US2014989A - Stringing of tennis and like rackets - Google Patents

Description

Sept. l?, 193 s. H. slElr-'F STRINGING OF TENNIS AD LIKE RACKETS Filed May 25, 1952 3 Sheets-Sheet l 7Min/mai S/ff/f.

@pt W, W35. s. H, slEFF STRINGING OF TENNIS AND LIKE RACKETS 5 sheets-sheet 2 Filed lMay 25, 1952 Sept.. l?, 1935. s. H. slEFF STRINGING OF TENNIS AND LIKE RACKETS Filed May 23, 1932 5 Sheetfs-Sheetv 3 Patented Sept. 17, 1935 PAENT OFFCE Application May 23,'1932, Serial No. 613,091

lin Great Britain June 6, 1931 claims. (el, 273-43) This invention relates to a -method of stringing tennis and other rackets, and apparatus for applying mechanically the required tension thereto.

The method at present used for hand stringing and tensioning tennis and the like raokets involves the use of two lengths of gut or other suitable material, one length being suficient to provide all the mains or longitudinal strings, and the other being sufiicient to provide all the cross strings.

In Stringing the cross strings the single length of gut is threaded through opposite holes in the racket frame at the handle end, and is pulled through until only a short length is left, at one end. This end is then knotted to prevent it from being drawn through the hole in the racket frame during tensioning, which operation is effected by the operator pulling on the opposite end of the gut, and when the required tension has thus been applied the hole in the racket frame through which the outer or free end of the gut passes is plugged so as to maintain the tension of the tted string. The gut is then threaded back in the opposite direction through the next pair of holes when the abovementioned operation is repeated and so on until all of the cross strings have been threaded and tensioned. In threading and tensioning the mains the operation is slightly varied in that the gut is rst threaded through the two holes at the handle end which lie one at each side of the centre, and then pulled through until the two ends are of equal length. These ends are then threaded through the equivalent holes at the opposite end of the racketl frame. One of the strings thus fitted is then held by plugging Whilst the other string is tensioned. The string thus tensioned is held as before by plugging and the next main is iitted by threading one of the free ends of gut through the next adjacent pair of opposite holes,

the operations of tensioning and plugging being around which the free ends of each string after threading are wound, the required tension being imparted by rotating such Winding spindles,l

means being provided for measuring or auto-A matically regulating the tension applied to a predetermined amount.

In all such apparatus the tension is applied to each string in turn as it is strung similarly to' the normal hand process. In effect therefore the operation is really slower than by the hand Y method as after each tensioning the free end 5 of the string has to be unwound from the winding spindle so that the same can be threaded through the next pair of holes.

One of the objects of the present invention is to provide a new and improved method of stringing and tensioning racket frames which will enable the operation to be effected more expeditiously than heretofore and without requiring any particular skill or physical exertion on the part of the operator. l5

iioat or buoyant body in a liquid.

In Stringing a racket frame by the method according to this invention it is preferred that the tensioning of the strings be effected one or more at a time in alternation, rstly on one side of the racket frame and then on the opposite side by gripping such string or strings on the outside of the racket frame the predetermined tension being applied thereto by a mechanically applied pull, each tensioned string being held during the release of the tensioning pull by gripping the same on the inside of the racket frame.

In the apparatus according to the preferred embodiment of the invention a predetermined and existing load is applied to the string or strings to be tensioned by rstly depressing the float or other buoyant body down into the supporting liquid, whilst the string or strings are engaged by suitable gripping means and then causing the required load to be applied either gradually or immediatelyby similarly releasing such float so as to permit the same to rise by reason of its buoyancy to its normal position in the liquid, such upward movement being caused to effect thel outward Withdrawal of the aforesaid gripping means by suitable operative connections.

In order that the invention may be clearly understood and carried into efect an apparatus according to such an embodiment of the invention will now be described by aid of the accompanying drawings in which:-

Figure l is a part sectional elevation of a racket string tensioning machine according to this invention.

Figure 2 is a top plan view thereof.

Figure 3 is a part sectional elevation to an enlarged scale of one of the racket frame grippers.

Figure 4 is a side elevation to an enlarged scale showing the string gripping mechanism with the parts in the positions at the commencement of tensioning.

Figure 5 is a similar view but showing the parts in the positions after tensioning has been completed.

