GB537876A - Improvements in or relating to liquid pressure remote control systems - Google Patents

Abstract

537,876. Hydraulic remote control systems. YORSTON, J., LANGLEY, T. W., and TECALEMIT, Ltd. Feb. 5, 1940, No. 2190. [Class 69 (ii)] In a hydraulic remote control system a dilatation compensator is associated with the control so as to balance the variation in the liquid capacity of the system due to change of temperature by a corresponding change in the volume of the liquid. in one form the system is connected by a pipe union to a screw-threaded socket 30 forming the upper end of the compensator which comprises a hollow spherical displacer member 1 formed of a low expansion alloy such as 36 per cent. nickel iron alloy. The displacer is supported in a metal sphere 2 formed of two parts screwed together and closed by a screw plug 8. The sphere is formed of an aluminium alloy of high thermal expansion and between the sphere and the displacer liquid is inserted which may be of the same nature as that of the hydraulic system. Above the sphere 2 is formed a cylindrical extension 9 with a stepped bore 10 and a connecting rod 13 slides in the bore and communicates the motion of a piston 11, which is displaced by expansion of fluid in the sphere 2, to a piston 19 of larger diameter which moves in a cylinder 16 fitted with a screw closure member 29 filled with the same fluid as the hydraulic system and connected thereto by the pipe union in socket 30. The piston 19 is fitted with a cup packing 20 and is pressed downwards by a spring 28. When the piston 11 is moved due to the differential expansion of the members 1, 2 and the liquid contained therein a corresponding movement is imparted to piston 19, but owing to the larger size thereof it can cause a compensation in volume in the hydraulic system which is greater than the differential expansion of the members 1, 2 and associated liquid. The piston 11 may be formed at its lower side with beaded edges which are pressed against the sides of a recess in the upper part of the sphere 2 by a screwed closure member formed with apertures to permit the compensating fluid to press on the lower side of the plunger. In a further modification Fig. 3, the screw closure member at the bottom of the sphere 2 may be arranged to receive a small amount of a liquid having a different expansion from that between the parts 1, 2, which is separated from the extra liquid by a diaphragm 40. The closure member 38 is fitted with a needle valve 42 normally fitted with a dust-excluding cap 44. The valve permits fluid to be inserted into the space 41 by means of a syringe.