U.S. patent number 3,777,732 [Application Number 05/236,039] was granted by the patent office on 1973-12-11 for device having coacting wheels for projecting tennis balls.
This patent grant is currently assigned to Metaltek, Inc.. Invention is credited to Donald P. Holloway, William H. Payne, Donald H. Peeler.
United States Patent |
3,777,732 |
Holloway , et al. |
December 11, 1973 |
**Please see images for:
( Certificate of Correction ) ** |
DEVICE HAVING COACTING WHEELS FOR PROJECTING TENNIS BALLS
Abstract
A ball throwing machine ejects tennis balls in regular sequence
and at a controlled velocity to simulate tennis service from an
opponent during practice sessions. The machine is adapted to
intermittently vary the vertical and horizontal angles of ball
ejection thereby providing game-like situations. An anti ball
jamming device is located in the base of a ball hopper. The machine
has structure for permitting rotation of the subframe about a
vertical axis to vary the horizontal angle of discharge of a
projectile. As an alternate method for varying the horizontal angle
of discharge of a projectile the subframe may be oscillated about a
vertical axis.
Inventors: |
Holloway; Donald P. (Raleigh,
NC), Payne; William H. (Raleigh, NC), Peeler; Donald
H. (Raleigh, NC) |
Assignee: |
Metaltek, Inc. (Raleigh,
NC)
|
Family
ID: |
22887875 |
Appl.
No.: |
05/236,039 |
Filed: |
March 20, 1972 |
Current U.S.
Class: |
124/78; 124/50;
124/51.1 |
Current CPC
Class: |
A63B
69/406 (20130101) |
Current International
Class: |
A63B
69/40 (20060101); F41b 003/04 () |
Field of
Search: |
;124/1,51A,3R,49,29A,50,32 ;254/DIG.2 ;273/26D |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Pinkham; Richard C.
Assistant Examiner: Browne; William R.
Claims
We claim;
1. A tennis ball throwing machine for throwing balls of a selected
substantially uniform compressible type comprising, in
combination:
a a main machine supporting frame;
b a pair of cylindrical-shaped ball throwing drums rotatably
mounted on said frame with their axes being parallel, laterally
spaced and positioned without lateral tilt and with a predetermined
rearward tilt, each said drum having an inwardly curved ball
engaging peripheral surface, said surfaces being opposed and said
arms lying in a common plane which is perpendicularly positioned
with respect to said axes, said surfaces being laterally spaced and
of sufficient rigidity such that the outer surface of a ball is at
least slightly compressed when passing between said surfaces;
c electrical drive motors mounted on said frame and operatively
connected to rotate said drums in opposite directions at a
predetermined speed and having in association therewith control
means for controlling the energization and speed thereof;
d a ball supply structure including a hopper supported on said
frame above said drums and having a ball discharge aperture in the
bottom thereof, an electrically driven ball gating wheel mounted on
said frame below said aperture and having structural gates to
sequentially receive and pass successive balls one at a time and at
a predetermined rate, and having in association therewith control
means for controlling the energization and speed of said ball
gating wheel, a flexible elongated hollow tube mounted with a ball
receiving end fixedly positioned below said gating wheel to receive
each said ball passed by said gating wheel in succession and with
the opposite discharge end of said tube being directed between said
drums whereby to guide balls through said tube to the drums in the
peripheral direction of said surfaces whereby each ball when
received, is at least slightly compressed between and is propelled
from and free of said surfaces at some predetermined speed, said
tube being flexible so as to permit changes in the angle of
rearward tilt of said drum axes;
e a pivotal subframe mounted on said main frame, said drums, drum
electrical drive and discharge end of said tube being mounted on
and movable with said subframe; and
f electrical operator means for controlling the tilting of said
subframe, said electrical operator means being mounted and
connected to said main and subframes so as to vary the position of
the subframe about the horizontal axis to cause rearward tilting of
said drum axis and thereby adjust the vertical angle of throwing
said ball while causing said tube member to be appropriately flexed
and its discharge end to be repositioned according to the amount of
such adjustment, said electrical operator means having an
associated control enabling control of its energization and the
degree of said tilt.
