Abstract: A golf club comprises a strain gauge attached to a surface of a hollow shaft in the vicinity of a kick point for detecting a bending of the shaft and a sound indicator for generating a sound when a strain of the shaft, particularly at the kick point, exceeds a predetermined level, so that a golf player can easily confirm whether or not sufficient force is exerted on the shaft during the downswing motion.

Abstract: A club head of a golf club comprises a head body having a face which is made of a material having high specific elasticity and a weight body made of another material having a specific gravity greater than that of the material of the head body and provided at and covering a substantial portion of a rear portion of the head body, the head body being provided therein with a cavity, the total weight of the weight body being heavier than that of the head body.

Abstract: A double-layered tubular grip (13) for a golf club shaft, comprises a tubular inner layer (14) made of a porous material secured to the outer surface of the butt end portion of the shaft (11). A tubular outer layer (15) made of a non-porous material having an elasticity greater than that of the inner layer (14) is formed separately from the inner layer (14). The outer layer (15) is pushed over the inner layer (14) and detachably fixed thereto after the inner layer (14) is secured to the outer surface of the golf club shaft (11).

Abstract: A construction of a club-head for a golf club comprising a club-head body (10) having a hollow inner shell (12) and an outer shell (13) which covers the inner shell. The inner shell includes two halves (14, 15) which are joined along peripheral openings thereof, in which one of the two halves is provided with at least one projecting portion (16) at the bottom thereof, and the projecting portion (16) is closely abutted against the inside bottom of the other of the two halves. This provides an improvement in the strength of the joined inner shell (12). A weight adjusting member (17) may be held within the projecting portion (16) by a closure plug (18).

Abstract: A head of a golf club comprises a head body having a front surface forming a hitting surface of the head for hitting a ball and a cut-off portion other than the front surface. A fitting member for adjusting at least the weight or weight-distribution of the head is made of a material different from that of the head body and fixed to the cut-off portion of the head body so as to form a part of the outer surface of the head other than the hitting surface thereof. A cushion member made of a resilient material is disposed between the head body and the fitting member, to prevent damage to the head body and separation of the fitting member from the head body caused by an impact force produced when a golf ball is hit by the golf club head.

Abstract: A golf club head is provided with a straight through hole for the passage of air extending from an inlet in the sole to an outlet in the central back side.

Abstract: A club-head (11) for an iron golf club in which the outer shell (13) and core body (14) of the club-head are formed of metals having a different specific weight from each other. The weight of the embedded core body is concentrated at the center of the hitting portion of the club head. This allows an improvement in the weight distribution and disposition of the center of gravity of the club-head (11), and since the outer shell (13) is made of a metal, prevents scratching and cracking of the surface of the outer shell (13).

Abstract: A golf ball comprises a body having a spherical outer surface and a plurality of first dimples arranged substantially uniformly in the spherical outer surface thereof. The body also has a plurality of indentations which are smaller than the first dimples and arranged substantially uniformly in the spherical outer surface and the inside surface of the first dimples. The indentations may be formed by grit blasting.

Abstract: A head of a golf club comprises a head body having a face portion, for hitting a golf ball, and a back portion. A surface structure for producing a turbulent boundary layer in the air on the outer surface of the head body is provided on the outer surface substantially throughout a region from the periphery of the face portion of the head body to the back portion of the head body. The surface structure may include a plurality of fine grooves or a plurality of fine fibers erected on the outer surface of the head body.

Abstract: A set of golf clubs, each having a striking surface with a different angle of loft and a coefficiency of friction. The coefficient of friction gradually increases in accordance with a gradual decrease of the angle of loft and a gradual increase of the club length. Therefore, the longer the club is, the smaller the angle of loft of the club and the larger the coefficient of friction becomes. It is easy to provide a back spin on a ball even with a longer club.

Abstract: A golf club set comprising a series of golf clubs, each having a hitting surface for hitting a two-piece type golf ball. The hitting surface of each club of the set having a loft angle increasing in angle relative to the loft angle of the immediately preceding club in the set. The hitting surface of the lowest loft angle club in the set having a loft angle larger than 40.degree.. The hitting surface of each of the golf clubs in the set having different coefficients of friction and the coefficient of friction increases with the increase in loft angle.

Abstract: A set of golf clubs wherein each club head includes a closed hollow behind the striking face. The thickness of each striking face is gradually decreased as the length of each shaft is gradually increased.

