US2271552A - Suction cleaner - Google Patents

Description

Feb. 3, 1942.

D. G. SMELLIE SUCTION CLEANER Filed July 1'7, 1939 5 Sheets-Sheet l I l l l I I Y I 5 i 4 9 l Y I G I O 2 2 2222;

A. 29 6' a s? \mk' (0R V 1 2e 7 I y I I J Il I 22 i 42 46 5| 42 1 58 5 2o 3 47 44 45 59 I I l g l9 25 6' so l5 4 INVENTOR Donald G. Smellze- 1942- D. G. SMELLIE 7 ,552

SUCTION CLEANER Filed July 17, 1939 5 Sheets-Sheet 2 HNVENTOR v 1 Donald a. sin ing..-

ATTORNEY Feb. 3, 1942. D. s. SMELLIE SUCTION CLEANER Filed Jui 17, 1939 s Sheets-Sheet 3 INVENTOR flmald 6. Smellz'e ATTO EY Feb. 3, 1942. D. G, SMELLIE 2,271,552

SUCTION CLEANER Filed July 17, 1939 s'sheets-sneet 4' INVENTOR ATTORNEY I fionald a. Sm'ellie' I Feb. 3, 1942. p 3-, L 2,271,552

SUGTION CLEANER 7 Filed July 17, 1939 5 Sheetg-Sheet s INVENTOR Dqnald a. gs'm llie ATTORNEY Patented Feb. 3, 1942 SUCTEEON CLEANER Donald G. Smellie, (Danton, Ohio,

Hoover Company, North ()anton,

poration of Ohio assignor to The Ohio, a cor- Application July 11,1939, Serial No. 284,822

(on. ll82l- 20 Claims.

The present invention relates to suction cleaners in general and more particularly to a new and novel rotary agitator for a suction cleaner. More specifically the invention comprises a rotary agitator for a suction cleaner in which the agitating elements subject to wear in use are adjustably mounted so as to provide the maximum adjustment at the point of maximum wear.

It is an object of the present invention to provide a new and improved suction cleaner. It is another object of the invention to provide a new and improved rotary agitator for a suction cleaner. A further object of the invention is to provide a rotary agitator embodying rigid beating elements and flexible brush elements, the latter being radially adjustable to compensate for wear. A still further object of the invention is to provide a rotary agitator including agitating elements subject to wear in use which are adjustably mounted in a manner which provides for the maximum adjustment at the point of maximum wear. A further object of the invention is to provide a rotary agitator for a suction cleaner which includes agitating elements subject to decrease in radial extension with wear and which are adjustably mounted by means which provide the maximum radial adjustment centrally of the elongated agitating element and a minimum adjustment at the ends thereof. These and other more specific objects will appear upon reading the following specification and claims and upon considering in connection therewith the attached drawings to which they relate.

Referring now to the drawings in which preferred embodiments of the present invention are disclosed:

Figure 1 is a side elevation of a modern suction cleaner embodying the present invention with certain parts broken away and shown in section;

Figure 2 is a partial longitudinal section through an agitator constructed in accordance with the present invention;

Figure 3 is a transverse section upon the line -33 of Figure 2 and illustrates the cam actuator;

Figure 8 is a section upon thu line 8-8 of Figure 6;

Figure 9 is a view illustrating diagrammatically the relative radial movement of the brush of the second embodiment at its ends and at its center with a given change in the manual adjustment mechanism;

Figure 10 is a partial side elevation of an agitator constructed in accordance with the third embodiment of the invention;

Figure 11 is a section upon Figure 10;

Figure 12' is a section upon the line [2-12 of Figure 10 and illustrates the position of the brush sections in the new brush position;

Figure 13 is a view similar to Figure 12 but with the brush sections adjusted to their worn brush position;

Figure 14 is a partial longitudinal section at the junction of the brush unit sections and'is taken upon the line |4 -l4 of Figure 10;

Figure 15 is a view in perspective of the pivoted brush carriers of the third embodiment of the invention removed from the agitator.

