Abstract: A propulsion device, designed especially but not necessarily solely for propelling tennis balls for training purposes, has in common with earlier devices a rotary distributor or magazine, feeding balls in successively following order into a discharge conduit. The balls are discharged through a barrel which is mounted upon the housing of the equipment for adjustment about a transverse axis, thus to dispose the barrel at selected positions of inclination, to vary the trajectory of the ball when propelled, with the adjustment being preserved after selection by the user.An improved oscillatory motion is imparted to the entire device, hence to the barrel, following adjustment of the barrel to the selected position of inclination.

Abstract: A device for propelling tennis balls has an oscillating discharge barrel to which balls are fed from a rotating distributor. A programmed relationship is provided, including a motion-translating linkage oscillating the barrel as an extension of the mechanism used for rotating the distributor. Programming is achieved to cause a predetermined number of objects to be propelled from the barrel, during each oscillatory cycle, as a direct response to rotation of the distributor.The linkage can be optionally provided without changing the basic design of propulsion devices heretofore made. The invention provides this through an extension shaft of the distributor, which rotates a member having openings spaced different radial distances from the axis of rotation of the member. A drop pin is extendable through any of the openings, and through a slot of a motion-translating link connected to a support bracket for the barrel.