US3621728A - Self-energizing belt training idler - Google Patents

Abstract

AN IMPROVED BELT TRAINING IDLER FOR A REVERSIBLE MATERIAL CARRYING BELT CONVEYOR WITH A SELF-ENERGIZING DOUBLE GUIDE ROLL ACTUATING MECHANISM ON EACH SIDE OF THE BELT. EACH ACTUATING ARM CARRIES AN UPRIGHT GUIDE ROLL ON EACH OF ITS ENDSF AND EXTENDS IN BOTH DIRECTIONS ALONG THE BELT FROM THE AXIS OF THE IDLER ROLL ASSEMBLY. THE ACTUATING ARM ASSEMBLY IS PIVOTALY MOUNTED ABOUT THE IDLER ROLL AXIS TO TILT IN A VERTICAL PLANE PARALLEL TO THE BELT AND IS ENTIRELY SUPPORTED ON THE IDLER END BRACKET SO THAT SPECIAL IDLER ROLL ASSEMBLIES ARE NOT REQUIRED. THIS MEANS OF MOUNTING IS ADAPTABLE TO A TROUGHED-BELT-CARRYING-RUN TRAINING IDLER, A FLAT-BELT-CARRYING-RUN TRAINING IDLER, OR A FLAT-BELT RETURN-RUN TRAINING IDLER. WHEN THE MISALIGNED BELT CONTACTS ONE OF THE GUIDE ROLLS, IT TILTS UPWARD AND ACTS TO SWIVEL THE ENTIRE IDLER ROLL ASSEMBLY TO APPLY A CORRECTIVE FORCE TO THE BELT.

Description

l Nav. 23, 1911 H. STEORTS, JR

SEIJFENERGIZING BELT TRAINING IDLER 4 Sheets-Sheet l Filed Dec. 10. 1969 I NVE/V TOR HUBERT STEORTS, JR

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SELFENERGIZING BELT TRAINING IDLER 4 Sheets-Sheet 2 Filed Deo. lO. 1969 O OI'IIIIIHlw-y.

/NVENTOR 818:89 HUBERT STEORTS, JR

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SELF-ENERGIZING BELT TRAINING IDLER 4 Sheets-Sheet 5 Filed Dec. lO. 1969 /N VEN TOE HUBERT STEORTS ,Jl-.

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Nov. 23, 1971 4 Sheets-Sheet 1L Filed Dec. l0, 1969 /NVENTOR HUBERT STEQRTSMQ.

United States Pate t U.S. Cl. 74-241 9 Claims ABSTRACT OF THE DISCLOSURE An improved belt training idler for a reversible mate rial carrying belt conveyor with a self-energizing double guide roll actuating mechanism on each side of the belt. Each actuating arm carries an upright guide roll on each of its ends and extends in both directions along the belt from the axis of the idler roll assembly. The actuating arm assembly is pivotally mounted about the idler roll axis to tilt in a vertical plane parallel to the belt and is entirely supported on the idler end bracket so that special idler roll assemblies are not required. This means of mounting is adaptable to a troughed-belt-carrying-run training idler, a at-belt-carrying-run training idler, or a flat-belt return-run training idler. When the misaligned belt contacts one of the guide rolls, it tilts upward and acts to swivel the entire idler roll assembly to apply a corrective force to the belt.

FiACKGROUND OF THE NVENTION Field of the invention This invention relates to material carrying belt conveyors and deals more specifically `with an improved self energizing belt training idler for correcting the misalignment of reversible belts.

Description of the prior art In long belt conveyors it is well known that one of the serious operating problems is misalignment of the belt and since the belt is usually the single most expensive component of a long conveyor, damage to the belt caused by misalignment should be prevented. There are many causes for the belt not tracking centrally over the longitudinal axis of the carrying and return runs of the conveyor, including improper alignment of the idlers and pulleys, incorrect splicing of the belt, uneven loading of the material on the belt, and the like.

To minimize such operating problems, belt training idlers are provided on both carrying and return runs at intervals with the iixed idlers to exert a correcting force on the belt so the belt is directed to its desired central position on the idlers. Many forms of training idlers are known and in use, but most of these are limited to belts running in a single direction. Sayers U.S. Pat. 2,012,089, FIG. 4, and Sollenberger U.S. Pat. 2,132,052 are examples. The applicants invention applies to an improved construction for reversible belts.

