turning first to fig1 an agitator assembly 1 according to the preferred embodiment of the invention is shown . agitator assembly 1 includes a dowel 3 , to which is fixedly secured a belt - drive pulley 5 for enabling the agitator assembly to be rotated by the drive belt from a vacuum cleaner in which the agitator assembly 1 is mounted . agitator assembly 1 further includes an end cap 7 which serves as a dust shield and bearing holder assembly , one of which being disposed at each end of dowel 3 . means are provided on the vacuum cleaner for fixedly securing the end cap 7 to the vacuum cleaner , so that the dowel is rotatable relative to the end cap and the outer ring of the bearing assembly fixed therein as described below . drive pulley 5 could be disposed anywhere along dowel 3 according to the nature of the vacuum cleaner in which the agitator is to be installed . drive pulley 5 could of course be replaced by other mechanical or electrical means depending on the drive apparatus of the vacuum cleaner . the surface of the pulley could be of any shape according to the type of belt or other drive mechanism . tufts 9 of bristles extend outwardly from pockets in dowel 3 in a predetermined manner in order to dislodge dirt from carpets and other surfaces over which the agitator assembly is rotated by means of the vacuum cleaner in which it is installed . tufts 9 could be held in dowel 3 by various means , such as by staples , bar anchors or fused in place . fig2 and 3 show the agitator assembly in greater detail . dowel 3 is cylindrical in form , and is preferably made by injection molding . dowel 3 could have other shapes , and could be made using other manufacturing techniques . also , other materials such as wood or metal could be used and still incorporate the concepts of the present invention . as will be explained in further detail below , injection molding gives fast , uniform results and yields a product of even density which does not require rotational balancing . rotational balancing is required in order for the agitator to continue to operate smoothly , uniformly and freely in response to the rotation of the belt drive of the vacuum cleaner . belt - drive pulley 5 is produced separately , and is included during the injection molding of dowel 3 in a properly designed die . belt - drive pulley 5 is also preferably made from plastic in an injection - molding machine . various pulley designs to accommodate various drive belts , such as crowned , v - groove , lugs and the like , could be used in different vacuum cleaners with other types of belt drive systems . appropriate plastics for the pulley include nylon , glass - filled nylon , abs and the like . metal pulleys may also be appropriate . extending through dowel 3 is a drive shaft 11 to which dowel 3 and pulley 5 are fixed , so that the latter two members rotate as shaft 11 rotates . shaft 11 is cylindrical in shape and is slightly tapered at its ends , as shown in fig5 to be described below . referring to fig1 - 4 and 7 , agitator assembly 1 is indented or recessed as shown in indentation , recess or depression 13 at its opposite ends and has an inclined side wall 15 defining the side of the depression . side wall 15 is inclined inwardly starting from the end of dowel 3 and proceeding towards the interior of the dowel , or being inclined outwardly if one considers the depression beginning inside the dowel and extending towards the end of the dowel . the interior end of depression 13 is in part defined by a flat end wall 17 so that depression 13 is in general a truncated cone . extending radially inwardly from wall 15 is a series of uniformly spaced multiple vanes 19 whose purpose is described below . as explained later with respect to fig7 there are eight vanes 19 in agitator assembly 1 . inclined wall 15 is at the base of vanes 19 . there are ball bearing assemblies 21 at opposite ends of dowel 3 which engage on their interior surfaces the end portions 23 of drive shaft 11 . this is shown most clearly in fig3 . each ball bearing assembly 21 includes an inner ring or race 22 with an inner diameter generally equal to the outer diameter of shaft 11 so that ring 22 will rotate with shaft 11 , an outer ring or race 24 with an outer diameter , and a set of ball bearings 26 . inner ring 22 rests on shoulder 28 of dowel 3 . the ball bearing assembly is also shown in fig1 . as explained in further detail below , shaft 11 , with dowel 3 and belt - drive pulley 5 , rotates with respect to outer ring 24 of ball bearing assembly 21 . it is very important to keep dust from contaminating ball bearing assembly 21 , since otherwise shaft 11 and dowel 3 could not freely and uniformly rotate . in order to help assist in keeping dust from ball bearing assembly 21 , an end cap 7 is provided . referring to fig3 and 9 , end cap 7 