. g., the top surface of the block and the cylinder wall. A point of high stress will be encountered where there is a sudden change in the temperature of the body. Good results are obtained where the pins are spacd an inch apart over the length of the crack.

The two main spots where a disloc'ating stress is most likely to occur in the crack Eli are the points 30, 32 at the valve seat and edge of the cylinder, respectively.

Therefore, according to my invention holes 21 are bored at said points and limit pins 26, 28 inserted in said holes. As in the case of the fixing ins 22, 24, the limit pins 26, 28 should be tightly fitted into the hole, either by screwing the same in or making a drive or force fit between the pins and the holes. It will be apparent that the fixing pins may, and preferably do, serve also as limit pins.

In the illustrative example, I have found that by locating all the pins 22-28 at an angle of 4 also reduces the possibility of overheating of mm and lessening the tightness of their fit in the holes 28, 21.

The diameter of the pins is relatively small, good results being secured when said diameter is about equal to the thickness of the cracked wall being repaired. Typical diameters range from one-eighth to one inch. Due to the manner in which both the fixing and limiting pins tie together the walls of the crack and cause them to act Jointly as a single member, said pins are sometimes hereinafter referred to as an anchoringsystem.

The block 12 has the appearance shown in Fig. 2 subsequent to incorporation of the anchoring system.

nis pointed out that the fixing and 111mm pins cause a spreading tension which also aids in preventing relative movement of the walls of the crack in a direction along the crack. Channeling theerterior course of the oracle After the fixing and limit pins are applied, the external surface of the block is channeled along the course of the crack to provide a groove 34 (Fig. 3). Said groove is so fashioned that it follows the crack with the visible side of the crack running substantially along the center of the bottom wall of the groove (see Fig. 4a) The grooving operation may be carried out in any manner well known to the art. as for example bygrinding or with a hammer and chisel. At

about 45 to the top surface of the block, highly satisfactory results are obtained. However, the angles at which said pins are inserted may be varied at will as long as they still can assume any stress which would tend to relatively move the opposite walls of the repaired crack, and as long as the fixing pins 22, 24 are in holes 23 so I located that the ends of a crack do not extend across any portion of the same.

The pins can, as shown, be of such length that they project into the circulating passageway I 8 of the water jacket, thereby making certain that said pins have their temperature changed in advance of 'anychange in temperature experienced by a surrounding part of the block due to change in temperature of the cooling medium. Projection of the pins into the circulating passageway the. time the groove is formed, the projecting ends of the pins 22--28 are removed and the groove is cut through said pins. The size and cross-sectional contour of the groove are not critical. I have obtained satisfactory results with a V-shaped groove having a rounded bottom wall and side walls sloped at an angle of about 60, the width and depth of the groove being about three-quarters of the thickness of the cracked wall of the block.

The foregoing sequence of steps may be modifled, if desired, to carry out the channeling operation before the fixing or limiting pins are inserted. In such case, it is preferable to dispose the head of the pin below the exposed surface of the block, e. g., the cylinder wall, valve seat or top of the block. It is further desirable, where such sequence of steps is employed, to locate the head of the pin near the bottom of the groove or to countersink said pin in the groove, for reasons which will shortly be apparent.

Depositing metal in the groove After the anchoring system has been applied and the crack channeled, metal 36 is deposited in the groove by electric bonding, it being remembered that the surface of the groove includes the heads of the fixing and limit pins as well as a part of the engine block, so that the electrically bonded metal will unitarily joint the anchoring system and the block.

The term "electric bonding" as used herein denotes an operation wherein metal is fused to and deposited upon a metallic surface from a consumable metallic electrode which is touched to point after point of said surface, while a low voltage, high amperage current flows through the electrode and surface. By way of example,

6 volts and 200 amperes are satisfactory current amperage may be varied considerably from, say,

I the repair ages.

