Patents Assigned to Sherman R. Plummer
  • Patent number: 4076239
    Abstract: A tennis teaching aid for use in instructing tennis players how to strike a tennis ball more consistently with a particular area of the tennis racket known as the "sweet spot," so that the ball is moved with a greater velocity and the player is afforded better control over each shot. The device includes two flat plates of relatively stiff but resilient material, disposed one on each side of the strings of the racket and clamped together about the strings by four threaded nuts and bolts engaging aligned holes in the plates. The device is provided with at least one area of padding material placed near the edge of each plate and between each plate and the strings of the tennis racquet to emit a distinctive sound when struck at its center by a tennis ball, and gives out another distinctive but different sound when struck at an off-center location.
    Type: Grant
    Filed: July 29, 1976
    Date of Patent: February 28, 1978
    Assignees: Sherman R. Plummer, Randall Porter
    Inventor: Charles O. Hall