US1523865A - Tennis racket - Google Patents

Description

1,523,865" B. J. CRAIG TENNI S RACKET Filed July 16 1921 Jnen for. k

Patented Jan. 20, 1925.

BUR-NIE J. CRAIG, OF CLEVELAND, OHIO.

TENNIS RACKET.

Application filed July 16, 1921. Serial No. 485,288.

To all whom v'zf may concern:

Be it known that I, BURNIE J. CRAIG, a citizen of the United States, residing at Cleveland, in the county of Ouyahogaand State of Ohio, have invented a certain new and useful Improvement in Tennis Rackets, of which the following is a. full, clear, and exact description, reference being had to the accompanying drawings.

This invention relates to tennis rackets and similar articles, wherein a suitable frame is provided with crossed members to afford a striking surface.

The crossed members are usually composed of resilient catgut which to secure the best playing condition should be placed under high tension.

, One of the ditliculties encountered in the manufacture of tennis rackets is to provide a frame which gives to a certain extent, but which also is sufficiently strong to'withstand the strain present in playing If the frame is rigid and the stringing t ght the gut is liable to break, while if the frame is flexible and the stringing tight, the frame ls'apt to break.

Many frames are now made l1ght and flexible and are strengthened by wrappings, by interposed fibre, by rawhide strips and by other means, but these frames cannot be strung so as to produce a playing surface of great resiliency without rendering either the gut or frame liable to break.

One of the causes of weakness in rackets which are tightly strung, I find, is due to the following conditions. Whenever a. ball is struck the gut of the racket is depressed at the point of contact. Under the tension sulting the sides of the frame are pulled in and the end, so to speak, is pushed out.

It will thus be seen that at the instant of impact the span across the racket is less than normal while the length of the playing surface is increased. When a blow 1s struck the decrease in width causes the transverse strings to bow down under less tension than is present in the longitudinal strings, the latter having been lengthened bv the lengthening of the frame. This 1s detrimental since at the time when the long strings should stretch the length between their points of attachment 1s increased. The throat is relatively rigid and hence this elongation. and stretching under impact occurring simultaneously, frequently produces strains in the gut and frame which are prohibitive and consequently either the gut'or frame breaks. I

The above is true notwithstanding that if the frame was perfectly rigid, the transverse strings would stretch more than the longitudinal. Experiments: show that in some rackets the longitudinal strings under onehalf inch depression at the center stretch about one twelfth of an inch, while the transverse strings stretch about one eighth of an inch.

From. the above it will be seen that in rackets heretofore manufactured there is an unequal distribution of load support which renders the frame or, gut liable to injury and prevents atrue, even, reaction to the blow by the playing surface.

It has been proposed to provide a rubber cord with a jacket of canvas and to place this cord in a channel which passes entirely around the racket frame. The gut is then looped diagonally around over the rubber cord. According to another scheme, a hollow rubbr tube is placed around the frame and the gut is strung over this tube after which the tube is inflated by means of a pump in the racket handle. The devices just described, as well as a number of others seeking to overcome the difficulties enumerated above, have proved impractical for the purposes intended.

I have found that by providing resilient cushions, which react only under great pres sure, for certain only of the strings that I can overcome the difliculties mentioned.

One of the objects of my invention is to provide a playing surface of high resiliency and at the same time render the racket less likely to be injured or to warp due to the tighter stringing employed.

Another object of the invention is to pro vide a racket frame wherein in the strung racket the frame will withstand great impact without breaking.

An additional object of the invention is to provide means whereby the playing surface is more uniform thus giving a better control of the ball and causing the ball to leave the racket sweeter and with a greater velocity.

A. further object is to provide means which will take up slack in the gut due to stretching and wear.

A specific object of the invention is to provide a resilient cushion for certain only of the strings of a tennis racket.

Additional objects will be apparent from l l (l resilient material such;

the following description talreninc onnection with the; accompanying, drawings, wherein Fig. 1 is a plan View of a tennis racket partly in section showing my inven tion applied thereto; Fig. 2 is a top plan of the same; Fig. 3 is a fragmentary sectionv of the top portion of a racket showingthe improvement; Fig. 4 is a sectional detail of a resilient cushion; Fig. 5 is an elevation ofa raclget showingthe effects of striking a ball; Fig. 6 is a sectional detailshowinga modification andlfig. 7 isa plan ,of a-modification.

, Referring. .to the drawings by reference characters, Ijhayeshown, 10, the frame ofa ratkfit, which may. be formed inthe usual mannerbya strip, of wood 11 bent into loop shape and hav-ing, its, ends merged into ahandle 14;. The usual throat piece12 may be inserted in the inner end of the frame. Securedto the frame is the customary net 15, comprising the. interwoven longitudinal and transverse, strands 16 and 1?, respectively, formed. ofcatgut or other.

material.

The rim is shown. as. formed with the usual transverse perforations 18, extending from the outer to, the inner surface of the Certain of the perforations 18 are frame. shown asconnected in pairsby peripheral slots19. The rim. may be strung in the ordinaryway, one or more catgut strands being used.

It will benoted in the drawings that the slots 19 are. shown somewhatideeper than.

parallel sides. androunded ends but other shapes may be .used, if desired.

guttapercha.

