US1989002A

US1989002A - Apparatus for stringing tennis rackets

Info

Publication number: US1989002A
Application number: US667260A
Authority: US
Inventors: Laurance C Doll
Original assignee: Individual
Current assignee: Individual
Priority date: 1933-04-21
Filing date: 1933-04-21
Publication date: 1935-01-22
Anticipated expiration: 1952-01-22

Description

Jan. 22, 1935.

1.. c, DOLL w 1,989,002

APPARATUS FOR STRINGING TENNIS RACKETS Filed April 21, 1933 2 Sheets-Shet 1 w, R dig. ,0

' /v 5k 9 Z /v 5 ,5 /v dag 0 F 0 J" l w-m. W m am" *5 H 1- 1 6 w 1: J 6i gwwntoc Patented Jan. 22, 1935 UNITED STATES PATENT OFFICE j APPARATUS FOR. STRINGING TENNIS V aAoKs'rs This invention reiates to certain new and useful' improvements in apparatus for stringing tennis rackets. a 1

The primary object of the invention isto provideapparatus for the stringing of tennis rackets with gut, sill: strings or the like, or for the tensioning of cables, cords or similar elements wherein an even tension is placed on a series of strings as in a tennis racket.

A further object of the invention is to provide apparatus for the stringing of tennis rackets comprising a stand for the support of a racket with means supported on the stand. andengageable with the racket and carrying a pressure operated string grip under manual control of the operator for drawing 'the'string through the racket to place the same under tension, the support per se for the racket being rotatably mounted upon the stand to present in succession string sections of the racket in line with the pulling force of the stringing apparatus controllable in its operation for placing even tension on all of the strings.

With the above and other objects in view that will become apparent as the nature of the invention is better understood, the same consists in the novel form, combination and arrangement of parts hereinafter more fully described, shown in the accompanying drawings and claimed.

- In-the drawings:-

Figure 1 is a perspective view of the stand and support for a racket-to be strung with the string tensioning device illustrated as adjustably supported on the stand;

Figure 2 is a detail sectional view showing the rotatable mounting of the tennis racket support on the stand; s

Figure 3 is a detail sectional view taken on line 33 of Figure 1, showing the mounting for one of the racket supporting horns on the support with a part of a tennis racket illustrated as clampingly retained in position on the horn;

Figure 4 is a top plan view of the string tensioning device; v

Figure 5 is a longitudinal sectional view taken on line 55 of Figure 4, showing the fluid operated piston carrying the string gripping jaws; Figure 6 is a cross-sectional viewtaken on line 66 of Figure 4, showing the manually operable pressure fluid supply and exhaust valve controlling operation .of the piston carrying jaws;

and

I Figure '7 isa detail sectional view taken on line ,7-'Z of Figure 5, showing the tensioned string gripping jaws;

Referring more in detail to the accompanying drawings, and particularlyto Figures 1 to 3, there is illustrated an apparatus for the stringing of tennis rackets and for the tensioning of the racket strings comprising a stand of tripod formation including a perpendicular tubular standard A having a head block B secured to the upper end thereof with angle legs C connected to the head block B, thestandard A and legs C being provided with floor anchor feet D.

A support per se' for a tennis racket is vertically adjustably mounted within the tubular standard A and is also rotatable in the standard in a stepby-step movement under control of pawl and ratchet devices, the supportincluding a shaft E having three arms F horizontally disposed and extendingradially of its upper end, the shaft E being mounted "in tubular standard A. As shown in detail in Figure 2, the shaft E passes through a disk G that is provided with anaxially depending annular flange H surrounding the opening through which the shaft E passes and said flange H is adjustably connected to the shaft E by means of a cross-pin I extending through diametrically opposite openings in the flange H and selectively through transverse openings J in the shaft E. The flange H seats in an annular pocket K in the upper side of the head block B and is rotatably retained therein by means of the stud screw L threaded radially of the head block B with its inner end extending into an annular groove M in the flange H. I

To accomplish the step-by-step rotary movement of the racket support, the under side of the disk G is provided with'a circular series of ratchet teeth G with which the tensioneddog B carried by the-stationary head block B is engaged. The dog and ratchet devices are so related as to bring the next string opening in the racket frame into pullingalinement with the string tensioning device.

The radial arms F are triangularly arranged as shown in Figure 1 and each arm is of channel formation and adjustably supports a perpendicular horn N retained in adjusted positions by the screws 0, the upper end of each horn N being shouldered as at P to provide a support for the frame Q of a tennis racket, two of the horns N carrying hinged clamp members R for holding the racket frame in position on the horns.

