Tennis training machine projecting balls - varies trajectory, power and frequency of projected balls

摘要

Control of a ball striking arm and horizontal and vertical trajectory is effected by a motorized rotating friction roller (12) engaging a tangentially aligned rotatable disc (13): radial disc velocity being varied by sliding the friction roller along a disc dia., i.e. roller at disc periphery and centre respectively correspond with maximum and minimum speeds. The ball striking arm (19) is welded onto an axle (15) projecting from the machine casing (6) and is actuated by a rotating disc (16) embodying peripheral hammer and buffer stops, strength of drive being produced by elastic tendons (23) engaging the arm heel.