US 2311172 A
Abstract available in
Claims available in
Description (OCR text may contain errors)
Feb. 16,1943. K HETZEL 2,311,172
' RACKVET 'Filed Oct. 29, 1940 Patented Feb. 16, 1943 UNITED STATES EATENT oFFicE RACKET Kurt Hetzel Washington, D. C.
Application October'29, 1940, Serial No. 363,342
This invention relates to rackets and in particular to means for adjusting the tension of the stringing whereby the Stringing may always be maintained at proper tension during use of the racket or slackened when the racket is not in use. An object of the invention is to provide cicient, light, and compact tension-controlling means readily associable with the Stringing of a conventionally strung racket. In order that the invention may be fully understood, I shall describe it with reference to the embodiment shown by way of example in the accompanying drawing, in which:
Figure 1 is a face view of a racket equipped in accordance with the present invention.
Figure 2 is a rear View of the throat portion of the racket of Figure 1.
Figure 3 is an elevation, partly broken away, of the tension controlling mechanism.
Figure 4 is a section on line 4-4 of Figure 3, and
Figure 5 is a section on line 5 -5 of Figure 3.
Referring to the drawing, reference numeral Ii) designates the racket frame, and reference nurneral i I the handle joined to the frame through a throat portion I2 in which a generally triangular opening I3 is provided. The frame is conventionally strung longitudinally in that the ends of a loop L are drawn through the top central holes i4 and I5, downwardly through holes I6 and il, and upwardly through holes I8 and I3 so that two central loops 2i) and 2l at the handle end of the frame are provided. The stringing is continued up and down and outwardly in both directions and the ends anchored in the customary manner. The cross Stringing C is also desirably conventional, starting with a loop at 22 and working back and forth toward the ends of the frame.
As here shown, a frame or box 23 is disposed in the opening I3, the frame comprising a triangular back plate 24 to which are joined side walls having parallel portions 25 and 25 and converging portions 21 and 2t, a front wall 29 joining the side wall portions 2l and 25 so that a rigid unit, which is preferably of very light metal, is provided. The portion of the frame constituted by the side walls and front wall 23 is snugly insertable in the opening I3 so that wall 29 is substantially flush with the throat structure at one side of the racket while the side portions of wall 24 overlie the margins of the throat structure at the other side, as shown Vin Figure 2. The free extremities of wall portions 25 and 25 are provided with expanded foot portions 30 and 3| adapted to bear against the bottom of the frame as shown in Figure 1.
A pin 32y has its ends journalled in wall portions 25 and 26 and has a tight t in a sleeve 32 which extends between the said wall portions and adjacent the latter has fixed thereon drums 33 and 34. Centrally sleeve 32 has xed thereon a worm gear 35 spaced from the drums so that additional drum portions 35 and 3l are provided by the sleeve. The adjacent edges of drums 33 and 34 are provided with inclined or undercut kerfs 38 and 39 so that overhanging lip or hook portions 4b and 4I are provided.
A pin 42 is journaled in wall portions 24 and 23 and includes an enlarged cylindrical head 43 in wall 24, the head. being provided with a central socket 44 engageable by a turning tool. As
shown in Figure 2, the socket is hexagonal for engagementv by a complementary tool. A worm 45 on pin 42 engages worm gear 35, the worm having collar portions 46 and 41 serving to position it operatively relative to the gear. The worm is fixed to pin 42 in any suitable manner, as by a pin 48, Figure 5.
With the unit positioned in the throat as above described, and as particularly shown in Figure 1, the central loops 20 and 2| areengaged in the kerfs 38 and 39, the inner endg of the kerfs being rounded and smoothed so as to prevent any injury to the loops. With the loops engaged in original Stringing as shown in Figure 1, the worm is preferably operated to wind a turn or two of the string on the drum portions 33, 34, 35 and 3l in order that the loops will not be lost when it is subsequently sought to slacken the Stringing. After the loops have been caught in the kerfs, the longitudinal Stringing may be completed in the customary manner as above described. To complete the assembly, a plate 49, of the same shape as wall 24, is secured to the frame 23 by means of a screw 50. The lower portion of the plate 43 is shown in full lines in Figure 1 and the remainder of its outlines in dotted lines.
