Abstract: A fastener for connecting structures having significantly different coefficients of thermal expansion which substantially eliminates thermal stress with varying ambient temperatures, while allowing said structures to be offset or spaced from each other. A frusto-conical bore through a wall of a first structure receives a frusto-conical surface of an elongated fastener which is coincident with said bore. The fastener has a base secured to a second structure. A shoulder is formed on said first structure around the narrow end of said bore, the shoulder having a frusto-conical outer edge. A flange member is secured to the vertex end of said fastener, said flange member having a surface configured to engage said outer edge in a coincident relationship. The fastener is tightened to bring both pairs of coincident conical surfaces into pressure contact. Both pairs of conic surface preferably have a common vertex which lies outside the fastener.

Abstract: A thermostat (10) comprising a metal hydride (26) encased in a bellows (16) and a second bellows (20) encasing available hydrogen gas (32) to be adsorped and desorped by the metal hydride (26). The metal hydride (26) mechanically expands its encasing bellows (16) during adsorption and contracts during desorption of the hydrogen gas while a change in gas pressure due to this adsorption/desorption expands and contracts its encasing bellows (20). Each bellows (16,20) is oppositely acting and each engage a valve seat (36,40), respectively, so that the flow of fluid is directed alternately through one valve seat opening or the other depending upon temperature affecting the gas absorping/desorping properties of the metallic hydride. The temperature at which the thermostat (10) operates may be adjusted by controlling the pressure of the gas in the gas bellows. Also disclosed is a variation of the invention as a thermal switch for space applications.