includes a generally flat end portion 25 having an inwardly directed , generally cylindrical end wall or collar 27 (“ inwardly ” means towards dowel 3 ). collar 27 has an interior bore generally equal to the outer diameter of the outer ring 24 which fixedly engages the outside surface 29 of ball bearing assembly 21 . this can be accomplished during manufacture by a press - fit . collar 27 extends inwardly beyond ball bearing assembly 21 into a pocket defined by an axial wall 31 and an inclined wall 33 , which pocket terminates at wall 17 of dowel 3 . the outside of collar 27 is inclined by the same amount as vanes 19 , but collar 27 terminates in the radial direction prior to its entering into the space between vanes 19 . also extending inwardly from end cap 7 is an outer or exterior cylindrical wall 35 which is spaced radially from the end of dowel 3 as shown . end cap 7 is fixedly retained in the vacuum cleaner in which agitator assembly 1 is mounted . this is accomplished according to the end cap holding apparatus in the vacuum cleaner . an outside edge 36 or an edge of a protrusion 37 ( discussed below ) could be fixedly held by the vacuum cleaner to keep outer ring 24 fixed with respect to dowel 3 as the latter rotates . the combination of the shaft , the dowel , the outwardly extending tufts , the bearing assemblies and the end caps is referred to as the agitator assembly . the outside of end cap 7 , shown in fig9 includes a square protrusion 37 having an inside recess 39 into which the end portion of shaft 23 extends . the end cap could be of any shape to accommodate being mounted in various housings specific to different customer designs . as referred to herein , the term dowel assembly , referred to by numeral 40 , includes dowel 3 , pulley 5 and tufts 9 . the ball bearing assembly can be considered part of dowel assembly 21 or end cap 7 , since inner ring 22 is fixed on shaft 11 and outer ring 24 is fixed in end cap 7 . disposed on dowel 3 is a first series of cutting channels 41 extending around the middle of dowel 3 and another set of cutting channels 43 extending around the end portions of dowel 3 . these can be seen most clearly in fig1 - 4 and 6 . as dowel assembly 40 rotates , it oftentimes picks up thread , yarn and other fibers , and they wind around dowel 3 and are difficult to simply grab onto and pull off ; yet they must be removed in order to properly clean the vacuum cleaner and to keep the agitator assembly running freely and uniformly . cutting channels 41 and 43 enable the user of a vacuum cleaner to insert scissors or some other cutting device into one of the channels 41 and into one of the channels 43 at both ends of agitator assembly 1 to cut the thread , yarn or other fiber , to enable it to be easily pulled from dowel 3 . cutting channels 41 and 43 could be grooves , such as radial grooves or slots , protruded surfaces or mounds , or a combination of grooves and protrusions . different grooving arrangements covering the length of the dowel to avoid interfering with specific tuft patterns may be used . another device for use in removing threads and other flexible articles wound about a rotational dowel is shown in fig1 . fig1 shows a dowel assembly 70 of the same type as dowel assembly 10 , but with all of the details omitted for sake of clarity except for a pair of cutting arrangements 74 extending along a dowel 72 . each cutting arrangement 74 includes a channel 76 shown extending longitudinally along the surface of dowel 72 , and a parallel and adjacent protrusion 78 . the combination of the channel 76 and protrusion 78 exposes free portions of threads and other flexible articles wound about dowel 72 , which can be easily cut by running a scissor blade , a knife blade or other cutting instrument along one of channels 76 or adjacent protrusion 78 . once cut , the material can be removed and discarded . many variations are possible . only one pair of a channel and a protrusion can be used . while the channel and protrusion are shown running in the longitudinal direction , they could follow a curved path , be provided in segments along dowel 72 , or have other patterns . either one or more channels , or one or more protrusions , could be used alone , spread apart from each other , or be used with other surface variations in dowel 72 . belt - drive assembly 5 will now be described in greater detail . with reference to fig3 and 5 , pulley 5 has a generally cylindrical exterior portion having a pair of parallel , cylindrical rails 45 , which are generally v - shaped in configuration , having a wide base , and each terminating in a pointed apex 47 . disposed on the outermost portion of pulley 5 is a pair of cylindrical end portions 49 which terminate at the beginning of guide rails 45 . a series of upwardly extending , v - shaped guides 51 , which