US2987838A - Excavating tooth - Google Patents

Description

June 13, 1961 A. v. STRATTON EXCAVATING TOOTH 3 Sheets-Sheet 1 Filed Aug. 5. 1957 INVENTOR ARV/N L/ STRATTON ATTORNEYS June 13, 1961 A, v, STRATTON 2,987,838

EXCAVATING TOOTH Filed Aug. 5, 1957 3 Sheets-Sheet 2 5 INVENTOR ARV/N l STRATTON A. V. STRATTON EXCAVATING TOOTH June 13, 1961 3 Sheets-Sheet 5 Filed Aug. 5. 1957 INVENT OR BY ARV/N V STRATTON A T TOPNEVS United Stat s P te 2,987,838 EXCAVATING TOOTH Arvin V. Stratton, 181 E. 200 South, Cedar City, Utah, assignor of one-third to Elton Stratton Filed Aug. 5, 1957, Ser. No. 676,218 Claims. (Cl. 37142) This invention relates to an excavating tooth of the type that includes an adapter and a replaceable tooth point therefor, and which tooth is one of a plurality of the corresponding teeth used on a power-driven shovel dipper and the like.

One of the objects of the invention is the provision of a tooth of the above character having a substantially longer life than the usual tooth heretofore used, and which tooth includes a point that is quickly and easily replaceable.

A still further object of the invention is the provision of an improved tooth point that is formed to cooperate with the adapter in a manner that will reduce the wear on the adapter.

In explanation of the above, the teeth on power-driven shovel dippers usually wear away in several places faster than others. The tooth point, being the portion that has the digging edge, naturally tends to wear away faster than the remainder. The adapter is the portion of the tooth that is connected with the bucket or dipper, and it also receives considerably more wear where the material dug by the point moves over it into the bucket.

Replaceable tooth points are old in the industry and they are normally connected with the adapter by means of a pin of some kind. The adapter usually has a nose that extends into a socket in the tooth point, and the pin usually extends through the upper and lower sides of the socket and through said nose. However, in the normal use of'the dipper or bucket that employs conventional teeth of the above character, the points andadapter frequently break where the key secures them together. Also the adapters wear out almost as rapidly as the points.

With the present structure no breakage occurs and the adapters will last almost indefinitely, or are so constructed as to enable them to readily be maintained so that-they will last almost indefinitely.

Other objects and advantages will appear in the description and in the drawings.

In the drawings,

FIG. 1 is an isometric view showing the adapter and a tooth point in which the latter is slightly separated from the adapter to show structure. The key for holding the point on the adapter is not shown in this view.

FIG. 2 is a fragmentary isometric view of the nose on the adapter that is adapted to extend into a tooth point.

FIG. 3 is a top plan view of an assembled tooth.

FIG. 4 is a cross sectional view taken along line 4--4 of FIG. 3.

FIG. 4a is a fragmentary sectional view showing a slight modification of the structure of FIG. 4.

FIG. 5 is a bottom plan view of the tooth of FIG. 3.

FIG. 6 is a part sectional and part elevational view of a tooth that is a modification of the one'shown in FIGS. 1 to 5.

FIG. 7 is a sectional view showing a modification of the tooth of FIG. 6.

FIG. 8 is a fragmentary top elevational view of a slight modification of the adapter shown in FIG. 1.

FIG. 9 is a fragmentary top elevational view showing a still further modification of the adapter of FIG. 1.

FIG. 10 is a view similar to that of FIG. 1 but showing a modification of the structure of FIG. 1 in which a replaceable wear plate is used at a critical point of wear.

FIG. 11 is a sectional view taken along line 11-11 of FIG. 10 but with the two parts of FIG. 1 in assembled relation instead of being spaced apart.

FIG. 12 is a perspective view looking upwardly at the. underside of a wear plate that is slightly modified from the plate shown in position on FIG. 10.

FIG.13 is a view similar to that of FIG. 11, but showing a reversal of the structure of FIG. 11 insofar as the dove-tail connections are concerned.

In the description the words forward and forward1y"; rear and rearwardly are used with reference to the digging edge of the tooth point which is at the forward end of the tooth, and with reference to the tang that is on the adapter for securing the tooth to the dipper or bucket, such tang being at the rear end of the tooth.

