Reverser apparatus for tennis rackets

A reverser apparatus for facilitating the cross stringing of tennis rackets to prevent the strings from frictional contact when pulling the cross strings through the longitudinally extending main strings, the apparatus comprising an in-line assembled plurality of similar members each with a string retainer, and actuator means for displacing, from an initial position in which all members are mutually aligned, every alternate member in one direction, and the members in between in an opposite direction. The members may include mating guide portions by which a member by its back side is slidably coupled to the front side of an adjacent member. The actuator means may consist of an actuator shaft bearing a plurality of eccenter cams. Between the members may be disposed spacers allowing to vary the mutual spacing of the members.

The present invention relates generally to the manufacture of tennis 
rackets and particularly to a reverser apparatus for stringing tennis 
rackets and more particularly to an apparatus for alternately raising and 
lowering portions of longitudinal strings stretching along a tennis racket 
frame to define weaving nest type clearances for introducing cross strings 
in the stringing of tennis racket frames. 
When stringing tennis racket frames, there are initially inserted and 
tensioned the longitudinal strings in the frame. When the longitudinal 
strings have been tensioned, the cross strings are introduced so as to 
intersect the longitudinal strings at right angles whereby the cross 
strings are alternately disposed above and below the longitudinal strings. 
When introducing the cross strings, particular care must be taken not to 
touch the tensioned longitudinal strings when pulling through the cross 
strings since when pulling the cross strings through the longitudinal 
strings there may be generated friction at the points in which the strings 
touch each other, and this friction may cause damage to the strings. For 
this reason it is required to raise the longitudinal strings that stretch 
along the tennis racket frame in a manner so that the cross strings may be 
pulled therethrough without touching the longitudinal strings. 
It is an object of the present invention to provide a reverser apparatus 
for tennis rackets, i.e. an apparatus for alternately raising and lowering 
portions of longitudinal strings stretching along a tennis racket frame to 
define weaving nest type clearances for introducing cross strings. 
It is another object of the present invention to provide a reverser 
apparatus of the stated type which apparatus may be adapted to the actual 
number of longitudinal strings stretching along a tennis racket frame and 
which apparatus may be readily applied to a larger or a smaller number of 
extended longitudinal strings, without requiring any specialized or 
additional devices, and which apparatus allows an adaptation to the 
spacing width between any two longitudinal strings. 
For achieving these objects, there is now proposed an apparatus of the type 
set forth in the beginning of the present specification which apparatus in 
accordance with the present invention comprises a plurality of discrete 
plate-shaped support bodies arranged in a line one behind the other, being 
releasably assembled and adapted for alternate sliding movement in a 
direction transversely of the longitudinal direction of the apparatus, by 
means of an actuator shaft and operating means such as a crank drive, 
eccenter gears, gearing or the like, in a manner to raise every second 
support body and to lower the support bodies disposed in between the 
raised support bodies, every discrete support body including a gripping 
arm with string retainer means. 
By means of an apparatus of this type, it is readily possible to effect the 
alternate raising and lowering of portions of longitudinal strings 
extending under tension along a tennis racket frame to define weaving nest 
type clearances for introducing the cross strings. Since the apparatus 
comprises discrete support bodies adapted to be assembled and having 
gripping arms with string retainer means, the apparatus may be adapted to 
a given number of longitudinal strings. Additionally, proper raising and 
lowering of the longitudinal strings is likewise possible in the end 
regions of tennis racket frames, and this is achieved by reducing the 
number of discrete support bodies. Since the support bodies with the 
gripping arms for the longitudinal strings are arranged on a common 
actuator shaft, it is possible to adapt the spacing of the individual 
support bodies to the spacing of the individual longitudinal strings. When 
operating the actuator shaft correspondingly, every second or alternate 
support body will be raised or lowered whereas the intermediate support 
bodies will be moved in the respective opposite direction so that by 
correspondingly raising and lowering of the longitudinal strings 
stretching along a tennis racket frame there may be defined clearances 
that correspond to a weaving nest in weaving so that cross strings may be 
introduced through these clearances without touching the longitudinal 
strings. 
