Abstract: A vehicle wheel, of the type that carries a tubed tire includes a wheel body, a rim which has a plurality of segmental rim parts, a solid retaining ring which engages all of the rim parts along one side thereof, cam and cam follower means between the rim parts and the wheel body which, when powered, urge the rim parts outwardly, and a power device connected to the wheel body which is capable of actuating the cam and cam follower to urge the rim parts radially outwardly into a final position, wherein there is established an equilibrium between the urging force applied to the rim parts from the power device, and, respectively, a restraining force applied to the rim parts by the ring due to its tensile stress.

Abstract: A welding method for joining self-supporting structures made of thermoplastics by assembling said structures to form an area of mutual overlap, generating heat in said area to produce a welding zone having an elevated temperature and containing said thermoplastics in an at least plastic state for mutual coalescence of said structures in said area; an expanding agent is provided in the welding zone to generate a gas pressure therein for promoting coalescence of the weld. The invention is particularly suitable for welding tubes and other pipeline elements, such as fittings or sleeves, of thermoplastics and produces a tumescent weld which fills any macroscopic voids while including a plurality of minute closed cell voids.