the spring structure of this invention and of the prior art thus as indicated in table 1 the percentage flexure is far better in the invention than in the prior art fig9 is a partial sectional perspective view conceptually showing another embodiment of the invention a movable disk 1 is fastened to a rotating shaft 3 which is rotatably supported by an intermediate bearing 120 and a lower bearing 121 a fixed part 6 in the shape of a shaft has a thrust bearing 61 by which a shaft body 302 of a cylindrical rotating body 301 is rotatably supported two spiral springs 11a and 11b which are oppositely coiled are accommodated in the rotating body 301 the first spiral spring 11a has its inner end connected to the rotating shaft 3 and the other end to the inner wall of the cylindrical rotating body 301 the second spiral spring 11b has its inner end connected to the fixed part 6 and its outer end to the inner wall of the cylindrical rotating body 301 when the disk 1 is rotated in the direction 2 the first spiral spring 11a connected to the rotating shaft 3 is wound to cause the second spiral spring to be wound by rotating body 301 the two springs are so wound because these springs are serially linked to each other fig1 shows another embodiment of the invention by a partial sectional perspective view wherein a movable disk 1 having a stopper 40 is fastened.