are concentric with guide rails 45 about the longitudinal axis of pulley 5 ( which is coaxial with the axis of shaft 11 when mounted thereon ), are provided for being engaged by the drive belt from the vacuum cleaner . the generally cylindrical portion of pulley 5 terminates at an interior cylindrical surface 53 , and from which extend inwardly multiple radial support members or spokes 55 which terminate at a hub 56 having an inner diameter 57 which is about the same as the outer diameter of shaft 11 . four spokes 55 are shown . of course , other numbers of spokes 55 could be used as well . during the assembly of agitator assembly 1 , pulley 5 is press - fit on shaft 11 to hold it in place , as shown , for example , in fig5 . as noted above , shaft 11 is cylindrical in form having tapered ends shown at 59 in fig3 . shaft 11 is preferably made from an appropriate steel or aluminum member . with further reference to dowel 3 , an annular indented portion 61 is shown in fig4 and 6 . this portion has longitudinal slots 63 having at their midpoint transverse , radial slots 65 . these are the recesses in which the spokes from pulley 5 extend , the pulley having been removed to enable a clear explanation of the embodiment . as noted above , the opposite ends of dowel 3 have a set of inclined vanes 19 . these vanes cooperate with collar 27 of dust shield and bearing assembly holder 7 to provide a very important purpose of the present invention . turning again to fig3 a belt from a vacuum cleaner engages belt - drive pulley 5 to rotate dowel assembly 40 which comprises shaft 11 , dowel 3 and pulley 5 . vanes 19 rotate about cylindrical collar 27 and outer ring 24 of bearing assembly 21 at both ends of the agitator assembly . this rotation causes air turbulence to occur in a cavity 66 which runs from the inner edge of bearing assembly 21 , around the inner portion of collar 27 to its termination at the inside edge of end cap 7 . this turbulence provides a barrier to dust which otherwise could flow through the cavity and contaminate bearing assembly 21 . moreover , any dust which happened to be in or around bearing assembly 21 would be thrown outwardly by centrifugal force . centrifugal force would cause the dust to move parallel to the inclined surface 15 to the gap between the respective ends of dowel 3 and the inner surface of dust cap and bearing assembly holder 7 . the dust would then be forced around the outer wall 35 and away from bearing assembly 21 . the invention thus provides an extremely efficient agitator assembly which can be made using normal manufacturing techniques , particularly with injection molding . an extremely effective yet economical provision is made for protecting the bearings from dust contamination . the parts can be made faster than with the former wooden dowels , would not require the rotational balancing which had been required for wood dowels , enables the uniform and fast assembly of the tuft bristles , and belt - drive pulley as discussed above . since the parts are made from plastic , they can be made in a variety of colors to render the unit attractive as well . the plastic should be hard and durable , and types of polypropylene should be appropriate . even though injection molded plastic has been found very useful for components of the preferred embodiment of the invention described above , in some instances wood , metal , glass or plastic other than injection - molded plastic might prove preferable while still incorporating the present invention . a beater bar could be made in a molding process as an integral part of the molded dowel if desired . the surface of the dowel could be smooth or textured . moreover , the inventive concepts described herein could be used on wetback cleaning machines , such as steam cleaners , shampooers and wet vacuum cleaners . the invention has been described in detail , with particular emphasis on the preferred embodiment thereof , but variations and modifications may occur to those skilled in the art to which the invention pertains .
an agitator assembly for a vacuum cleaner comprises a dowel assembly with recesses at its opposite ends defined by outwardly inclined walls . each recess has inwardly facing radial vanes , and a shaft end for holding the inner ring of a bearing assembly . end caps extend over the ends of the dowel , and each has a collar for holding the outer ring of the bearing assembly and an outer longitudinal wall for providing a dust shield . the rotating vanes create an air barrier to preclude dust from moving towards each bearing assembly , and the inclined walls of each recess direct dust tossed outwardly by centrifugal force out of the agitator assembly . the end caps and the walls defining each recess further define a labyrinth seal to keep dust from traveling to each bearing assembly .