US2720721A - Dust applicator - Google Patents

Description

Oct. 18, 1955 5. A. REYNOLDS, JR.. ETA!- DUST APPLICATOR 2 Sheets-Sheet 1 Filed June 27, 1950 Smaentor GEORGE A .REYNOLDS JR. FRA NKL I K. {{OLBROOK E'Il3 1 (Ittorneg Oct. 18, 1955 G. A. REYNOLDS, JR. ETAL' 2,7

DUST APPLICATOR 2 Sheets-Sheet 2 Filed June 2'7, 1950 3maentor GEORGE A. REYNOLDS .1! nu mu m K. noLanoolr (Ittorneg United States Patent Cfiice 2,720,721 Patented Oct. 18, 1955 DUST APPLICATOR George A. Reynolds, Jr. and Franklin K. Holbrook, San Jose, Calif., assignors to Food Machinery and Qhernical Corporation, San Jose, Cali, a corporation of Defiaware Application June 27, 1950, Serial No. 170,62

8 Claims. (Cl. 43-148) The present invention relates to dusting mechanisms, and more particularly to a hand operated mechanism for applying insecticidal and other dusts to agricultural products.

An object of the present invention is to make an improved hand duster.

Another object is to make a hand duster having improved dust feeding characteristics.

Another object is to reduce the cranking effort required to operate a hand duster.

Another object is to make a hand duster wherein the dust is positively fed in uniform quantities to a blower for air borne movement toward a point of application.

Another object is to avoid the settling out and packing of insecticidal dusts in parts of a hand duster which would interfere with the feeding of the dust through a blower and discharge tube.

Another object is to provide a hand duster with improved means for keeping a feed slot clear of packed dust and lumps with a minimum loss of power through frictron.

Another object is to provide an improved blower mounting and drive arrangement wherein a blower is mounted on the opposite side of the duster from a hand crank and the hand crank is operatively interconnected with a blower fan wheel for eflicient operation thereof.

Another object is to make an improved type of dust feeding rotor with diagonally oflfset portions thereof arranged to wipe the dust toward a feed opening.

Another object is to arrange a blower fan wheel in relation to a dust feeding opening so as to provide a continuous air borne movement of dust from a dust hopper through the feeding opening, and into and through the fan wheel.

Another object is to provide improved means for controlling dust feed in a hand duster.

Another object is to simplify and strengthen structural features of a hand duster.

These and other objects and advantages of the present invention will be apparent from the following description and the accompanying drawings wherein:

Fig. 1 is a perspective view showing an operator using a hand duster embodying the present invention.

Fig. 2 is a perspective view of the hand duster shown in Fig. 1, as it would appear when viewed from above and at one side thereof with the straps and nozzle tube omitted.

Fig. 3 is an enlarged fragmentary vertical sectional view showing the impeller mounting and dust feeding arrangement of the duster of the present invention, the view being taken substantially along line 33 of Fig. 5.

Fig. 4 is a section taken along line 44 of Fig. 5.

Fig. 5 is a section taken along line 55 of Fig. 4, a portion of a feed rotor vane being broken away.

Fig. 6 is a fragmentary section taken along line 66 of Fig. 4.

In the illustrated embodiment of the invention the dust hopper 10 comprises a cylindrical shell 11 with a pair of stiffening beads 12 and 13 formed therein. A filling opening 14 is provided in the top of the cylindrical shell 11 and a curved door 15 (Figs. 2 and 4) conforming to the curvature of the shell 11 is mounted on hinges 17 to cover but not seal the opening 14 when the duster is in use. A latch 13 is adapted to secure the cover in closed position. Radially projecting flanges 19 and 20 are provided around the ends of the hopper shell 11, and a pair of disk- like heads 21 and 22 have their marginal edge portions crimped over the flanges 19 and 20, respectively, to secure the heads to the shell in rigid, dust tight relation. Upper and lower shoulder harness attaching hooks 23 and 24, respectively, (Figs. 1, 4 and 5) are welded to each of the heads 21 and 22.

