Tennis exercise device

An exercise device for learning to guide a tennis racquet which includes an upwardly open ball track that is curved approximately like a horseshoe from a top view, and a support device by which the ball track is supported inclined on the ground in such a manner that the lowermost point of the ball track lies in an apex area of the curved track.

FIELD OF THE INVENTION 
The invention relates to an exercise device for learning to guide a tennis 
racquet during forehand and backhand top-spin strokes. 
BACKGROUND OF THE INVENTION 
An exercise device for learning to guide a tennis racquet is known from the 
German Gebrauchsmuster 8427527. This exercise device includes a guide rail 
following a path horizontal in the rear and rising to the front, on which 
the head of a tennis racquet is supposed to be guided in order to learn a 
defined stroke movement. The guide rail is forked in its rear area. Two 
branches are in this manner created, one of which is supposed to serve the 
learning of the forehand movement and the other one the learning of the 
backhand movement. The exercise device has two stops for the tennis 
racquet at its forked ends and a roller at its front end. The roller is 
supposed to lend the tennis racquet a tilting movement when leaving the 
guide rail. This guide rail is mounted on an elevationally adjustable 
stand. 
SUMMARY OF THE INVENTION 
The basic purpose of the invention is to provide an exercise device for 
learning to guide a tennis racquet, with which an increased success during 
learning to guide the racquet can be achieved. It is in particular the 
purpose of the present invention to provide an exercise device which makes 
it easier to learn the correct sequence of movement when stroking a tennis 
ball with forehand and backhand top-spin strokes. 
This purpose is attained according to the invention with an exercise device 
which includes an upwardly open ball track that is curved approximately 
like a horseshoe in the top view, and a support device, whereby the ball 
track can be supported inclined on the ground by means of the support 
device in such a manner that the lowermost point of the ball track lies in 
the apex area. Thus the exercise device of the invention is distinguished 
in particular by three characteristics, which in cooperation with one 
another enable quick success when learning the correct sequence of 
movement. According to a first important characteristic of the invention 
an upwardly open ball track serves to guide the tennis racquet. This 
enables the learning of the sequence of movement carried out during the 
stroke of a tennis ball, whereby in spite of a significantly slowed down 
sequence of movement for the purpose of the exercise ("slow-motion") a 
contact with the ball is possible. The tennis ball is moved along in the 
ball track with the racquet, which is moved resting with its head on the 
ball track. While right from the start the learning of the correct 
sequence of movement with ball contact is possible, the feeling for the 
ball is improved and the learning of the correct racquet position is made 
easier. The movement of the racquet can be accelerated toward the end of 
each cycle of movement while obtaining contact with the ball. The cycle of 
racquet movement, as such, can be accelerated progressively, corresponding 
with the progress, without having any influence on the contact with the 
ball. 
The second important characteristic is the design of the ball track in such 
a manner that it is curved approximately like a horseshoe in the top view. 
Also this characteristic favors the learning of the natural sequence of 
movement since the head of the racquet during the course of the "loop" 
carried out during the stroke is placed onto the ball track already prior 
to the point of contact of the ball on the racquet. This is valid for both 
the forehand stroke and also the backhand stroke. The guiding of the 
racquet head on the ball track starts, in each case, in the extent of the 
one branch of the ball track and extends over the apex and the other 
branch of the ball track. The exercise device of the invention acts in 
this manner against a "tearing" of the racquet. Rather, it trains to carry 
out a harmonic stroke, during which the racquet is pulled in an ideal loop 
through the point of contact of the ball on the racquet. 
According to a third important characteristic of the invention, the ball 
track is supported inclined on the ground by means of the support device 
in such a manner that its lowermost point lies in the apex area. A tennis 
ball received in the ball track thus assumes, due to the force of gravity, 
a position lying in the apex area of the ball track each time a ball is 
placed on the track. During repeated sequences of movement during strokes 
made by guiding the racquet head along on the ball track, the racquet 
picks up the tennis ball every time at the same spot. This gives the 
student the correct feeling for the relationship between the sequence of 
movement and contact of the ball on the racquet. 
The three above-discussed characteristics characterizing the exercise 
device of the invention enable, in their combination, a particularly quick 
learning of the correct sequence of movements for forehand and backhand 
top-spin strokes. 
A particularly preferred further development of the exercise device of the 
invention is characterized in that the ball track is curved 
three-dimensionally by being approximately S-shaped in the side view with 
the maximum drop in the apex area between the free ends of the branches. 
