(US4455824-A)      The apparatus is for converting the periodic undulations of a body of water into electrical energy and includes a support structure adapted to be mounted in a fixed position relative to the surface of the body of water and extending a distance above the surface. The apparatus also includes a float member movable relative to the support structure in response to the undulations of the surface, an electrical generator mounted on the support structure for generating electricity, and a nut and lead screw assembly of the type comprising a threaded screw member, a threaded nut member, and bearings placed in between where the screw and nut members are axially and rotatably movable relative to each other.    The screw member is connected to the float member, and the nut member is operatively connected to the generator where movement of the screw member with the float member drives the nut member and generator. (8pp)n    (GB2100358-B)      An apparatus for converting the periodic undulations of a body of a fluid into energy, said apparatus comprising: support means adapted to be mounted in a substantially fixed position relative to the surface of the body of the fluid; flat means movable relative to said support means in response to the undulations of the surface; energy generating means mounted on said support means for generating energy; a nut and lead screw assembly of the type comprising a threaded screw member, a threaded nut member, and bearing means disposed between said screw member and said nut member whereby said screw and nut members are axially and rotatably movable relative to each other; and means operatively connecting one of said members to said float means and the other of said members to said generator means whereby movement of said one of said members with said float means drives said other of said members and said generator means and wherein said connecting means includes clutch means secured to said other of said members of said nut and lead screw assembly for movement therewith and having a first position engaging said energy generating means to drive the latter to generate energy when said one member of said nut and lead screw assembly is rising and a second position disengaged from said energy generating means when said one member is falling.f    (DE3220381-C)      The appliance is for conversion of the periodic wave movement of a fluid into usable energy. It uses the relative movement between a float and a carrier frame with energy converter and a screw/spindle arrangement. Part of this is connected to the float, and another part is connected via a clutch to the energy converter, the connection is formed in one movement direction, and released in another movement direction.    A ball cycle bearing is located between spindle (32) and nut (34), part of the arrangement connected to the energy converter may be lifted into a first position, in which it is connected to the converter, and lowered into a second position, in which it is disconnected.