A troughed, tapered fan wheel drive shaft housing 25 (Figs. 4, 5 and 6) has a pair of outwardly bent side flanges 27 and 28 (Fig. 5) formed thereon, which conform to the underside of the hopper 10 and are secured thereto by spot welding. The larger end of this shaft housing 25 is flanged outwardly at 29 and projects very slightly beyond the left hand end of the hopper 10, as shown in Fig. 4.

A marginally flanged disk-like blower housing support plate 30 is spot welded to the end flange 29 of the shaft housing 25, and also to a pair of embossed islands 31 and 32 (Fig. 6) formed on the head 21. The thickness of the embossed islands 31 and 32 is the same as the distance which the end flange 29 extends beyond the end of the hopper 1%. A slight clearance is thus provided between the head 21 and the blower housing support plate 34 to permit the insertion therebetween of a dust feed control lever 33 to be described later herein.

A sheet metal blower housing 35, which is of usual volute shape, is made in a well known manner of two complementary halves, die formed and fitted together in overlapping relation. The two halves of the housing are spot welded together along their overlapping edge portions at 37 (Fig. 4).

The blower housing 35 has a usual air inlet opening 41 in a side thereof, with an inwardly curved flange 42 surrounding the air inlet opening to improve thevair flow characteristics of the blower. The blower housing 35 also has a tubular blast discharge spout 43 onto which an extension tube 44 of desired length is adapted to be fitted to carry and direct the dust laden air blast from the blower housing toward a desired point of application.

The diameter of the blast discharge spout 43, and of any extension tube 44 which may be mounted thereon, is preferably much larger than has been the practice in the past, namely of a diameter of approximately two and one-half inches. This provides a discharge blast having from two and one-half to three and one-half times the cross sectional area of what, in the past, has been considered almost standard practice for hand dusters. A spreader hood 46 (Fig. 1) made from a disk of sheet metal formed to fit over the end of the tube 44, is secured to the tube by a clamping band 55 to spread the dust when so desired.

The blower housing 35 (Fig. 4) is secured to the hopper 1!) to be rotatively adjustable about the axis of rotation of the impeller 40. To provide such a mounting arrangement, a circular mounting opening 45 is provided in the side of the blower housing opposite the air intake opening 41. A marginal flange 47 surrounds the mounting opening 45 in the housing 35 (Fig. 4) and is adapted to fit closely within, and to conform to, the marginal flange around the disk-like support plate 30. A marginally flanged frictional clamping ring 48 (Fig. 4) is adapted to fit within the inner side of the marginal flange area of the blower housing 35 surrounding the mounting opening 45 therein. Mounting bolts 49 (Figs. 4 and 5 are inblower housing between them and in dust tight relation to the housing support plate 30. Adjusting the nuts on the bolts 49 provides adesired amount of frictional resistance to rotative adjustment of the blower housing 35 on its support plate 30;

A gear housing 50 is mounted on the opposite end of the dust hopper from the blower housing 35. The gear housing 50 (Figs. l, 2 and 4) comprises a marginally flangedv base plate 51 (Fig. 4), spot welded to the head 22, and a dished cover plate 52. The gear housing base plate 51 extends downwardly below the lower end of the hopper 10 and covers the smaller end of the impeller drive shaft housing 25. The cover plate 52 is formed with a flatmarginal flange 53 adapted to fit against the base plate 51 within the marginal flange thereof. A plurality of small bolts 54 secure the two parts of the gear housing together. Before assembling the gear housing cover onits base plate 51 the cover flange 53 may be coated with suitable sealing compound or provided with a conventional gasket (not shown) to provide a dust tight joint.

.A'crank shaft bearing 57 (Fig. 4) is mounted in the gear housing cover plate 52 to'be disposed co-axially of the hopper 10, and a gear hub 58 having a drive gear 59 pressed thereon to have driving engagement therewith is journaled in this bearing. The gear hub 58 is secured to a crank shaft 607to rotate therewith by a pin 61 inserted in aligned holes in the hub and shaft. The crank shaft 68 has a crank arm 62secured thereto by a set screw 63, and

a usual hand grip 64 is rotatably mounted on the oifset outer end of the crank arm. The crank shaft 69 (Fig. 4) passes with a slight clearance through aligned holes provided therefor in the head 22 and the gear housing base plate 51. A felt sealing washer 65 surrounds the crank shaft and is gripped between an indentation in the head 22 and the base plate 51 to prevent the entry of dust into the gear housing.

