Abstract: An underframe construction for rolling stock vehicles comprising side sills disposed in parallel in the longitudinal direction of the underframe at the opposite outermost locations thereof, end sills connecting the side sills at the both ends in the longitudinal direction of the side sills, body bolsters arranged at positions at which a vertical load applied on the underframe is supported, center sills connecting each one of the end sills and each one of the body bolsters adjoining to one of the end sills, and a plurality of support members, each said support member being composed of upper horizontal flange, bottom plate and vertical web. The support members are disposed sequentially in the longitudinal direction of the underframe in such a fashion that the adjoining vertical webs of the support members are in contact to be bonded together and the both ends of the support members are secured to the side sills.

Abstract: A tube-hole structure for an expanded tube-to-tube-sheet joint which is formed by axially moving a rod within each tube member in each tube hole of the tube sheet by external drive means, thereby imparting an elastic mass placed inside the tube with a sufficient compressive load to expand the tube uniformly in the radial direction to provide a rigid joint between the tube and tube hole, characterized in that each tube hole has at least one circumferential groove with an axial dimension or length of 1.5/.beta. to 3.0/.beta. (.beta. being ##EQU1## WHERE R is the mean radius of the tube member to be expanded, t is the wall thickness of the tube, and .nu. is the Poisson's ratio).