In detail, referring to FIG. 1 the adapter comprises a shank portion generally designated 1, and a tooth point, generally designated 2. The shank portion 1 may be of any suitable type insofar as its structure for securing it to a bucket or dipper is concerned. Normally the shank portion will include rearwardly opening recesses 3 in its opposite lateral sides and a rearwardly projecting tang 4 that is used for securing the shank portion to a dipper or bucket.

The upper and lower surfaces of the shank portion, forwardly of the tang 4, extend convergently in a direction forwardly from the tang.

A wedge shaped nose 5 is integral with the shank portion 1 and projects forwardly therefrom. Said nose has upper and lower wedge faces that extend convergently in a forward direction from the shank portion. The vertical opposite sides of said nose are substantially parallel;

Said side surfaces and said upper and lower wedge faces of the said nose 5 are spaced inwardly from the side and top and bottom surfaces of the shank portion '1, thereby providing forwardly facing upper and lower shoulders 6, 7 above and below nose 5, and forwardly facing shoulders 8 at the sides of the nose. These forwardly facing surfaces are preferably coplanar.

The upper surface of the shank portion 1 that is adjacent to shoulder 6 is preferably formed with spaced grooves forming ribs 9 (FIG. 2) between adjacent grooves,

' and which grooves and ribs are parallel with shoulder 6.

The forward rib 9 is preferably spaced slightly rearwardly of shoulder 6, and also the ends of the ribs are preferably spaced slightly from the lateral sides of the shank portion. The grooves between the ribs 9 are filled with a filler 10 of extra hard metal integrally united with the metal of the shank portion, which hard filler may be that of a hard welding rod applied by a welding operation. This filler also extends along the sides of the adapter across the ends of ribs 9, and along the forwardly facing side of the front or forward rib. The face of shoulder 6 and the forward side of the filler along said forward rib may be substantially even.

While the forward ribs 9 shown in FIGS. 1, 2 are shorter than the others, the ribs may all be of the same length, as seen in FIG. 9 at 11. Also, the ribs, as seen at 12 in FIG. 8, may be relatively short and at right angles to the shoulder on the shank portion. In any event, the filler of hard metal will extend along shoulder 6, or the corresponding shoulder in FIGS. 8, 9, and along the sides of the shank portion at the ends of the ribs (FIGS. 1, 9) or along the end ribs as seen in FIG. 8. The tooth point 2 is formed with a rearwardly opening socket in which the upper and lower sides of which rearwardly facing edge extending approximately from one side of the tooth point to the other along the rear edge of the upper wall 15. This upper wall is preferably relatively thick, as seen in FIG. 4, and the tongue 18 is formed on the lower half of the wall 15.

The central portion of tongue 18 is thickened to provide a substantially rectangular central section 19 that is flush on its upper surface with the upper surface of the wall 15. This section is integral with the tongue 18 and with wall 15 and projects rearwardly from wall 15 the width of the tongue. The opposite lateral sides 20 of the section 19 are preferably approximately vertical.

The shank portion 1 is formed with a recess 21 that opens forwardly of said portion through the forwardly facing shoulder 6 at a point just above nose 5. This recess is complementary to the tongue 18 and section 19. The lower wall 16 of the tooth point 2 is formed with a rearwardly projecting portion 22 centrally between its ends. This portion 22 extends horizontally a substantial distance along the rear edge of wall 16 and is disposed in a plane that is substantially parallel with the plane in which the tongue 18 is disposed. It is spaced upwardly from the lower surface of wall 16 thereby providing a rearwardly facing shoulder along its juncture with wall 16.

The shank portion 1 is formed with a recess 23 that opens forwardly through the forwardly facing shoulder 7 on said shank portion just below the nose 5. This recess '23 is complementary to the projection 22. I When the tooth point is fitted on the nose 5 the upper surface of wall 15 is spaced below the upper surface of the shank portion for the major portion of its width. This spacing may substantially equal the vertical thickness of the exposed forwardly facing .filler 10 that is along the forward side of the rib 9 that is nearest to nose 5 and to the wall 15. Thus the entire exposed forwardly facing shoulder 6 may be of extra hard metal that is harder than the remainder of the metal of the shank other-than that of filler 10.

'In the form of the invention shown in FIGS. 1, 2 a pair of parallel, upstanding ribs 24 are in upward continuation of the side walls of the tooth point. These extend from the rear edges of the lateral sides of said point to approximately the forward edge 17 of the tooth, and they are of progressively reduced thickness in a direction from said rear edges toward said digging edge, with the rear edges being of a height about equal .to the height of shoulder 6.