$6 to 20 volts and 200 to 400 amperes. The metal of the electrode and of the metallic surface are fused together at their point of contact at the moment the electrode touches said surface whereby to firmly bond the deposited metal to the surface. The current and voltage do not range so high as to deeply affect the metallic surface, as where an arc welding voltage and current are used. It may be mentioned that depositing metal in the groove by arc welding will not yield satisfactory results as in such case, with the large current and amperage employed the block will be heated deeply and create new stresses upon cooling which may give rise to further cracking. However, when metal is deposited in the channel by electric bonding the heating of the block is only skin deep and no new local stresses are set up.

Any suitable metal may be deposited in the groove as, for example, nickel, iron, copper, brass and bronze. The use of nickel is preferred because the same has no tendency to oxidize or corrode under the conditions to which objects such as engine cylinder blocks are normally subjected.

The electric bonding step may also include any additional processing which serves to compact the electrically bonded deposited metal, as for example, rapidly vibrating the metallic electrode toward and away from the metallic surface and/or directing a stream of a gas non-combustible with air against the metal being de- Sufflcient electrically bonded metal is deposited in the groove to build beyond the original sur face of the block, 1. e., before channeling and/or wear, and after this amount of metal is deposited the block may be subjected to a metal-removing operation to bring the level of the electrically bondeddeposited metal back to Such original surface. clude grinding, planing, shaping, milling, boring, chiseling and filing.

The repair now has the final finished appearance indicated in Fig. 4 and is characterized by the provision of an anchoring system which isolates the crack and prevents relative movement of the side walls thereof and a bonding system which couples into an integral body the metal of the anchoring system and the surrounding body of the object being repaired.

Sealing the repair out. This comprises sealing the pores or interstices in the deposited metal and the fine crevices around the pins.

- Although it is essential in carrying out my invention that the metal within the groove be applied by electric bonding in order to prevent overheating the bod while yet securing a good bond between the deposited metal, the pins and said body, nevertheless m'etal deposited by electric bonding is inherently spongy and there is, therefore, a tendency for fluid to leak therethrough as well as through the hair line crack around the pins.

It is for this reason that the final step of my invention is essential.

This step is performed by subjecting the block in the region of the repaired crack to the action Suitable metal-removing operations in-' Such leakage increases as at least partially into the electrically bonded metal and which includes a sealing material tion, or when the solution is subjected to pressure in the presence of either heat or cold. Alternatively, the sealing material may be characterized by its abilit to solidify from the solution merely upon exposure to air as, for example,

upon dehydration. The solution must be readily removable from the block where the material has not solidified and solidification of the material must be slow or controllable so that deposit of a large mass of a solid can be prevented. Materials having the foregoing characteristics, and which, therefore, are capable of use in conjunction with my'invention to flll in the pores in the electrically bonded meta1 and the fine crevices around the pins, are the various alkali metal silicates, drying oils and ground fiaxseed. The fluent vehicle preferably is water in which the sealing material is dissolved or dispersed.

In addition, the sealing solution may include dispersed powders of metals having atomic weights not less than that of aluminum. I have found that these powders cause the sealing material to bond more firmly with the metal of the article and of the repair. Examples of such substances are aluminum, iron and copper, which have been comminuted by ball milling to amorphous powders.

I have also obtained good results where the powdered iron is derived by reducing rouge (iron oxide), with hydrogen in a manner well known by chemists. The a resultant amorphous iron powder is extremely fine and pure] The sealing solution also may include a substance which will react mildly with the metal of the article being repaired or that of the pins or electrically bonded metal. This is believed to aid the sea] by cleaning the surfaces of the material in the crack or cleaning the pins or electrically bonded metal and thereby enabling the sealing material to cohere better in the repair. Such materials include, by way of example, sodium, magnesium and iron hydroxides,

If desired, the sealing solution may also comprise a filler, as for instance, fuller's earth or alumina.

Another substance whose incorporation in the sealing solution increases the efficacy of the seal is any lithium compound which does not react with water, such compound including, by way of example, lithium silicate, hydroxide, chloride and nitrate.

