U.S. patent number 3,876,212 [Application Number 05/402,438] was granted by the patent office on 1975-04-08 for swing-accommodation apparatus.
Invention is credited to Jess Oppenheimer.
United States Patent |
3,876,212 |
Oppenheimer |
April 8, 1975 |
Swing-accommodation apparatus
Abstract
A device for training a user to properly swing an implement such
as a golf club. The device includes an overhead arched support
mounted on rollers, which support is adapted to be rotated about a
fixed axis to selected positions on a supporting surface. Extending
downward from the support, and slideable therealong, is a
mechanical system including three movably interconnected shafts,
the lowermost one of which is adapted to be connected to the
implement to be swung. The system functions: (a) to follow the
swing of one who is engaging in a sports activity, (b) through
power application, to cause one to emulate the swing for a given
sports activity, (c) provide the function of a swing as it would be
carried out in a sports activity without the necessity of a user
being present, or (d) a combination of the foregoing. A system
including hydraulic fluid, valves, electrical sensors and
electrical actuators is provided either for detecting movements of
the shafts or causing selected movements of the shafts. When the
device is adjusted so that no resistance is offered to movements of
the club implement, the shafts permit the club implement to be
moved along its axis, about its axis, and in all planes relative to
its axis, including planes orthogonal to each other. The principles
of operation of the device maybe illustrated by attaching a
flexible cord to a point on an inverted cone located above a
golfer, and securing the other end of the cord to a point adjacent
the head of a golf club. The axis of the cone is positioned such
that the effective length of the cord (if kept taut) is shortened
and lengthened as it is wrapped and unwrapped around the cone
during the execution of the backswing and downswing with the club.
Also disclosed is a helmet-like device for restraining movements of
the golfer's head.
Inventors: |
Oppenheimer; Jess (Los Angeles,
CA) |
Family
ID: |
23591884 |
Appl.
No.: |
05/402,438 |
Filed: |
October 1, 1973 |
Current U.S.
Class: |
473/221; 434/252;
473/229 |
Current CPC
Class: |
A63B
69/38 (20130101); A63B 21/00181 (20130101); A63B
21/00178 (20130101); A63B 69/36213 (20200801); A63B
2220/16 (20130101); A63B 21/008 (20130101) |
Current International
Class: |
A63B
69/36 (20060101); A63B 69/38 (20060101); A63B
21/008 (20060101); A63B 24/00 (20060101); A63b
069/36 () |
Field of
Search: |
;273/186,190,191,192
;35/29 ;73/13 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Marlo; George J.
Attorney, Agent or Firm: Nilsson, Robbins, Bissell, Dalgarn
& Berliner
Claims
What is claimed is:
1. Swing-accommodating apparatus comprising:
a support means having a base member and being adjustably
positioned to accommodate various swings and various users;
means for locking said support means in position after said support
means has been properly positioned;
swing-accomodator means activatable by a user of said apparatus for
connection at one end to a device to be manipulated and at the
opposite end thereof to said support means, said swing-accommodator
means including:
a. means for adjustment thereof for definition of a reference about
which a particular swing is to be performed, and
b. shaft means movable in unrestrained manner along the axis
thereof and rotatable about the axis thereof simultaneously, and
movable in an unrestrained manner in all planes relative to the
axis thereof including planes orthogonal to each other thereby
permitting full and free movement of said device by action of said
user of said apparatus.
2. Swing-accommodating apparatus as defined in claim 1 wherein said
shaft means includes a first shaft connected at one end thereof to
said support means, a second shaft being extensible and retractable
along its longitudinal axis and connected at one end thereof to
said device, and a third shaft connected between the other end of
said first shaft and the other end of said second shaft.
3. Swing-accommodating apparatus as defined in claim 2 which
further includes means for locking a preselected one of said shafts
in a predetermined position to preclude movement thereof thereby to
assist in teaching a user of said apparatus by eliminating motions
of said device normally permitted by said locked shaft.
4. Swing-accommodating apparatus as defined in claim 2 wherein each
of said shafts may be rotated about its axis and moved linearly
thereof.
5. Swing-accommodating apparatus as defined in claim 4 wherein each
of said shafts has transducer means for sensing movement thereof
linearly and rotationally.
6. Swing-accommodating apparatus as defined in claim 5 wherein each
of said shafts has actuator means for causing said shafts to move
linearly and rotationally, and control means for imparting desired
motion to said actuators.
