a description will hereinafter be given of one embodiment of a tennis ball emitting device of this invention with reference to the drawing . in fig1 and 2 , 1 designates a supporting base made of steel or the like , 2 a cylindrical column erected on the base 1 , and 3 a crank member . the crank member 3 consists of vertical portions 3a , 3b and horizontal portions 3c , 3d . the vertical portion 3a is rotatably journalled in the upper end of the cylindrical column 2 and provided with a flange 4 which functions as a stopper to limit the engaged position of the vertical position 3a . at the upper end of the cylindrical column 2 there is mounted a motor mounting plate 5 , and a motor 6 for horizontal rotation is secured to the lower surface of the free end of the motor mounting plate 5 . the motor 6 serves to rotate the crank member 3 in a horizontal direction through a link member 7 disposed between the mounting plate 5 and the horizontal portion 3c of the crank member 3 . reference numeral 8 indicates a motor mounting plate which is fixed to the vertical portion 3b of the crank member 3 to support a motor 9 for vertical rotation at its one surface . the horizontal and vertical rotating motors 6 and 9 are of low speed and rotatable in forward and reverse directions by reversing the input current fed to these motors . that is , these motors function to minutely control horizontally inclined angle and vertically inclined angle of a ball emitting cylinder , which will be described later . if the input currents fed to these motors are reversed , it is possible to reverse the rotating directions of these motors and hence to correct the inclined angle of a ball emitting cylinder in the opposite direction . in fig1 and 2 , 10 represents a ball emitting cylinder , 11a and 11b upper and lower ball emitting pulleys located at the up and down sides of the cylinder 10 , each pulley having a peripheral portion partially protruding into the ball emitting cylinder 10 through a corresponding one of slits 12 ( refer to fig4 ) formed in the upper and lower peripheral surfaces thereof ( such ball emitting means is well known ), 13a and 13b upper and lower pulley driving motors , 14 a mounting base plate secured to the ball emitting cylinder 10 for mounting the driving motors 13a and 13b , and 15 a cylinder secured to a ball emitting cylinder supporting member , which will be described later . the cylinder 15 engages the horizontal portion 3d of the crank member 3 and is connected through a link member 16 to the vertical rotating motor 9 as shown in fig2 and 4 . the ball emitting ability and methods of adjusting the vertically and horizontally inclined angles of the ball emitting cylinder 10 ( θ 1 in fig1 and θ 2 in fig3 ) or the like can be understood if referred to the above description . each of the upper and lower ball emitting pulleys 11a and 11b is provided around its outer periphery with a rubber tire . since the peripheral speed of each pulley can be changed by controlling the input voltages applied to the driving motors 13a and 13b , it is possible to apply a desired spin to balls before emission . in fig2 designates an electric supply source box secured to the cylindrical column 2 , and 17 &# 39 ; a cable which is led from the electric supply source box 17 to a remote control panel ( not shown ). further , in fig1 designates a ball feeding flexible hose which is connected to the end of the ball emitting cylinder 10 , and 19 a blower which is coupled to the hose 18 and generates a wind pressure to transfer balls into the hose 18 . there is also provided a ball delivering unit 20 shown by two - dot chain lines , which functions to deliver a ball at every constant time into the flexible hose 18 at its base portion . however , this unit 20 has already been described in the aforesaid related applications and hence its detailed description will be omitted . as mentioned above , this invention is designed to apply spin to a ball emitted from , for example , the ball emitting device as mentioned above at a desired angle . in order to achieve the above object , there are provided the mounting base plate 14 , which is secured to the ball emitting cylinder 10 through , for example , bosses 21 as shown in fig4 and a supporting member 22 for rotatably supporting the ball emitting cylinder 10 , thereby controlling the inclined angle of the base plate 14 relative to the supporting member 22 . thus , the inclined angles of the ball emitting pulleys 11a and 11b are adjusted to have for example , an angular range of θ 3 on both sides of the perpendicular as shown in fig2 so that the spin of emitted balls may be variously selected . in the embodiment of this invention , the emitting cylinder supporting member 22 has a u - shaped plan configuration and is normally provided with ball bearings 23 at its both side plates , for example , at the outer sides thereof to support the emitting cylinder 10 at its predetermined axial position . a rear side plate 22 &# 39 ; of the supporting member 22 is extended downward and a low speed reversible control motor 24 , similar to the above mentioned rotating motors , is secured to the outer surface of the thus extended plate 22 &# 39 ;. in addition , a link member 25 is disposed between the downward extended rear side plate 22 &# 39 ; and a bent plate 14 &# 39 ; of the base plate 14 . the motor 24 is connected to the electric supply source box 17 . with the construction as mentioned above , the operation and effect of the ball emitting device of this invention will be understood clearly . that is , in addition to the control of the ball emitting cylinder 10 in its horizontal and vertical rotations , inclined angles of the ball emitting pulleys 11a and 11b relative to the surface of tennis court can be almost freely selected and controlled , so that emitted balls can be spun or rotated in various directions . accordingly , players who utilize the tennis training system can enjoy a great deal of benefits in learning the technical skill of the game . having described specific preferred embodiments of the invention with reference to the accompanying drawings , it is to be understood that the invention is not limited to those precise embodiments , and that various changes and modifications may be effected therein by one skilled in the art without departing from the scope or spirit of the invention as defined in the appended claims .
a tennis ball emitting or serving device includes a ball emitting cylinder having controllable horizontal and vertical angles . the ball is driven by contact with the peripheral surfaces of rotating ball emitting wheels or pulleys . to impart various directions and speeds of spin to the ball , the ball emitting wheels may be rotated at various speeds and the axes of the wheels may be independently disposed at variable angles .