The tooth point 2 is releasably secured onto nose 5 by means of an elongated, vertically extending key 25 that extends through aligned openings in walls 15, 16 and in nose 5.

These key receiving openings, designated 26 for the opening in wall 15, and 27 for the opening in nose 5, and 28 for the opening in wall 16 are positioned midway between the opposite lateral sides of the tooth point and nose 5.

Key 25 has tapered forward and rear edges making it thicker at its upper end than at the lower end and the upper end of said key is provided with a forward extension 29 integral therewith. This extension is adapted to be received in an enlargement 30 of theopening 26 at the forward side of said opening.

The lower end of the key projects below wall 16 and is formed with an opening in which is held a transversely extending pin 31. The ends of the pin 31 project to opposite sides of the lower end of key 25, and said pin extends parallel with the digging edge 17. The projecting ends of said pin fit in complementarily formed recesses 32 that are in the lower face of wall 16. Said lower wall 16, in turn, is formed with a downwardly projecting guard lip 33 that extends across the forwardly facing :edge of the projecting lower end of key 25.

The forward extension 29 on the upper end of key 25 overlies ahelicalspring=34, whichspring, in turn,-is seated at its lower end in a shallow upwardly opening recess formed in nose 5 at the forward edge of key 25. This spring is normally under expanding tension to yieldably hold the pin 31 in recesses 32, and when the pin is so held, the upper surface of the key 25 may be substantially flush with the upper surface of wall 15, or even slightly below said surface.

In order to remove the tooth point, it is merely necessary to force key 25 downwardly until pin 31 can be knocked out of the opening in the key. The new tip is locked onto the nose by forcing key 25 downwardly against the resistance of spring 34 until the pin 31 can be inserted into the opening in the lower end of the key, and after the pin is so inserted and the key is released, the pin will be held in recesses 32.

In operation, the earth, sand or other material that is being dug, will pass over the upper surfaces of the tooth point and adapter and into the dipper. A portion of the earth, sand, etc. is caught against the shoulder 10 to form a layer over which the remainder of the material passes, hence the Wear on the adapter is materially less than where the upper surface of the adapter and tooth point are flush with each other. The ribs 24 assist in holding the dirt on the tooth point ahead of shoulder 6, and they also strengthen the tooth point, making it possible to use a lighter weight point that will not bend under the lifting strains. Whether or not the ribs 24 are used, the principle is generally the same and the dirt held on the tooth point ahead of the shoulder 6 will result in greatly reduced wear on the tooth point as well as the forward upper surface end of the shank portion.

With respect to the foregoing, it may be noted that the tempering of the metal along the digging edge or the use of a hard metal facing along said edge, has been done, but the sliding of the dirt past said edge and over the upper surfaces of the tooth point and the adapter wears away the metal rearwardly of said digging edge and the tooth points have quite frequently broken oh along the key openings. By providing the shoulder 6 of hardened metal so that the layer of dirt ahead of the shoulder will support the dirt that slides over said layer, this wear on the tooth does not occur.

Various efforts have heretofore been made to prevent the breakage of the adapter point and to prevent loose play of the tooth point on the adapter. Usually these efforts have taken the form of extensions, ears or reinforcements on the tooth point that are exposed to wear, and once this wear reaches a certain amount, the breakage will occur.

In the present instance, the tongue 18 and projection 22 fit into the shank portion 1 or adapter to give adequate strength where most of the strain occurs, and as these portions are within the body of the adapter they cannot be worn off or weakened. Also the section 19 provides additional strength and eliminates loose play between the tooth point and the adapter.

The structure of the key is important in that heretofore most attempts to hold the key in the openings has involved forming the key with a recess or depression in which a rubber block or other element is yieldably urged. In actual practice these attempts have been objectionable for the reason that the rubber block or metal urged into the key depression has frequently broken off and has so wedged the key as to make it impossible to remove it without resorting to a cutting torch.

In the present instance, the sides of the key are straight, hence it can easily be driven out of the openings in which it is fitted.

FIG. 4a shows the same structure as is shown in FIG. 4 except that a rubber block 35 replaces spring 34.

In the form of invention shown in FIGS. 6, 7, the same adapter or'shank portion 1 is shown, as in FIGS. 1 to 5, hence the same numbers will be used in referring to it.