7. Swing-accommodating apparatus as defined in claim 1 wherein said
swing-accommodator means includes sensor means for producing output
signals proportional to movement of said device.
8. Swing-accommodating apparatus as defined in claim 1 wherein said
swing-accommodator means includes actuator means interconnected
therewith to control movement of said device commensurate with
input signals representative of a desired swing.
9. Swing-accommodating apparatus as defined in claim 1 wherein said
shaft means includes sensor means for producing an output signal
proportional to movement of said device; said shaft means including
actuator means interconnected therewith to control movement of said
device commensurate with input signals representative of a desired
swing; and electronic data processor means interconnected to
receive signals generated by said sensors and to generate signals
for application to said actuators.
Description
BACKGROUND OF THE INVENTION
It has long been desired in various sporting events where a
particular motion such as a swing is utilized to provide apparatus
whereby a participant may be instructed in the correct swing for
accomplishing the object of the game. Such is particularly true
where the participant utilizes an object to strike a ball such for
example as in golf, baseball, cricket, tennis or the like. Such
however is also desirable in those sports where the participant
projects a ball or similar apparatus toward a predetermined target
such as in bowling or the like.
Much prior art apparatus has been developed in an attempt to
accomplish the foregoing. Such apparatus traditionally falls in two
classes, either that which is worn by the participant and is
connectable to the object being manipulated by him, or that which
is attachable to the object being manipulated by the participant to
control movement of the same. Irrespective of into which prior art
apparatus falls, it is limited with few exceptions (see patent
3,595,583) to a structure wherein the movement of the structure to
be swung by the participant is restricted to a predetermined path
of movement. For example, see U.S. Pat. Nos. 3,604,712; 1,567,530;
3,319,963; 3,415,523; 3,415,524; 3,419,277; and Canadian Pat. No.
708,502.
SUMMARY OF THE INVENTION
The present invention provides a significant advance in the art
relating to training devices for use by participants in sporting
events. The present invention accommodates all of the various
complexities of the swing irrespective of the sport in which the
same is utilized. That is, the swing may be accommodated even in a
sport having a swing as complex as that of golf wherein the club
may travel through a continuously changing swing plane and which
changes may themselves change depending upon the particular club or
the various parameters dictating the required shot to be executed,
even when the same club is utilized from shot to shot. Not only
will the present invention accommodate such variations, but may be
actuated to guide the user thereof through a predetermined swing
commensurate with a particular set of parameters dictating such
swing.
A swing-accommodating apparatus in accordance with the present
invention includes fixed support means, swing-accommodator means
for connection to an instrument to be swung, and means
interconnecting the support means and the swing-accommodator
means.
In other particular aspects of the apparatus in accordance with the
present invention, sensor means are operatively associated so as to
detect movements representative of the swing and to generate output
signals representative of such movement. The signals generated may
be assimilated and applied to a computing apparatus for analysis of
the user's swing. Such analysis may result in a comparision with
swings of others or earlier swings of the user to determine the
relationship of the user's swing to an ideal or to plot improvement
by the user as a result of his practice.
In accordance with other aspects of the present invention, the
apparatus may have associated therewith an actuating device which,
subject to input signals, may position the members so as to cause
the apparatus to pass through the various positions representative
of a predetermined swing with or without a user gripping the
instrument. Under such circumstances, when a user is in position,
the user may grip the instrument and passively follow its movement
as generated by the swing-accommodating apparatus and the actuators
thereto so as to sense the desired movements to accomplish the
predetermined swing. The apparatus may be caused to provide timing
and sequence to the swing with the user providing the motive power
through swinging the instrument affixed to the apparatus.
Alternatively, the apparatus may be used for striking an object
(ball) with the sporting device (club) without a user holding the
club.
In accordance with yet other detailed aspects of the present
invention, the apparatus may be utilized in such a manner that the
sensor, the computer and the actuating apparatus are all
simultaneously operative, thereby causing the sensors to detect
actual movement as generated by the user of the apparatus, the
computer to compare the same with a predetermined swing that is to
be generated by the actuator devices and as a result of any
discrepancies, provide signals to correct the positioning of the
object which is being gripped by the user, thus causing the user to
recognize discrepancies between his swing and that which he desires
to accomplish, thereby enabling him to correct the same. As will be
evident to those skilled in the art, the apparatus may provide an
audible or visual signal when the user deviates from the programmed
swing.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic illustration of one form which apparatus
constructed in accordance with the present invention may take.