When the stringing is to be tensioned, the key is applied to the socket 44 and the worm is turned in a manner to drive the worm wheel 35 in a clockwise direction, Figure 5. The inner portions of the loops 20 and 2| are Wound on drum portions 35 and 31 and the outer portions are wound on the drum portions 33 and 34, the latter drum -portions being considerably larger, i. e., having a greater circumference than the former. This means that the outer `portions of the loops are predominantly affected, this being desirable in view of the relatively long lengths of Stringing toward the Sides of the frame. I have found that by the use of this specific arrangement uniform tensioning of the longitudinal Stringing is obtained, the Stringing Sliding in the holes of the frame to the necessary extent. When considerable slack is to be taken up, it is desirable to strike the Stringing during the tensioning operation in order to assist in the distribution of stresses. Tensioning of the longitudinal stringing, of course, tends to straighten it where it crosses the cross Stringing and, consequently, the latter is also tensioned. Moreover, it is my opinion that the tensioning of the longitudinal stringing tends to bulge the frame somewhat laterally with consequent tensioning eiTect on the cross Stringing. However, this may be, the tensioning operation results in uniform tautness of the strings.
Properly designed the described tension controlling unit is applicable to rackets of conventional form and adds but little weight which may be readily balanced out. While I have shown in the drawing a tennis racket assumably made of wood, the invention is, of course, not limited as to type of racket nor as to the material of which it is made, and, of course, strings ciY any suitable material may 'be used. The invention is not limited in these respects, nor as to details of structure and disposition of the tension controlling unit except as in the following claims.
I claim: Y
1. The combination with a racket including a frame, conventional longitudinal Stringing carried by said frame, and a handle, of winding means, hook means on said winding means engaging the central loops of said Stringing beyond the handle end of said frame, and means operable to adjust said winding means whereby to adjust the tension of the Stringing.
2. The combination with a racket including a frame, conventional longitudinal Stringing carried by said frame, and a handle, of two pairs of aligned rotary drum portions, means between each pair of said drum portions eachengaging a loop of said Stringing beyond the handle end of said frame, and means for rotating said drum portions and engaging means whereby to adjust the tension of said Stringing.
Y continuous 3. The combination according to claim 2 wherein the drum portions engaging the outer portions of said loops are larger than the d-rum portions engaging the inner portions of said loops.
4. The combination with a racket including a frame, conventional longitudinal Stringing carried by said frame, and a handle, a rotary shaft beyond the handle end of said frame having two pairs of drum portions, means between each pair of said drum .portions each engaging a loop of said Stringing, a worm gear fixed on Said shaft, and a worm engaging said Worm gear, the drum portions engaging the outer portions of said loops being larger than the drum portions engaging the inner portions of Said loops.
5. The combination with a racket including a frame, conventional longitudinal Stringing carried :by said frame, and a handle,
` the throat of the racket having an opening therein immediately below said frame, of a tensioning unit inserted and secured in said opening and bearing against the lowerportion of said frame, said unit including a box, Winding means joui'- naled in said box and engaging the central loops of the Stringing, and means :carried by said Ibox for adjusting said winding means.
6. For association with a racket 4including a frame,- conventional longitudinal Stringing carried by said frame, and a handle, the throat of the racket having la generally triangular opening therein with its apex toward the handle; a tensioning unit comprising a .box having side walls which converge at one end, front and rear box portions joining said walls at said end, a shaft journaled in said side walls remote from said end, a worm wheel xed on said shaft centrally thereof, a-pair of drum -portions at each side of said wheel, loop engaging means 'between each pair of drum portions, and a Worm journaled in said front and rear box portions and engaging said wheel to drive or lock the latter, Said box being insertable and securable in said opening with its convergent end fitting in the apex of said opening.