Such a three-dimensional curvature of the ball track is capable of further 
improving the schooling result and shortening the time needed to learn the 
correct sequence of movement. Because right from the start, the tennis 
student slowly guides his tennis racquet with the head on the ball track 
along the spacially correct sequence of movement. Here too, the invention 
again utilizes the knowledge that a defined movement can best be learned 
when it is initially exercised extremely slowly and deliberately, and only 
little by little the speed is increased. 
According to a further preferred development, the free branches of the ball 
track have open ends. This makes it possible that the tennis ball received 
by the tennis racquet in the apex area of the ball track and initially 
rolled along in the ball track is accelerated toward the end of the 
respective branch of the ball track and leaves the ball track in flight. 
Also, this characteristic contributes again to an improvement of the 
success in learning by not only (nondynamically) schooling the path of 
movement of the racquet head, but by also schooling the dynamics of the 
sequence of movement. It is particularly advantageous in this connection 
when the branches of the ball track have an inking, that increases in 
intensity toward their respective ends. This makes learning the dynamics 
of the sequence of movement easier by increasing the speed of the tennis 
racquet in correspondence with the increase of the intensity of the inking 
of the ball track. 
Two again preferred further developments of the invention are distinguished 
in such a manner that the ball track is not designed symmetrically but 
rather asymmetrically in the top view. On the one hand, both branches of 
the ball track are not advantageously equally expansive. Rather it is 
advantageous that the one branch of the ball track, namely the backhand 
branch (this is the branch over which the ball is rolled during a backhand 
stroke), is less expansive (narrower) than the other branch (the forehand 
branch). Advantageously, both branches of the ball track are not equally 
long. Rather the one branch, namely the backhand branch, is slightly 
shorter than the other branch. This is a particularly advantageous 
exercise device of the invention, in which the forehand branch is designed 
longer and expanded more than the backhand branch. 
The ball track of the exercise device of the invention has advantageously, 
at least in certain areas, an asymmetrical cross section in that the outer 
wall has a smaller radius of curvature than the inner wall. The curvature 
of radius of the outer wall corresponds thereby advantageously essentially 
with the radius of curvature of the tennis ball or is slightly less than 
same. This assures an optimum, exactly defined guiding of the tennis ball 
and prevents the tennis ball from leaving the ball track too easily. In 
this connection, one must also pay attention to the height of the ball 
track. The height is advantageously 30% to 40% of the diameter of one 
tennis ball. 
The exercise device of the invention includes, according to a further 
preferred embodiment, a center unit and two branches of the ball track 
releasably fastened to the center unit. The center unit, which includes 
the apex of the ball track, is thereby advantageously supported on a first 
stand, and the two branches of the ball track are each supported with a 
further stand. To adjust the exercise device to the dimensions of the body 
of the tennis student, all three stands are advantageously designed 
elevationally adjustable. Also the releasable fastening of the individual 
branches of the ball track to a center unit enables the adjustment of the 
exercise device to the dimensions of the body of the tennis student by 
being able to exchange differently formed ball tracks (wider or narrower) 
with one another. Furthermore, differently designed ball track branches 
can be connected to the center unit for lefthanders on the one side and 
righthanders on the other side. Moreover, this modular design of the 
exercise device of the invention makes its handling and use easier. 
Yet another preferred further development of the invention is distinguished 
in such a manner that adjacent to the area of the apex of the ball track 
there is provided a ball magazine. From such a ball magazine it is 
possible to supply, after each stroke, a new tennis ball to the ball track 
in the area of its apex so that several strokes can be carried out 
directly one after the other. Once again, the learning of the correct 
sequence of movement is made easier. 
Such a ball magazine can, according to a particularly preferred development 
of the invention, include a storage track arranged outside of the ball 
track and lower than the ball track, the storage track being suited to 
receive a plurality of tennis balls, and being connected to the ball track 
through a supply track and a ball lifter. Such an arrangement of the 
storage track is particularly advantageous in view of the fact that the 
track does not hinder the sequence of movement and in addition can be 
loaded without the tennis student having to step out of the exercise 
device. The storage track can thereby be curved in a particular 
approximately parabolic shape. This results in a particularly compact 
design of the device of the invention. The outer wall of the ball track 
has, in the area of the mouth of the supply track, advantageously a recess 
through which the tennis balls are placed into the ball track. A pivotally 
supported scoop is advantageously provided for placing the balls from the 
supply track into the ball track, to which scoop the respective tennis 
ball is fed by means of a supply track. The scoop can thereby be operated 
advantageously by means of a lever rotatably supported adjacent to the 
recess and projecting over the ball track in its base position. The 
respective lever is thereby operated by the racquet head shortly after the 
head has received the ball lying ready in the ball track. It is 
particularly advantageous when two such operating levers are provided, 
such that the one operates the scoop during forehand strokes and the other 
during backhand strokes. The respective lever not serving the operation of 
the racquet head is thereby, when the racquet head is guided through the 
apex area of the ball track, moved by the racquet head in such a manner 
that it bridges the recess in the outer wall of the ball track so that the 
racquet head does not sink into the recess. 