In general the prior art includes two major types of reversible belt training idlers; one type has a pivoted shoe or disc axially located with respect to the idler rolls which creates a frictional drag on the belt that pivots the idler roll assembly to a corrective position, and the second type has two guide rolls on each side located in a leading and trailing position about the axis of the idler roll assembly so that the operating guide roll applies a corrective turning moment to the idler roll assembly. Sayers U.S. Pat. 2,012,089, FIG. l, and Lemon U.S. Pat. 2,109,923 are illustrative of the iirst type. Schott U.S. Pat. 2,821,291, Evans et al. U.S. Pat. 3,066,547 and Hartzell U.S. Pat. 3,303,924 are illustrative of the second type.

3,dl,728 Patented Nov. 23, l97l SUMMARY OF THE INVENTION This invention is directed to an improvement on the mechanism disclosed in the Evans et al. U.S. Pat. 3,066,547, wherein the double guide roll supporting arm assembly may be simply added to a basic training idler assembly in lieu of having a special end roll construction. The applicants design permits a single basic training idler to be used as a single guide roll positive action non-reversing belt idler, an actuating shoe idler or a double guide roll self energizing idler for a reversible belt with only the addition of the minor assemblies for these three types of actuators. In the Evans construction the idler end rolls have special shaft extensions to support the double guide roll arms; thus these rolls were only usable with the double guide roll actuator. In the applicants improvement standard idler rolls and end roll brackets are used and a special pivot assembly mounts over the standard roll adjusting nut to provide a journal for the pivoting actuating arm while being rigidly attached to the standard end roll bracket. All of the advantages of the Evans actuator are thus retained while a more versatile and economical construction is obtained. Further it is readily adaptable to a troughed-type carrying-run, a fiat-belt carrying-run or a nat-belt return type training idler, thus having further manufacturing advantages.

It is, therefore, a primary object of this invention to provide an improved type of belt training idler which will function automatically to apply a corrective force to realign the belt regardless of the direction of travel of the belt.

Another important object of this invention is to provide an automatically operable training idler for a reversible belt which utilizes standard training idler components and to which the proper actuating arms are easily assembled.

Still another object of ths invention is to provide a pivot assembly for the actuating arm of an automatically operable training idler for a reversible belt conveyor which readily couples to the standard training idler assembly and is secured to the standard end roll bracket.

Other objects and advantages of the invention will be apparent during the course of the following description.

BRIEF DESCRIPTION OF THE DRAWINGS In the accompanying drawings forming a part of this specification and in which like numerals are employed to designate like parts throughout the same:

IFIG. 1 is a side elevational view of a belt training idler embodying the invention and shown associated with the carrying run of a hat belt conveyor;

FIG. 2 is an end elevational view of the idler of FIG. l;

FIG. 3 is a section elevational view of the pivot assembly taken along line 3-3 of FIG. 1;

FIG. 4 is a transverse elevational view of a troughed belt conveyor showing a troughed type carrying run training idler and a iiat belt return run training idler embodying the invention;

FIG. 5 is an enlarged sectional elevational view of the end of an idler roll, the idler roll end bracket and the actuating arm pivot structure;

FIG. 6 is a sectional elevational View of the idler roll end bracket and actuating arm pivot taken along line 6-6 of FIG. 5;

FIG. 7 is a sectional plan view of the idler roll bracket and actuating arm pivot taken along line 7-7 of FIG. 6;

FIG. 8 is a diagrammatic exploded view of the actuating arm parts;

FIG. 9 is an end elevational view of the training idler showing the actuating arm tilted in operating position for corrective action;

3 FIG. is a plan view of the actuating arm, without its guide rolls, taken along line 10-10 of FIG. 2; and

FIGS 11-13 are diagrammatic views which illustrate the successive operation of the belt training idler of FIGS. 1-2.

DETAILED DESCRIPTION In the drawings wherein, for the purpose of illustration, are shown the preferred embodiments of this invention, and first particularly referring to FIGS. 1 and 2, there is shown a belt training idler associated with the carrying run 21 of a flat belt conveyor. The training idler comprises a fixed frame 40, a pivoting frame 35, a roll assembly 25 and two actuating arm assemblies 55.