Without limiting my invention thereto, I have given below examples of various sealing solutions which will perform satisfactorily in the practice of my invention, and of which each includes a plurality of the above mentioned substances:

1 Example 1 Sodium silicate, 47 Baum gals 55 Fuller's earth lbs do Copper powder lbs 1 Aluminum powder; lbs 1 Flaxseedmeal lbs 1 or a sealing solution which is caused to permeate Water gals 5 These ingredients are thoroushly and intimately blended by placing the same in a fast mixer where they are worked for approximately two hours and then drawn oi'f. The resulting mixture is a concentrated sealing solution which is used by adding one pint thereof to six gallons of water. Weaker or stronger diluted solutions can also be employed. The diluted sealing solution is particularly well suited for use in the repair of cracks in engine blocksin accordance with my invention. If said solution is circulated past the electrically bonded metal at a rate of about 10 cubic feet per minute and at a temperature of about 160 F. for about 20 minutes. it will completely seal the pores in the electrically bonded metal and the fine crevices around the pins.

It should be particularly noted that these pores and crevices are of a considerable lesser order of magnitude than the crack being repaired, and it is for this reason, I believe, that the sealing solution, which at best could only serve as a temporary expedient to close the crack, will permanently seal the pores and crevices.

Example 2 Sodium silicate, 47 Baum cc 100 Potassium silicate, 405 Baum cc- 25 Amorphous iron (prepared by reducing iron oxide with hydrogen) grams 3 Powdered anhydrous alumina do Water I cc 35 The concentrated sealing solution is prepared by mixing the alumina and amorphous iron with water and adding the mixture to the silicates which previously have been compounded. Said solution is diluted in a ratio from one pint thereof to about two to live gallons of water. The dilute sealing solution, which sets by dehydration, is satisfactory for general operations. Due to the presence of the pure iron powder, the seal will bond particularly rapidly with the metal of the crackedarticle and will also bond well with the pins and the electrically bonded metal.

Example 3 Sodium silicate -17 Baum cc 100 Potassium silicate, 40.5" Baum cc 5 Red iron oxide grams 3 soy bean oil cc 4 Sodium hydroxide grams 4 Water -cc 25 The concentrated sealing solution is prepared by mixing the sodium hydroxide in half of the water, and then adding thereto the soy bean oil and stirring the resulting mixture. The rest of the water is added to this mixture and the same is then added to the silicates which previously have been compounded and the entire fluid body mixed well. The concentrated sealing solution is diluted in the ratio of about from one part thereof to about 200 to 5,000 parts of water. At the formerratio. particularly good results are obtained with sulphated castings. This sealing solution, in general, is useful in the repair of cracked castings which are subjected to acids.

Example 4 Sodium silicate, 47 Baum cc 100 Potassium silicate, 405 Baum cc 5 Lithium silicate, 40 Baum cc 1 Magnesium hydroxide grams 0.2 Anhydrous alumina powder do 0.4 Oleic acid ..do 0.2 Ferric hydroxide do 0.1 Water -cc 20 The concentrated sealing solution is prepared by adding water to a mixture of the alumina and the magnesium hydroxide in suiilcient quantities to make a thin paste. The oleic acid is added to said paste and the mass is heated to emulsify the same. Then, enough water is added to make a thin liquor. The ferric hydroxldeis added to the silicates which previously have been compounded and the mixture is stirred well while adding to it the thin liquor. The concentrated sealing solution may be used in dilutions of about one part thereof to from about 1.000 to 50 parts of water. In dilute form, said solution shows gOOd results in the repair of cracks for articles employed for heavy duty operation in salt water, and. in general for the repair of cracks in heavy thick castings composed either of ferrous or non-ferrous alloys. Castings repaired in accordance with my invention and with the use of this sealing solution, will stand a great deal of vibration, as the seal is believed to be a heavy alkaline saponiiled gel, with good surface tension.

Although the alkali metal silicates described in the various foregoing examples have all been illustrated as having the same viscosity, it will be understood that these specific viscosities are only exemplitive.