The racket stringing and tensioning device for the strings is carried by a bracket S adjustably mounted asat T upon the tubular standard A,

the upper end of the bracket S being angularly bent as at U to provide a horizontal shelf support for the string stretching and tensioning device V illustrated in detail in Figures 4 to 7.

The string tensioning device comprises a cylinder 10 secured to the horizontal shelf by means of a screw 10a projecting laterally of the cylinder 10 and extending through a slot 10b in the shelf to receive the clamping nut 100, the cylinder being adjustable longitudinally of the shelf.

The cylinder 10 has a piston 11 reciprocating therein that is normally influenced in its movement toward the end of the cylinder 10 carrying,

the head 29 that constitutes a valve device by means of a coil spring 22 having abutting engagement at one end with the cylinder cap 24 retained in position by the screws 25. The cylinder 11 is provided with an axial bore 11a opening at the end thereof directly toward the end cap 24 and said coil spring 22 extends into the bore 11a, the relatively long stud 23 carried by the end cap 24 providing a guide support for the coil spring 22 and extending into the bore 11a of the piston 11. The cylinder 10 is longitudinally slotted as at 10d at a point substantially midway its ends to the end adjacent the cap 24 for the clearance of string gripping jaws carried by the piston 11. i

As shown more clearly in Figures 5 and 7 a block 13 is secured by means of screws 12 to the piston 11 and is slidable in the slot 10d, the block 13 being cut away at its outer side for the reception of a pair of cooperating wedge shaped string gripping jaws 14 that have their opposed faces suitably fashioned for gripping engagement with a racket string without in any manner injuring the latter. The opposed'faces of the gripping jaws l4 and the block 13 are relatively inclined to cause movement of the jaw members 14 toward each other when they are shifted longitudinally of the block 13, the opposed faces of the wedge shaped jaw members and block 13 being further cut away to provide mating recesses for the reception of coil springs 17 acting to maintain the jaws 14 in string gripping relation. The jaws 14 are guided in their movement by means of pin and slot connection between the jaws 14 and block 13. A pair of spaced cover plates 15 overlie the jaws 14 and are secured to the block 13 by means of screws 16. When the piston 11 carrying the string gripping jaws 14 is disposed at the end of the cylinder 10 adjacent the valve head 29 underinfluence of the spring 22, the normally projecting ends of the jaws 14 as shown in Figures 4, 5 and 7 are in engagement with an abutment block 21 carried exteriorly of the cylinder 10 said block serving to hold the string gripping jaws 14 separated from one another against the tension of the spring devices 17 for receiving a racket string therebetween. As soon as the piston 11 moves in the cylinder 10, the springs 17 exert their force to shift the wedging string gripping jaws 14 into engagement with a string, the jaws 14 being displaced from the abutment lug 21. The outer end of the piston 11 has a flexible gasket 26 secured thereto by means of a metallic washer 2'7 and set screws 28 entering the outer end of the piston with the gasket moving in working contact with the inner wall of the cylinder 10.

The valve head 29 embodies manually operated devices designed for the introduction of fluid under pressure to the outer end of the cylinder 10 for moving the piston 11 against the tension of the spring 22' and to accomplish the exhausting of fluid from the cylinder to permit the spring 22 to shift the piston 11 to the position shown in Figure 5. The valve head 29 is provided with a transverse bore 29a in which a valve stem 30 is reciprocably mounted, one end of the valve stem 30 being socketed as at 30a with the socketed end directed toward a cap 32 secured by means of set screws 33 to a tubular boss 29b carried by the valve head 29. .14 pin 32a carried by the end cap 32 projects intothe' recess 30a in the Valve stem 30 and is surrounded by a coil spring 31 engaging the inner side of the cap 32 and the bottom of the recess 30a in the valve stem 30 for normally shifting the valve stem 30 to a closed position relative to fluid supply passages or bores through the valve head 29. The side of the valve head 29 opposite the cap 32 carries a tubular boss 290 into which the valve stem 30 extends and the outer end of said boss 290 carries an end cap 3'7 secured thereto as at 38 and provided with a slotted opening for the projection of the handle 34a carrying a button 34 at its outer end, the handle 340. being pivotally connected by means of a cross pin 35 at its inner end to the adjacent end of the valve stem 30. The handle 34a is provided with a shoulder 36 to be engaged by the part of the cap 37 for retaining the valve stem 30 projected in open position for the flow of fluid under pressure to the cylinder 10 and against the tension of the spring 31 engaged with the valve stem 30. A flexible conduit or other conductor 39a in communi-' cation with a source of fluid of any character under pressure is attached to the nipple 39 entering the lower side of the valve head 29 and said valve head has a port 2911 extending between the supply nipple 39 and the bore 29a of the valve head. The valve stem 30 has an angle port 301) therein that is normally out of communication with the port 29d in the valve head as shown in Figure 6 and this angle port 301) is also normally out of communication with the port 296 in the valve head that is shown in Figure 5 as extending between the cylinder 10 and the bore 29a in the valve head. With the valve 30 in the position shown in Figure 6, the port 29d is closed by the valve and the port 300 in the socketed end of the valve is in communication with the port 29c as shown in Figure 5. When the valve 30 is shifted against the tension of the spring 31 by manual operation of the handle 34a, the angle port 30b forms communication between the ports 29d and the port 29c so that fluid under pressure flows into the cylinder 10 for moving the piston 11 against the tension of the spring 22. To exhaust the fluid from the cylinder 10 and to permit the spring 22 to move the piston 11 in the cylinder for freeing the jaws 14 from engagement with the racket string, the valve 30 is shifted to the position shown in Figure 6 for closing the supply port 29d and bringing the port 300 into registry with the port 29c, as shown in Figure 5 whereupon fluid trapped in the cylinder 10 flows into the socketed end 30a of the valve to escape through the exhaust port 32b in the cap 32. .A pair of spaced lugs 40 rises from the upper side of the valve head 29 for abutting engagement with the frame of the racket Q with the racket string passing between the lugs 40 and engaged with the string gripping jaws 14.

