| 摘要 |
<p>A cross-stream increment of material is removed from an enlongate conveyer belt (20) having drive means (23) for moving the belt longitudinally at a desired velocity using a sampler (28) that includes a sample sweep (41) mounted adjacent the belt for rotation about a rotative axis (33) so as to pass through the material on the belt, a pair of cranks (44, 45) connected to the sweep for rotating the sweep about the axis, a double-acting pneumatic cylinder (50, 51) operatively connected to each crank for imparting a force to its associated crank to cause the crank to rotate the sweep, and a valve (69) for alternately pressurizing and venting chambers of each double-acting pneumatic cylinder. The sweep is controlled and rotated to accomplish removal of the cross-stream increment by pressurizing a selected chamber of each cylinder to provide balancing forces to hold the sweep in a predetermined ready position, thereafter alternately pressurizing and venting selected chambers of the cylinders to provide forces to rotate the sweep through an arcuate path which passes through the body of material to be sampled to remove the cross-stream increment of material from the belt, and thereafter pressurizing selected chambers of the cylinders to return said sweep to the ready position. An advantage of the method is that it enables the attainment of high sample speeds to facilitate the removal of acceptably representative samples from the conveyer while it is moving.</p> |
