Abstract: A tennis ball projector comprises a chamber (1) communicating with a source 10) of compressed air. There is also a barrel (13) for projecting balls (16), communicating with the chamber (1) through a valve (27) located close to the end face (14) of the barrel (13), and a branch pipe (17) to admit the balls (16) into the barrel (13). The valve (27) is actuated by a pneumatic chamber (28) communicating with the source (10) of compressed air and also communicating with the atmosphere through an additional valve (32) provided with a remote control arrangement (46).

Abstract: A ball throwing device comprising a pusher (16) operatively associated with a striker (12) through a timing mechanism (21) which incorporates a crank (22) set on a drive axle (23) and linked to the pusher (16). The crank (22) is adapted to rotate together with the drive axle (23) at the same speed, and also at a speed higher than the axle speed when the pusher (16) causes the ball (6) to move to the stroke position. Respective projections (31, 32) are provided on the drive axle (23) and on the crank (22), adapted to interact with each other. Such a projection (33) is also formed on the striker (12), while a yoke (36) is fixed stationary on the casing of the drive (24) and a spring-actuated stop (34) is made on the crank (22), the stop being adapted to interact with the striker projection (33) and with the yoke (36).

Abstract: A ball throwing machine comprises a pipe (4) for supplying balls (5) and an impeller (9) with a hammer (10) fitted on a drive shaft (8). There is provided a follower (11) to which are cantilevered two support tabs (15) adapted to receive and retain the ball (5). The support tabs (15) are spaced from each other at a distance smaller than the diameter of the ball (5) and greater than the width of the hammer (10) of the impeller (9) and positioned in such a manner as to let the hammer (10) of the impeller (9).

Abstract: An apparatus comprises a container having discharge orifices, inlet pipes for feeding liquid and gas into this container, distributors adapted for uniformly introducing into said container the gas and the liquid, and a source of compressed gas. The apertures of the gas distributor are located above the uppermost discharge orifices of said container and the apertures of the liquid distributor are located below the uppermost discharge orifices of said container. A method of employing the apparatus comprises feeding liquid into the container and a positive pressure is provided over the free surface of this liquid. Then the liquid is caused to issue in jets from the container, which jets are dispersed to form droplets either spontaneously or under the disturbance action being applied. Depending on the required output the delivery of the liquid is controlled so that its level within the container varies between the levels of location of the uppermost and lowermost discharge orifices of the container.

Abstract: An attachment to a ball throwing machine includes a stationary sleeve secured to the ball throwing machine barrel, a movable sleeve mounted for rotation onto the stationary sleeve, and a rotatable deflecting frame of two T-shaped levers with rollers, mounted on said movable sleeve. Rotation of the frame is restricted by stops, and at least one retainer is provided to lock the frame in one of the extreme positions, the retainer having the form of a flat spring connected to one of said levers and controlled by a cable through a helical compression spring.