Although I contemplate passing the solidinable fluent material over either side of the electrically bonded metal, that is, either over the surface of the hollow body which has been grooved and electrically bonded, or within the interior of said body, it is much simpler when repairing certain types of metallic castings to introduce the fluent pore-sealing material inside the body. This is particularly so where the repair is to be eifected in a body such as an engine block which has internal passageways adapted normally to-pass a circulating medium. The only drawback to the use of these passageways is that many of them open on the top face or the block and this would entail the laborious task of refastening the cylinder head on the block after repairing the crack and, possibly, subsequently removing said head to ascertain whether the crack is completely repaired.

To aid in carrying out my invention I have provided an apparatus through whose use the circulating system of the block may be employed to receive said solldlflable fluent material without the tedious procedure of mounting and subsequently dismounting the cylinder head. Said apparatus comprises a plate 18 of such configuration that when superimposed on the engine block l2, it will close 011 all water passageways opening at the top surface of said block. A satisfactory configuration is seen in Fig. 6 wherein the openings 40 which normally furnish communication for a coolant between the cylinder block and the valve head are shown blocked oil by the plate 38. If desired, the Plate 38 may be lightened by providing apertures 42 therein, matching the cylinder bores l6, and the plate Il may be skeletonized generally as long as it effectively blocks the. openings I. Said .plate may also be provided with apertures 44 and indentations It to afford free passage for the cylinder head bolts 48.

In order to avoid the troublesome individual attachment of nuts on theseveral bolts ll, I.

provide a single means to dctachably secure the plate 38 to a block. Said means comprises a spider 50 having a plurality of depending coplanar feet 5l which are adapted to rest on the 76 upper surface of the plate ll. These feet radiate from a central huh I! which is apertured to slidably receive and 54. Said rod, which is adapted to extend through a cylinder bore" It, carries a plate 56 at its lower end which engages the bottom of the block. The upper end of said rod is threaded to receive a capstan nut 58. A washer 60 is interposed between the nut II and hub 52.

The foregoing apparatus is employed in the following manner: After the crack I. (Fig. '1) has been located, pinned, grooved, electrically bonded and had the exposed surfaces of the electrically bonded material machined, the block I! is placed upon the plate It and a gasket 62 of the type conventionally employed with the block I2 (but abbreviated to the approximate contour of the plate 38) is placed upon the upper surface of said block. Next, the blocking plate 38 is set on the gasket and the spider ll slipped on the rod 54. Then the nut 58 is threaded on said rod and is screwed fast. The block is now ready to have the pore-sealing fluent material introduced through the bottom radiator connection. If desired, said material may be circulated through the block by employing another connection to the block as, for example, the drain tap or one of the openings ll which may be left unblocked by the plate 38. Circulation is facilitated by using a flow unit including a pump and heater. Several plates may be provided. one for eachdifferent type of engine, or a single plate may be employed which is large enough for any block and which has a single aperture to receive only the rod 54.

The above apparatus for closing the circulating openings in the top of an engine block also may serve as a means for twting the repaired block for leakage, the same being accomplished merely by leaving the apparatus in place after said fluent material has been circulated through the block and after sufficient time has elapsed to solidify said material in the deposited metal. A fluent testing substance, such as a smoky gas or water, is placed under pressure in said block, and if the crack is not repaired, the testing material will leak therethrough.

It will further be appreciated that the solidiflable fluent material may be circulated through the block under pressure and the repair watched during the period of circulation. When leaking stops, the repair will be completely eflectuated. Thus, during this period, said apparatus functions both as a repairing means and as a testing means.

It may be mentioned that the method of repair described herein and the apparatus used in conjunction therewith is mostly used in connection with the repair of cracks in hollow cast bodies, inasmuch as, although welding, due to its simplicity and economy, is ordinarily employed to repair cracks, cast bodies cannot be welded without an elaborate pre-treatment which renders the repair by welding of such bodies costly in comparison with the method of repairing said bodies in accordance with the present invention.

It will thus be seen that I have provided a method for repairing cracked hollow metallic bodies which achieves the several objectsof my invention and which is well adapted to meet the conditions of practical use.

As various possible embodiments might be made of the above invention and as various changes might be made in the embodiment above set forth, it is to be understood that all matter he 10 in set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.