Further advantageous embodiments of the present invention are recited in 
the sub-claims. In a particularly advantageous embodiment are arranged, 
between the support bodies, spacers forming longitudinal string spacing 
adapter means so that the spacings between the support bodies may be 
adapted to the spacings between the longitudinal strings.

The apparatus of the invention for alternately raising and lowering 
portions of longitudinal strings 101, 102, 103, 104 and 105 stretching 
along a tennis racket frame 100 is indicated in FIG. 1 generally by the 
reference numeral 10 and comprises several discrete support bodies 20, 21, 
22, 23, 24 arranged in a line one behind the other. The support bodies are 
mutually assembled in a manner allowing alternate displacements in a 
direction transversely of the longitudinal direction of the apparatus. In 
FIG. 1 are shown five support bodies 20 to 24 whereby a certain number of 
further support bodies arranged between the two support bodies 23 and 24 
is not shown. This is to say that the number of support bodies is 
optional; it will depend upon the number of longitudinal strings 
stretching along a tennis racket frame 100. 
Every support body 20 to 24 consists of a plate-shaped member 20a of a 
rectangular, circular or square configuration. The member 20a of every 
support body may also be of another geometrical configuration. Since all 
support bodies 20 to 24 are of the same design, the support body 20 will 
be described more in detail in the following. 
The support body 20 includes in its upper region a gripping arm 30 of a 
rod-like configuration. This gripping arm 30 extends centrally from the 
member 20a of the support body 20. The member 20a and the gripping arm 30 
are integral. An assembly of several parts is likewise possible. The 
gripping arm 30 will then be connected to the member 20a by means of screw 
or adhesive fasteners (FIGS. 1 and 3). 
The member 20a of the support body 20 furthermore includes integral front 
and rear guide elements which in the embodiment shown in FIG. 2 consist of 
dovetail guide grooves 41 and mating profiles 42 of a corresponding 
configuration. The support body 20 includes in the region of its front 
surface 20b the dovetail guide groove 41 whereas the back surface 20c of 
the member 20a of the support body 20 includes the mating profile 42 of 
the corresponding configuration so that this mating profile 42 engages the 
guide groove 41 of the support body next in line (FIG. 2). These guide 
elements 41, 42 are arranged on every support body in a direction 
transversely of the longitudinal direction of the apparatus and 
perpendicularly so that by means of these guide elements the individual 
support bodies 20 to 24 may be slidably displaced with respect to each 
other transversely of the longitudinal direction of the apparatus and in 
the directions of the arrows x and x.sub.1 (FIG. 1). The guide elements 
41, 42 concurrently serve to mutually mount the individual support bodies 
20 to 24 so that a desired number of support bodies may be readily 
assembled in a line. Instead of the above described guide elements 41, 42 
as shown in FIG. 2, there may also be provided guide elements of a 
different design. If for example all support bodies 20 to 24 are assembled 
by a peripheral frame 61, then the guide elements may be provided at the 
narrow surfaces of every support body 20 to 24 whereas the corresponding 
mating profiles may then be arranged at the mutually facing wall surfaces 
of the frame 61. The individual support bodies 20 to 24 are then slidably 
movable with respect to each other within the frame 61 (FIG. 2). In order 
to ensure that likewise in this embodiment there may be employed a desired 
number of support bodies 20 to 24, the frame 61 is of a design allowing 
shortening or extending by employing corresponding modules with plug 
connectors. 
The gripping arm 30 of the support body 20 is provided in its upper region 
with string retainer means 40 in the form of an approximately circular 
recess 40a extending transversely of the longitudinal direction of the 
apparatus and being accessible externally. This recess 40a may also be of 
a different geometrical configuration. The recess 40a must, however, be 
always designed so as to include a section 40c which is lower than the 
entry opening 40b in the front wall of the gripping arm 30. Upon 
introducing a longitudinal string in the direction of the arrow y, the 
longitudinal string will be received in this lower section 40c of the 
gripping arm 30 so that when slidably displacing the support bodies 20 to 
24 the longitudinal strings retained in the string retainers 40 may not 
escape by sliding out in lateral direction. 