The other end of the crank shaft 60 (Fig. 4) is journaled in a bearing 67 mounted centrally of the head 21. A felt sealing washer 68 surrounds the crank shaft and is retained in position on the inner end of the bearing 67 by a cup shaped sheet metal cap 69 fitted over the felt washer and pressed onto the projecting inner end of the bearing.

Both of'the crankshaft bearings 57 and 67, as well as all of the other fixed bearings of the present mechanism (Fig. 4) are of a well known type,,being made of ductile bearing metal, such as babbitt, having a portion 76 (Fig. 4) of reduced diameter adapted to be inserted with a fairly close'fit in a hole in a sheet metal support member such as, for example, the gear housing cover 52. Each bearing thus inserted is secured in position by upsetting a portion 71 (Fig. 4) of the materialof the bearing and forcing this upset portion against the sheet metal in which the bearing is inserted. This grips the sheet metal of the supporting member between the upset portion 71 and the shoulder formed by the reduction in the outside diameter of the bearing. a V p The gear 59 secured to the crank shaft 60, is the first in a train of gears providing speed increasing driving con nection between the crank shaft 60 and an impeller drive shaft 72. The gear 59 is in meshed driving engagement with the pinion portion of a combined gear and pinion 73 journaled on a bearing bushing 74. The bushing 74 is mounted on a post 75 which is inserted through axially aligned holes in oppositely indented recesses in the gear housing base plate 51 and cover plate 52. The inner. end of the post 75. (Fig. 4) is headed, and the head is retained between an indented portion of the gear housing base plate 51 and the head 22;

The larger diameter gear portion of the combined gear and pinion 73 is in meshed driving engagement with a pinion 77 secured by a pin 78 to the impeller drive shaft 4. 72. The impeller drive shaft 72 is journaled in axially aligned bearings 80 and 81 mounted at opposite ends of the tunnel formed by the fan shaft housing in aligned openings in the gear housing base plate 51 and centrally of the blower housing support plate 30, respectively. The

common axis of the bearings 80 and 81, and of the impeller drive shaft 72 journaled therein, is parallel to the axis of crank shaft rotation. V

The gear train connecting the crank shaft 60 to the impeller shaft 72 is such' as to provide a gear ratio of approximately twenty-eight to one. This is approximately onehalf that of previous hand dusters, and results in a reduction of approximately one-half in the discharge velocity of the air blast over hand dusters of the prior art.

Both the gear housing base plate 51 and the blower housing support plate are welded to the hopper 10. Therefore, by assembling these parts on the hopper with the aid of a conventional jig, not shown, accurate axial alignment of the bearings is easily attained; This, in. addition to the structural rigidity and protection to the crank shaft afforded by the housing 25, tends to maintain the bearings and shaft in accurate axial alignment throughout the life of the machine, and thus avoids impairment of the free running qualities. of the relatively high speed impeller shaft 72. Oil holes 76 and 79 (Fig. 4) are provided in the underside of the fan 'shaft housing 25 to facilitate oiling of the bearings 80 and 81. p

The left hand face of the pinion 77 as shown in Fig. 4

' is adapted to .bear against the outer or right hand end of the right hand fan shaft bearing 81, and the right hand end of the'impeller shaft 72 is adapted to bear against the inner side of an indented portion 82 ofthe gear.

housing cover 52 to limit axial displacement of the shaft 72.

The fan wheel or impeller 40, in general of a well known radial discharge type, is secured by a set screw 83 on the left hand end of the shaft 72, as shown in Fig. 4. A felt sealing washer 84 (Fig.3) surrounds the impeller shaft 72 and is held under light compression between the impeller hub 85 and the impeller shaft bearing 80. 1

A disk-like impeller back plate 87 is fitted onto a reduced portion of the hub 85, and is secured thereon by a flange 88 upset from the material of the hub 85 in a manner similar to that. described previously herein for mounting the fixed bearings. (see Fig. 3).

