| 摘要 |
Apparatus for collecting a projectile such as a tennis ball and launching it through the air is disclosed. The apparatus includes a conduit having an upstream end adapted to receive the projectile and a downstream end at which the projectile is expelled. A transfer valve is interposed in the conduit and prevents passage of air through the transfer valve towards the upstream end of the conduit. Suction is provided to the conduit immediately upstream of the transfer valve and forced air is provided immediately downstream of the transfer valve. The projectile is sucked through the conduit from the upstream end thereof to the transfer valve. The transfer valve allows the projectile to pass, and the forced air forces the projectile through the remainder of the conduit so that it is expelled at the downstream end thereof. A ball restraining flange may be interposed in the conduit downstream of the transfer valve to restrain the projectile until the forced air builds up to a predetermined pressure so that the projectile is expelled at relatively high velocity.
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