657,749. Rotary brushes, stocks, bristles fixing. OSBORN MANUFACTURING CO. July 25, 1947, No. 20167. Convention date, May 6, 1943. [Class 19] A rotary brush section comprises an annular channel-form brush back and brush material retained therein, the sides of said Lack being formed into alternate depressed areas and intermediate bands, such depressed areas extending transversely the entire width of the side and a disc having recesses in its periphery, each recess underlying at least one of said depressed areas in said backs. A rotary brush may comprise a plurality of such brush sections the discs being formed with mutually aligned recesses corresponding with the depressed areas in the backs thus providing direct ventilation of the brush. The brush backs may alternatively be mounted on a support formed to provide transverse ducts that communicate with the areas in the backs. In another form a rotary brush comprises a support having a grooved face and a plurality of the channel form mesh backs mounted on said support face, the depressed areas being so spaced that one or more thereof will communicate with the respective grooves in the support face whatever the relative position of said back thereon. In a further modification a rotary brush comprises a plurality of brush sections constituted of successive convolutions of a helical channel-form back the sides of such back being formed with depressed areas and intermediate lands, such depressed areas providing in effect ventilating passageways extending transversely the entire width of the side and a support formed to provide transverse ducts that communicate with the depressed areas in the back. In the drawings, Fig. 2 shows two assembled brush sections each provided with a disc-shaped adapter, Fig. 1. The side walls of the brush back 1 are formed into depressed areas 4 and intermediate bands 5, Fig. 3. The adapter whereby the brush back is mounted on an arbor comprises a disc 10 with its periphery cut away to form recesses 11. The disc 10 may be of laterally compressible material and slightly thicker than the brush back, Fig. 2, and may comprise a central layer 10a of indurated fibre board and a facing layer 10b of softer composition such as ordinary composition board or heavy cardboard. The brush back is secured on the adapter disc by means of lugs or tongues 14 struck up from the bottom wall of the brush back and these are then bent inwardly to interlock with the central layer 10a. The modified form of brush in which the brush back is constituted of the successive convolutions of a channel form brush base in the shape of a helix is shown in Figs. 6, 8 and 10. The side walls of the channel base 20 have teeth 22 punched inwardly at spaced intervals and disposed transversely to the walls and in overlapping relation so as to secure the retaining member 23 around which the brush material is looped. The side walls are formed with radial depressions 25 and spaced depressions 26 so that when the brush backs are assembled on a supporting member 27 depressed areas are provided which in effect extend across the entire side walls. At spaced intervals the member 27 is provided with transverse passageways 28 which provide free communication with such of the depressions 25 as coincide in location with such passageways. Further, the channel form base of the brush element is provided at its inner corners so that circumferentially extending spaces 25a will be provided between the sections to afford communication between the passageways 28 and such of the depressions 25 as do not directly coincide in location. In the form illustrated alternate portions 30 of the side walls of the supporting member which may be of sheet metal are extended radially outwardly to engage the assembled brush sections laterally while the intermediate portions 31 are bent transversely to seat the sections. The transverse passages 28 are formed in the portions 31 and the portions 30 are provided with openings 32 which coincide therewith so that recesses or grooves are freely open at both ends when the brush is assembled. In the form shown in Fig. 12 annular basis 35 each provided with alternating depressed areas and intermediate bands as described for the first form of brush are supported on a tubular member 36 between a fixed flange 37 and a threaded flange 38. The member 36 carries one or more (three as shown) discs 39, and secured to the outer face of the discs is a series of radially disposed bars 40 on which the brush bases are supported. Each of the flanges 37, 38, 39 has apertures 41 to give free ventilation of the brush. Instead of air flowing through the brush, other fluids may be used, e.g. cleaning and cutting fluids or abrasive bearing fluids, either liquid-or gaseous. The brush back may be of straight channel form. Thus a number of straight lengths of channel form brush back may be mounted so that each extends parallel to the rotational axis of the rotary brush thus forming a cylindrical brush. Specifications 645,407 and 655,263 are referred to.