In the use of the device, a tennis racket Q is engaged with the shoulders P of the horns N, retained thereon by the clamp R and one of the openings in the bracket Q is aligned with the string stretching and tensioning device V. The lugs 40 are abuttingly engaged with the frame of the rocket Q and the racket thread is passed between the lugs 'ii-and is'threadedintothe open space betweenthe gripping jaws 514'. The valve stem 30 isthen shifted'by means of the'operating head 34against the tension of the spring 31 to move the port 30cinto registry with the port 29e,'--'and'at which time fluid undera predetermined'pressure isdirectedinto the outer end of the cylinder for moving the piston 11 therein against the tension of the spring 22. As soon as the gripping jaws 14 are spaced from the abut ment lug 21 the springs 'lt associated with the gripping jaws 14' cause the latter to grippingly engage the racket string, continued movement of the piston 11 under influence of fluid pressure placing the racket string under tension. A suitable wedge or the like isthen inserted in the thread opening in the frame of the racket Q' for retaining the stretched string'at the tension placed thereon bythe device. When the valve stem 80 is shifted to its retracted or closed position by means of the spring 31, the supply of fluidlunder pressure is cut ofi and-fluid trapped inthe'cylinde'r- 1i) escapes throughthe-valve head 29 which restores the piston 11f to the position shown in Figure 5 for the release of the-racketstring from the gripping jaws 14; The racket support is then rotatably'shifted a single'step by means of the pawl and ratchet devices G and B to present the next opening in the racket frame in line with the abutment lugs 40 and gripping jaws 14, whereupon the stretching and tensioning operation on the string is repeated. It will be seen that an even tension can be placed on all the strings of a tennis racket and the tension of the strings of different rackets may be varied under control of predetermined pressure of fluid supplied to the device. It is to be understood that the fluid operated string stretching and tensioning device may be operated either pneumatically, hydraulically or in any preferred manner and the statements herein referring to fluid operation is not to be con-, strued as limiting the invention to the character of motivating forces.

While there is herein shown and described the preferred embodiment of the invention, it is nevertheless to be understood that minor changes may be made therein without departing from the spirit and scope of the invention as claimed.

I claim:

1. In a stringing and tensioning device for tennis racket strings, a support for a tennis racket, a string stretching and tensioning device associated with the support and including a cylinder, a fluid operated tensioned piston therein, string gripping jaws carried by the piston and valve means for controlling the supply and exhaust of fluid under pressure to the cylinder, and lugs carried by the cylinder for abutting engagement with the racket in opposition to the string pulling force of the jaws.

2. In a stringing and tensioning device for tennis racket strings, a support for a tennis racket, a string stretching and tensioning device associated with the support and including a cylinder, a fluid operated tensioned piston therein, string gripping jaws carried by the piston and valve means for controlling the supply and exhaust of fluid under pressure to the cylinder, and means carried by the cylinder to be engaged by the jaws for disengaging the jaws from the racket string.

3. In a stringing and tensioning device for ten nis racket strings, a support for a tennis racket, a string stretching and tensioning device associated with the support and including a cylinder,

a fluidoperated tensionedipiston therein, string gripping jaws carried by the piston and valve means for controlling the supply and exhaustof fluid under pressure to the cylinder, and lugs carried by the cylinder for abutting engagement with theracket in oppos'ition'to the string pulling force ofthe jaws, and means carried by the cylinder to be engaged by the jawsior disengaging the jaws from the racket string.

