| 摘要 |
The training ball-firing machine includes a firing tube (1), a loading nozzle (2) for feeding in the balls (3), a cylindrical chamber (4) with a movable sprung ram (5), a compressed-air tank (6) and a valve (7) with an adjusting unit (8) for supplying surges of air from the compressed-air tank (6) into the firing tube (1) at the instant of ejection of the ball (3). The chamber (4) has an opening (4a) for passing through of the ball from the nozzle (2), an opening (4b) for exiting of the ball into the firing tube (1) and a duct (4c) for supplying air from the compressed-air tank (6) into the chamber (4). On the front end faces of the chamber (4) and of the ram (5) there are formed sealing surfaces (13 and 14), which come into contact with each other when the ball is brought into the launching position (3c) by the ram (5). On the rear face of the ram (5) there is provided an annular collar (11), and between the chamber (4) and the firing tube (1) there is provided a duct (15) for supplying the air between the ram (5) and the ball (3), which duct can be closed by the valve (7). The training ball-firing machine can be used for the training of tennis players and footballers. <IMAGE>
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