GB419309A - Means for effecting thermal compensation or adjustment in fluid pressure systems - Google Patents

Abstract

419,309. Hydraulic transmission of power. LOCKHEED HYDRAULIC BRAKE CO., Ltd., BOUGHTON, E. B., and RODWAY, J., Brock House, Langham Street, London. May 12, 1933, No. 13874. [Class 69 (ii).] In hydraulic control systems for brakes, valves and other purposes thermal compensation is effected by the provision of a shadow pipe line substantially following the main pipe line and acting as a thermostat for operating adjusting means in a mechanic. ally functioning part of the system. A transmission system suitable for the throttle control on an aircraft, comprises a master cylinder 5, Fig. 1, mounted on a pivot 6 and connected by pipe line 1 to a cylinder 25 slidable on a piston 28 pivoted at 29 and connected to the throttle lever 26 pivoted at 27. The master piston 8 is operated by lever 18 through a compensating cylinder and piston 15, 16 and a lever 11, the transmission being through liquid in the cylinder 15 which communicates with a pipe 23 that follows the pipe line 1 and is closed at its end by an adjusting plug 24. Tension springs 31, 32 connected to the levers 11, 26 keep the liquid in the pipe 1 under pressure and ensure movement of the lever 11 and piston 8 when the lever 18 is moved to the left, without the tendency to form a vacuum in the cylinder 15. The liquid in the pipe 23 is subject to the same temperature conditions as that in the pipe 1 so that if the temperature rises the effective length of the link formed by the cylinder and piston 15, 16 increases by an amount corresponding to the movement of the piston 8 due to the expansion of the liquid in the main system, the position of the levers 18, 26 being unaffected. Fig. 2 shows the pedal lever 40 of, for example, a hydraulic brake system the lever being connected to the master piston at 47 and being displaced to compensate for thermal changes in the system by mounting it upon an eccentric 43 connected by arm 45 and link 46 to a piston controlled by the shadow pipe line. Specification 414,794 is referred to. According to the Provisional Specification, compensation may be effected by movements of a wedge-shaped cam interposed in a thrust connection between a master piston and its operating lever so as to vary the overall length of the connection or the main hydraulic system may have a branch connection to an additional piston which is connected to the piston of the compensating pipe line so as to vary the volumetric capacity of the main system.