449,253. Sand-blast; centrifugal fans. AMERICAN FOUNDRY EQUIPMENT CO., Byrkert Street, Mishawaka, Indiana, U.S.A.- (Assignees of Minich, V. E.) Dec. 18, 1934, Nos. 36295 and 36299. Convention dates, Feb. 23 and May 26. Addition to 442,539. [A Specification was laid open to inspection under Sect. 91 of the Acts, July 1, 1935.] [Class 60] [See also Group XXVI] Modifications in details of the centrifugal abrasive-throwing apparatus of the parent Specification are described. The machine shown comprises side discs 201, 202 mounted on a rotatable shaft 6 and connected by radially-extending vanes 204; guard vanes 203 forming passages p for the abrasive may also be provided. Throwing blades 100 formed of hard material are removably and replaceably supported on the vanes 204 and extend from a central space c defined by their inner edges to the periphery of the apparatus, abrasive being outwardly fed at a predetermined angular position from this space. The blades shown are of channel form, being provided with shallow side walls 101, and their inner ends 105 are bevelled to avoid rebound of the abrasive striking them. They are secured in position by screws 214 in the disc 202, which force shoulders 209 formed on them into engagement with a rib 210 on the disc 201. Abrasive is supplied radially from an opening 92 in a feed pipe 90 passing through a large opening in the end plate 16 of a rotating impeller, the blades 17 of which throw the abrasive through an aperture or apertures 12c in the wall of a surrounding cylindrical control member 10 mounted in the space c and angularly adjustable so that the point at which the abrasive is fed to the vanes may be varied. Two offset rectangular discharge openings are shown, each of which may be approximately half the axial width of the impeller. The combined axial width of the openings should be not more than that of the throwing members 100 to avoid contact of the abrasive with the side walls of the apparatus. Two or more discharge openings may be provided at different points in the control member to enable articles at different sides of the wheel to be treated simultaneously. Specification 441,466 is referred to. The Specification as open to inspection under Sect. 91 comprises a number of other modifications. In the wheel shown in Figs. 3 and 4 (Cancelled), the passages p for the abrasive are formed by hollow spokes connecting the hub and rim of the wheel and joined at one side by a web 5. The pockets 4 between the spokes are closed by a removable cover plate 70 and contain weights 80 by which the wheel may be dynamically balanced. The removable throwing blades 100 are held by screws 31 having tapered ends engaging ribs 102 on the underside of the blades, which are thus forced inwardly until their inner ends abut against a centring-plate 19. Rubber facings 60, 61 may be provided to prevent wear of the collar 7 by which the wheel is attached to the shaft, and also of the rim of the wheel, by the abrasive. In a modification, the web 5 is replaced by a web in the central plane of the wheel, forming with the spokes open pockets on both faces of the wheel, in which the balance weights are secured. The discharge opening in the control member 10 may have the form of a triangle or an inclined slot. Fig. 21 Cancelled) shows a modified form of apparatus in which the abrasive is discharged from a pipe 90 on to the periphery of a drum 309 having a rubber covering or projecting ribs 311, from which the abrasive is thrown on to channel-shaped throwing blades 304 removably attached to a disc 301. The direction of flight of the abrasive is determined by the position of the discharge end of the pipe 90, but a tubular control member 10 with a discharge opening 12 may surround the drum. This subject-matter does not appear in the Specification as accepted.