The fixed frame 40 includes two cross beams 41 which extend transversely of the belt and are secured at their ends to bent end plates 42. Each of these end plates is suitably arranged for mounting on the top flange of a conveyor Stringer channel frame 23, as by fasteners 24. In order that the roll assembly 25 may apply a corrective force to realign the belt 21 when the latter has moved off of its central position, the training idler is provided at its mid-point with a pivot for the pivoting frame assembly 35, as shown in FIG. 3, to swivel about a vertical axis at the transverse mid-point of the belt when it is centered. The fixed lcross beams 41 have a bearing support assembly 43 bolted thereto by fasteners 44 at its mid-point t0 rotatably support a pivot shaft 39. The bearing support 43 is arranged with recessed pockets 45 for two anti-friction bearings 46, concentrically mounted with the pivot shaft 39. A suitable shoulder 47 on the pivot shaft and a threaded end 48 on which a washer 49 and nut 50 may be placed provide means for carrying the thrust of the loaded idler plus permitting low friction pivoting of the assembly in a conventional manner.

The pivoting frame assembly 35 consists of an inverted transverse beam 38 on each end of which a channel shaped end bracket 36 (FIG. 2) is mounted to project upwardly. An open ended slot 37 (FIG. 6) is provided in the top of the web portion of each bracket. The pivot shaft 39 is rigidly attached to and is located at the mid-point of beam 38. This shaft projects downwardly to be supported in the bearing support assembly 43 as previously described. The assembled beam, end brackets and pivot shaft comprise the pivoting frame assembly.

The roll assembly 25 is supported in the slots 37 in the end brackets of the pivoting frame assembly. As shown in FIG. 5 this roll assembly includes an outer shell 26 and an inner tube 27 joined by an end disc 28 at each end. The inner tube 27 is rotatably supported at each end on a xed shaft in an anti-friction bearing 28 with a seal 29 and a deflector 22. Shaft 30 has threaded ends 31 and axially located threaded holes 32 which are used for lubrication purposes. A hexagonal adjusting nut 33 having a centrally located peripheral groove 34 is threaded on to each end of the shaft to adjust and secure the bearing and Seal assemblies.

To effect the swiveling movement of the idler roll assembly 25 about its pivot axis when the belt is misaligned, the pivoting frame assembly is provided with one of said actuating arm assemblies 55 on each of its end brackets. As shown on FIGS. 8-10, each assembly includes an actuating arm 56 which supports two cylindrical guide rolls 65 on its opposite ends and is pivotally mounted on an idler end bracket 36. Thus, when assembled, these guide rolls are positioned along the belt on both the upstream and downstream side of the roll assembly 25 and on each side of the belt, normally in a position out of contact with the side edges of the belt when the belt is properly centered as shown in FIG. 1l. The actuating arm 56 (FIG. 8) is a beam member having a central hub 58 with a bore 59 therethrough and a laterally extending portion 56a on each side of the central hub, generally perpendicular to the axis of the bore. A threaded lubrication hole 60 (FIG. 5) is provided in the lower side of the hub midway of its length. In proximity to the central hub, but on each side of it, a projection 61 (FIG. 8) depends from the underside of the beam member which has side surfaces that form stops 62 for limiting the amount of travel in a vertical plane of the actuating arm. Each portion 56a of the beam member further extends laterally from the projection 61 in a generally downward direction and, as seen in FIG. 10, inwardly toward the belt so that, at its end, a hub 76 (FIG. 2) therein supports the guide roll 65 in a tilted position approximately 10 from the vertical in the FIG. 2 position and toward the axis of the idler roll 25 but in a plane parallel to the longitudinal centerline of the conveyor belt 21. The guide rolls 65 are adjacent the side of the belt but slightly away from the edge of the belt when it is centered. Each hub 76 on the end of the beam has a hole 63 (FIG. l0) therethrough and a second hole 64 which is drilled and tapped at right angles to the rst hole for receiving a set screw 74 (FIG. 8) for locking the end of a guide roll shaft 66.

Each guide roll assembly 65 (FIG. 8) comprises the shaft 66, with a retaining groove `67 near its outer end, a retaining ring 68 in this groove, and a capped outer tube 69 in which two anti-friction bearings 70 are mounted. When the tube is assembled over the shaft and a seal 71 is inserted, a lower locking collar 72 and a set screw 73 will retain the assemblyvon the shaft. The assembly is then inserted in hole 63 in the actuating arm 56 and locked by the set screw 74.