A plurality of axial flow blades 89 (Fig. 4) are cut from the metaltof the impeller back plate 87, and are bent outwardly, or toward the right as shown in Figs; 3 and 4, to lie at acute angles to the plane of rotation of the back plate. The free edges-of these blades 89 face forwardly relatively to the direction of fan wheel rotation and act similarly to the blades of an axial flow fan to induce a flow of dust laden air into the impeller through the openings in the back plate formed by the outward bending of the blades 89. V

The impeller 40 (Fig. '4') has a cylindrical sheet metal blade strip 90secured by a flanged seam 91 to the periphery of theback plate 87. A plurality of forwardly curved impeller blades 92 are cut and bent uniformly outwardly from the material of the blade srtip 90. A usual shroud ring 93 is secured by a flanged seam 94 to the front orair intake side of the blade strip, the central opening in the shroud ring conforming to, and being disposed closely interiorly of, the 'air inlet opening 41 in the blower housing to facilitate a free flow of air into the impeller wheel. 7

An arcuate dust feed slot 977(Figs. 3, 4, 5 and 6) is provided in the head 21, the curvature of the slot being concentric with the axis of the impeller shaft 72., A

similar, but larger, registering dust feed slot 98 is pro- .vided in the blower housing support plate 30. The food 7 control lever 33 has a relatively wide lower end portion (Fig. 6) which is inserted (Figs. 3 and 4) in the space provided between the head 21 and the blower housing support plate 30, referred to previously herein. A hole in this wide lower end portion of the lever 33 fits onto a reduced outer portion of the impeller shaft bearing 80 to mount the lever for pivotal movement thereon. The two embossed islands 31 and 32 (Fig. 6) on the head 21 serve as stops to limit the pivotal movement of the feed control lever.

The wide lower end portion of the feed control lever 33 (Fig. 6) is of suificient size to cover the registering feed slots 97 and 98 in the head 21 and blower housing support plate 30 in all pivotally adjusted positions of the lever. A slender upper portion 100 of the feed control lever 33 projects upwardly above the blower housing, and a pair of manipulating tabs 101 are bent upwardly from the material at the upper end of the lever itself to facilitate moving the lever to a desired adjusted position. The feed control lever 33 is made of springy material such as spring bronze or steel, and before assembly is bent to a slightly curved condition lengthwise thereof so that when inserted in the space between the head 21 and the blower housing support plate 30 the resiliency of the lever will urge it into frictional engagement with the members between which it is mounted to retain it in adjusted position.

The wider lower end portion 99 of the feed control lever has an arcuate slot 102 therein, adapted, in one limit of pivotal movement of the lever, to register with the slotted openings 97 and 98 in the head 21 and blower housing support plate 30, respectively, and in its other limit of pivotal movement to completely close off the feed slot 97 in the head 21. Markings 96 (Fig. 6) are provided on the head 21 adjacent the upper end of the lever 33 to indicate the adjusted condition of the feed slot.

The feed slot 102 in the lever 33 is slightly wider than slot 97 in the head 21 (Figs. 3, 4 and 6) and slightly narrower than slot 98 in the blower housing support plate 30, so that the walls of the feed opening formed by the registering of these three slots will be of an outwardly stepped, diverging nature as best shown in Fig. 3. This prevents the dust from packing in the feed opening and bridging over the feed slot on its exterior or discharge side. A dust feed rotor disk 103 (Figs. 4 and 5) is mounted Within the hopper on a hub 104 secured to the crank shaft 60, by a set screw 105. The rotor disk 103 has a dished central portion 107 (Figs. 4 and 5) with four holes 108 therein. The marginal portions surrounding these holes are flanged inwardly as at 109 for stiffening the disk and for agitating the dust in the hopper during rotation of the disk.

A plurality of radially extending vanes 110 are provided around the periphery of the rotor disk 103, each of the vanes having a trailing end portion 111 extending rearwardly therefrom with respect to the direction of rotation of the disk when the machine is in use. The vanes 110 are spaced well apart from each other to avoid bridging of the dust between adjacent vanes when using dusts which have a tendency to adhere or pack. The trailing portions 111 of the vanes are bent outwardly (Figs. 3, 4 and 5) at an acuate angle toward the head 21 to exert a cam-like pressing or troweling action on the dust between the vanes and the feed slot 97 in the head 21 to urge the dust toward and through the feed slot.