The apparatus illustrated in the drawings comprises a horizontal table I upon which is mounted the means for supporting each racket frame, which' has been previously tted with the strings to be tensioned, and the gripping mechanism for engaging such strings during tensioning. This table Iv is mounted upon the upper end of a cylindrical or other shaped tank 2 containing a float 3 and water or other suitable liquid 4. This iloat 3 is arranged to slide up and down a central vertical spindle 5, such movement of the float being imparted by means of suitable connections, hereinafter to be described, to the string gripping devices in such a manner that when the float is depressed against the action of the liquid such devices are moved inwards towards the racket frame to a position where they can be engaged with the strings to be tensioned, the tensioning then being eiected by permitting the float to rise again on account of its buoyancy.

As previously mentioned each racket frame, before being placed in position on the machine, is fitted by hand with both the main and cross strings by a simple threading operation requiring but little skill on the part of the operator. The loosely strung frame, whichis indicated in the drawings by the reference numeral 6, is then clamped into position above and central of the horizontal table I. The clamping means adopted for this purpose in the example illustrated comprises four lugs 'I each of which is provided with a depending do'wel pin 'Ia adapted to t in holes or recesses drilled for the purpose from the top surface of supporting plates 8 which are mounted so as to be movable along slides 8a carried bya base 8b which rests upon the surface of the table I sdthat such lugs are free to partially rotate and accommodate themselves to the inside contour of the racket frame. Movement of the plates 3 towards or away from each other is imparted simultaneously by means of` a screw 8c. The pull imposed upon the racket frame during the tensioning of thestrings is resisted by upstanding portions Ib forming part of the arofesaid lugs l', such upstanding portions being shaped to t closely against the inside faces of the racket frame bythe outward movement of the two plates 8 and of such a height as to come just below the level of the strings. frame when thus positioned upon the upper faces of these lugs is heldtightly in position ,thereon by means of four clamping bars 9, one to each lug. These clamping bars, which are illustrated most clearly in Figure 3, are provided at their outer ends with thumb screws 9a and at their The racket inner ends with broad or spatular portions I adapted to rest upon the upper surfaces of the positioned racket frame. The necessary clamping pressure is applied to the racket frame by turning the thumb screws 8a and such pressure is resisted by abutments II which extend outwards from the edge or" the plate 8. These abutments also serve as a support for the fulcruin pin I2 of the clamping levers, such pins being carried by the lower ends of pairs of lugs I 2a forming part of and depending from the clamping levers. In the construction illustrated the clamping levers with their fulcrum pins and thumb screws are detached, when desired by withdrawing the same over the ends of the abutments II, whilst the racket frame is released by moving the plates 8 inwards towards each other.

The string engaging mechanism is most clearly illustrated in Figures 4 and 5 and comprises pairs of carriages I3 mounted within slides I4 on the upper surface of the table I, and on opposite sides of the racket frame supporting plate 8. The carriages in each pair are arranged to move in their slides towards or away from each other by means of right and left handed screws I5 such screws engaging nuts I6 attached to said carriages and being rotated by means of handles II.

Slidably supported by each carriage, and so as to move in a direction towards or away from a positioned racket frame, is a squared rod I8 each of which carries at its outer end a pivoted hook I9 having a depending extremity Isa fitted with a roller or other anti-friction device, and a further pivoted arm having the same fulcrum pin as the hook I9 on the outer end of which is mounted a device adapted to grip one of the strings of the racket during tensioning.

In the form illustrated this gripping device comprises a Xed jaw 2i and a movable jaw 22 the movable jaw being forced towards the fixed jaw by means of a cam actuated by a handle 22a. The string to be engaged is fitted from one side of the device betweenthese two jaws and is clamped in position therebetween by pulling over the handle from the dotted position shown in Figure 4 to the full line position or vice versa. When the engaged string has been tensioned it is engaged on the inside of the racket frame by means of a further clamping device 23 slidably mounted upon an arm 2.4 pivoted as at 25 to each carriage I3 such arm during the tensioning of the rst string being swung back to the position shown in Figure 4. To engage it with the tensoned string it is swungfover to the position shown in Figure 5, the operation of engaging the tensioned string and itsaction being similar to the other device carried by the arms 20 and serving to lock the same on the arm 24.

