# US 4,531,738 A · Racquetball racquet with increased hitting area > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 4,531,738 A - Document ID: US4531738A - Status: Granted - Kind: A - Application number: 06/560,538 - Filed: 1983-12-12 - Granted: 1985-07-30 - Earliest claimed: 1983-12-12 - Assignees: Ektelon - Inventors: Raymond L. Mortvedt; Steven M. Thompson - Web page: https://patentgrep.com/patent/US4531738A ## CPC - A63B 49/00: Stringed rackets, e.g. for tennis (strings therefor A63B51/00) - A63B 49/02: Frames - A63B 2049/0202: {surface area} - A63B 2049/0203: {height} - A63B 2049/0204: {width} - A63B 2049/0207: {with defined overall length} - A63B 2049/0212: {with defined weight} - A63B: APPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT (apparatus for passive exercising, massage A61H) ## Abstract The improved racquetball racquet has a strung surface which is larger in area than the strung surface of a conventional racquet, and in which the strung area is both longer in length and width than the strung area of a conventional racquet. However, the overall weight and balance of a conventional racquetball racquet which have proven necessary for good playing characteristics for all such racquets have been maintained. The racquet has synergistically combined the weight of the racquet, the center of mass of the racquet, the stiffness of the frame, and the response characteristics to create a racquet of sufficient durability with a larger "sweet spot" to facilitate the playing of the sport and to increase the level of skill, particularly of the novice and intermediate players. The racquet has an overall length of 181/2 inches to 221/2 inches and a width of 12 inches to 143/4 inches, a weight of 220 grams to 270 grams, and a center of gravity at a location within a range of 3/4 inch toward the handle and 1/2 inch toward the head as measured from the longitudinal center point of the racquet. ## Claims ### Claim 1 A racquetball racquet comprising a frame having a head connected to a handle grip so as to have an overall length of 19 to 221/2 inches and a weight of 220 grams to 270 grams, said head having a strung surface of 75 to 100 square inches, the length of said strung surface in a direction along the longitudinal axis of the racquet being between 12 and 143/4 inches and between 53 and 68 percent of the length of the racquet, said strung surface having a maximum width between 91/2 and 111/2 inches in a direction generally perpendicular to said longitudinal axis, the center of gravity of the racquet being at a location within a range of 3/4 inch toward the handle grip and 1/2 inch toward the head as measured from the longitudinal center point of the racquet, and the center of percussion average is spaced from the center of gravity toward the head a distance substantially greater than 3.6 inches. ### Claim 2 (depends on 1) The racquetball racquet defined in claim 1 in which the head has a generally oblong shape with a slightly flattened outer end; and in which major and minor axes intersect at a location on the longitudinal center line of the racquet spaced above the center point of the strung area. ### Claim 3 (depends on 2) The racquetball racquet defined in claim 2 in which the lower portion of the head frame between the minor axis and handle grip is defined by two symmetrical curved sections which join at their lower ends at the handle grip; and in which each of the curved sections include an upper outwardly convex curved section and lower inwardly concave curved section. ### Claim 4 (depends on 3) The racquetball racquet defined in claim 3 in which a head frame includes a straight section located between the convex and concave sections of each of the lower portions of the head frame. ### Claim 5 (depends on 2) The racquetball racquet defined in claim 2 in which the lower portion of the strung surface is defined by a concavely shaped throat. ### Claim 6 (depends on 2) A racquetball racquet as defined in claim 2 in which the minor axis as measured across the widest portion of the frame defines a chord which subtends an arc, said arc defining an upper portion of the head and being comprised of three arcuate sections having three separate center points. ### Claim 7 (depends on 6) A racquetball racquet defined in claim 6 in which a center arcuate section of said three arcuate sections has a radius that is approximately three times longer than the length of each of the radii of the other two arcuate sections which are equal to each other. ### Claim 8 (depends on 7) The racquetball racquet defined in claim 7 in which the arcuate length of the center arcuate section is approximately 10 degrees and the arcuate length of each of the other two arcuate sections is approximately 85 degrees. ### Claim 9 (depends on 8) The racquetball racquet defined in claim 8 in which the center points of said other two arcuate sections lie generally on the minor axis, each located on an opposite side of the longitudinal center line of the racquet. ### Claim 10 (depends on 1) The racquetball racquet defined in claim 1 in which the racquet has an overall length of 201/2 inches, a strung area of 85 to 95 square inches, and a weight of 240 to 250 grams. ### Claim 11 (depends on 1) A racquetball racquet as defined in claim 1 in which the center of gravity is at a location within a range of 1/4 inch toward the handle grip and 1/2 inch toward the head of the racquet as measured from the longitudinal center point of the racquet. ### Claim 12 (depends on 1) The racquetball racquet defined in claim 1 in which the strung surface is strung with strings at a tension of between 30 and 45 pounds. ### Claim 13 (depends on 1) The racquetball racquet defined in claim 1 in which said handle grip has a free end and wherein the center of percussion average is located about 151/4 inches from the free end of the handle grip. ### Claim 14 (depends on 1) The racquetball racquet defined in claim 1 in which the length of the strung surface is within the range of 20 and 60 percent greater than the width of the strung area. ### Claim 15 (depends on 1) A racquetball racquet as defined in claim 1 where the longitudinal moment of inertia is between 50 to 90 g. in. sec.sup.2. ### Claim 16 (depends on 1) The racquetball racquet as defined in claim 1 where minimum frame stiffness is defined as follows: (EI).sub.xx .gtoreq.30000#in..sup.2, (EI).sub.yy .gtoreq.7000#in..sup.2, (GJ) 700#in..sup.2, (AE).gtoreq.0.8.times.10.sup.6 #in..sup.2 where (EI).sub.xx is the longitudinal bending stiffness, (EI).sub.yy is the lateral bending stiffness, (GJ) is the torsional stiffness and (AE) is axial stiffness. ### Claim 17 (depends on 1) A racquetball racquet as defined in claim 1 therefor: wherein said head has a top portion located opposite the point where said head and handle grip are connected and wherein about 62.9 percent of said strung surface is located on the top portion side of a line located transversely through the midpoint of at least one central longitudinal string.