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.