The outer ends of each of the square reciprocating rods I8 are connected to the iloat 3 by means, in the example illustrated, of ilexible wires or the like 26, levers 2l and connecting links 28, such wires or the like passing around compensating pulleys 2Q carried by and adjustable in position on the outer ends of the levers 2l such adjustment being effected by means of screws and hand wheels 3|.

The iioat 3 is depressed, in the example illustrated, by means comprising a pulley 32 mounted upon the inner end of a spindle 33 having at its outer end a suitable operating handle 34 and exv ible wires or cords 35 which at their inner ends are woundaround said pulley 32, their outer ends being connected to levers 36, mounted 0n shafts 75 '31 said shafts having also mounted thereon levers 38 which pass through openings 39 in the table I and are connected together at theirV outer ends by members 40, which engage hooks 4I forming part of or rigidly attached to the inner ends of the square spindles I8.

When the operating handle 34 is turned the consequential partial rotation of the pulley 32 causes the levers to be turned and bring the members 40 into engagement with the hooks 4I. In consequence the square spindles I8 are pulled inwards towards the racket frame. At the same time the outer ends of the levers 21 are pulled up by the connections 26 whilst their inner ends and the float to which they are attached are depressed.

In stringing a racket with a machine according to this invention two of the hooks I9 at one side of the machine are engaged in the loops of adjacent strings on the same side of the racket, such hooks having been brought into position for such engagement by depressing the float into the liquid within the tank 2. As previously explained this is effected by the operato-r turning the hand Wheel 34.

When the loops of the strings to be tensioned have thus been engaged the operator slacks back the hand wheel thus allowing the float to commence to rise and so impart corresponding outward movement to the square rods I 8 carrying the hooks I9. In consequence the engaged strings are pulled out away from theY racket frame and this movement is continued until sufcient string projects for the same to be engaged by the gripping device proper. These devices are then operated to engage the extremities of the particular strings to be tensioned when the operato-r releases the hand Wheel 34 allowing the float to rise again to its normal position and in the `process to apply the correct and predetermined tension to the engaged string. These strings are then engaged by the grippers 23 when the tensioning grippers and the hooks I are released after which a further pair of string loops are engaged on the opposite side of the racket frame,

the operation being repeated alternately at opposite sides of the racket frame until all of the mains or cross strings have been tensioned.

To lcomplete the tensioning of the remaining cross strings or mains the racket frame is turned through a right angle by first lifting and then rotating its supporting plate 8, such lifting movement being necessary to permit the handle of the racquet to clear the gripping devices.

In an alternative construction the carriages I3 are dispensed with, the gripping devices and the pivoted arms carrying the same being mountr ed so as to be free to slide along and be swung about horizontal supporting rods the operator moving the same by hand along such rods into the positions required for engaging the strings to be tensioned.

Alternatively the string gripping devices may be attached to the upper arms of vertically arranged bell-crank levers through a suitable compensating link, an equivalent link serving to connect the other or lower arms of such levers to the oat. In such an arrangement the aforesaid slides and reciprocating rods are dispensed with. The depression of the float in this arrangement can be effected by flexible connections such as 25 and an operating pulley such as 32.

In practice when tensioning the cross strings it is preferred to work from the middle strings outwards towards the outer strings; similarly with the main strings.

Any suitable means may be provided for holding the handwheel 34 against the action of the float such as ratchet and pawl mechanism and/ or a hand or foot operated brake. As shown a stop is provided to limit the turning movement of such handwheel, such stop comprising a xed nger 42 and a 'co-acting pin 43 movable with the handwheel. l

The operation of threading the strings to be tensioned is preferably effected away from the tensioning machine and such operation is facilitated by the use of a pair of clamping plates, having interengaging projections and recesses so l arranged as to crimp the longitudinal strings which are fitted first and to provide aligned passages for the transverse strings. The string may be threaded by means of a ilexible needle having, for example a tapered threaded hole in one end 2 into which the free end of the string is screwed. Other xing means may however be used.

I claim:

l. Apparatus for mechanically tensioning the strings of rackets wherein the required tensioning 2 load is applied to the strings to be tensioned by the action of a float or buoyant body in a liquid.