In the modern suction cleaner the agitation of a surface covering is accomplished by the-contact therewith of a high speed rotating agitator which embodies rigid heating elements and flexible brush elements. The latter are flexible bristles usually and are subject to wear with use. Decrease in radial extension of these brush elements makes necessary either their replacement or radial adjustment. Replaceable brushes are old and well known and manually adjustable.

the line ll--Il of brushes'have been used, Experience has taught that the elongated brush upon the rotary agita tor accomplishes a desirable type of cleaning action. It has been discovered that the maximum wear of such elongated brush elements occur not at the point of initial contact but at substantially the midpoint thereof and for reasonable distances at the sides thereof. In the agitator constructed in accordance with the present invention the brush element is moveable in a manner which gives to the center portion of the brush a greater radial movement than the end portions thereof for each adjustment.

Referring again to the drawings and to Figures 1 to 5, inclusive, the first preferred embodiment of the invention is illustrated. In Figure' 1,.in particular, a modern suction cleaner is illustrated and is seen to comprise a nozzle! I which is interiorly connected byan air passageway 2 to a fan chamber 3 which is formed with. an exhaust outlet 4. A suction-creating fan 5 is positioned within the fan chamber 3 being carried upon the dependent end of a motor shaft 6 which is formed at its lower extremity as a pulley I. The exhaust outlet 4 is formed with a bag attaching flange 8 provided with manually operable bag-securing means 3 which clamp in place a dirt-filtering bag l0. Immediately over the fan chamber 3 is the motor casing H which houses' an unshown driving motor of any suitable type. Within the nozzle I is a rotary agitator indicated generally by the reference character l5 which will be hereinafter more fully described and which is seen to be driven from the pulley I by a power-transmitting belt IS. The agitator is movably supported by wheels I! and there is provided, as in the usual cleaner construction, a pivoted handle I 8 through which the operator can exert the cleaner-propelling force.

Referring now to Figures 2 to 5, inclusive, the rotary agitator which specifically comprises the invention is illustrated in detail. The agitator is about the adjacent bearing 22.

Seated upon the surface of the cylindrical body 26 are helically extended rigid beater bars or elements 25 which are adapted to contact the surface covering undergoing cleaning and impart thereto a positive vibration inagitator rotation. The agitator body 20 is seen to include an elongated brush seat 26 which extends helically and in cross section, as illustrated in Figure 4, extends through an arc of substantially 90 degrees circumferentially. The brush seat 26 is preferably a detachable element which is removably secured to the remainder of the agitator body by screws 21. For purposes of illustration one side only of the agitator is illustrated but it is to be understood that the agitator is substantially identical upon both sides of the depressed central portion l9 which forms a pulley.

Within each brush seat 26 is an elongated brush 29 formed of a plurality of helically arranged brush tufts each of which is carried by its own seat 3| pivotally mounted upon a helically extending shaft 32 carried by the rigid brush back 33. At the opposite ends of back 33 is a pair of parallel supporting posts 35 which are slidably mounted in parallel sleeves 36 formed in the brush seat 26. Each post 35 extends through the sleeve 36 into theinterior of the agitator body 20 where it is provided with an inclined. transverse slot 33 and with a fiat end which is contacted by a leaf spring 39 which at all times urges the post upwardly so as to move the brush 23 radially outward.

Connecting the opposite ends of each brush seat 26, and between its ends and extending around the supporting shaft 23, is a connector bar 4| connected to the seat by screws 42. Suspended centrally from the bar 4| by means of a screw 43 is a plate-like cam actuator 44, the opposite ends of which are inclined as indicated at 45 to form cams which extend in the slots 38 in the posts 35. A coil spring 46, also carried by the supporting screw 43 at the center of the actuator 44, contacts at one of its ends the actuator and at its opposite ends an internally threaded sleeve 41 carried by the agitator body 20 and exerts a force upon the actuator 44 which is counterclockwise as viewed in Figure 3. Positioned within the threaded sleeve 41 which is fixedly mounted on the agitator body 20, is a screw cone 5|. A cover cap 49 is provided to keep dirt out of sleeve 41 and is provided with a tool receiving groove so that it may be rotated and removed for access to the screw cone 5|, which is also provided with a screw driver slot so that it may be rotated. The cone 5| extends upwardly and into contact with an enlarged opening 52 formed immediately thereabove in the actuator 44, the spring 46 exerting a force which holds one side of the op'ening 52 in contact with the cone face and prevents rotation of the cone. As the opening 52 is larger in diameter than-the end of the screw cone 5|, it is clear that inward advance of the cone will cause the cone to move further into the aperture 52, relative to which it is olfcenter, with the resultant pivotal movement of the actuator 44 within the limits indicated by the full line and dotted line positions illustrated in Figure 3.