2. In a tennis ball machine as claimed in claim 1 wherein said
pivotal subframe is pivotally mounted for pivoting on horizontal
and vertical axes and including an electrical subframe operator
therefor arranged to pivot said subframe about said vertical axis
to vary the horizontal trajectory of successive balls and having an
associated electrical control for said subframe operator.
3. In a tennis ball machine as claimed in claim 1 including a
baffle plate having smooth curved edges and secured to said hopper
within said aperture and above said receiving end of said tube and
an elongated resilient member secured at one end to said baffle
plate and at an opposite end to the edge of said aoerture to
resiliently urge and direct arriving balls away from and around
said baffle plate whereby to prevent jamming of balls in said
gating means space proximate said tube's ball receiving end.
4. In a tennis ball machine as claimed in claim 3 wherein said
resilient member comprises a coil spring.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to pitching machines used for projecting
balls of various types during practice sessions. Specifically, the
invention relates to machines adapted to project tennis balls in
simulated ball service.
2. Description of the Prior Art
The sport of tennis has gained in popularity throughout the past
decade as an individual as well as team sport. Where tennis is
being taught, whether in schools, athletic clubs or other
institutions, there is frequently a need for a type of ball
throwing machine which can be used during practice sessions to
simulate game-like situations for the benefit of the individual
novice or professional. Machines which have been devised to date
for throwing tennis balls have largely been adaptations of baseball
pitching machines. Though these machines have been effective in
propelling tennis balls, they have imparted considerable
objectionable spin to the ball, caused a significant amount of wear
on the covers of the balls and have led to frequent jamming. In
addition, they have required an attendant to manually operate the
controls and refill the ball magazine. In this respect none of the
pitching machines of the prior art have been adapted to fully
automatic operation. A prior patent teaches the concept of
utilizing high speed rotating cones or discs, obliquely situated,
to propel tennis balls. This invention, however, falls short of
fully automatic operation in that there is no remote means by which
to start or stop the machine. The user is faced with the same
practice shot repeated time after time unless he makes frequent
trips to the machine to alter the adjustments and even then he
cannot substantially alter the type of throw he will receive.
Based on the above, there is an obvious need for a type of tennis
ball serving machine which will more closely simultate game
situations and which will be capable of truly automatic operation
for use in the absence of an attendant or additional player. These
and other objects of the present invention will be perceived in the
following description and appended claims.
SUMMARY OF THE INVENTION
The apparatus of the present invention as disclosed herein
comprises a frame and housing which mounts a ball discharge
mechanism, a ball feed mechanism, remote and machine located
control means, and appropriate handles and wheels for portability A
plurality of balls are placed into a feed hopper and are
individually selected by a rotating gate and fed into a flexible
tube. Upon reaching the end of the tube, each ball enters a
propelling mechanism which consists of two narrowly spaced
cylindrical drums which are synchronously rotated about parallel
axes by electric motors. The moving tennis ball, having entered the
propelling mechanism, is engaged between the two drums by friction,
momentarily compressed, and discharged outwardly at a velocity
approximating the circumferential speed of the rotating drums. A
pivotal portion of a frame member which supports the discharge
mechanism enables the vertical angle of ball discharge to be
varied. The horizontal angle of discharge is controlled either by a
movable deflecting baffle situated outward of the rotating drums or
by oscillating a sub-frame which supports the discharge
mechanism.
DESCRIPTION OF THE DRAWINGS
FIG. 1 is a front view of a machine built in accordance with the
invention, showing an aperture in the housing to permit the
discharge of tennis balls.
FIG. 2 is a rear view of the complete machine.
FIG. 3 is a side view of the machine showing the handle and wheel
structure.
FIG. 4 is a top view of the machine revealing the ball hopper and
feed mechanism and an anti-jamming spring guide.
FIG. 5 is a front view of the machine without the housing,
revealing the ball discharge mechanism.
FIG. 6 is a rear view of the machine without the housing, showing
the location of the electronic controls.
FIG. 7 is a left side view showing details of the ball feed and
ball discharge mechanisms.