The tooth point is much the :same as the one shown in FIGS; 1 to 5, with the main difference being inthe-manper in which the tooth point is secured to the adapter.

In FIG. 6 the tooth point, generally designated 36, is formed with a rearwardly opening socket for the nose 5 of the adapter. Upper wall 37 and lower wall 38 form the upper and lower sides of the socket, and aligned openings 39, 40, 41 respectively formed in the upper wall 37, nose 5 and lower wall 38 are to receive a vertically extending tapered key 42.

This key 42 does not have any lateral extension on its upper end, but the sides of the key extend straight to the upper end. However, the lower and thinner end of the key is formed with a slight rearward projection 43 that is adapted to hook over the rear edge of the opening 41 when the lower end of the key is urged rearwardly. Openings 48, 41 are sufiiciently wide in the front to rear direction to enable the lower end of key 42 to swing forwardly a sufiicient amount so that projection 43 will clear the rear edge of the opening 41 to permit the key to be driven out of the openings 40, 41, 39 in an upward direction, as seen in FIG. 6.

The lower end of the opening 40 at the forward side of the key is formed with a recess in which a rubber plug or body 44 is held, and it is the expansion of this plug against the forward side of the lower end of the key that urges the projection 43 into holding relation with the rear edge of opening 41.

In this instance the projection 43 on the key is what holds the key in the openings that are in the tooth point and in the adapter and the rubber block 44 merely prevents the projection from moving out of engagement with the lower wall of the point, but it does not, in itself, hold the key against withdrawal from the tooth.

It should be noted that there is virtually no wear on the bottom of the tooth point during digging operations.

The modification shown in FIG. 7 is the same structure as is shown in FIG. 6 except that a spring 45 is used instead of the rubber block or body 44 and a wear button is interposed between the spring and the key to slidably engage the latter. In FIGS. 6, 7 it is seen that the upper end of the key 42 has a slight forward projection 47 to act as a limit stop, although the taper of the pin would accomplish the same purpose if the portion of the pin in the opening in wall 37 were accurately fitted.

In FIGS. 4 and 6 the rear portion 48 (FIG. 4) and 49 (FIG. 6) of the lower surface of the nose extends substantially parallel with the upper wedge surface of said nose which enables the rearward projection 22 (FIG. 4) and 59 (FIG. 6) to be formed in a manner to enter the complementarily formed recess in the shank portion.

In FIG. 10, a hard, replaceable metal plate 51 is used instead of the material 10. The upper surface of the shank portion 52 is cut away to receive this plate, and dovetail ribs 53 formed on the lower side of said plate extending longitudinally of the tooth are adapted to slide endwise into complementarily formed dovetail groove 54 (FIG. 11) formed in the relieved upper surface of the shank that is adapted to receive plate 51 (FIG.

The tooth point on the adapter has the rearward tongue 56 and the central section 57 the same as tooth point 2 of FIG. 1, and the lower side of plate 51 may be recessed at 58 to receive said section 57.

In the form shown in FIG. 10, the opposite sides of the nose 55 may also be formed with dovetail grooves 59 that are parallel with the upper wall 69 of the point 61, and the opposite side walls 62 of the point are formed with inwardly projecting ribs 63 that are complementary to the grooves 59 so that said ribs will slide endwise into the grooves 59 upon positioning the point 61 on nose 55. The ribs 63 preferably project rearwardly of the rear end of the tooth, as at 64 (FIG. 10) so as to enter complementarily formed recesses 65 in the shank at the sides of the rear end of nose 55.

' The lower forward portion 67 of the shank 52 projects forwardly and is integral with nose 55 and extends into the complementarily formed rearwardly and downwardly directed recess 68 formed in the lower portion of the tooth 61 (FIG. 10).

The key opening 69 extends through the upper wall of the point and through the nose and portion 61 and the same key structure is used as in FIG. 4 except that the lower wall of the point 61 terminates ahead of the key, and the key locking pin 31 lies in a recess in the lower side of the portion 67.

In FIG. 12, the plate 76 shown therein has transverse ribs 71 of dovetail contour to fit in transverse complementarily formed grooves (not shown) in the adapter. This and a recess 72 in the lower side of the plate would receive the section 57 to lock the plate against movement transversely of the adapter or shank.