All gripping arms 30, 31, 32, 33 and 34 of the support bodies 20 to 24 are 
of identical design and include identical string retainers 40. The entry 
openings 40b of the recesses 40a in the gripping arms 30 to 34 all extend 
in one direction, in order to allow simultaneous introduction of the 
longitudinal strings into the recesses 40a of the gripping arms 30 to 34 
of the support bodies 20 to 24 (FIG. 1). 
For allowing relative sliding movement of the support bodies 20 to 24 so as 
to raise every second support body whereas the respective intermediate 
support bodies are in a lowered position, every support body 20 to 24 is 
provided with operating means 50. 
In the embodiment shown in FIG. 3 the operating means 50 includes an 
elongate hole 51 in the member 20a of the support body, the elongate hole 
extending transversely of the longitudinal direction of the apparatus. The 
elongate hole 51 is delimited by two opposing and parallel sections 51a 
and 51b which merge at their ends into arcuate portions 51c and 51d. 
Within this elongate hole 51 is held and guided an eccenter disc 52 which 
is mounted on an actuator shaft 45. All other support bodies 21 to 24 are 
arranged identically to the above described design of the support body 20 
shown in FIG. 3. Merely the arrangement of the eccenter discs 52 of the 
individual support bodies 20 to 24 is mutually different. The eccenter 
discs 52 of all support bodies 20 to 24 are arranged on the common 
actuator shaft 45 which extends from the overall apparatus 10 at one end 
or at both ends and mounts at one of its ends an actuator wheel 46 or 
mounts actuator wheels at both ends. Instead of employing an actuator 
wheel 46, the free end or both free ends 45a and 45b of the actuator shaft 
45 may be arranged in the form of a crank so that by operating the crank 
or the actuator wheel 46 the actuator shaft 45 may be rotated either in 
the direction of arrow y.sub.1 or in the direction of arrow y.sub.2. The 
actuator shaft 45 concurrently serves to support and mount all support 
bodies 20 to 24. Advantageously, the actuator shaft 45 is of a square 
cross-section. The eccenter discs 52 of the individual support bodies 20 
to 24 are then provided with apertures of a corresponding configuration 
through which the actuator shaft 45 may be inserted. Because of this 
design of the actuator shaft 45 a special attachment of the eccenter discs 
52 to the actuator shaft 45 is not required. The apertures in the eccenter 
discs 52 for inserting the actuator shaft 45 are thereby sized so that the 
eccenter discs 52 will be retained by press fit on the actuator shaft 45. 
For allowing mutual sliding displacement of the support bodies 20 to 24 the 
individual support bodies with their eccenter discs 52 are arranged as 
follows: As shown in FIG. 3, the actuator shaft 45 is arranged in a 
position approximately centrally of the elongate hole 51. The eccenter 
disc 52 of the support body 20 is arranged so that the larger portion 52a 
of the disc faces the outer edge 20b of the member 20a of the support body 
20. The support body 21 next in line to the support body 20 is arranged 
with respect to its eccenter disc on the actuator shaft 45 and within the 
hole 51 so that the larger portion 52b of the eccenter disc faces the 
other outer edge 20c of the member 20a of the support body 20. The 
eccenter disc 52 of the support body 20 thus assumes the position A shown 
in FIG. 3 whereas the eccenter disc of the support body 21 next in line to 
body 20 assumes the position indicated at B. The support body 22 which in 
turn is next in line to the support body 21 is again in an eccenter disc 
position that corresponds to the position of the eccenter disc 52 of the 
support body 20. In this manner the eccenter discs 52 of the first support 
body 20 and the eccenter discs of every second support body 22, 24 assume 
the position A shown in FIG. 3 whereas the eccenter discs of the 
respective intermediate support bodies 21 and 23 assume the position B. 
