Propulsion device for tennis balls and like spherical objects

Abstract

A propulsion device is provided, designed especially for discharging tennis balls for practice purposes, at selected angles of inclination, and at a predetermined, selected velocity. Employed in the device is a distributor, which is disposed between a hopper and an air pressurizing drum, the distributor being designed to feed balls, one at a time, to the drum, at predetermined intervals. The distributor is disposed between the hopper and drum in such fashion as to cause the spherical objects to be efficiently agitated within the hopper, by passage over the exteriorly cylindrical surface of the drum while moving to the point at which the objects feed into the drum. Efficient agitation of the spherical objects within the hopper thus assures to the maximum extent that the distributor will be fully charged with said objects. A trap door, normally closed by air pressure within the drum, is moved with maximum speed to an open position responsive to the free fall of a spherical object from the distributor into the drum, and moves with equal speed back to a closed position. By holding the open time of the trap door to a minimum, it becomes possible for the device to be interiorly constructed with a simple receiving pipe characterized by an absence of annular induced air flow assemblies and other arrangements which have heretofore been employed.