GB550346A - Improvements in or relating to hydraulic remote controls - Google Patents

Abstract

550,346. Hydraulic control systems; valves. LANGLEY, T. W., and TECALEMIT, Ltd. Aug. 22, 1941, No. 10706. [Classes 69 (ii) and 135] A hydraulic remote control device is constructed so as to compensate automatically for thermal dilatation, and so as to compensate for leakage and to indicate the extent of leakage. The compensation device is connected by pipes 67, 68 to the opposite ends of a master cylinder 42' and is constructed of a pair of compensating cylinders 1, 3 screwed together and fitted with pistons 9, 10 connected together and adapted to be moved simultaneously. A further piston 11 is' also connected to the piston 10 and moves in a reaction cylinder 8 connected by a pipe 31 and a valve 30 to the second compensating cylinder 3, or to the first cylinder 1. The ratio of the volumetric capacity of cylinder 1 to that of cylinders 3, 8' combined is made constant for all positions of the pistons. The pistons 9, 10 are urged upwardly by a spring 18 which also presses upwardly an indicator tube 16 formed with annular coloured bands adapted to be visible through ports 17 in the wall of cylinder 3 to indicate the amount of leakage from the cylinders 1, 3 which initially are filled with liquid the amount of which is adjustable by varying the position of the upper closure member of the cylinder 1. The areas of cross sections of the cylinders 1, 3, 8 being denoted by A 1 , A 2 , Ar, are constructed so that 2A 1 =A 2 -Ar and this ensures that changes of volume due to temperature variation are compensated by movements of the pistons 9, 10, 11. The valve 30 is constructed of a flanged cup shaped member normally pressed away from an aperture 28 by a spring, acting on the flange. The cup is formed with perforations, and the valve remains open to permit a. flow of liquid due to rise in temperature to pass through it. When, however, pressure applied to the master piston causes a quick depression of the pistons and overcoming of the bias of spring 18 the valve 30 is closed. Plugs for venting and replenishing the liquid in the system are provided. In modifications the pistons 9, 10, 11 are not connected together but their movement is correlated by link mechanism to move in cylinders which are not collinear. The reaction cylinder may be connected to the first instead of the second compensating cylinder in which case the relation of the areas of cross section is given by the equation 2A 1 = A 2 + Ar. The master cylinder is connected by pipes 84, 85 to a slave cylinder.