Each idler roll end bracket 36, as shown in FIGS. 2, 6 and 7, is a channel shaped, formed member so arranged that the lower portion of the web portion is cut out to t over the cross beam 38 and to be welded thereto. Flanges 75 of the bracket are inclined outwardly from top to bottom so that the lower end of the web portion is slightly wider than at the top. At the upper end of the web the U-shaped slot 37 is cut in the web portion and is of proper size to receive the grooved portion of the adjusting nut 33. Suitable holes 77 are located in each flange below the center of the nut 33 for securing a pivot member to be described later. The end bracket 36 is so located that the web portion at the top is vertical and perpendicular to the cross-member 38 and parallel to the end face of the idler roll 25. Below the contact area of the roll locknut 33 the end bracket is formed with a concave curve 78 (FIG. 5) to provide clearance for preventing build up of spilled material.

The arrangement for mounting the actuating arm assembly 55 on the end bracket 36 will now be described. After the idler roll assembly 25 and its nut 33 are assembled in the end bracket slot 37, a pivot member 80 is added. As shown in FIGS. 5, 6, 7 and 8, the pivot member consists of a hub 80a with attached downwardly projecting legs `81, 82 and 83 and a hollow cylindrical journal 84 projecting outwardly from the hub, axially aligned with the center of the idler nut 33, and perpendicular to the end face of the idler roll and to the upper web portion of the idler end bracket 36. As best seen in FIGS. 5 and 6, one surface of the hub porti-on of this pivot member has a partial hexagonally shaped pocket 85 to fit over the top of nut 33 and lock it from turning. The downwardly projecting ange legs 81 and 82 incline outwardly slightly and are matingly shaped to nest within the flanges 75 of the end bracket 36. Holes 86 are provided in these legs to match holes 77 in the brackets. The hole in leg 81 is threaded to receive a bolt 87, whereas a bolt S18 and nut 89 are used with an Unthreaded hole in leg 82 to securely fasten the pivot member to the end bracket. It is to be noted that the holes 77 are staggered and not in line vertically so as to better resist any pivoting of member 80 about these holes and thus provide a rigid mounting. The third downwardly projecting leg 83, which is under the vertical centerline of the hub, is parallel to the web portion of the end bracket 36 and bears against the end face of the idler roll nut 33. Its length is determined to Contact the curved section 78 (FIG. 5) of the web portion of the end bracket 36 and thus provides further rigid support for the pivot member. The cylindrical journal portion 84 has a retaining ring groove 91 near its outer end and a central longitudinal hole 92 completely through the pivot member providing a passageway aligned with the lubrication passageway 32 in the idler roll shaft 30 for access and lubrication purposes. A flanged cylindrical bearing bushing 93 and a straight cylindrical bearing bushing 94 is then assembled over the journal section of the pivot member, with a short axial gap therebetween to provide a lubricant passageway 95 to the two bushings from the hole '60 and lubricating tting 79 in the actuating arm hub 58. A threaded pipe member 96, with a pipe coupling 97 and a lubrication fitting 98 attached, is then inserted in the journals longitudinal hole 92 and threaded into the idler roll shafts mating hole 32 so that the lubrication fitting 98 extends slightly beyond the end of the journal.

The actuating arm assembly 55 may now be assembled on the pivot member 80 by placing the bore 59 of the hubportion 58 over the assembled bearing bushings 94 and 93 (FIG. 5). The hub is pushed up against the ange of bushing 93. Deflector washer 99 is then assembled over the outer end of the actuating members hub 58. Retaining ring 90 is then placed in the retaining ring groove 91 to hold the actuating arm assembly so as to be free to pivot easily on its lubricated bearings in a vertical plane perpendicular to the axis of the idler roll assembly 25 In FIG. 2 the actuating guide roll assembly is in its horizontal or non-operating position with both guide rolls extending above the top of the belt 21 as when the belt is aligned. FIG. 9 shows the assembly when it is tilted or in a position to exert a corrective force to overcome belt misalignment. In this tilted position and for the direction of belt travel indicated by arrow 100, the rear or trailing guide roll 101 is raised and the forward or leading guide roll 102 is lowered below the surface of the beltuntil the projection 61 on the actuating arm 56 contacts the end bracket 36 and limits further lowering.