The operation of this embodiment of the invention is as follows: Let it be assumed that the agitator is new and the bristle tufts 30 of the brush 23 upon each side of the agitator are of maximum full length. The adjustment screw 5| will be in its outermost position with its conical end in contact with one side of the aperture 52 in the actuator 44. The latter element will be held by the force of spring 46, in the position illustrated in Figure 2 in which the posts 35 are held in their innermost position by the contact with the outer ends of the cam surfaces 45.

In the operation of the cleaner and the rotation of the agitator the rigid beater elements 25 and the flexible brush 23 will contact, beat and brush the surface covering, the pivotal brush tufts pivoting in their operation by that contact although, it is to be understood, the adjustment here described is applicable as well to agitating elements which are not pivotally mounted. After a considerable period of use the brush bristles will become shortened by wear, those near the.

center position of the brush being worn to a greater extent than the end portions thereof. It is then indicated that the operator should adjust the brushes to compensate for this wear.

Adjustment is accomplished by the operator advancing or retracting screw cone 5| by the application of a screw driver to the slot in the head thereof, Rotation of this screw causes the ad'- vancement of the conical head into the aperture 52 in the actuator 44. As the conical head advances into the aperture, the actuator 44 is pivoted, as viewed in Figure 3 in a clockwise direction, and the cams 45 at the end thereof advance in their slots 38 in the posts 35 causing those posts to move outwardly. As the posts 35 at each end of the brush are parallel and are spaced at equal distances from the supporting shaft 23 and upon opposite sides thereof, it is seen that only one part of the brush length will move in a truly radial direction and that that portion will be the center thereof. All other parts will be moved at an angle to the true radius andtherefore will receive a radial adjustment less than the central portion. The degree of adjustment which the operator gives to the brush is controlled by the extent of his rotation of the screw cone 5|, it being desirable that the brush be adjusted sufliciently so that its radial extension be sub- .the extremities of which seat within the end plates 83 of reference character tend from this connecting bar 80 and carry, by

oted about the same of the brush midpoint of the not move directly radially but instead at an stantially equal to that of the rigid beater elements 25. The samev adjustment is to be made with the brush upon both sides of the pulley [9. After the adjustment has been completed the cleaner can be again put in use and the agitator will operate as when new.

Referring now to Figures 6, '7. 8 and 9 in particular, the second preferred embodiment of the invention is illustrated. In this embodiment the cylindrical hollow agitator body is indicated by the reference character 6|! and is formed centrally with the reduced pulley portion 6|. The

body 60 is rotatably supported upon the centrally positioned elongated supporting shaft i2 15 the agitator body, a bearing 64 being interposed at each end. A thread guard 65 is again screw threaded on to the end of the shaft 62 and overlies the end of the agitator body to form a protecting construction to prevent the accumulation of foreign material upon the bearing.

As in the first embodiment helically extended rigid beater elements 68 of hard polished metal are secured to the surface of the body and extend a fixed radial distance therebeyond. The brush seats, indicated by the reference character 68 in this embodiment, are again helically extending and are formed with diverging side walls. These brush seats areseparate elements from the agitator body and are secured fixedly in place by suitable securing screws 69. Within each brush seat 68 is a helically extending brush unit comprising a helically extending rigid back It which carries a helical supporting rod 12 upon which the rigid brush sockets I3 of a plurality of brush tufts or elements 14 are pivotally mounted.

The elements and their back ll together form a brushunit which is indicated generally by the 15. This brush unit I! is adjustable within the brush seat 68 and is properly positioned when the extremities of brush elements extend to, or slightly beyond, the radial extension of the rigid beating elements 66.

The radial adjustment of the brush unit 15 is accomplished by a manually operable mechanism which includes parallel supporting pins 18 at the opposite ends of the rigid back 1| and which ar parallel and slidingly mounted in sleeves 19 formed in the side walls of the brush seat 88. A curved connector bar so extends between the ends of the brush seat 68 from points adjacent the sleeves 19 and passes around the supporting shaft 62 between its ends, as is perhaps best illustrated in Figure 6. Depending supports 8| ex- 82, a pair of arms 83 the bifurcated and are pivbrush-supporting means of .pivot pins outer ends of which are oted to the inner ends of the pins ll bypivot pins 84.

