GB1292775A - Temperature-compensated adjustment arrangement - Google Patents

Abstract

1292775 Screw-and-nut mechanism INTERNATIONAL STANDARD ELECTRIC CORP 19 April 1971 [9 Feb 1970 (2)] 20875/71 Heading F2Q In a temperature compensated lead screw arrangement comprising a base member 2, a fixed element 3 secured to the base member 2 and spaced therefrom, a shaft 4 constrained from rotation but arranged for axial movement towards and away from the fixed element 3 by rotation of a lead screw member 5 which is captive with the base member 2, and a nut 7 engaging a lead screw threaded portion 6 over a length short compared to the length of the screw threaded portion 6, the nut is fixed to the shaft 4 by means of a re-entrant member 8 coaxial with the shaft 4 and of a material of a different coefficient of thermal expansion from that of the shaft material. The shaft 5 may be connected to the screw threaded portion 6 at its centre or at one end thereof. In a vacuum variable capacitor shown in Fig. 2, a set 10 of concentric cylindrical capacitor plates is mounted on an end plate 11 of an evacuated envelope having a base member 12 at the opposite end of the envelope. A set of axially movable plates 13 is mounted on a plate 14 secured to a hollow shaft 15 having a re-entrant member 31 made of a material having a co-efficient of thermal expansion different from the material of shaft 15. Threads 34 on the member 31 are adapted to engage a lead screw. The member 31 has an adjustable screw-threaded connection 32 with the shaft 15 in order to vary the amount of differential expansion that can occur between them. In a modification, a threaded sleeve 6, Fig. 3, is secured at one end 50 to a shaft 5, the materials of the sleeve 6 and shaft 5 having different coefficients of expansion. Alternatively, the sleeve 6 and shaft 5 may be joined at a position intermediate their lengths.