Patent ID: 9687718
Date: 2017-06-27
CPC Classifications: A63B

Claim:
1. A tennis service swing trainer comprising: a shaft; a grip on one end of said shaft; a cap on another end of said shaft; and a ball having a cylindrical passageway aligned on a center axis thereof, said passageway permitting said ball to freely slide on said shaft between said grip and said cap; a steel washer mounted at the inward end of said grip; and a washer-like magnet mounted on said ball, said magnet and said washer having sufficient force of magnetic attraction therebetween to secure said ball against said grip until a threshold centrifugal force causes said ball to be released from said grip; said force of magnetic attraction, a length of said shaft from said grip to said cap and a weight of said ball being coordinated so that a service swing of the trainer executed at a maximum design speed of the trainer causes said ball to strike against said cap not later than at an upward apex point of travel of the trainer during the tennis service swing.