Abstract: In a FRP leaf spring consisting of a main body and a rib, the main body has a taper portion so tapered that the thickness of the main body varies continuously along the longitudinal direction thereof, and the rib is projected integrally from the main body in the direction of the thickness thereof, extending along the longitudinal direction of the main body, so that the total sectional area of the main body and the rib, as well as the width of the main body, is kept substantially fixed in every position along the longitudinal direction to ensure uniform stress distribution.

Abstract: An apparatus for controlling the spring constant of a laminated leaf spring assembly includes a clamping mechanism mounted on the laminated leaf spring assembly for clamping the laminated leaf spring assembly in the direction of thickness thereof. The clamping mechanism includes a fixed spring-supporting member on which a helper spring unit of the assembly is attached to be separated a determined distance from a main spring unit of the assembly. A movable press member positioned to face the helper spring unit and press the main spring unit against the helper spring unit is also provided. The controlling apparatus further includes a piston arrangement for pressing the press member to urge the main spring unit against the helper spring unit.