| 摘要 |
<p>The training equipment is for ball games, particularly tennis, throwing balls to one or more persons. It comprises a holder for the ball to be played, and two or more components with surfaces compressing the ball between them and shaped to fit its surface. One or both components can be driven, so as to impart speed to the ball, and the speed can be adjustable, while the components consist of rollers with hollow part-circular recesses, each directly driven by a variable-speed electric motor. The rollers surfaces can be roughened, or can have a relatively high coefficient of friction.</p> |