FIG. 8 is a right side view showing details of the ball feed and
ball discharge mechanisms.
FIG. 9 is a top view showing the location of the flexible tube
connecting between the ball feed and ball discharge mechanisms.
FIG. 10 is a view of the underside of the machine showing details
of the height adjustment assembly.
FIG. 11 shows in a somewhat schematic view a tennis ball being
engaged between the rotating drums.
FIG. 12 is a partial view of the rotating gate drive mechanism.
FIG. 13 is a partial view of the flexible tube in cooperative
arrangement with the gate mechanism.
FIG. 14 is a partial perpsective view of the deflector plate
camming assembly.
FIG. 15 is a partial perspective view of the deflector plate
showing the position of the solenoid.
FIG. 16 is a partial side view of the deflector assembly.
FIG. 17 is a partial side view of the height adjustment
assembly.
FIG. 18 shows an alternate height adjustment assembly utilizing a
reversible electric motor.
FIG. 19 shows the control panel.
FIG. 20 is a circuit diagram of the preferred embodiment
circuitry.
FIG. 21 is a circuit diagram of an alternate embodiment
circuitry.
FIG. 22 is a diagram of the pitching drum dimensions used in one
embodiment.
FIG. 23 is a perspective view of a ball guide.
FIG. 24 is a top perspective view of an alternate embodiment of the
invention showing a sub-frame adapted to laterally oscillate the
ball discharge mechanism.
FIG. 25 is a bottom partial perspective view of the oscillator
mechanism of the alternate embodiment.
FIG. 26 is a partial elevation view of a height adjustment
mechanism of the alternate embodiment and showing in dashed lines
an elevated position.
FIG. 27 is a somewhat schematic and enlarged view of the
anti-jamming mechanism.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to FIGS. 1 through 4, in a preferred embodiment the
pitching machine of the invention, generally identified by 10,
comprises a frame 15 composed of tubular aluminum segments joined
by welding or the like into a rectangular base supporting vertical
and horizontal structural members. Two U-shaped leg members 16, 17
are adapted to provide upright support and are secured to said
frame member and fitted with respective hand grip portions 19, 20,
axle 25, and wheels 26, 27. A removable housing member 30 formed of
sheet aluminum includes four sides walls, and in the front wall a
ball discharge aperture 31 which permits the exit of discharged
tennis balls. A control access aperture 32 and an associated door
36 are located on the rear wall which permits access to the manual
controls. The complete housing assembly is open at the bottom and
attaches to frame 15 at appropriate screw attachment points 18.
Housing 30, immediately below its open upper end, is fitted with a
metal ball hopper 33 formed with a depressed area at the top of
said housing adapted to hold a plurality of tennis balls. A bottom
aperture 34 permits the entry of balls into the machine from the
hopper. Ball hopper 33 is provided with an anti-jamming assembly 35
later described. It is contemplated that the entire housing
assembly may be of unitary construction and fabricated of formed
aluminum sheeting.
A ball feed mechanism 40 is suitably secured to the frame 15 and is
situated immediately beneath the hopper aperture 34 to receive the
balls one by one. A rotatable feed gate 42 is adapted to rotate
about shaft 43 which is fitted with a pulley 44 and a belt 45 for
being driven by a variable speed, drive motor 46 through reduction
means 47, as best shown in FIGS. 5, 12 and 14. Control of gate 42
is of course obtained by control of motor 46 with respect to being
on or off and speed. Rotatable gate 42 is composed of sleeve 49
which mounts on shaft 43, vertical dividers 50, 51, 52 and a
surrounding cylindrical wall member 53. Thus, gate 42 effectively
forms six open-ended colums each of which is adapted to temporarily
contain no more than one tennis ball. A tension arm 60, FIG. 12, is
pivotally secured to frame cross member 14 and is tensioned by
spring 61 which connects between tension arm 60 and a supportive
vertical member 13. An idle roller 62 is situated intermediate the
ends of tension arm 60 and is rotatably secured by appropriate
means thereto. Tension arm 60 is adapted to apply sufficient
tension to belt 45 to cause normal rotation of feed gate 42 while
allowing slippage between belt 45 and pulley 44 in the event of
malfunction of jamming of feed gate 42.