In FIG. 13 the same general structure is used as in FIG. 11 except that the dovetail ribs and grooves indicated in FIG. 11 are reversed, and instead of the ribs 53 being in the plate 51 of FIG. 11, the ribs 73 are on the adapter and the recesses 74 therefor are on plate 75. Also, in FIG. 13 instead of the ribs 63 being on the side walls of the tooth point, as seen in FIG. 11, the ribs 76 are on nose 77 and recesses 78 for said ribs 76 are in the side walls 79 of the point.

It is pertinent to note that the forward edge of plate 51 (FIG. 10) or plates or 75, provides the exposed shoulder against which dirt will be held, the same as in FIG. 1. The upstanding portions 24 of the side walls is not shown in FIGS. 10 to 13 although it may be used if desired, particularly where sand or loose material is being loaded into the bucket or dipper. Also in FIG. 10 the tooth point covers the ends of the dovetail ribs and hence cooperates with the plate 51 to hold the latter on the adapter.

I claim:

1. An excavating tooth comprising, in combination, an adapter having a shank portion and an integral substantially Wedge-shaped nose having opposite upper and lowerwedge faces, a separate tooth point formed with a rearwardly opening socket having an upper wall and a lower wall extending divergently relative to each other toward the open rear end of said socket and defining the upper and lower sides of said open rear end, said upper and lower walls having generally opposed surfaces adapted to seat against said wedge faces, aligned openings formed in said upper and lower walls and nose, a key within said openings releasably holding said tooth point on the nose of said adapter, said tooth point having a digging edge at its forward end opposite to said open rear end of the socket therein, a shoulder on said adapter at substantially the juncture between said nose and said shank projecting above the upper surface of said upper wall and facing generally toward said digging edge to cooperate with said upper surface for retaining a layer of earth along said shoulder over which earth dug by said tooth is adapted to pass, said adapter being formed with a recess formed in said shank below said shoulder substantially equal to the width of said upper wall, a tongue integral with and projecting from said upper wall into said recess, said tongue including a central portion substantially equal to the thickness of said upper wall and having side portions at opposite sides of said central portion of less thickness than said central portion and the contour of the inner surfaces of said recess being complementary to the exterial contour of said tongue.

2. An excavating tooth comprising, in combination, an adapter having a shank portion and an integral substan tially wedge-shaped nose having opposite upper and lower wedge faces, a separate tooth point formed with a rearwardly opening socket having an upper wall and a lower wall extending divergently relative to each other toward the open rear end of said socket and defining the upper and lower sides of said open rear end, said upper and lower walls having generally opposed surfaces adapted to seat against said wedge faces, aligned openings formed in said upper and lower walls and nose, a key within said openings releasably holding said tooth point on the nose of said adapter, said tooth point having a digging edge at its forward end opposite to said open rear end of the socket therein, a shoulder on said adapter at substantially the juncture between said nose and said shank projecting above the upper surface of said upper wall and facing generally toward said digging edge to cooperate with said upper surface for retaining a layer of earth along said shoulder over which earth dug by said tooth is adapted to pass, said shoulder being of harder material than the material of said shank and being secured on the latter, a recess formed in said shank below said shoulder opening forwardly toward said digging edge and having an upper side, a lower side and rear side, said upper wall having a tongue integral therewith projecting into said recess, said tongue having a central portion substantially equal to the thickness of said upper wall and said central portion having substantially vertical lateral sides, side portions on said tongue of lesser thickness than said central portion projecting laterally therefrom and spaced below the upper surface of said central portion, said tongue terminating in a horizontally curved rear edge facing away from said digging edge, and said upper, lower and rear sides of said recess being complementary in contour to the contour of said tongue.