The inner ends of the lever arms 83 are pivaxis upon an internally threaded nut member 86 which is carried by a manually rotatable screw 81 the outer slotted end of which is positioned within a recess 88 in the surface of the agitator body and the inner end of which is rotatably positioned in the bar 80.

Examination of the construction of this second embodiment, particularly in Figures 7 and 9, illustrates that with brushv adjustment all parts unit 15 are moved absolutely parallel and that it is the longitudinal midpoint only of the brush element which is in fact movable in an exactly radial direction. At each side of this brush element at the ends thereof the brush does 76 angle thereto so that it follows that the midpoint of the brush will have a greater :radial extension, with a given radial adjustment of the brush unit, than any other part ofthe brush along its length. Reference to Figure 9 in particular discloses that, when the adjusting screw 81 has been turned sufllciently to change the normal operating position of the central brush tuft 14a. a radial distance R1, the brush tufts 14b and He spaced at the opposite ends of the brush unit have only moved radially a lesser distance R2. It is clear that the distance R=R cos on where a is the angle between the center lines of the brush tufts at the axis of rotation, the tufts being in their central operative relationship. The same relationship exists where the brush tufts are rigidly related to one another. In view of the fact that it is the central portion of each element which is given the greatest wear and which diminishes in radial extension the fastest,

structed in accordance with this second embodiment of the invention is as follows:

Upon the agitator having been used for a sufficient period of time to require that the brush elements be extended radially in order to have substantially the same extension as the rigid beater elements 66, the operator, in order to adjust each-brush unit, need only rotate the bolt member 81 by a simple and common tool such-as a screw driver. tion, as viewed in Figure 6, results in the inner ends of the cantilever arms 83 being drawn outwardly thereby forcing the outer ends of those arms towards the brush seat 68 and thereby causing the supporting pins 18 to move outwardly into the brush seat. This movement is, of course, directly transferred only moving in a direction which is absolutely radial for itself.

As in the first embodiment the brush elements 14 are pivoted upon their contact with the surface being cleaned in the rotation of the agitator. Thispivotal movement causes the elements to move angularly from their true radial positions, in which they are held by centrifugal force, to trailing positions. They return to their true radial positions, however, upon passing the surface. So far as the manual adjustment is concerned, howeversit can function equally well with non-pivoting elements.

Referring now to Figures 10 to 15, inclusive, the third preferred embodiment of the invention is illustrated. The agitator body is here indicated by the reference character I00 and is hollow and cylindrical'as in the first two embodiments. It is also formed substantially in its center with a reduced groove which functions as a pulley and which is indicated by the reference character llil. A supporting shaft I02 extends the length of the agitator and from the thread guards I03 as in the first embodiment. The agitator is provided with the helically extending rigid beater elements I04 which have a fixed and permanent radial extension beyond the surface of the agitator body. As in the preceding embodiments an adjustable brush unit formed of two sections and each of which is indicated generally by Rotation of bolt 8 in a clockwise directo the brush back H which is shifted, the entire length of the brush being moved outwardly with the center part thereof the reference character I06,

is provided upon each side of the pulley IOI. Each section of each brush unit is seen to comprise a plurality of adjacent brush tufts or elements I01 including rigid metallic tuft seats I each of which is pivoted upon a helically extending supporting rod I09 carried by a pivoted brush section carrier H0. The. carriers III! of each brush unit are pivoted oppositely, that is, along their opposite edges, as is clearly illustrated in Figures 10 and 15.

Sleeves II5 upon the carriers IIO pivotally mount those members within the brush seat II2,

foreign material into the interior of the agitator.

Radial adjustment of the brush inthe agitator is accomplished by the manual rotation of a radial screw member II 8 which is threaded into the seat II2 substantially centrally of its length and which extends through slots H9 in the overlapping ends of the carriers. at all times pressed upwardly into contact with the overlying head of the screw I I8 by coil springs I20 which encircle the pivotal axes H4.

The adjustment of the agitator brush constructed in accordance with this embodiment of the invention is as follows: With the agitator brush new the screw II8 will be positioned at its innermost position, as illustrated in Figure 12, and the carriers III) will lie substantially flat against the brush seat II2. After the agitator has been used for a period of time, however, it will be necessary to adjust the brush elements to compensate for wear and to give to the brush unit' a radial extension substantially equal to that of the rigid beater elements. To accompllsh this result the operator rotates the screw II8 by a screw driver causing it to advance radially outward to a position as illustrated in Figure 13. This permits the carriers III) to be pivoted outwardly under the actuation of the coil springs I20 to the extent allowed by the overlying head of the screw. The operator can control the adjustment by this screw, and the adjustment can be made as frequently as desired.

