PURPOSE: To carry out ready control of support body rigidity responding to physical properties of warp by fixing the lower part end of mutually parallel adjacent plate springs to a frame, fixing the upper part end to an element and supporting a back rest by a support constituted variably to the spring plate rigidity.
CONSTITUTION: Two plate springs 12 and 13 are arranged parallel and mutually side by side and the lower end parts 14 and 15 are each fastened and fixed between a support 19 fixed to the frame 18 and fastening tools 21 and 22 with a bolt 20 and the upper end parts 16 and 17 are fastened and fixed through fastening tools 25 and 26 to the element having a sheet part 28 by a bolt 27. Further, the position is moved in the length direction of plate spring 12 and 13 and a support 34 capable of changing spring rigidity to constitute a support 11. Both end part of a back rest 3 is supported by a pair of the support 11.
MIKAERU BUANDEBUEGUHE
BARUTO REFUEBUEERU