One or more of the vanes 110 is provided with a headed, tapered rubber brush or finger 112 inserted with a tight press fit in a hole provided therefor in the vane in which it is mounted. The finger 112 has a tapered free end portion 113 and is of a length to cause this free end to brush lightly against the inner surface of the head 21 upon rotation of the rotor disk 103. The finger 112 is mounted at a radial distance from the axial center of the rotor so that the tapered end of the finger will brush the feed slot 97 lengthwise thereof at each revolution of the crank shaft 60. This brushing action clears the feed slot of any lumps or packed powder which otherwise might tend to obstruct its inner side.

The only times the rubber fingers may be necessary are when using material containing lumps of a size too large to pass through the feed opening, or when the feed opening has been made very small by adjustment of the feed control lever, and the dust being used is of a type which packs easily, such as, for example, lead arsenate or other dusts of an oily or sticky character. By providing two of these brushing fingers on diametrically opposite vanes on the rotor disk 103, the slot 97 will be brushed clear twice during each rotation of the crank shaft. This has been found adequate even for dusts which have a tendency to pack very easily. The fingers 112 are lubricated by the dust through which they are carried during their rotative travel around the head, and therefore any slight frictional resistance they may cause is negligible.

A helical dust agitating rod 114 has a pair of hub blocks 115 and 116 secured to the inner ends of radially inwardly extending end portions 118 thereof. The hub blocks 115 and 116 are secured to the crank shaft 60 by set screws 119 to dispose the helically curved portion of the agitator co-axially of the shell 11 of the hopper 10 and spaced inwardly slightly therefrom. The hand of the helix is such as to urge the dust toward the left hand end of the hopper as shown in Fig. 4. A felt sealing washer 117 surrounds the crank shaft 60 and is interposed between the hub block 116 and the head 22 to prevent the escape of dust into the gear box.

The general operation of the illustrative embodiment of the invention will be obvious to those familiar with the art. With respect to some of its novel features however a brief description may be of assistance in understanding the invention. The duster is suspended in front of an operators body by means of a shoulder harness 120 as shown in Fig. l. Rotation of the impeller or fan wheel 40 by means of the hand crank 62 causes the peripheral impeller blades 92 to discharge air from the interior of the impeller radially thereof, whence it is carried around the volute housing 35 and out the discharge spout 43 in a usual manner. This creates a pressure drop in the interior of the impeller 40, drawing air into the interior of the impeller through the air inlet opening 41 in the blower housing.

The axial flow blades 89 in the impeller back plate 87 draw air axially into the interior of the impeller through the openings in the back plate provided by the bending outwardly of the blades 89. This causes a reduction in pressure in the space between the impeller back plate 87 and the blower housing support plate 30. The feed slot 98 in the blower housing support plate 30, as controlled by the feed slot 102 in the lever 33, opens into this latter space. Therefore, since the pressure within the unsealed hopper remains at atmospheric due to infilatration around the unsealed cover 15, the pressure drop on the outer side of the feed slot within the blower housing, even though slight, tends to produce an air flow through the feed slot. In addition to their axial air propelling action, the blades 89 in the impeller back plate 87 exert a swirling or rotative effect on the air and dust particles in this space between the impeller back plate and the blower housing support housing plate 30 which even at comparatively low impeller speeds prevents the accretion of dust on the surfaces enclosing this space and insures an air borne flow of dust from the feed slot into the impeller.

Rotation of the feed rotor disk 103 causes the flanges 109 around the holes 108 in the disk, the vanes 110, and the rubber fingers or brushes 112, to agitate the dust through which they pass in their rotative paths, thereby assisting in maintaining the dust in the hopper in a fluent state. Each outwardly bent trailing end portion 111 of the vanes 110 also exerts a diagonal pressing force on the dust between it and the head 21, tending, in effect, to trowel the dust into and through the feed slot. With some sticky or oily dusts such troweling action might tend to pack the feed slot closed were it not for the intermittent clearing action of the brushes 112, each of which sweeps the feed slot lengthwise at each revolution of the crank shaft 60. Rotation of the helical agitator 114 operates in mitted through the open back plate to the discharge side of the feed passage, plus the combined suction and air swirling effect produced by the axial flow blades 89 in the manner described previously herein, causes an air flow which picks up the dsut passing through the outwardly flaring, walls of the dust feed passage formed by the successively wider feed slots 97, 102 and 98 (Fig. 3) and carn'es it into the impeller'40, whence it isdischarged along with the relatively low velocity large volume air blast created by the blower.