Of course, it is also possible to utilize differently designed ball 
magazines and ball supplies to the ball track within the scope of the 
invention. For example it is also possible to supply the tennis balls from 
the ball magazine of the ball track through a hole from below, whereby in 
this case the supply system includes a feedpipe.

DETAILED DESCRIPTION 
According to the basic design illustrated in FIGS. 1 to 3, the exercise 
device illustrated in the drawings includes an upwardly open ball track 1, 
which in the top view is bent approximately like the shape of a horseshoe. 
The ball track 1 is thereby dimensioned such that a tennis ball 2 is 
securely guided in the track (see FIG. 4). Ball track 1 is 
three-dimensionally curved (see FIG. 2) by being approximately S-shaped in 
the side view with the maximum drop between the apex area 3 and the free 
ends 4 of the branches 5. The free ends 4 of the two branches 5 of the 
ball track 1 are open so that a tennis ball 2 can leave the respective 
branch of the ball track in its extension. The two branches 5 of the ball 
track 1 have an inking E, which increases in intensity toward the ends 4. 
A front stand 6 is provided in the area of the apex 3 of the ball track. 
Front stand 6 includes essentially two U-shaped curved bars and a 
connecting web. Each of the two branches 5 of the ball track 1 is 
supported by a further rear stand 7. These rear stands each include a 
support base and a telescopic pipe. The front stand 6 and the two rear 
stands 7 are elevationally adjustable to adjust the height of the ball 
track 1 above the ground 8 relative to the body mass of the tennis 
student. Independent of the adjusted height of the ball track 1 above the 
ground 8, the ball track is aligned in a manner such that the lowermost 
point of the ball track lies in the area of the apex 3. A tennis ball 
received in the ball track 1 assumes, based on the force of gravity, a 
position in the apex area 3 of the ball track 1. 
The branch 5 of the ball track 1, in which the tennis ball rolls along when 
learning the forehand stroke, is designed slightly longer and more 
expansive than the other branch 5A of the ball track, namely the one in 
which the tennis ball rolls along when learning the backhand stroke. The 
exercise device illustrated in the drawings is configured for a 
right-handed player. A ball magazine 9 is provided in the area of the apex 
3 of the ball track. The ball magazine 9 includes a storage track 10, 
which is arranged outside of the ball track 1 and lower than same. The 
storage track 10 is connected to the ball track 1 in the apex area 3 
through a supply track 11 and a ball lifter 17 (see FIGS. 5 to 7). 
Two stepping plates T are part of the exercise device. These are placed on 
the ground 8 and mark the ideal foot position during the forehand or 
rather during the backhand stroke. The position of the tennis student in 
relationship to the exercise device can, in this manner, be reproduced. 
The stepping plates T have small nails at their undersides which penetrate 
the ground 8 and prevent a slipping of the stepping plates. 
The cross section of the ball track 1 is asymmetrical in this manner so 
that the outer wall 12 is curved with a lesser radius of curvature than 
the inner wall 13. According to FIG. 4, the radius of curvature of the 
outer wall 12 is slightly less than the radius of a tennis ball, whereas 
the radius of curvature of the inner wall 13 is approximately 50% larger 
than the radius of a tennis ball. 
FIGS. 5 to 7 show in detail that the exercise device includes a center unit 
14, to which the two branches 5 of the ball track 1 are releasably 
connected. Furthermore, the two branches 15 of the storage track 10 of the 
ball magazine 9 are connected to the center unit 14. The supply track 11 
is defined on the center unit 14 through two guide bars 16. The supply 
track 11 extends from the storage track 10 of the ball magazine 9 to a 
ball lifter 17. The outer wall 12 of the ball track 1 has, in the area of 
the ball lifter 17, a recess 18 through which the tennis balls are moved 
into the ball track 1. The oppositely lying, inner wall 13 of the ball 
track 1 has here an elevation 19, that prevents a tennis ball moved by the 
ball lifter 17 into the ball track from jumping off inwardly from the ball 
track. 
