| 摘要 |
Screening apparatus having a valve in the rejects conduit controlling the discharge of material therethrough. The valve includes a plurality of chambers separated by a wall containing one or more openings of smaller cross section than the chambers and is rotatably driven at a predetermined speed by a drive motor to alternately connect each chamber to the upstream portion of the rejects conduit while the other chamber is connected to the downstream portion of such conduit. The drive motor is reversible to automatically reverse the direction of rotation of the valve in the event that the latter, during rotation in either rotary direction, becomes jammed by rejected material; and a valve in the inlet conduit of the screening apparatus is automatically closed when the first-mentioned valve is not in operation.
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