FIG. 2 is a schematic representation in block form illustrating
utilization of signals developed in accordance with the apparatus
in accordance with the present invention.
FIGS. 3 and 4 are schematic representations of sensors and
actuators as utilized in accordance with the present invention.
FIG. 5 is a more detailed view of a portion of the apparatus taken
along the line 5--5 of FIG. 1.
FIG. 6 is a more detailed fragmentary view of a portion of the
apparatus taken along the line 6--6 of FIG. 1.
FIGS. 7A, 7B and 7C are schematic illustrations of the operating
principles of the apparatus of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
Apparatus constructed in accordance with the present invention
includes a support member shown generally at 10 mounted upon a base
12 which in turn is supported upon rollers 14 or the like so as to
be positionable as illustrated by the arrow 16. Such positioning
may be accomplished through the application of motive power to a
drive member 18 or the like as is indicated by the arrow 20. When
properly positioned, the support member may be fixed in place by
pins 22 which are inserted into openings 24 in the base 12.
A swing accommodator 30 depends from the support member 10. The
term "swing accommodator" as used throughout the specification and
claims is intended to mean apparatus which functions to (a) follow
the swing of one who is engaging in a sports activity, (b) through
power application to cause one to emulate the swing for a given
sports activity, (c) provide the function of a swing as it would be
carried out in a sports activity without the necessity of a user
being present, or (d) a combination of the foregoing.
The swing accommodator 30 is adjustably secured to the support
member 10 by a bracket 32. The bracket 32 includes rollers, gears
or the like 34 which engage the support member 10 and may be
utilized for movement of the swing accommodator 30 relative to the
support member 10. Once the swing accommodator 30 is positioned as
desired (as will be described more fully hereinbelow), the bracket
32 may be locked in position.
The primary function of the swing accommodator 30 is to provide
apparatus which will grip a sports item that is to be swung and to
provide a reference for or define the arc of the swing. Each
particular swing for a given sport, for example, tennis, baseball
or golf, has a different reference about which the swing may
generally be constructed. This reference will vary from sport to
sport in its position and may, depending upon the particular swing
to be utilized, vary in its position as the particular swing to be
accommodated within the sport changes. For purposes of description
of the apparatus of the present invention, a golf swing will be
used as the example, it being however understood that such example
is not to be taken by way of limitation on the present
invention.
The swing accommodator as illustrated in the embodiment of FIG. 1
includes first, second and third shafts 36, 38 and 40,
respectively. The shaft 36 provides a rotational movement about its
axis 42 as is shown by the arrow 43 and is also positionable in a
linear fashion along its axis as is illustrated by the arrow 44.
The shaft 38 is rotatable about its axis 46 as is indicated by the
arrow 48, and in addition thereto, is linearly movable along its
axis as is indicated by the arrow 50. The shaft 40 is rotatable
about its axis 52 as is indicated by the arrow 54, and in addition
thereto is linearly movable along its axis as is indicated by the
arrow 56.
The shaft 40 is connected to be a bushing 58 (FIG. 5) which is
journaled into a wheel 60 to provide the rotation of the shaft 40
about its axis. The wheel 60 is received within a yoke 62 and is
rotatably supported upon an axle 62 so as to be freely rotatable
thereabout. The shaft 40 is extensible in that a reduced diameter
portion 66 thereof is telescopically received within the upper
portion 68 thereof for a purpose to be more fully described
hereinbelow. The shaft 38 (not shown in FIG. 5) is connected by way
of a tongue 70 which fits within a groove 72 provided in the lower
portion of the shaft 36. As will be recalled, the yoke 62 is
supported upon the end of the shaft 38 which is rotatable about its
axis 46. Thus, it may be seen that the shaft 40 is free to move as
indicated by the arrows 74, 76, 78 and 80, as a result of the
manner in which it is mounted. The movement represented by arrows
74 and 76 may be described as being in planes orthogonally disposed
to each other. The movement represented by the arrow 80 may be
described as an effective extension or retraction of the shaft 40
and may be accomplished by the telescoped construction of the shaft
40. However, the same effective movement may be obtained with the
apparatus of the present invention through manipulation of the
various axes and shafts. For example, the shaft 40 may remain of
fixed (non-telescoping) length and the shaft 38 be allowed to move
along its axis 46 as well as to rotate as shown by the arrows 50
and 48 respectively; or, the shaft 36 may be locked to preclude
rotational movement thereof and allowing the effective
extension-retraction to occur in the shaft 38 linear movement
and/or the telescoping of the shaft 40. It will also be recognized
that the amount of telescoping which occurs in shaft 40 (assuming
shafts 36 and 38 rotate about axes 42 and 46 respectively but shaft
38 is fixed linearly) is determined by the position of the wheel 60
which in turn is fixed by positioning the shaft 38.
