| 摘要 |
A ball projecting device, preferably pneumatically operated, is provided wherein the projected ball has "spin". The device comprises a projection tube including a curved portion, wherein the area of maximum curve radius of the curved portion, preferably is provided with a material having a high coefficient of friction; the ball is caused to roll along this high friction area, thereby imparting spin. The tube is preferably pivotable about two transverse axes, such that the elevation and spin-directing orientation of the tube end can be adjusted. The curved portion of the projection tube has a device for varying the radius of curvature from substantially infinite, i.e., a straight tube, to the desired minimum value.
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