Having thus described my invention, I claim as new and desire to secure by Letters Patent:

1. A method of repairing a hollow cast body having a crack therein extending from the hollow interior to the exterior thereof: said method comprising locating the crack, forming holes in the body from the exterior to the interior thereof through the ends of the crack, forming holes in the body from the exterior to the interior thereof at spaced points along the crack, tightly fitting pins in said holes whereby to isolate the crack from the sound portion of the cracked body and prevent relative movement of the walls of the crack along the crack, channeling the exterior of said body along the course of the crack, and then depositing sufilcient metal in the resulting groove and on the pins by electric bonding to restore the original surface of the body.

2. A method of repairing a hollow cast body having a crack therein extending from the hollow interior to the exterior thereof: said method comprising locating the crack, forming holes in the body from the exterior to the interior thereof through the ends of the crack, forming holes in the body from the exterior to the interior thereof at spaced points along the crack, where stressing of the body after repair of the crack would cause relative movement of the walls of the crack in a direction along the crack, tightly fitting pins in said holes whereby to isolate the crack from the sound portion of the cracked body and prevent relative movement .of the walls of the crack along the crack, channeling the exterior of said body along the course of the crack, and then depositing sufficient metal in the resulting groove '"and on the pins by electric bonding to restore the original surface of the body.

3. A method of repairing a hollow cast body having a crack therein extending from the hollow interior to the exterior thereof: said method comprising locating the crack, forming holes in the body from the exterior to the interior thereof through the ends of the crack, forming holes in the body from the exterior to the interior thereof at spaced points along the crack, tightly fitting pins in said holes whereby to isolate the crack from the sound portion of the cracked body and prevent relative movement of the walls of the crack along the crack, channeling the exterior of said body along the course of the crack, then depositing suilicient metal in the resulting groove and on the pins by electric bondingto restore the original surface of the body, the crevices around the pins and the pores in the deposited metal being of a lesser order of magnitude than the crack, and sealing the pores in the deposited metal and the fine crevices around the pins, by introducing into the interior of said body in the region of the crack a fluent material which will permeate at least partially into said crevices and pores and solidify therein. 7

4. A method of repairing a hollow cast body having a crack therein extending from the hollow interior to the exterior thereof: said method comprising locating the crack, forming holes in the body from the exterior to the interior thereof through the ends of the crack, forming holes in the body from the exterior to the interior thereof at spaced points along the crack, tapping said holes, tightly screwing threaded pins in said holes whereby to isolate the crack from the sound portion of the cracked body and prevent relative 1 movement of the walls of the crack along the crack, channeling the exterior of said body along the course of the crack, then depositing sumcient metal in the resulting groove and on the pins by electric bonding to restore the original surface of the body, the crevices around the pins and the pores in the deposited metal being of a lesser order of magnitude than the crack, and sealing the pores in the deposited metal and the flne crevices around the pins, by introducing into the interior of said body in the region of the crack a fluent material which will permeate at least partially into said crevices and pores and solidify therein.

5. A method as set forth in claim 4 wherein the upper ends of the pins are placed below the original surface of the body before metal is deposited by electric bonding.

DUDLEY ANSON MERCER.

12 emcee cn'm Theiollowingretmandmdinthe flleolthispatentz UNII'ID STATE PHI-ITS Number Name Date 1,019,532 Balm llar. 5, 1912 1,452,936 Bchuman Apr. 24, 1923 1,645,585 Burton Oct. 16, 1927 1,648,065 Ray Nov. 8, 192'! 1,648,866 Ray Nov. 8, 1927 2,011,464 Harman Aug. 13, 1936 7 2,178,156 Aulbach Oct. 31, 1939 2,228,087 Rose Jan. 7, 1941 2,252,986 Beott Aug. 19, 1941 2,267,033 Kerkling Dec. 23, 1941 Re.22,39'l Meduna Nov. 30, 1943 2,361,106 Jensen Oct. 24, 1944 2,410,464 Scott Nov. 0, 1940

Images