Abstract: A cutter for a rotary shredder has a cutter tip which is divided into separate first and second picks which are mounted side by side on the cutter. The picks have offset leading edges so one pick reaches the material being shredded before the other pick. The picks also may have different profiles, which causes them to shred the material in a different manner.

Abstract: The invention is a screening apparatus for classifying material of different sizes. A screen is rotatably mounted on a frame for rotation around a first axis which is angled upwardly away from the horizontal, at an angle of from 0 to 30 degrees. The screen is symmetrical about the axis and has an open upper inlet end and a lower outlet end. The screen has a cylindrical portion extending from the inlet end towards the outlet end, having a diameter larger than its length, and a conical portion extending from the cylindrical portion towards the outlet end, tapering inwardly to a central outlet opening, the lowest point of the outlet opening being substantially higher than the lowest point of the screen. The frame is pivotally mounted on a trailer for pivoting about a longitudinal axis near a lower side edge of the trailer. The open inlet end of the screen faces one side of the trailer.

Abstract: The hammers provide multiple impact points for debris, by providing impact points via tips at different radii from the axis of rotation of the hammer mill. The tips preferably are at substantially the same radius from the axis of rotation of the hammer about the hammer support shaft, so that efficiency is maintained even as the hammers lay back. The multiple impact points produce a more effective result, by partially sizing the debris on initial impact, before more precise final sizing in the grinding chamber. Angled surfaces on the hammer tips provide more effective shearing and tearing action than with conventional bar hammers. Wear patterns are such that grinding efficiency as the hammers wear down is maintained throughout the life of the replaceable tips. Preferably, the hammers weigh substantially more than conventional hammers, to provide a higher energy impact, and to reduce the tendency of the hammers to lay back.

Abstract: A tub grinder is disclosed in which material which is already sufficiently small in size, primarily being abrasive aggregate or earthen material, may be discharged from the receptacle to bypass the comminution apparatus and thus substantially reduce wear thereto. A portion of the cylindrical wall of the receptacle is provided with classifying openings, for example by providing a screened opening as a band around the receptacle. The classifying openings permit material which is already smaller than the size of the openings to fall therethrough, thereby bypassing the comminution apparatus. Preferably, a conveyor is positioned beneath the receptacle, to catch and discharge the material which falls through the screen or other classifying openings to a pile located away from the receptacle. Sidewalls positioned on either side of the receptacle stop any material which is flung out to the side, and redirect it down onto the conveyer.

Abstract: In a percussive tool in which a very high pressure and preferably cavitating water jet is directed through an opening in the working surface of the tool, the jet is formed by a nozzle positioned in a cavity behind the opening and decoupled from the tool by a bearing layer of water from the jet. A supply pipe extends rearwardly of the nozzle without contacting the tool, and is supported externally of the tool, on a machine which operates the tool, by a support which allows the fluid bearing to center the nozzle within the cavity while restraining movement of the nozzle axially of the tool.