The training action is fully disclosed in the -Evans et al. U.S. Pat. 3,066,547. Briey described, this action is the result of the slight angular tilt of the guide rolls and the motion of the belt in contact with the peripheral surface of the guide roll when the misaligned belt contacts the roll. The frictional contact of the belt with the freely rotating guide roll creates an upward component of force as though a helical thread were provided on the guide roll. The rearward location of the contacted guide roll with respect to the axis -of the idler roll assembly and the side thrust of the misaligned belt create a turning moment to cause the pivoting idler frame assembly to pivot as shown in FIG. l=3. This position then creates a corrective force for recentering the belt. FIGS. ll-l3 show successive positions of the belt and the training idler.

While the above description covers the flat roll conveying run idler shown in FIGS. l and 2, two further embodiments of this invention are shown in FIG. 4. The upper half of the latter figure shows the same type of automatic reversible actuating arm assemblies 106 applied to a troughed-belt carrying-run training idler 105. The pivoting frame assembly 107 has a bent cross-frame member 108 which has portions parallel to the axes of the three idler rolls, and the fixed idler frame 109* has simple straight end brackets 110y for attaching the idler to'the top flanges of the conveyor stringers 111. The midspan pivot assembly i112 and the actuating arm assemblies 106 are the same as previously described in the iirst embodiment. In the lower half of FIG. 4, a return belt training idler 115 of the same general type as previously described is shown. The only ditference is that the end brackets 116 of the -xed frame 117 are slightly different in height and normally fasten to the lower flanges of the conveyor stringers 111.

The same basic training idler assemblies may be used as a single roll positive action training idler for `a non-reversing belt by the addition of a suitable bracket carrying a single vertical guide roll bolted over each slot 120, shown in FIG. 2, of cross beam 38 and so arranged that the guide roll is on the trailing side of the idlers axis and transversely positioned the same as shown in FIG. 1. The double guide roll actuating arm assemblies are then omitted.

Also the same basic training idler assemblies may be used as an actuating shoe type training idler for a reversing belt by the addition of a member having an inclined curved surface extending above the plane of the top of the idler roll assembly and rigidly attached to each end roll bracket in holes 77 shown in FIG. 6. The double guide roll actuating arm assemblies are then omitted.

Although the best mode contemplated for carrying out the present invention has been herein shown and described, it vm'll be apparent that modification and variation may be made without departing from what is regarded to be the subject matter of the invention.

What is claimed is:

1. In combination with an endless belt of a power driven conveyor having an upper carrying run and a lower return run and with a self-energizing training idler having a rotatable roll supported in end brackets for pivotal movement, the improvement which comprises a pivot member rigidly attached to each of said end brackets and an actuating arm member, one of said members having an extending projection and the other of said members having a cavity to receive said projection for pivotal support of said actuating arm member, whereby misalignment of said belt causes said actuating arm assembly to pivot in a vertical plane upon contact with one edge of the belt and continued pressure of the belt causes said roll assembly to pivot in a horizontal plane to a skewed position which will realign the belt.

2. In combination with an endless belt of a power driven conveyor having an upper carrying run and a, lower return run and a self-energizing training idler having a rotatable roll assemby supported in end brackets on a frame pivotally mounted on a xed frame attached to the conveyor structure, the improvement which comprises:

(a) pivot means rigidly attached to each of said end brackets, said pivot means comprising a cylindrical journal portion extending outwardly and away from the end bracket; and

(b) an actuating arm assembly pivotally supported on each of said pivot means, independently of said roll assembly, said actuating arm assembly further including a hollow hub portion which is pivotally mounted on said journal portion in coaxial relationship with said journal portion, whereby misalignment of said belt causes said actuating arm assembly to pivot in a lvertical plane upon contact with one edge of the belt and continued pressure of the belt causes said roll assembly to pivot in a horizontal plane to a skewed position which will realign the belt.

3. The combination as described in claim 2 in which said pivot means further comprises a hub portion, at least one leg depending therefrom, and means to removably fasten said pivot means to said end bracket.

4. The combination as described in claim 2 in which said roll assembly includes a nut with a peripheral groove and a shaft on the rolls rotatable axis having a threaded end portion to which the nut is attached, said end bracket having a slot in its upper end to matingly receive the groove in said nut and said hub portion of said pivot means having a projection adjacent said roll assembly with a mating pocket to surround at least part of said nut to prevent its rotation, said hub portion being further located so that the axis of the mating pocket is in alignment with the axis of the journal portion of said pivot means.