The ball lifter 17 includes a scoop 20, which is pivotally supported about 
a horizontal axis aligned transversely with respect to the extent of the 
supply track 11 by means of a hinge 21. The scoop 20 is pretensioned in 
its lowermost position, in which a tennis ball supplied through the supply 
track 11 can roll onto the scoop, by means of an elastic strip 22, which 
extends between the underside of the scoop 20 and a holding clamp 28. 
FIG. 6 shows the scoop 20 both in its lowered position and also (in broke 
lines) in its raised position, in which a supplied tennis ball rolls off 
from the scoop and through the recess 18 into the ball track 1. For a 
better understanding the scoop is identified in the lifted position with 
reference numeral 20' and the associated elastic strip with reference 
numeral 22'. 
Each operating lever 23 is supported pivotally about an axis 24 on both 
sides of the recess 18 on the outer wall 12 of the ball track 1. The two 
operating levers 23 are designed symmetrically and thus mirror each other. 
They have each two arms, which are essentially opposite one another, 
namely one first art 25 projecting upwardly beyond the ball track 1 in the 
base position G (illustrated in full lines in FIG. 7) and an oppositely 
lying second arm 26. An elastic strip 27 is connected to the second arm 26 
of each operating lever 23. The oppositely lying end of elastic strip 27 
is fixed to the holding clamp 28. Each operating lever 23 is pretensioned 
into the upright base position G through the associated elastic strip 27. 
The second arms 26 of the two operating levers 23 are moveover also among 
one another connected by an elastic strip 29, the operation of which will 
be discussed hereinafter. 
When the head of a racquet is guided according to the arrow A over the ball 
track 1 in the area of the central unit 14, then the operating lever 23, 
which the racquet hits first, is flattened (see arrow B in FIGS. 7), 
until, in the flat position F illustrated in broken lines, its first arm 
25.sub.F bridges the recess 18. Wherever subscripts appear, they represent 
the same element moved into a different position. The other operating 
lever is swung according to the arrow C into an inclined position N 
(illustrated in broken lines in FIG. 7) through the elastic strip 29.sub.F 
hinged to the second arm 26.sub.F. The head of the tennis racquet slides 
now on the first arm 25.sub.F of the flattened operating lever 23.sub.F 
over the recess 18, whereby it picks up the waiting tennis ball 2. During 
continued movement the racquet head frees the flattened operating lever 
23.sub.F,and the lever swings back into its base position due to the 
restoring force provided by the elastic strip 27.sub.F. The second 
operating lever 23.sub.N swung into its inclined position N is, at the 
same time, moved by the racquet head (see arrow D in FIG. 7), whereby the 
second arm 26.sub.N swings the scoop 20 upwardly (see FIG. 6). The tennis 
ball, which lines on the scoop 20, moves thereby through the recess 18 
into the ball track 1. In order to prevent a tennis ball from rolling 
underneath the upwardly swung position of the scoop 20' (see FIG. 6), a 
strip 30 of an elastic material placed in the area of the base of the 
supply track 11 is connected at its underside to the scoop 20. When the 
scoop 20 is swung into its upwardly swung position 20', the strip 30 first 
lying at the base of the supply track 11 assumes the inclined position 30' 
(see FIG. 6). 
Suitable damping means ensure that the operating levers 23 do not bounce 
back undamped out of their traversed or rather flattened positions 
represented by F and N in FIG. 7. Moreover stops 32 are used for limiting 
the movement of the operating levers 23 (see arrow D in FIG. 7). 
In the area where the two branches of the storage track come together there 
is arranged a resilient small plate 31. At the same time, the two guide 
bars 16 are curved at varying degrees in the area. This arrangement 
guarantees a priority control in the area of the ball supply so that 
obstructions do not occur in the area where the two branches come 
together. 
FIG. 8 shows an exercise device, which different merely in two aspects from 
the exercise device according to FIG. 1. On the one hand each of the two 
branches 5 is divided into three differently inked areas, which is shown 
by the varying shading. The differently inked areas make it easier for the 
tennis student to learn the sequence of movement, which has a varying 
characteristic in the three partial areas. 
Furthermore, two stepping plates are not placed on the ground 8. Rather one 
single larger stepping plate T' is provided, which indicates the area, in 
which both feet of the tennis student must stand. Especially during a 
forehand stroke, a certain variation possibility exists for the position 
of the feet so that the defined position of both feet specified according 
to FIG. 1 is not absolutely necessary.