3. An excavating tooth comprising, in combination, an adapterhaving a shank portion and an integral substantially wedge-shaped nose having opposite upper and lower wedge faces, a separate tooth point formed with a rearwardly opening socket having an upper wall and a lower wall extending divergently relative to each other toward the open rear end of said socket and defining the upper and lower sides of said open rear end, said upper and lower walls having generally opposed surfaces adapted to seat against said wedge faces, aligned openings formed in said upper and lower walls and nose, a key Within said openings releasably holding said tooth point on the nose of said adapter, said tooth point having a digging edge at its forward end opposite to said open rear end of the socket therein, a shoulder on said adapter at substantially the juncture between said nose and said shank projecting above the upper surface of said upper Wall and perpendicular to said upper surface and facing generally toward said digging edge to cooperate with said upper surface for retaining a layer of earth along said shoulder over which earth dug by said tooth is adapted to pass, upwardly projecting ridges integral with said upper wall extending from said shoulder toward said digging edge, the rear edge of said upper wall being substantially in engagement with said shoulder, said shoulder being of substantially harder material than that of said shank, the upper surface of said shank and said ridges being sub stantially coplanar and the rear ends of said ridges being substantially in engagement with said shoulder, the face of said shoulder being flat and substantially at right angles to the upper surface of said tooth point whereby said shoulder and said tooth point will cooperate to retain such layer of dirt in a position protecting said shank against wear at said shoulder.

4. An excavating tooth comprising, in combination, an adapter having a shank-portion and an integral substantially wedge-shaped nose having opposite wedge faces; a separate tooth point formed with a rearwardly opening socket having two walls extending divergently relative to each other in a direction toward the open rear end of said socket providing generally opposed surfaces adapted to seat against said wedge faces, aligned openings respectively formed in said two walls and nose, a key within said openings removable therefrom for releasably holding said tooth point on said nose, means on said key and on said tooth point in releasable engagement with each other for holding said key stationary within said aligned openings, and yieldable means yieldably reacting between a-portion of said key and between a portion of said nose yie'ldalbly holding the means on said key and on said tooth point in said engagement with each other, said two walls being positioned one above the other to provide an upper wall and a lower wall, said upper wall and said lower wall being integrally connected along their edges that are remote from the open rear end of said socket to form a digging edge, said key being vertically elongated, the means on said key and the means on said tooth point in said engagement with each other being, respectively, a lateral projection carried by said key at its lower end and part of the marginal portion around said opening in said lower wall into which said key extends, the upper end of said key having a lateral extension projecting over a portion of-said nose, said yieldable means being positioned between said-lateral extension and said nose.

5. An excavating tooth comprising, in combination, an adapter having a shank portion and an integral substantially wedge-shaped nose having opposite wedge faces; a separate tooth point formed with a rearwardly opening socket having two walls extending divergently relative to each other in a direction toward the open rear end of said socket providinggenerally opposed surfaces adapted to seat against said wedge faces, aligned openings respectively formed in said two walls and nose, a key within said openings removable therefrom for releasably holding said tooth point on said nose, means on said key and on said tooth point in releasable engagement with each other for holding said key stationary within said aligned openings, and yieldable means yieldably reacting between a portion of said key and between a portion of said nose yieldably holding the means on said key and on said tooth point in said engagement with each other, said two walls being positioned one above the other to provide an upper wall and a lower wall, said upper wall and said lower wall being integrally connected along their edges that are remote from the open rear end of said socket to form a digging edge, said key being vertically elongated, the means on said key and the means on said tooth point in said engagement with each other being, respectively, a lateral projection on said key at its lower end and part of the marginal portion around said opening in said lower wall into which said key extends, said key being tapered longitudinally thereof with its upper end having the greatest width and in engagement with opposite edges of the opening formed in said upper wall; said lower end of said key being movable laterally in said last mentioned opening against the resistance of said yieldable means to free said lateral projection from engagement with said part of said marginal portion, and said yieldable means being positioned between the lower end of said key and said portion of said nose.

References Cited in the file of this patent UNITED STATES PATENTS 1,003,663 Skelton Sept. 19, 1911 1,174,331 Mankins Mar. 7, 1916 1,188,480 Pemberton June 27, 1916 1,834,514 Brune Dec. 1, 1931 1,835,701 Edmunds Dec. 8, 1931 1,870,044 Fellmeth Aug' 2, 1932 1,890,981 Finkl Dec. 13, 1932 1,951,988 Mekeel Mar. 20, 1934 2,050,014 Morrison Aug. 4, 1936 2,312,802 Crawford Mar. 2, 1943 2,429,494 Stephens Oct. 21, 1947 2,483,032 Baer Sept. 27, 1949 2,657,482 Launder et al. Nov. 3, 1953 2,689,419 Daniels et al. Sept. 21, 1954 2,702,490 Launder Feb. 22, 1955 2,707,343 Baer May 3, 1955 2,762,139 Launder Sept. 11, 1956 2,891,333 Van Buskirk June 23, 1957 2,896,345 Peklay July 28, 1957

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