An aperture plate 41 has a wedge-shaped aperture 73 through which
the balls pass from gate 42 to flexible tube 70. Plate 41, except
for aperture 73, provides a temporary ball support surface for any
balls in any of the gate columns. A flexible feed tube 70 is
secured by suitable clamping means 71 below aperture plate 41 and
in a position immediately below and in alignment with aperture 73.
Thus, as gate 42 rotates at a selected speed and as the columsn in
feed gate 42 each containing a tennis ball pass over aperture 73,
each respective ball will be permitted to exit said column and fall
freely through aperture 73 into the flexible feed tube 70. The
opposite end of feed tube 70 is connected by similar clamping means
to a pivotal frame member 74 which is movably supported on a
vertical frame member 12 so as to introduce a ball arriving at said
opposite tube ending, into an adjacent ball discharge mechanism
100. Final guidance is provided by a V-shaped metal guide 69 having
a discharge end positioned to guide the balls to the pitching drums
80, 81 as shown in FIGS. 16 and 23.
As will be more fully appreciated from later disclosure, flexible
and extensible tube 70 provides a unique advantage to the overall
invention. In particular, the flexibility allows the discharge end
of the tube which mounts the V-shaped metal guide 69, FIGS. 16 and
23, to be moved to different angles for variation in loft of the
ball as later described. However, irrespective of any such angular
position the ball is given a positive, low friction path of
guidance through the tube. Various helically reinforced, flexible
tubes such as used in vacuum systems are of course readily
available for such purpose.
The ball discharge mechanism 100 includees two variable speed DC
electric pitching motors 72, 72' having drive shafts 75, 76. Motors
72, 72' are mounted on pivotal framing member 74 and are oriented
such that the shafts of the motors rotate about parallel axes.
While not shown, it should be noted that the motors are mounted on
slots allowing lateral adjustment to vary the spacing between the
shafts 75, 76. Two cylindrical drums 80, 81 are rotatably secured
to the mentioned drive shafts and reside in the same plane in
opposed positions. These drums, best shown in FIG. 11, may be of
hollow aluminum or magnesium casting or solid construction and have
concave circumferential edges fitted with a soft compressible
material, i.e., rubber, vinyl or the like so as to be adapted to
conform said edges to the outside diameter, texture, and hardness
of a given ball. As shown diagrametically in FIG. 11, drums 80, 81
are adapted to be synchronously rotated in opposite directions
outwardly, represented by the solid arrows, such that a ball upon
reaching the end of flexible tube 70, indicated by the dashed
lines, will be introduced into, temporarily engaged between and
instantaneously discharged from drums 80, 81 at a velocity
approximating their circumferential speed. Motor adjustment slots
previously mentioned enable the distance between the motors, and
correspondingly between the drums, to be altered so as to adapt the
discharge mechanism for use with relatively lightweight balls of
varying sizes, i.e., tennis balls, handballs, whiffle balls,
softballs, as well as various types of rubber practice balls.
Various motors may be employed for performing the pitching
furnction of motors 72, 72'. In one embodiment a pair of DC type
pitching motors are employed for motors 72, 72' and are supplied
from an AC source through AC to DC converter circuitry. The
pitching motor speed is controlled by keeping the field voltage
constant and varying the armature voltage by sensing the back emf
(electromotive force). The speed in this embodiment ranges between
1,200 and 3,600 r.p.m. For a standard 2 5/8 inch diameter tennis
ball the radius R in this embodiment, shown in FIG. 22, is two
inches and the spacing X is held between 1 3/4 inch and 1 7/8 inch.
During projecting the center line of the ball lines up with the
central axis Y--Y. In the same embodiment the base diameter Z of
each drum is 6 inches. Other diameters may be used.
