US RE14832 E
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Description (OCR text may contain errors)
A. T. SAUNDEHS.
TENNIS BALL. APPUCATION FIL'EU4 DEC. 4, 1919.
Reissuffd Mau'. 30, 1920. 14,832.
UNITED sTATEs PATENT oEEIoE.
ADDISON T. SAUNDERS, 0F CHICOPEE, MASS & BROS., OF JERSEY CITY, NEW JERS ACHUSET'IS, ASSIGNOR TOr A. G. SPALDING' EY, A CORPORATION 0F NEW JERSEY.
Specification of Ressued Letters Patent. ReiSSued lVIal. 30, 1920. Original No. 1,287,766, dated December 17, 191.8, Serial No. 247,604, filed .Tuly 31, 1918.
Application for reissue filed December 4, 1919. Serial No. 342,514.
To all whom t may concern Be it known that I, ADDISON T. SAUNDERs, a citizen of the United States, and resident of Chicopee, Massachusetts, have inventedl certain' new and useful Improvements in Tennis-Balls, of which the following is a specification.
IMy invention relates to playing balls for the game of tennis.
The general object of my invention is to produce a tennis ball which, while possessing all the desirable qualities. of the present type as to behavior in play, will obviate the use of the usual covering of felt and thus avoid the distortion so generally produced in tennis balls in the act of laying on the covers, or by the uneven stretching of the sections thereof, as is evidenced by the flat sides which frequently exist, and which cause uneven and off direction plays.
Other objects are to secure greater uni- ,formity of character and behaviorenable greater accuracy of play, increase durability or wearing qualities, make the ball waterproof and washable, render it capable of better retaining the compressed'air, and susceptible of manufacture at a .lower cost than the balls are'now made.
The common type of tennis ball comprises anso-called center consisting of a hollow ball having but a thin wall composed of a vulcanized rubber compound of such character as to resist undue distention by the .charge of `compressed air elnployed therein, while possessing the desired distortability and resiliency under impact which operates in conjunction with that of the compressed air, said center having the property of retaining, in a degree, the air charge, and a cover consisting of sections of felt cemented to, and sewed together around this center.
Functions of the usual felt cover are to afford a surface which slightly grips or clings to the ut of the racket in cut shots, aid control, o er by skin friction a certain resistance to the air in flight,` reinforce the center and give the desired light color.
The felt cover and the cement therefor make up a considerable part of the total weight of the finished ball thus limiting the weight, 'and hence the thickness, of the wall of the center admissible under the regulations. l
Aside from the high cost of the material, the employment of a cover of felt involves numerous objectionable features. No thread has been made or found for stitching together the sections of the cover which has sufficient strength to withstand the harder blows of the racket when spun to the fineness of size required to avoid bad seams. It is wellknown that when played by strong expert players some stitches usually break out with a few blows and that the cover is raised at these points, not only being unsightly but affecting unfavorably the action of the ball in play.
As will be understood the common tennis center, or a modicatio-n thereof, by increase in' weight to the total Weight desired, or regulation weight for a ball, will not give satisfactory playing qualities without a cover.
In my improved ball the felt cover is omitted and the functions thereof are performed by an outer layer of a rubber compound, of a softer character than that of the center and this outer covering while meeting all the requirements in play avoids the obj ections which exist to the use of the felt covering.
A preferred form of my invention is illustrated in the accompanying drawing in which, l
1 indicates a tennis center of the usual character; 2 a layer of fiberized rubber com` may be-somewhat closer together and stag-l gered instead of in rows. They may be made considerably smaller with proportionate spaces between. In practice I may malte them flat bottomed and with sides at an angle of about forty-fve'degrees.
When making a ball in accordance with the above I prefer to rst makeup and vulcanize in a suitable mold a center of the usual compound and character. flate this in the mold if made by the twoJ marking for the surface of the ball;
I may inf cure of this center from that required for a finished center to allow for the later cure described below. Y
yThis center is bued in the usual way to prepare it for adhesion of a suitable cement which is next applied. This cement is to cohere the center l and the layer of berized rubber compound 2, which I prefer to make of a nearly pure, gum and sulfur mixture with nely dividedcotton ber in as great proportion as practicable. This-berized compound is sheeted and then laid upon the center lto form an even layer, or plurality' of layers, either by laying on and cutting with shears to Join the edges and l gr1 ation of a felt cover.
remove the superfluous stock in the manner Well known to the -art for laying and joining sheeted stocks,for I may mold the berized stock into thin hemispherical parts and bring two of these Ytogether over the cemented center.