Abstract: A golf club head for a wood type club comprises a head body (11) having a face for hitting a golf ball, the face being inclined upward and backward. A face plate (12) is provided in the face of the head body (11), and a sole plate (13) is provided in the backside of the head body (11). A bar-shaped weight (18) is provided in the head body (11) and extends substantially perpendicular to the face from the backside of the face plate toward the backside of the head body (11) so that the longitudinal axis of the bar-shaped weight (18) passes through the central portion of the face of the head body (11). A back weight (19) is provided in the backside of the head body (11) so that the line connecting the center of gravity of the golf club head (11) and the sweet spot thereof coincides with the longitudinal axis of the bar-shaped weight (18).

Abstract: A club-head for a golf club includes a hitting portion (11) having a front surface (11a) for hitting a golf ball, a rear surface (11b), a sole surface (11c) and heel and toe ends (11d, 11e), and a hosel portion (12) extending obliquely upward from the heel end (11d) of the hitting portion. The hitting portion (11) comprises a main body (13) made of a fiber-reinforced plastic for defining at least a part of the front and rear surfaces (11a, 11b) of the hitting portion. A metal sole member (14) having a specific gravity greater than that of the main body (13) is integrally joined to the main body (13) along the underside of the main body for defining at least the sole surface (11c) of the hitting portion (11). A reinforcing plate (19) is fitted at the lower end portion thereof into the sole member (14) and extends upwardly from the sole member into the main body (13) substantially in parallel to the front surface (11a) of the hitting portion (11).

Abstract: A club-head for a golf club includes a hitting portion (11) and a hosel portion (12). The hitting portion (11) comprises a main body (13) made of a fiber-reinforced plastic. A metal sold member (14) is integrally fixed to the under surface of the main body (13). A weight member (18) made of a heavy material such as a heavy metal and formed separately from the sole member (14) is inserted into the main body (13). The weight member (18) is rigidly connected to the sole member (14) by means of connecting members (19) formed separately from at least one of the sole member (14) and the weight member (18).

Abstract: A club-head (10) for an iron golf club comprising a hitting portion constituted by a main body (11) made of fiber-reinforced plastic and a sole member (12) including a rib (15) made of metal, in which a plate-like back member (16) made of a heavy material such as a heavy metal is added to the main body (11) along or near the backside surface of the main body (11). This allows an improvement in the disposition of the center of gravity of the club-head and provides a wide selection of golf clubs suitable for the respective golfer.

Abstract: A magnetic head actuator assembly for a disk drive, having dissimilar materials with different linear expansion coefficients, is provided with thermal compensation. The movable member of the actuator assembly has spring elements attached at spaced locations thereon and is associated with a cooperating pulley that drives a band. The band ends are connected to the spring elements such that rotation of the pulley imparts motion to the movable member. The spring coefficient of the band, spring, and connector structure between the pulley and one spaced location and the spring coefficient of the band, spring, and connecting structure between the pulley and the other of the spaced locations on the movable member are chosen so that the displacement of the magnetic head with respect to a record track on a cooperating disk surface caused by temperature variation is compensated. In one modification, a bimetal is used to replace a spring element in the thermal compensating system.

Abstract: A club-head (11) for an iron golf club in which the outer shell (13) and core body (14) of the club-head are formed of metals having a different specific weight from each other. The weight of the embedded core body is concentrated in an area defining the periphery of the hitting portion of the club head. This allows an improvement in the weight distribution and disposition of the center of gravity of the club-head (11), and since the outer shell (13) is made of a metal, prevents scratching and cracking of the surface of the outer shell (13).

Abstract: A device for measuring a stiffness of a golf-club shaft comprises a clamp for holding one end of a golf-club shaft so that the golf-club shaft extends in a substantially horizontal position. A pointer member having a tip end and a root portion is detachably attached at the root portion thereof to the other end of the golf-club shaft held by the clamp so that the pointer member extends in a substantially horizontal position perpendicular to a longitudinal axis of the golf-club shaft. A counterweight is detachably attached to the tip end of the pointer member and applies a predetermined flexure and torsion load to the golf-club shaft through the pointer member. A vertical displacement measuring instrument is provided to measure the amount of vertical displacement of the tip end of the pointer member produced by torsion and flexure of the golf-club shaft when the predetermined load of the counterweight is applied to the golf-club shaft through the pointer member.