As the brush extends helically and as the brush sections I06 are aligned and pivot upon the axes III which are parallel to the axis of the agitator, it follows that one end of each brush section is at a greater distance from the pivotal axis of its carrier than is the opposite end thereof. This is clearly illustrated in Figures 10 and 15. It follows directly thatas the brush carriers H0 are pivoted that the distance moved by the brush elements at greater radial distance from.the pivotal axes will be greater than the movement of the brush elements at the lesser distance. Reference to Figure 10 in part cular will illustrate that as the brush sections I06 upon the opposite sides of the longitudinal center of the brush are pivoted upon axes which are upon the opposite" sides of the brush units, and as the brush tufts at the center of the brush unit are at the greater radial distance from the pivotal axes, that with agiven pivotal movement of the brush carriers by the controlling screws IIB the brush tufts at The. brushes are er radial extent than the brush tufts at the ends the center of the brush will be adjusted to a greatthereof. As in the preceding embodiment this result is desirable for it is the centrally positioned brush tufts which are subjected to greater wear in use.

I claim:

1. A rotary agitator for a suction cleaner or the like comprising a rotatable body, a brush seat in said body, a helically extending brush in said seat, means supporting said brush for translation in which each point therein moves in a straight parallel line with the center only moving radially relative to the axis of rotation, and means to adjust the brush on said supporting means with the center of said brush moving radially relative to the axis of rotation and the ends thereof in paths parallel thereto.

2. A rotary agitator for a'suction cleaner or the like comprising a rotatable body, an agitating element carried by said body and extending helically'relative to the axis of agitator rotation, means supporting said element for parallel straight line translation of each point therein and means to adjust. the center of said element radially relative to the axis of rotation and the ends thereof in paths parallel thereto.

3. A rotary agitator for a suction cleaner or the like comprising a rotatable body, an agitating element subject to decrease in size with wear carried by said body and extended helically relative to the axis of agitator rotation, means mounting said element for translatory movement in which all parts thereof move in straight parallel lines, one of said lines being radial to the axis of rotation, and meansto adjust said element in said mounting means.

l. A'rotary agitator for a suction cleaner or the like comprising a rotatable body, an agitating element subject to decrease in size with wear carried by said body and extended helically relacam means.

5. A rotaryagitator for a suction cleaner or the like comprisin a rotatable body, an agitat ing element subject to decrease in size with wear carried by said body and extended helically relative to the axis of agitator rotation, means mounting said element for movement in which all parts thereof move in straight parallel paths and including supports near the ends of said element extended into said body, cam means acting on said supports to exert a radial moving force thereon, and manually operable means to position said cam means.

6. A rotary agitator for a suction cleaner or the like comprising a rotatable body, an agitating element subject to decrease in size with wear carried by said body and extended helically relative to the axis of agitator rotation, means mounting said element for movement in which all parts thereof move in straight parallel paths, one of said paths being radial to the axis of rotation, lever means to urge said element radially, and manually operable means to exert an actuating force on said lever means.

7. A rotary agitator for a suction cleaner or the like comprising a rotatable body, an agitating element subject to decrease in size with wear carried by said body. and extended helically relathe like comprising a tive to the axis of agitator rotation, means mounting said element for movement in which all parts thereof move in straight parallel paths and including supports near ment extended into said body, pivoted levers connected to said supports to exert a moving force thereon, and manually operable means to pivot said levers. g

8. A rotary agitator for a suction cleaner or the like comprising a rotatable body, an agitating element subject to decrease in size with wear carried by said body and extended helically relative to the axis of agitator rotation, means mounting said element for movement in which all parts thereof move in straight parallel paths and including supports near the ends of said element extended into said body, a pivoted lever connected to each of said supports, and manually operable means to adjust synchronously said levers.

9. A rotary agitator for a suction cleaner or the like comprising a rotatable body, an elongated brush extended helically relatively to the axis of agitator rotation and comprising a plurality of individually pivoted brush tufts carried by a rigid back, means mounting said back for movement relatively to said body and in which all parts thereof move in straight parallel paths,

exactly radial to the axis said element in one of said paths being of rotation, and means to adjust said mounting means.