From the foregoing, it will be realized by those familiar with the
golf swing that, as the golfer properly executes the golf swing, a
sequence of events occurs such that, if a flexible cord of fixed
length were attached from the golf club to a fixed support
displaced from the golfer, the cord (if it remains taut at all
times) would be caused to become shorter to completion of the
backswing and then be allowed to increase in length to its original
length through impact and follow-through. This may better be
illustrated and clarified by reference to FIGS. 7A, 7B and 7C. At
FIG. 7A, the golfer is shown at address position. A flexible cord
of fixed length 200 is affixed at one end thereof to the golf club
201 at a point 202 near the club head and at the other end thereof
to a point 204 on a cone 206. The cone 206 is fixed, displaced from
the golfer, on an axis 208 which intersects approximately the point
where the golfer grips the golf club 201. FIG. 7B shows the golfer
with the golf club 201 at the top of the back swing and is a view
toward the left side of a right handed golfer (as in FIG. 7A). The
original position of the cord and club are shown in phantom in FIG.
7B. As can be seen, the cord 200 has effectively shortened and
would be slack at the top of the backswing but for the surface of
the cone. With the cone, the flexible cord wraps around the surface
thereof thus guiding the golf club to the proper position at the
top of the back swing. FIG. 7C is a view taken toward the rear of a
right-handed golfer with club and cord at the top of the backswing
shown in phantom. It will also be recognized that as the golfer
executes the downswing and follow-through, the cord 200 will
effectively lengthen from the top of the backswing position to its
full length a point just before, during and immediately after
impact and then once again will effectively shorten. All the
foregoing assumes the cord remains taut at all times.
The apparatus of the present invention may be adjusted or set as
above described to accomplish the foregoing effective shortening
and lengthening of the fixed-length cord. The various shafts of the
apparatus of the present invention interconnected between the club
and the support means function to provide the cord of fixed length
and the conical surface as described above. As used throughout the
specification and claims the term "effectively extensible shaft" is
intended to encompass the shortening and lengthening of the cord,
while retaining its taut condition, as above described. The term
extensible is intended to include either construction.
Shown generally at 82 (FIG. 1) is a structure for use in assisting
the golfer to maintain his head in a fixed position relative to the
remainder of his body during the golf swing. The structure 82
includes a column 84 which is upwardly adjustable as is shown by
the arrow 86. Extending outwardly from the column 84 is a
transverse member 88 which is adjustable along its axis as is shown
by the arrow 90. A head-engaging member 92 is attached to the end
of the transverse member 88 and includes a downwardly-extending
section 94. The golfer may move his head downwardly or to the right
but through the utilization of the head-engaging member 92-94, he
will be precluded from moving his head upwardly or to the left
(assuming the golfer is right-handed) during the swing. The column
84 is supported upon a base 96 or if the installation is permanent,
it may be permanently installed.
Interconnected with each of the shafts 36, 38 and 40 is a
motion-sensing apparatus as well as a power drive (actuating)
apparatus. For clarity of illustration and ease of description,
such apparatus has not been shown in detail with respect to each of
the shafts. Referring however to FIGS. 3 and 4, there is
illustrated exemplary apparatus which may be utilized in accordance
with the present invention at each point needed in the device. As
is shown for example in FIG. 3, linear motion along the axis of any
of the shafts may be obtained by providing a hydraulic actuator
having a cylinder 102 with a piston 104 reciprocally mounted
therein. As fluid under pressure from a source 106 is applied,
through a control device such as an electro-hydraulic servovalve
107 under control of electrical signals applied to the input 108,
fluid flows into or out of the chambers 110 and 112 through the
interconnecting lines 114 and 116, respectively. Such fluid motion
causes the piston and the shafts 118 and 120 connected thereto to
move reciprocally as indicated by the arrow 122. As the piston and
the interconnecting shafts move, the position thereof may be
indicated by a sensor and feedback element as is schematically
illustrated at 124, the output signals therefrom being transmitted
over the electrical leads 126 as position or feedback information
for use in other apparatus. Such electrical feedback apparatus may
take the form of a linear-motion potentiometer, a differential
transformer, a variable-permeance transducer or the like.
