GB457473A - Altimeters, aneroid barometers and pressure measuring instruments - Google Patents

Abstract

457,473. Electric signalling systems. McLELLAN, A., 30A, Peters Court, Porchester Road, Bayswater, London, and WRIGHT, G. M., Broom Hall, Bicknacre, Chelmsford. May 29,1935, No. 15582. [Class 40 (i)] [See also Group XIX] Comprises an aneroid type of altimeter or other pressure measuring instrument in which the spring 6 opposing the movements of the box or capsule 1 is constituted by a rotating bar subjected to bending strain. Fast with the moving face of the box 1 is an abutment member 3 free to move between two closely spaced adjustable limit stops 4, 5. A bar 6 of circular section runs in a knife edge bearing 7 the housing of which is fixed to the box 1, and a second knife-edge bearing 8 carried by the base 2 and acting as a fulcrum about which the bar may bend. At the end of the bar 6 is another knife edge bearing 9 the housing of which is attached by a chain 10 to a shaft 11. The bar 6 is rotated from a motor 14 through shafts 13 and gearing 12, while a shaft 15 driven from the same motor carries a friction wheel 16 which can be moved across the surface of a friction wheel 18 on the shaft 11. The wheel 16 is shifted longitudinally on its shaft by solenoids 19, 20 in circuit with the stops 4, 5 so that when the member 3 engages one or other of these stops the wheel 16 is shifted to one side or other of the centre of the friction wheel 18 to drive the shaft 11 in one direction or other and influence the bending of the shaft 6 and move the member 3 away from its stop. An automatic brake, not shown, holds disc 18 in whatever position it may be at such instant when the wheel 16 crosses the centre of the disc 8. The force applied through the spring thus always balances the force exerted on the box by the atmosphere. Readings of height or pressure are obtained by a counter or the like 21 driven from the shaft 11.