10. A rotary agitator for a suction cleaner or the like comprising a hollow rotatable body, a supporting shaft extended through said body, an agitating element subject to decrease in size with wear carried by said body and extended helically relative to the axis of agitator rotation, means mounting said element for movement in which all parts thereof move in straight parallel paths and including support near the ends of said element extended into' said body upon opposite sides of said supporting shaft, a pivoted lever connected to each of said supports, and manually operable means to adjust synchronously said supports.

11. A rotary agitator for a suction cleaner or rotatable body, a helically extending brush including a rigid back and bristles subject to decrease in extension with wear and to a maximum degree at the longitudinal center of the brush, means mounting the entire brush for differential radial movement relative to the axis of rotation of said body, and means to adjust said brush relative to said body to impart maximum movement tothe center thereof.

12. In a rotary agitator fora suction cleaner, a body, means to support said body rotatably, an elongated brush helically extended on said body and formed of two sections, mounting means including pivotal lever arms pivotally mounting each section of said brush, the pivotal lever arms being of greatest length at the center of said brush, and means to pivot said lever arms.

13. In a rotary agitator for a suction cleaner, a body, means to support said body rotatably, an elongated brush helically extended on said body and formed of two sections, means pivotally mounting each section of said brush, said brush being positioned between the pivotal axis of said sections and the pivotal distance separating the brush from the pivotal axes being a maximum at the central portion .of the brush, and means to pivot said pivotal mounting means to adjust said brush relative to the axis of rotation.

the ends of said eleincreasing to a maximum thereof, and mean to pivot said carriers syn-y 20.

' and formed of radially relative to the axis of rotation 14. In a rotary agitator for a suction cleaner, a body, means to support said body rotatably, an elongated brush helically extended on said body two sections, means pivotally mounting each section of said brush onto said body by means of pivotal lever arms which are longest at the center of said brush, and manually operable means to adjust said pivotal mounting means synchronously.

15. In a rotary agitator for a suction cleaner, a rotatable body, a divided brush extended helically on said body relative to the axis of rotation, a carrier supporting .each section of said brush and pivoted upon an axis extended parallel to the axis of body rotation, the pivotal axes being upon opposite sides of said brush and the distances separating said brush from said axes at the central portion chronously to adjust said brush.

16. A rotary agitator for suction cleaners comprising an elongated cylindrical body rotatable about a longitudinal axis, a helically extending brush seat in said body, a helical brush in said seatpivoted upon an axis extended in the direction of the axis of rotation, and means to adjust manually the radial extension of said brush.

17. A rotary agitator for suction cleaners comprising an elongated cylindrical body rotatable about a longitudinal axis, a helically extending brush seat in said body, a helical brush in said seat pivoted upon an axis extended in the direction of the axis of rotation, said brush including flexible elements and a rigid back, and means positioned interiorly of said body to adjust said brush radially comprising a brush-carrying-element and mean operable from the exterior of said cylinder to adjust said brush-carrying-element within said cylindrical body.

18. A rotary agitator for a suction cleaner comprising a cylindrical body, means to rotatably support said body, a brush unit mo'vably mounted on said body and extended helically, and means to adjust a central part of said brush and the other-parts at an angle to a truly radial direction in order to provide a maximum radial adjustment between the ends thereof and a minimum radial adjustment at the ends thereof.

19. In a rotary agitator for a suction cleaner, a helical brush, means rotatably supporting said brush, means adjustably supporting said brush relative to the axis of rotation to move a portion thereof radially and the remainder thereof in a direction at an angle to a true radial direction to'provide said portion with a maximum radial adjustment and said remainder with a lesser radial adjustment.

20. In a rotary agitator for a suction cleaner, a cylindrical body, means to support said body for rotation about a major axis, an elongated continuous helical brush including a rigid back and surface contacting brush bristles adapted to describe with its surface-contacting bristle-ends a portion of a circle concentric with the axis of rotation, said elongated brush being adapted to receive a maximum of wear with use at its central portion, and means adjustably supporting said brush for movement toward and from the axis of rotation with each point therein traveling in a flat plane whereby the central portion of said brush receives the maximum radial adjustment.

DONALD G. SMELLIE.

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