Where rotary action is to be accomplished, such as is illustrated
by the arrows 48, 54 and the like, a double-vane rotary actuator
such as is illustrated in FIG. 4 may be utilized. As is therein
shown, there is provided a housing 130 with a rotary vane 132
disposed therein. Openings 134 and 136 are provided to receive
fluid, for example, as from the electro-hydraulic servovalve 107,
as above described. As the fluid enters one of the openings such as
at 134, it applies the force to the upper surface of the vane 138
and passes through the passageway 140 to apply force to the lower
surface of the vane 142, thereby causing the vane to move in a
counter-clockwise direction. As such movement occurs, fluid flows
out of the opening 136. By the reversal of the fluid flow paths,
the reverse motion of the vane will occur. Again, an appropriate
transducer may be utilized for sensing the particular position of
the vane and thus the position of the shaft attached thereto.
Apparatus of the type schematically illustrated in FIGS. 3 and 4
including the servovalves, the actuators, and the transducers are
well known in the prior art and thus more detailed descriptions
thereof will not be provided herein. For example, see the book
Electro-hydraulic Servomechanisms, by Allen C. Morse, Library of
Congress Catalog Card Number 63-15024, published 1963, by McGraw
Hill Publishing Co., particularly chapters 3, 4 and 5 thereof.
A control system 150 may be interconnected through the utilization
of a cable 152 with the swing-accommodating apparatus. The control
system would be utilized for receiving information from the various
sensors interconnected with the shafts and also for providing
control signals to the actuators connected therewith for
positioning the same. By reference to FIG. 2, a control system for
example may be interconnected with the various sensors represented
schematically at 154. The electrical signals would be carried over
a cable 156 to an analog-to-digital converter 158. Such a converter
is necessary since the signals developed by the various sensors are
traditionally analog signals. The output of the analog-to-digital
converter would be applied over the cable 161 as input signals to
an electronic data-processing apparatus 162. The electronic data
processor 162 may also receive input signals from other data
sources such as is illustrated at 164 and may for example include
signals from a programmer, a keypunch, a data terminal, or the
like, as desired. The output from the electronic data processor may
include numerical signals which would be applied over the cable 166
from the pre-programmed information obtained in the electronic data
processor or alternatively may also include signals which would be
applied over the cable 168 as a result of information from the
other data sources as above mentioned. This numerical information
would be applied to a digital-to-analog converter 170, the output
of which would be applied over the cable 172 to the various power
actuators represented schematically at 174 and which may take any
desired form as above described.
The shaft 40 is adapted at its end 176 for connection to an
instrument to be swung, for example, the golf club 160. Preferably
the interconnection between the shaft 40 and the club 160 is such
as to allow the club to rotate about its own axis. However, if the
particular sport or swing within a sport is such that the
instrument is to remain in a non-rotating mode through the swing,
the attachment should preclude (or limit) such rotation. One form
of such interconnection is shown in FIG. 6. The shaft 40 terminates
in a yoke 180 having a pair of clamps 182-184 threadably received
in arms 186-188 respectively thereof. The shafts 190-192 supporting
the clamps are journaled for rotation in the arms 186-188. Thus,
the club 160 may be held firmly in position by the clamps and at
the same time be allowed to rotate as is evident.