4. In a stringing and tensioning device for tennis racket strings, a support for a tennis racket, a string stretching and tensioning deviceassociatedv with the support and including a cylinder, 2. fluid operated tensioned piston therein, string gripping jaws carried by the piston and valve means for controlling the supply and exhaust or fluid under pressure to'the cylinder, the support including a rotatable frame; a stationary stand supporting the frame and pawl and ratchet devices between the frame and stand whereby the support is rotated in a step-by step movement for the successive tensioning of the racket strings.

5. In a stringing and tensioning device for tennis racket fstrings,fa support for a tennis racket,

a string stretching and tensioning device. associated with the support and including a cylinder, a'fluid operated tensioned piston therein, string grippingv jaws carried by the piston andvalve means for controlling the supply and exhaust of fluid' under pressure to the cylinder, means carried by the cylinder to be engaged by the jaws for disengaging the jaws from the racket string, the support including a rotatable frame, a sta tionary stand supporting the frame and pawl and ratchet devices between the frame and stand whereby the support is rotated in a step-by-step movement for the successive tensioning of the racket strings.

6. In a stringing and tensioning device for tennis racket strings, a support for a tennis racket,

, a string stretching and tensioning device associated with the support and including a cylinder, a fluid operated tensioned piston therein, string gripping jaws carried by the piston and valve means for controlling the supply and exhaust of fluid under pressure to the cylinder, and means carried by the cylinder to be engaged by the jaws for disengaging the jaws from the racket string, the support including a rotatable frame, a stationary stand supporting the frame and pawl and ratchet devices between the frame and stand whereby the support is rotated in a step-by-step movement for the successive tensioning of the racket strings.

7. In a stringing and tensioning device for tennis racket strings, a support for a tennis racket, a string stretching and tensioning device associated with the support and including a cylinder, a fluid operated tensioned piston therein, string gripping jaws carried by the piston and valve means for controlling the supply and exhaust of fluid under pressure to the cylinder, and lugs carried by the cylinder for abutting engagement with the racket in opposition to the string pulling force of the jaws, and means carried by the cylinder to be engaged by the jaws for disengaging the jaws from the racket string, the support including a rotatable frame, a stationary stand supporting the frame and pawl and ratchet devices between the frame and stand whereby the support is rotated in a step-by-step movement for the successive tensioning of the racket strings.

8. In a stringing and tensioning device for tennis racket strings, a support for a tennis racket, a string stretching and tensioning device associated with the support and including a cylinder, having a side slot, a piston in the cylinder,'-a block fixed to the piston and projecting through the slot,.a pair of tensioned string gripping jaws carried by the block and means for moving the jaws to disengaging position relative to the racket string when the piston is at its limit of movement in one direction. a

9. In a stringing and tensioning device fortennis racket strings, a supportfor a tennis racket, a string stretching and tensioning device associated with the support and including a cylinder, having a side slot, a piston in the cylinder, a block fixed to the piston and projecting through the slot, a pair of tensioned string gripping jaws carried by the blockand means for moving the jaws to disengaging position relative-to the racket string when the piston is at its limit ofmovement in one direction, valve meansfor controlling the supply of fluid under pressure. to the cylinder and a spring associated with the piston for moving the same to exhaust fluid from the cylinder when the supply valve is closed.

10. In stringing and tensioning mechanism for tennis racket strings, a support for a tennis racket, and a string stretching and tensioning device having means engageable with the outer side of the racket and fluid operated means aligned with the aforesaid means engageable with, a racket string outwardly of the racket for effecting a pulling strain, on the string in opposition to the means engaged with the racket,

11,. In stringing and, tensioning mechanism for tennis racket strings, a support fora tennis racket, and a' string stretching and tensioning device having means engageable with the outer side of the racket and fluid operated means aligned with the aforesaid means engageable with a racket string outwardly of the racket for effecting a pulling strain on the string in opposition to the means engaged." with the racket, the fluid operated means including a-pair of slidablytensio'ned wedging jaws and a movable member carrying the jaws.

12. In stringing and tensioning mechanism for tennisracket strings, a support for a tennis racket, and a string stretching and tensioning device having means engageable with the outer side of the racket and fluid operated means aligned with the aforesaid means engageable with a racket string outwardly of the racket for effecting a pulling strain on thestring in opposition to the means engaged with the racket, the fluid operated means including a pair of slidably tensioned wedging jaws and a movable member carrying the jaws, and-means associated with the movable member for normally positioning thev wedging jaws for releasing engagement relative to the string. LAURANCE c. DOLL.