A height adjustment mechanism 87, best shown in FIGS. 7, 8, 17 and
18, is mounted on frame 15 and enables the vertical angle of ball
discharge to be varied. Mechanism 87 comprises an arm 75 which is
movably secured at one end to pivotal frame member 74, and at an
opposite end to yoke 76, which rides screw or worm gear means 77
and to which is secured a handle 78. Turning of handle 78 in one
direction or the other is thus adapted to effect the rotation of
the screw means 77 to cause arm 75 to move in and out and to
correspondingly vary the vertical angle of pivotal frame member 74
whereby to vary the vertical angle of rearward tilt V to vary the
angle of ball discharge. Note here the flexible and extensible tube
70 follows this adjustment. In an alternate embodiment, shown in
FIG. 18, a reversible motor 79 is employed with suitable, controls
to effect the same adjustment by moving arm 75.
Referring now to FIGS. 14, 15 and 16, a ball deflecting mechanism
90 comprises a support member 91, solenoid 92 and related solenoid
mounting barcket 93 secured to a horizontal frame member 91.
Deflector mechanism 90 further includes a deflector arm 98 having a
shaft 94 rotatably secured to frame member 91 and a baffle 95
mounted on shaft 94. A spring 96 connects between solenoid mounting
bracket 93 and deflector arm 98 and is adapted to maintain tension
on arm 98 during operation of the machine. As shown in FIG. 16,
frame member 91 is secured to pivotal frame member 74 so as to
position baffle 95 immediately outward of rotatable drums 80, 81.
As shown diagramatically, in FIG. 15 the normal path of a ball
being discharged is represented by the solid arrow, the position of
the activated deflector arm and baffle is indicated by dashed lines
and the deflected path of a ball by the dashed arrow. Deflector
mechanism 90 is adapted to be positioned with respect to the normal
path of a discharged ball so as to occupy a non-interfering
position while not in operation, but upon activation of solenoid
92, to interfere with the normal path of the discharged ball
thereby deflecting it and altering its horizontal direction.
A camming assembly for controlling power to solenoid 92 is best
shown in FIG. 14. A microswitch 111 is mounted to engage cam 112
which may be conveniently incorporated into feed mechanism pulley
44. As further shown in FIG. 13, microswitch 111 is mounted on
flange 113 which is secured to a frame cross member 115,
immediately beneath ball feed mechanism 40. While not shown, it
will be understood that appropriate electrical connections
communicate between switch 111 and solenoid 92 enabling the
solenoid, upon being supplied with an appropriate power supply to
become energized during each interval switch 111 is in the "on"
position and thus deflect the ball as depicted in FIG. 15.
To summarize the control features previously discussed, it can be
seen that the frequency of ball pitching, the vertical angle of
pitch, the horizontal angle of pitch and the speed of pitching are
all subject to control and variation to present a great variety of
play experiences. Frequency of ball pitching is controlled by
varying the speed of variable speed motor 46 which rotates ball
gate 42 whose speed thus determines how often a ball is pitched
toward the player. The vertical angle of pitch is controlled either
manually by handle 78 ro electrically by reversible motor 79, FIG.
18. The horizontal angle of pitch is controlled by solenoid 92
which in turn controls the deflecting baffle 95. The speed of
pitching or velocity imparted to the ball is controlled by
simultaneously varying the speed of the variable speed pitching
motors 72, 72' which in turn control the speed of the pitching
drums 80, 81. The description next refers to the circuitry used
with these various controls.
The electronic control circuitry of the preferred embodiment is
shown in a generalized and somewhat schematic block circuit diagram
in FIG. 20. The control means include a remote control receive 120,
having appropriate electronic switching capabilities electrically
connected to control feed motor control 121. Receiver 120 receives
signals through antenna 126. A remote circuit transmitter 122 is
adapted to send signals to activate receiver 120. The control
circuit of FIG. 20 also includes a deflector control 125 as shown
in FIG. 20 and which is adapted to energize the deflector mechanism
90. The control further includes a motor speed control circuitry
123, interconnecting circuitry and leads 127, 128 which connect the
control circuit to a suitable source of power. Manual control
switches 55, 56, 57, 58 and 65, shown in FIG. 20, control the
functions indicated. Since remote controls and circuitry of this
type are well-known and are clamied only in conjunction with the
specific application it is not deemed necessary to further detail
this circuitry, per se. Switches 66, 67 control the ball interval
and speed respectively. A control panel 130, best seen in FIGS. 6
and 19, is secured to frame member 15. Fig 19 shows the detailed
location of appropriate manually operable switches and dials of the
control panel which, in the assembled machine, are concealed behind
door 31.