When an individual is to utilize the machine constructed in
accordance with the present invention for purposes of instruction
in the swing of a golf club (for example only), he would first take
his position upon the platform 98. Each of the shafts 36, 38 and 40
would be free to provide positioning relative to the particular
size of the individual user. Upon being appropriately positioned,
the linear position of the shaft 36 would be determined and the
shaft would then be locked in place so that movement along the axis
as illustrated by the arrow 44 would no longer occur. The shaft 38
likewise would be locked in position so that no further motion of a
linear nature, as is illustrated by the arrow 50, could occur
(assuming the use of a telescoping shaft 40). However, in all other
fashion, the various shafts 36, 38 and 40 would be permitted to
move fully. The power actuation would be removed from the system
and all hydraulic chambers would be interconnected to provide no
resistance to movements by the golfer. In addition thereto, each of
the shafts would be counterbalanced so as to preclude the
application of friction to the swing of the golfer insofar as such
is possible. Under these circumstances, the golfer would then be
requested to take a normal swing and strike several golf balls. In
the process thereof, the outputs from the various sensors connected
to the shafts 36, 38 and 40 would detect all motions which may be
imparted by the golfer to the golf club 160 as he performs the
swing function. This information would be received by the
electronic data processor 162 which may be programmed to provide a
readout in the form of a curve, graph, chart or the like, showing
the actions of the golfer as compared to some predetermined norm or
standard swing.
Thereafter, if it is desired for the golfer to feel the movements
of the club during a correct swing being performed, the power
actuators could be activated with the electronic data processor
through pre-programmed signals causing hydraulic fluid to be
applied to each of the actuators as required to cause the golf club
160 to be swung in the desired fashion. Under these circumstances,
the user would be a passive force merely holding onto the golf club
and experiencing the sensation of a proper swing. Under these
circumstances, the golfer may be taken through the motions of a
proper swing several times so that he begins to get the correct
feel therefor.
Thereafter, the apparatus may be utilized with a combination of the
sensors and the power actuators being activated so that the golfer
may then be required to take a normal swing and strike the golf
ball. As such occurs, the motions imparted by the golfer to the
golf club will be sensed by the sensors and applied to the
electronic data processor. As the data processor receives the
information, it will be compared against the norm or standards for
the desired swing and signals may then be applied to the power
actuators from the electronic data processor to make corrections in
errors being committed by the golfer. The golfer would thus be
caused during the process of taking a swing to make corrections so
that the swing is properly executed.
During the swinging by the golfer, the various shafts may be fixed
so as to preclude movement thereof in a given position for purposes
of demonstrating a particular portion of the swing, as may be
desired. For example, as the shaft 40 is effectively reciprocated,
as is illustrated by the arrow 80 (FIG. 5), such indicates changes
in the wristcock or the plane of the swing of the golf club. The
accommodation of such changes in the plane of the swing is one of
the unique features of this apparatus as compared to prior art
apparatus. As was previously pointed out, all prior art apparatus
known to applicant causes the swing of the golf club to occur in a
generally semi-circular arc about some fixed point. When utilizing
apparatus constructed in accordance with the present invention,
such a swing may be in fact accommodated but would be detected in
that the lower portion 66 of the shaft 40 would not be caused to
move during the swing with respect to the upper portion 68 thereof.
However in the event the golfer at the top of the backswing then
moved his weight toward the left and commenced the downswing in the
traditional fashion to cause an inside-out swing to occur, the
plane of the swing of the golf club is changed. Just beyond the
point of impact, slightly after the club head is brought into the
ball, the shaft 66 is returned to its original position at address,
thereby indicating the proper type of swing. To accommodate this
aspect of the golf swing, the shaft 36 will rotate a few degrees
causing the shaft 38 to move slightly to the golfer's right
(assuming a right-handed golfer) at the beginning of the downswing.
Such motion may be accomplished by a simple stop mechanism such as
a detent, or the like, properly positioned or by properly
programming the data-processing equipment. Such motion is
accommodated by the apparatus in accordance with the present
invention. Thus, all motions of the golfer including rotation of
the wrists, hands and forearms as well as cocking of the wrists and
the plane change may be accommodated, detected, and/or instructed,
as such is desired.
It will become apparent to those skilled in the art that the same
apparatus may be utilized for teaching other swings useful in
sports other than golf. For example, the bracket 32 may be moved
along the support member 10 to bring the intersection of the shafts
38 and 40 substantially over the head of the user. As opposed to a
golf club 160 being attached to the end of the shaft 40, there
could be attached a baseball bat. The bat could then be swung in
the traditional fashion with the extensible portion 66 of the shaft
40 being utilized to detect variances in the desired level swing
and the wristcock. Similarly, the apparatus so adjusted could be
utilized in the swing of a tennis racket or a cricket bat, or the
like.
* * * * *