5. A self-energizing training idler adapted for use with a belt which may travel in opposite directions comprising:

(a) a pivoting frame mounted for swiveling movement about an axis normal to the transverse middle portion of the belt;

(b) an end bracket attached to each end of the pivoting frame, having an open ended slot in its top portion;

(c) a roll assembly having a fixed shaft with attachment means on each end for being supported in the slot in said end bracket and having a cylindrical roll rotatably mounted on said shaft;

(d) pivot means rigidly but removably attached to each of said end brackets having a cylindrical journal portion extending outwardly from said end bracket, a hub portion connected to said journal portion and extending over the top of said end bracket with a pocket for locking engagement over said roll assembly shaft attachment means and at least one vertical leg depending from the hub portion for mating engagement with said en-d bracket;

(e) an actuating member independently pivotally supported on said pivot means having a central hub with a bore therethrough in coaxial alignment with said journal portion of the pivot means, stop means on each side of said hub to limit the pivotal movement and arm portions normal to said bore extending in opposite directions from said hub longitudinally of and parallel to the edge of the belt; and

(f) a cylindrical guide roll rotatably supported in each end portion of said actuating member adjacent to the edge of the belt, extending in a plane normal to said roll assembly axis above the top edge of the belt when said actuating arm is horizontal and whose axis is inclined so that the axes of the two rolls converge toward and above the roll assembly whereby, when the belt is misalignment and one edge contacts the peripheral surface of at least one of said guide rolls, a helix angle is formed between the belt edge and the guide roll in which a component of force is axially exerted along the guide roll axis causing the actuating arm to tilt so that the guide roll on the approach side of the roll assembly will be automatically raised above, and the other guide roll lowered below, the edge of the belt, continued misalignment of the belt causing the swiveling of the pivoting frame to a position in which the roll assembly will realign the belt.

6. A training idler as described in claim in which said cylindrical journal lportion of said pivot means is in axial alignment with the longitudinal axis of said roll assembly.

7. An actuating arm assembly for a self-energizing training idler adapted for use with a belt which may travel in opposite directions and of the type having an idler roll assembly rotatably mounted on a pivoting frame supported to swivel about a xed frame transverse to the belt which comprises:

(a) an end bracket attached to each of the outer ends ofthe pivoting frame having an open slot inthe upper end of each bracket in which the outer ends of the idler roll assembly are supported;

(b) pivot means rigidly but removably attached to said end bracket having a cylindrical journal section axially in alignment with the longitudinal axis of said idler roll assembly extending outwardly and away from said end bracket;

(c) an actuating member pivotally supported on the journal section of said pivot means, independently of said idler roll assembly, having a central hub with a bore therethrough in coaxial alignment with said journal section, stop means on said actuating meinber to limit the pivotal movement by contacting said end bracket and arm sections extending in opposite directions from said hub longitudinally of and parallel to the edge of the belt; and

(d) a cylindrical guide roll rotatably supported in each end section of said actuating member adjacent to the edge of the belt extending in a plane normal to said idler roll assembly axis above the top edge of the belt when said actuating arm is horizontal and said guide roll axis is inclined so that the axis of the two rolls converge toward and above said idler roll assembly.

8. An actuating arm assembly as described in claim 7 in which each outer end of the idler roll assembly has a nut with a peripheral groove for mating engagement in the open slot of said end bracket and said pivot means further having a hub section connected to said journal section extending over the top of said end bracket having a mating pocket for said nut to prevent its rotation and having at least one vertical leg depending from said hub section for mating engagement with said end bracket.

9. An actuating arm assembly as described in claim 8 further comprising said end bracket being a U-shaped member with -anges extending outwardly from the outer end of said roll assembly, each of said flanges having a hole therethrough below the axis of said journal section and in non-aligned vertical relationship with each other, said pivot means having a leg depending from the hub on each of its sides parallel to the hubs longitudinal axes and having a hole matingly located with the hole in each of said end bracket flanges, and fastening means for securing said pivot means to said end bracket.

References Cited UNITED STATES PATENTS 2,109,956 3/1938 Corbin 198-202 2,160,057 5/1939 Carus et al 198-202 3,058,575 10/1962 Arnot et al 198-202 3,066,547 12/ 1962 Evans et al 74-241 3,278,002 10/1966 Robins 198-202 3,303,924 2/ 1967 Hartzell, Jr 74-241 X 3,342,311 9/1967 Robins 198-202 LEONARD H, GERIN, Primary Examiner U.S. Cl. X.R.

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