The guttapercha. is highly resilient and,

the ivory ,also possesses great resilient properti s. The ivory is particularlyuseful as it prevents thegut from cutting the softer The ivory being hard. also has theadvantage that thepull onthe ivory blocks is transferred over the entire area .of the guttapercha whereby the maximum resilient properties areobtained; If desired,1 the ivory Olfltop ply may have a groove in the outer. face in. which the gutstring lies to thereby dispose the latter.

below the surface of the frame. The lower surface of the guttapercha may be serrated, as at 26, to add to theresiliency.

In Fig. 4 at, ,the left the cushion is shown 7 as inserted before the, string 16 is tightened while at the right the parts are shown as they appear after. the gut is taut.

It will be noted that before being placed under compressiom the cushion projects a short distance above the frame and that afterstringing the cushion is flush with the frame.

In Fig. 6, I haye shown a modification wherein the cushion 29 comprises a piece of suitable metal 30 bent to provide resilient portions 31. The cushion isshown as in serted. inn suitable slot 32 in the frame 11. The cushion may be only as wide as the string 16 or wider, as desired. The-gut may be passed oyer thetop of the cushion and into the apertures 18, as shown.

hen the improvement herein described is used in connection with rackets wherein double stringingor strin ing wherein the center vstringsare arranger closerithan the sideones, thus necessitating that two strings pass through the sameapertures, I may. if desired, construct the cushions arranged beneath such strings so that the layer of resilient material will be heavier beneath such strings. In case two strings pass through the same aperture and then diverge, I may use two, cushions arranged end to-end, as shown in Fig. 7.

In using the resilient member such as described in connection with racketframes of which are constructed from layers of wood having an interposed layer of vulcanized, fibre or bakelite, I may, ifdesired, make the slots 19 extend down to the intels posed reinforcing layer and. thus support the resilientmembers directly on the reinforcement.

InFig, 5 the result of the racket striking aball isshown. The frame is pulled in at each sideA and is pushed out at the end B. The throat is relatively rigid hence there is no distortionat that point. This causes, increased distortion at the end B. The dotted. lines show the position of the frame when the ball is struck.

Having thus described my invention, I claim:

1. A racketcomprisingu frame havin a handle, and haying. apertures extending through said frame, a set of longitudinal and a set of transverse. strings. threaded through said apertures and extending from one end of the frame to the other and from one side of .the frame to the other respectively, to afford a playing surface, undresilient cushion members arranged on the frame, said resilient cushion members be ing arranged beneath and cooperating with the strings comprising but one of the sets. to afford added resiliency for saidone set of strings, the other set of strings directly engaging the material of the frame, said rcsilient cushion memberseach including a stiff upper portion and a resilient lower lllO portion, said string engaging said stifi portion.

2. A tennis racket having a frame and a handle, a slot in the frame, a support for a tennis racket string in said slot, said sup port comprising a member the top and bottom of which are substantially plane and parallel, said top portion being hard, a groove in the top of said support to re ceive a playing string, said groove terminating at points spaced from each end of the support, in an apenture which leads to the underside of said support and a string threaded through the apertures and extend ing to the opposite side of the frame, the effective length of the support being greater than the distance between the apertures.

In a tennis racket, a frame having a handle at one end, and having apertures arranged in the frame in pairs and extending through the frame, strings looped through the apertures and extending from one side of the frame to the other, and from one end of the frame to the other, to provide a playing surface, slots connecting certain pairs of apertures at the end of the frame opposite the handle, and means in said slots to increase the resiliency of the strings which extend from one end of the frame to the other, said means comprising resilient cushions located in said slots, said resilient cushions having apertures therein aligning with the apertures in the frame, the top of said resilient members being hard whereby the string will not cut the resilient members.

t. In a tennis racket, a frame having a handle and having apertures arranged in pairs and extending through the frame, said pairs of apertures in one portion of the frame being connected by slots in the outer face of the frame, said slots being Wider than the apertures, a separate, independent, resilient cushion, comprising a lower elastic portion and an upper hard port-ion, both of the same configuration and both of the configuration of the slot arranged in each of the slots and strings threaded through the apertures and over the resilient cushions and extending to another portion of the frame.

5. A tennis racket having a frame and a. handle, a slot in the frame, a support for a tennis racket string in the slot, said support comprising a built up member including two superimposed layers, the layer which engages the bottom of the slot being soft and elastic and the second layer being relatively hard with regard to the other layer, said relatively hard layer having groove in its upper surface, which groove terminates short of each end of said layer, each layer having a pair of apertures extending entirely therethrough, one aperture being located at each end of the groove, and a string threaded through said apertures and having a portion lying in said groove, said string extending to another portion of the frame and being secured thereto.

6. In a tennis racket, aframe having a handle at one end, and having apertures arranged in pairs and extending through the frame, strings looped through the apertures and extending from one side of the frame tothe other and from one end of the frame to the other to provide a playing surface, slots connecting certain pairs of apertures, and means in said slots to increase the resiliency of certain of said strings, said means comprising resilient cushions located in said slots, said resilient cushions being longer than the distance between the pairs of apertures which they connect and having a bearing surface on the frame greater than the distance between two apertures, said cushions having apertures therethrough aligning with the apertures in the frame.

In testimony whereof, I hereunto atfix my signature.

BURNIE J CRAIG,

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