A major objection by operators to the use of hand dusters of the piror art has been the amount of efiort required to crank them. Such effort has been considered an" inherent function of this type of machine, since it was thought essential to use paddle bladed fan wheels turning at high speed'in order to pass thedust through the blower without having it pile up on the fan blades and in the blower housing, thereby fouling the machine. It has been customary such prior art machines to use an air blast discharge opening of approximately one and one-half inches in diameter in order to carry the dust outwardly approximately three feet from the air blast discharge outlet'before dissipation would cause the air blast to lose most of its discharge velocity. Such an air blast is adequate to give the penetration of foliage by the dust necessary for satisfactory operation, but requires strenuous cranking on thepart of the operator to achieve it. The illustrated machine, discharges approximately twice the volume of air at approximately one-half the formerly required velocity. The result is that the higher. volume, lower velocity air blast of the illustrated machine, carriestthe dust outwardly as far as that of the prior machines and gives equal foliage penetration. Tests indicate that the air blast velocity of the illustrated machine, at a point approximately three feet from the point of discharge is approximately the'same as with the high speed machines of the prior art. However due to the great reduction in gear ratio and air blast discharge velocity permitted by the arrangement of the present machine, the cranking effort required to operate it at an optimum rate of thirty-five to forty revolutions per minute has been found to be much less than that required to operate the 8. t hopper, drive means operatively interconnecting said shaft and a blower element, a dust feed rotor mounted in driven relation to .said shaftto rotate interiorly of said hopper adjacent said feed opening, vane portions on said rotor i inclined at an acute angle to theplane of rotor rotation and adapted to sweep adjacent said feed opening upon rotative movement of said rotor to push dust from said former higher velocity, higher gear ratio machines of equal dust distributing capacity.

While we have illustrated and described a preferred embodiment of the present invention, it will be understood however that various changes and modifications may be made in they details thereof without departing from appended claims.

Having thus described the invention, what we claim as new and desire to protect by Letters patent is as follows:

l. In a hand duster having a dust hopper with a dust feed opening therein, and a hand crank journalled in said hopper, a feed rotor mounted to have a marginal portion thereof rotate adjacent said feed opening, said rotor comprising a'dished central portion secured centrally to said 2. A duster cornprising a hopper. having a dust feed opening therein, a blower mounted to receive and discharge dust ejected from said hopper through said feed opening, a shaft journaled to rotate relatively to said thespirit and scope of the invention as setforth in the hopper into and through said feed-opening, and a resilient finger mounted in oneof said vane portions and having a narrow tip portion adapted to enter'and brush lightly through said feed opening at each rotation of said feed rotor to clear the feed opening.

3. A hand duster comprising a hopper, a hand crank journaled thereon, a blower housing mounted on said hopper, a feed passage from the hopper into the blower housing, an impeller comprising a plate having an 7 opening therein and a plurality of cylindrically arranged radial dis charge blades rotatively mounted in said housing withthe impeller plate adjacent said feed passage, an air propelling axial flow blade formed in said impeller plate adjacent the opening therein, the leading edge of said axial fiow blade being mounted to pass adjacent said feed passage on rotation of said impeller, and drive means interconnecting said hand crank and said impeller to reduce air pressure in said housingadjacent said feed passage and to produce air currents between the impeller and the feed passage to cause air borne movement of dust from the housing side of said feed passage through theopening in the impeller plate into the impeller.

4. A hand duster 7 comprising a hopper, a pair of spaced apart embossed islands thereon,a hand crank journaled on said hopper, a fan shaft housing mounted along a side of said hopper and having an end thereof in the same plane as the tops of said islands, a blower housing mounted on said islands and on the end of said fan shaft hous ing, with a portion of said housing spaced slightly from said hopper, and saidblower housing and hopper having registering feed openings therein to provide a feed passage from the hopper into the blower housing, a fan shaft journaled to lie within said fan shaft housing, a fan wheel mounted on said fan shaft to rotate therewith within said blower housing, drive means interconnecting said hand crank and said fan shaft, and a feed control lever pvoted' on said fan shaft to lie between said embossed islands and interposed between the hopper and said slightly spaced portion of said blower housing, ,said lever having a feed opening therein adapted in one position'of lever movement to register with the openings in said hopper and said blower housing, and inanother position of lever movement to be moved out of register with the latter openings to close off one of said openings.