When now rotating the actuator shaft through 90.degree. in the direction 
of the arrow y.sub.3 of FIG. 3, the larger portion 52a of the eccenter 
disc 52 likewise rotates in the direction of the arrow y.sub.3, and due to 
the positive guidance of the eccenter disc 52 within the elongate hole 51 
the whole support body 20 will be moved upwardly in the direction of the 
arrow x.sub.3. When rotating the actuator shaft 45 through 90.degree. in 
the direction of the arrow y.sub.3, the eccenter discs of all other 
support bodies will likewise be moved. By the different arrangement of the 
eccenter disc of the support body 21 next in line to the support body 20, 
the larger portion 52b of the eccenter disc of the support body 21 is 
likewise moved in the direction of the arrow y.sub.3 so that because of 
this positive guidance of this eccenter disc in the corresponding elongate 
hole of the support body 21 there will be effected a movement by which the 
support body 21 is moved downwardly. The overall movement resulting from 
rotation of the actuator shaft 45 is shown in FIG. 4. As may be seen, the 
support bodies 20, 22 and 24 assume an upper position whereas the other 
support bodies 21 and 23 assume a lowered position. The longitudinal 
strings 101, 102, 103, 104, 105 will then have been moved from the basic 
or initial position shown in FIGS. 1 and 7 in which the gripping arms 30 
to 34 are inserted into the longitudinal strings 101 to 105 into the 
position shown in FIG. 4 whereby the longitudinal strings 101, 103, 105 
are raised whereas the longitudinal strings 102 and 104 are lowered (FIG. 
8). In this position of the longitudinal strings 101 to 105 will be 
defined, between the raised and lowered longitudinal strings, a clearance 
110 which corresponds to a weaving nest in weaving. Through this clearance 
the cross string 125 may be introduced in the direction of the arrow z, 
without touching the longitudinal strings. When the cross string 125 has 
been passed therethrough and has simultaneously been extended through the 
frame beams, the actuator shaft 45 will again be rotated through further 
90.degree. with the result that the support bodies 21 and 23 will be moved 
from the lowered position shown in FIG. 4 into the raised position whereas 
the remaining support bodies 20, 22 and 24 are lowered, with the result 
that the longitudinal strings 102 and 104 are raised and the longitudinal 
strings 101, 103 and 105 are lowered. In this position of the longitudinal 
strings 101 to 105 will be formed anew a clearance 110 so that the cross 
string 125 extended in the first run may be passed through this new 
clearance, with the results that there will be obtained an intercepting 
string system in which the cross strings lie alternately above and below 
the longitudinal strings. 
Instead of the above described and illustrated operating means 50 there 
exists likewise the possibility of employing operating means of a 
different design for the alternate displacement of the individual support 
bodies 20 to 24. Thus, it is possible to arrange the operating means in 
the form of a crank drive or gearing. When employing gearing, the 
individual support bodies 20 to 24 will be provided in the region of one 
of their two longitudinal sides with a respective tooth rack the teeth of 
which engage the teeth of a pinion which is arranged jointly with all 
other pinions of the respective support bodies on an actuator shaft. By 
correspondingly arranged intermediate gears it is possible to move, upon 
actuation of the axis, part of the support bodies upwardly and the other 
part of the support bodies downwardly. 
The dimensions and particularly the width of each support body 20 to 24 are 
selected so that every string retainer 40 in the individual gripping arms 
30 to 34 of the support bodies 20 to 24 will be associated with a 
longitudinal string. Since the spacings between the longitudinal strings 
stretching along a tennis racket frame may vary from one type of tennis 
racket to another racket, there is provided, in accordance with a further 
embodiment of the present invention, the arrangement of spacer discs 60 
between every pair of support bodies 20 and 21. In adaptation to the 
spacings between two longitudinal strings correspondingly dimensioned 
spacer discs may be provided as spacers between the individual support 
bodies whereby these spacer discs 60 are provided with a corresponding 
guide profile that is similar to the one of the individual support bodies 
so that the spacer discs 60 and the support bodies 20 to 24 may be readily 
assembled by a module type assembly operation. By guide elements of this 
type the spacer discs 60 may be connected to the support bodies (FIG. 2). 