I next superpose a layer of a compound of rubber of a softer and more yieldable character than that of thecenter, and in applying this layer I may use the method described .above in connection with applying the berized layer. I next vulcanize `this cover ortion over the center in a suitable mold or a time and at a temperature which does not "impair the center. To this end I vmay employ in the compounds of theselayers an organic accelerator in the usual manner.
yThe layer of a compound of softer character than the center 1 forms a clinging or ping surface for the gut strings of the racket.'
-It will be understood that the somewhat hard or stili' character of thecenternecessary forvright behavior-does not afford a surface which can' seat itself upon the gut of the racket or afford that clinging or gripping effect which isrequired for control. The layerof softer rubber does this and thus successfully supplies this function of the felt cover.
The markings upon the surface, .the use of which is optional, furnish the skin fric- They also contribute in some degree to the gripping or clinging action, upon the racket.
After curing as above, the ball is-cleansed and oo'acted with a white rubber paint, or
mineralized cement, comprising, preferably v a rubber solution with a volatile solvent and as a pigment litho ne or zinc oxid. This is applied by ippmg. When' dry this paint 1s fixed by a vaporcure. Y
Instead of making a distinct layer of berized compound 2, I can get the reinforcing i effect of the ber by mixing it into the comppund of the center lor of the softer rubr layer 3, or in both, distributing it so that I require a less proportion in each compound, but I* can get a better air-retaining effect by the construction rst described.
I may also, as an alternative forthel white rubber paint, mix the whitening pigments with the soft layer 3, oruse 'a white pigmented com ound laid upon the layer 3 before curing, but I get a whiter color by use of the rubber paint ap lied as described.
I may also lay up, be ore curing, all of the elements, 1, 2 and 3, and cure themA at one cure. AIn this case I use the `accelerator in the compound for the center 1, and thus get the greater cure required for that element-omitting the accelerator from the other compound or compounds.
Other forms of markings for the softer outer layer may be substituted for the depressed markings, such as raised markings or pebbling.
It will be understood that'the employment of the layers of rubber compound, particularly the outer softer rubber layer greatly increases the air retaining properties of the ball over that ofl a ball with the usual center and a felt cover.
I may substitute for the layer or layers of berized compound 2 a layer or layers of f-rictioned fabric.
I have made balls which played well without any intermediate ber or frictioned fabric layer by modifying the compounds and cures to get the non-distensibility in that way, such ball consisting of the center 1 of rubber and the covering layer 3 of rubber, these layers being of different degrees of hardness with the softer outside.
It will be observed that a balll of my construction is built up without stitching at any point thereof, one layer being ,superimposed on the other and united integrally therewith by curing. The softer rubber exterior cover is not intended' to function as a means for preventing distention of the ball,this function being performed by the harder ball, center 1, and when the intermediate-layer is used this functions as the y means for holding the ballto size and shape. f
tures mentioned not being included as limitations on the scope of the invention, which is defined by the following'- claims.
What I claim is: Y
l. A tennis ball comprising a hollow eenter of rubber compound and an outer layer or rubber compound, the latter being softer than the compound of the center, substantially as described.
2. A tennis ball comprising a hollow center of rubber compound, an outer layer of rubber compound, softer than that of the hollow center, and an intermediate layer composed of rubber and fibrous material, substantially as described. 3. A tennis ball comprising a hollow-center of rubber, an outer layer of rubber compound softer than that of the center, and a rubber paint coating on the softer exterior layer, substantially as described.
4. A tennis ball comprising a hollow center of rubber compound, an outer layer of rubber compound softer than that of the center, and an intermediate layer composed of rubber and fibrous material free from stitching, substantially as described.
5. A tennis ball comprising a hollow cen ter of rubber compound and an outer layer of rubber compound softer than that of the center and having high and low surface portions, substantially vas described.
6. A tennis ball comprising a hollow eenter of rubber compound, an outer layer of rubber `compound softer than that of the center, and an intermediate layer composed of rubber and brous material free from stitching, said softer layer havinghigh and low surface portions. r,
7. A hollow tennis ball having a wall composed of rubber and fabric 'and of substantially the ordinary resiliency and thickness of a tennis ball wall, said ball having on its exterior low portions consisting of depressions formed in the normal thickness of the said resilient wall and distributed over its ent ire surface, substantially as described.
In testimony whereof, I aix my signature.
ADDISON T. SAU NDERS.