5. A hand duster comprising a hopper, a blower housing, an exit tube from said blower housing, a dust passage from said hopper into said blower housing, a large volume output type fan wheel having a-plurality of forwardly curved impeller blades peripherally. mounted thereon in said. blower housing, a plurality of air propelling axial flow blades mounted on the side of said fan wheel to rotate with said fan wheel and to pass adjacent the housing end of said dust passage, a hand crank rotatively mounted on said duster, speed increasing drive means connecting said crank to said fan wheel, and means for feeding dust from said hopper through said dust passage, for air borne movement by said axial flow blades intosaid fan wheel for discharge from said blower housing.

6. In a dust applicator having a dust hopper, a blower housing and a dust passage extending from the hopper into the blower housing, and a fan wheel rotatively mounted within said blower housing and having a back plate disposed in spaced parallel relation to the inner wall of said blower housing through which said dust passage extends to form an air chamber therebetween, said back plate having a circular row of air propelling axial flow blades angularly bent to extend into said chamber and a corresponding row of openings in said back plate through which dust-laden air passes from said chamber into the interior of said fan Wheel for discharge thereby, said axial flow blades having their free leading edges disposed so that dust-laden air is drawn into the interior of the fan wheel by the action of such axial flow blades to thereby reduce pressure Within said chamber and induce dust flow through said dust passage, and coincidentally therewith exert a swirling effect upon the dust-laden air Within said chamber to prevent accretion of dust upon the surfaces of same and insure an air-borne flow of dust from the dust passage to the fan Wheel interior.

7. A duster compriisng a hopper having a dust feed opening therein, a blower mounted to receive and discharge dust fed from said hopper through said feed opening, a crank shaft journaled on said hopper, drive means operatively interconnecting said crank shaft and a blower element, a dust feed rotor mounted in driven relation to said crank shaft to rotate interiorly of said hopper, a plurality of vanes extending radially from said rotor, a portion of each of said vanes extending rearwardly relatively to the direction of rotor rotation, said rearwardly extending vane portions being at an acute angle to the plane of rotation of the rotor to push dust from said hopper into and through said feed opening, and a tapered resilient finger mounted on said rotor adjacent said vane portion so as to project therefrom with its axis substantially normal to the plane of rotation of said rotor and having a portion thereof adapted to enter said feed opening at each rotation of said feed rotor to clear the dust from the feed opening.

8. In a duster having a dust hopper With a dust feed opening therein, a feed rotor mounted to have a marginal portion thereof rotate adjacent said feed opening, a radially extending vane on said marginal portion, said vane having a portion at an angle other than a right angle thereto positioned to move across said feed opening on each rotation of said rotor to push the dust into the opening, said rotor having a finger mounted thereon and provided with a tapered resilient end portion adapted to enter and sweep across said feed opening on each rotation of said feed rotor to clear the dust from said feed opening.

References Cited in the file of this patent UNITED STATES PATENTS 707,992 Warner Aug. 26, 1902 1,058,273 Thompson Apr. 8, 1913 1,188,127 Wright, II June 20, 1916 1,229,994 McWhorten June 12, 1917 1,459,927 Otis June 26, 1923 1,551,877 Henning Sept'. 1, 1925 1,652,732 Root Dec. 13, 1927 1,666,350 Pitt Apr. 17, 1928 1,750,147 Wright Mar. 11, 1930 1,911,927 Root May 30, 1933 1,982,638 Chater et al. Dec. 4, 1934 2,099,289 Anderson Nov. 16, 1937 2,115,199 Erlandson Apr. 26, 1938 2,255,910 Baudry Sept. 16, 1941 2,348,205 Chater May 9, 1944 2,526,397 Nyden et al Oct. 17, 1950

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