2. Apparatus for mechanically tensioning the strings of rackets comprising a tank or the like containing a liquid, a oat or other buoyant body P disposed within and supported by said liquid, means for engaging the strings to be tensioned, means operatively connecting said string engaging means to said float and means for periodically depressing the iloat into the-liquid during the engagement of the string or strings to be tensioned by the said engaging means whereby upon the release of the oat and its consequent upward movement in the liquid a predetermined tensioning pull is imparted to said engaged string or 4 strings.

3. Apparatus for mechanically tensioning the strings of tennis and other rackets comprising a horizontal table supported by a cylindrical or other shaped tank containing a vertically movable i oat or the like, and, in use, a liquid for supporting said float, said table being adapted to support each racket frame, the strings of which are to be tensioned, and the means for applying the required tensioning pull to one or more of said 5 strings in turn said pull being imparted by an upward movement of the float in the liquid through a suitable operative connection between said float and said pull applying means.

4. Apparatus for mechanically tensioning the 5 strings of rackets comprising in combination means for securing a racket frame in position on the machine, means for engaging the outer loops of a pair of strings previously threaded across the racket frame and on one side of the 6 racket frame, means for applying a predetermined tensioning pull to said engaged strings simultaneously and means for engaging said tensioned strings on the inside of the racket frame so as to hold the same under tension and permit 6 the pull applying means to be disengaged from said tensioned strings.

5. Apparatus for mechanically tensioning the strings of rackets comprising in combination means for securing a racket frame in position on the machine, means for engaging the outer loops of a pair of strings on one side of the racket frame, further means for engaging the outer ends of a pair of strings on the opposite side of the racket frame, load applying means for withdrawing said engaging means away from the racket frame so as to apply a predetermined tension to each pair of engaged strings successively, and means associated with said outside engaging means for engaging each pair of strings after being tensioned on the inside of the racket frame to hold the same under tension during the release or the load applying means.

6. Apparatus for mechanically tensioning the strings of rackets comprising means for securing a racket frame in position on the machine, string engaging means on the outside of the racket frame, said means being movable towards and away from the racket frame, load applying means operatively connected to said string engaging means and tending to hold the same in the outer position, means for forcibly moving said string engaging means inwards towards the racket frame against the action of the load applying means and for effecting engagement between the strings to be tensioned and said string engaging means so that upon the outward movement of the string engaging means imparted by the load applying means a predetermined tension is applied to the engaged strings, and means for engaging the tensioned strings and holding the same under tension during the release of the load applying means.

'7. Apparatus for mechanically tensioning the strings of rackets comprising means for securing a racket frame in position on the machine, string engaging means movable towards and away from the racket frame, load applying means operatively connected with said string engaging means and tending to hold the same in outer position, and means for moving said string engaging means inwards towards the racket frame against the load applying means for engaging the strings to be tensioned, tensioning of said engaged strings being effected by outward movement of the string engaging means under the action of the load applying means.

8. Apparatus for mechanically tensioning the strings of rackets comprising load applying means and string engaging means movable inwards towards a positioned racket against a load to permit engagement with the string or strings to be tensioned, and when released movable outwards away from the racket frame by said load applying means to impart tension to the engaged string or strings.

9. Apparatus for mechanically tensioning the strings of rackets comprising string engaging means movable towards and away from a positioned racket frame, a buoyant body operatively connected to said string engaging means and located within a chamber adapted to contain a body of liquid, and means for moving said string engaging means inwards towards the racket frame topermit said string engaging means to be engaged with a string or strings to be tensioned and to eiect depression of the buoyant body into said body of liquid whereby upon the release of the buoyant body depressing means, the buoyant body is permitted to rise in the body of liquid thereby to move the string engaging means outwards and impart tension to the engaged string or strings.

1G. Apparatus for tensioning the strings of rackets comprising means for securing a racket frame in position on the machine, string engaging means slidably mounted on opposite sides of the positioned racket frame soas to be movable towards and away from said racket frame, a container for a body of liquid, a iloat vertically movable within said container, an operative connection between said oat and said string engaging means, whereby inward movement of said string engaging means effects depression of said float within the liquid in said container, and means for eiiecting said inward movement of the string engaging means and the depression of the fioat thereby to permit said string engaging means to be engaged with the strings to be tensioned on opposite sides of the racket frame in alternation, the tensioning of said engaged strings being effected by the outward movement of the string engaging means imparted automatically by the upward movement of the float in the liquid.

SOLOMON HIRSH SIEFF.

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