Every spacer disc 60 may consist of two plate-shaped members the outer 
wall surfaces of which are then provided with corresponding guide elements 
into which engage the guide elements of the next adjacent support bodies 
in front and behind. When every spacer disc 60 consists of two 
plate-shaped parallel arranged members, then it is possible to vary the 
mutual spacing of the two members, for example by means of spindle type 
screw elements so that the adjustment of the desired spacings between two 
support bodies will be possible without having recourse to several spacer 
discs of different thicknesses. The spacer discs 60 are provided with 
corresponding apertures through which the actuator shaft 45 may extend. It 
is likewise possible to extend the spacer discs 60 at their bottom and to 
interconnect the extended portions by a mounting plate so that the spacer 
discs 60 are rigidly interconnected whereas the support bodies 
respectively arranged intermediate two spacer discs may be slidably moved 
in vertical direction. 
The invention is not restricted to the above described embodiments shown in 
the appended drawings. Different configurations and arrangements of the 
support bodies should be considered to be within the scope of the 
invention just as well as operating means of a different design but of an 
equivalent operation for the vertical displacement of the individual 
support bodies. 
The support bodies 20 to 24 with their gripping arms 30 to 34 and the 
eccenter discs 52 are made of hard plastic materials or other suitable 
materials. By module type addition or removal of individual support bodies 
may be provided an apparatus having a number of gripping arms for the 
individual longitudinal strings corresponding to the number of 
longitudinal strings stretching along a tennis racket frame. The apparatus 
10 may be manufactured economically since the individual support bodies 
are of the same design. When the support bodies are provided with an 
elongate hole and an eccenter disc as operating means, the overall 
apparatus comprises merely three members, i.e. a support body with an 
eccenter disc and an actuator shaft. 
In the embodiment shown in FIG. 5 every support body 20 to 24 is arranged 
in a pocket type mounting 70 in which the support body is retained so as 
to be slidably displaceable within the inner space of the mounting 70 by 
rotating the actuator shaft 45. The mutually opposing walls of every 
mounting 70 include apertures for passing therethrough the actuator shaft 
45. The mountings 70 are retained in a frame 72 by means of guides 71 and 
are slidably movable in the horizontal direction so as to vary the spacing 
between two support bodies. In this manner it is possible to readily adapt 
the support bodies 20 to 24 to the actual spacing of two tennis racket 
longitudinal strings. By means of set screws or the like the mountings 70 
may be locked in the individual positions. 
Since the tennis racket frames taper toward their end regions, it will be 
required to operate with a lesser number of support bodies 20 to 22 in the 
racket end regions. As shown in FIG. 6, the support bodies 20 to 24 are 
maintained between two end mountings 80, 81 which are arranged on the 
actuator shaft 45 without interfering with the free movability of the 
actuator shaft 45. The end mounting 80 is delimited on the actuator shaft 
45 by the grip type handle 46a whereas the other end mounting 81 is biased 
by a resilient element such as a spring or the like 83 which engages by 
its one end 83a the end mounting 81, and by its opposite end 83b a limit 
disc 84. The limit disc 84 is arranged on the actuator shaft 45 on the end 
thereof. 
If the overall apparatus consists for example of sixteen support bodies and 
when for the tennis racket frame end regions only fourteen support bodies 
are required, the end mounting 81 will be urged against the spring 83 in 
the direction of the arrow z so that the first support body and the last 
support body will be no longer gripped by the end mountings 80, 81. These 
two support bodies will then be rotated through 180.degree. in the 
direction of the arrow z.sub.1 so that the gripping arms of these support 
bodies point downwardly. An apparatus which is reduced by this number of 
support bodies may therefore likewise be employed in the tennis racket end 
regions.