In an alternate circuitry embodiment shown generalized and
schematically in FIG. 21, the circuitry enables the principle
functions of the machine to be remotely controlled. In the circuit
of FIG. 21 there is provided a remote control receiver 120' which
is electrically connected to a servomechanism 129 . Servomechanism
129 is deemed to have appropriate electronic swtching and rheostat
capabilities to remotely govern (a) the speed of the pitching motor
speed control 123', (b) activation of the deflector mechanism
control 125', (c) the feed motor speed control 121', and (d) the
height adjustment 130 through the alternate reversing motor 79 of
FIG. 18. Manual override controls, not numbered and shown
schematically, enable all functions to be manually operable from
the alternate machine control panel, not shown.
According to the invention's first embodiment, operation of the
machine 10 proceeds in the following manner. A plurality of tennis
balls are placed into hopper 33 and machine 10 is wheeled to a
playing surface and positioned to discharge tennis ball across a
net in the direction of the player. Prior to assuming the playing
position, a player connects the machine to a suitable source of
power, energizes the controls, and manually pre-sets the desired
speed of ball discharge, height of ball trajectory, the desired
rate of ball feed, and whether or not the deflector is to be
utilized. At this time, pitching motors 72, 72' are rotating,
however, ball feed motor 46 has not yet been energized. Next the
player switches the manual controls over to the "remote" mode of
operation, at which time he takes the transmitter with him to the
opposite side of the net. Having assumed the playing position, on
the opposite side of the playing surface from the machine, a player
may now energize the ball feed motor 46 through the controls on his
remote transmitter to start the machine and initiate simulated
play. Correspondingly, individual balls ar now being selected from
the ball hopper 33 by rotating gate 42 and are being permitted to
fall through aperture 73 down into tube 70, whereupon a ball
travels to the opposite end of tube 70 over guide 69, FIGS. 16 and
23, and becomes introduced into ball discharge mechanism 100. The
ball is then drawn into and momentarily engaged between tht two
outwardly rotating drums 80, 81 and is prooelled outwardly at a
fast rate of speed. If the deflector mechanism 90 has been
energized, the deflector baffle 95 will intermittently interfere
with the path of the discharged ball according to the rotation of
cam 112, thus providing a series of simulated tennis "returns"
falling at different locations on the playing surface. Alternately,
if the deflector mechanism 90 has not been energized, the machine
will provide a series of precisely controlled simulated tennis
"serves". Play may be terminated or resumed at will through the use
of the remote transmitter 122.
In the alternate embodiment of FIG. 21, the transmitter 122' is
deemed to have sufficient controls such that when the manual
controls shown in FIG. 21 are closed and transmitter 122' is on
command all principle functions become remotely controllable. Thus,
drive motor 46 is controlled remotely as to on-off and speed as are
pitching motors 72, 72'. Also, the deflector control meachism 125'
and height adjustment 130 are controlled remotely either by the
player or his instructor.
At best shown in FIGS. 4 and 27, hopper 33 is provided with the
previously mentioned anti-jamming assembly 35. This assembly
includes a somewhat semi-circular shaped plate 35 which is secured
to hopper 33 and is horizontally positioned above the open,
receiving end of tube 70. The area of plate 35 is sufficiently
large to prevent the dropping of balls into the gate 40. That is,
any ball which is to be dropped into tube 70 must have found its
way into gate 40 prior to arriving at the position at which plate
35 is located. Furthermore, in order to minimize the tendency of
balls tending to jam the gate 40 at the point of exit into tube 70
a coil spring 36 is secured at pont A on plate 35 at one end and at
point B on hopper 33 at its opposite end. Spring 36 thus provides a
means for resiliently urging such incoming balls, as indicated by
the solid arrow in FIG. 27, away from the edge of aperture 34 and
away from the ball entry position above tube 70 as to assume the
dashed line arrow direction shown in FIG. 27. The lack of any kind
of baffle above tube 70 has been found to produce both jamming and
entry of more than one ball at a time into tube 70. It has also
been found that a baffle having a fixed guiding edge in the same
position as spring 36 fails to avoid jamming whereas the resilient
guiding edge provided by spring 36 does substantially eliminate
both jamming and multiple ball dropping when combined with the
smooth edge of plate 35.
