Patent GB-1494517-A (GB)
Title: Tennis racket with variable balance and weight
IPC: A63B49/04
Filed: 1975-01-02
Abstract: 1494517 Tennis racquet P HUFENUS 2 Jan 1975 77/75 Heading A6D A tennis racquet is provided with a movable element and slidable along a guide disposed between a stringing frame 4 and handle grip 1 and being automatically latchable with the guide at spaced latching positions thereon. Movable weight 8 is adapted via guide member 6 to slide axially in the cavity defined in the handle of the racquet shown. As shown (Fig. 3) a movable weight 8 is selectively locatable via finger action at one of a number of positions along guide member 6 each defined by cavities 6a. In a second embodiment (Fig. 4 not shown) a circular weight element is adapted to slide along a circular section guide between fixing positions defined by pairs of points of increased section of the guide; an elastic annular disc carried by the slidable weight being forcible between the points to effect fixing. Alternatively the elastic disc may be a force fit on the guide itself, fixing points on the guide then being pairs of annular grooves into which the inner surfaces of, the disc are receivable. In a third embodiment (Figs. 5-7 not shown) the movable weight includes a spring loaded ball urged against the guide member, fixing being obtained by the provision of ball receiving cavities spaced along the guide. Details are given for the provision of noiseless sliding action; the engaging parts being sheathed in, or comprising, a non-metallic material e.g. an elastomer of polyesters polyolefins if necessary reinforced. Spring pressure is adjustable and the weight element may be adapted via an aperture member for circular or rectangular section guide members. A fifth embodiment provides fixing means for the guide member and weight assembly allowing for pivotal movement of the assembly in a plane perpendicular to that of the racquet whereby interchange of weights is possible. The lower end of the guide is received by a pivot member (Fig. 11 not shown) mounted transversal to the racquet axis in the upper portion 2 of the handle grip; the pivot length being expansible by the operation of a mill screw wheel to forcibly engage the inner surfaces of cavity 2 defined in Fig. 2. The pivot member may alternatively comprise an elastic insert rigid enough to be compressibly housed 'within the cavity. The upper end of: the guide is releasably secured to the lower string frame portion 4 by a hinged loop element (Fig. 10 not shown) or alternatively by a tubular loop member which is bent around the stringing frame, the ends then brought together and received in a hollow end portion of the guide and held under the spring action of the tube loop. In a further embodiment (Fig. 9 not shown) the guide member is received into an axial, through bore of the handle grip and screwed into position by a millscrew with the upper end of the guide either screwed to the frame or formed into a hook and received into an eye screw affixed to the base of the stringing frame. In yet a further embodiment (Fig. 8 not shown) a guide member having bifurcated end portions is adapted to be located between the grip cavity 2 and stringing frame 4, rotation of a threaded sleeve being effective in increasing the separation of the guide ends and thereby securing the guide member into the racquet handle cavity. In a yet still further embodiment the racquet is designed so that with the movable element positioned in an extreme position adjacent the racquet frame, the centre of gravity of the racquet portion above the grip will lie: at a distance less than 5 cm. from the geometric centre of the stringing frame measured on the side of the handle. To effect this requirement a removable load is distributed along the uppermost portion of the frame. Details are given of preferred weights for the racquet components. The invention also provides a guide and moving element assembly fixable to a racquet not displaying the handle cavity of Fig. 2. In an embodiment (Fig. 15 not shown) a guide member having rails whereon the movable element is slidably located is strapped to the front face of a racquet, the moving element including a spring-ball assembly co-operating with recesses along the guide as described. The guide member may be located perpendicular to the plane of the racquet, and the ball may engage front or side faces of the rails. In a final embodiment (Fig. 14 not shown) the guide/weight assembly is adapted to be screwed to the grip (via a collar) and frame (via a clamp bracket) to be held in a plane spaced parallel to that of the racquet.