To further describe the drums it will be noticed that the inwardly
curved, ball engaging surfaces are centrally positioned around axis
Y-Y and that the central plane which includes Y--Y is the central
plane of the surfaces and that such plane is perpendicular to the
drum axis. The drum axis has no lateral tilt but may be tilted
rearwardly as previously stated up to about 45' or more off
vertical though substantially less adjustment is normally
sufficient. While both on machine direct wired and off machine
radio "remote" controls are shown, it is also contemplated that the
"remote" control could be through a long electrical extension cored
from the machine to a control box.
An alternate means for varying the lateral angle of ball trajectory
is shown in FIGS. 24, 25 and 26. In this embodiment a sub-frame
member 74 mounts the previously mentioned synchronous motors 72,
72' and associated rotating drums 80, 81. Sub-frame 74 is adapted
to rest upon a rotatable bearing assembly 131. Assembly 131
includes top and bottom circular plates 135, 133 which are arranged
horizontally with an integral race means adapted to receive a
plurality of ball bearings 134. The bearing assembly bottom plate
133 is suitably secured to the previously mentioned framing 15 and
the bearing assembly top plate 135 is secured to a U-shaped
sub-frame member 132 such that sub-frame member 132 is adapted for
rotation on the bearing assembly through an arc of at least
10.degree..
A motor 138 having a drive shaft 139 turns a cam 140. Motor 138 is
secured to framing 15 proximate sub-frame member 132. An arm 142
connects between cam 140 and a suitable pivot point 144 on
sub-frame member 132 and thus sub-frame member 132 to oscillate
upon the energization of motor 138 and the corresponding rotation
of cam 140.
A flange 150 is secured to pivotal framing member 74. Flange 150
supports the discharge end of the flexible feed tube 70 as the
sub-frame member oscillates so as to maintain accurate feeding of
the tennis balls between the rotating drums 80, 81.
A height adjustment mechanism 152 includes a threaded shaft 153
which extends through a correspondingly threaded pivotal yoke
member 151. Yoke member 151 is movably secured to pivotal frame
member 74 and an anchor member 154 is movably secured to sub-frame
member 132 and is adapted to rotatably secure an end 156 of thread
shaft 153. A flexibly shaft 155 extends between an opposite end 157
of threaded shaft 153 and a handle 158. Handle 158 is rotatably
secured through a journal opening 159 in framing 15 which enables
threaded shaft 153 to be rotated in response to rotation of handle
158 thereby enabling the vertical angle of ball trajectory to be
varied accordingly. As threaded shaft 153 is rotated in a clockwise
direction, movable yoke 154 is correspondingly urged rearwardly
along threaded shaft 153, and said pivotal frame member 74 assumes
a substantially horizontal or lower position. Conversely, as
threaded shaft 153 is rotated in a counterclockwise direction,
pivotal frame member 74 is raised as indicated by the dashed lines
in FIG. 26.
In keeping with the objective of fully automatic operation,
appropriate electrical linkages may be substituted for selected
remote controls of the preferred or alternate circuitry embodiment
as indicated by dashed lines 160 in FIG. 21. The circuitry which
controlled the deflector mechanism may, in this last embodiment,
now control the oscillator function as indicated.
It is contemplated that this alternate form of the invention
provides an opportunity for variation in a tennis ball pitching
machine heretofore not possible with conventional pitching
machines. In addition, rather than the intermittently deflected
shots of the preferred embodiment utilizing the previously
described deflector mechanism, oscillation of the sub-frame, which
is achieved in the alternate embodiment, provides a sequence of
balls having continuously changing lateral trajectories, simulating
actual playing conditions.
* * * * *