GB601589A - Improvements in or relating to apparatus for indicating and/or recording small relative displacements in aneroid barometers, altimeters and similar instruments - Google Patents

Abstract

601,589. Indicating-apparatus; gauges. WALLACE & TIERNAN PRODUCTS, Inc. Nov. 10, 1943, No. 18682. Convention date, Sept. 24, 1941. [Classes 106 (ii) and 106 (iv)] This invention relates to apparatus for translating small displacements of sensitive precision instruments into enlarged movements of an indicating device such as a pointer for use in aneroid barometers, altimeters and similar instruments. As shown in Fig. 1, a bellows 20 of an aneroid barometer carries a post 21 and is centrally mounted at 22 to the inside of one arm of a U-shaped supporting member 23, the other arm 24 of which extends to a position close to the post 21 and has a lug 25 mounted on a vertical post 26, Fig. 4. The member 23 has an extension 30 which is held by a coil spring 32 against an adjusting screw 31 and which is guided between a pair of vertically spaced pins 38 extending from a block 34 on the screw 31. A lever 45 is attached to the post 21 and the member 23 by two flexible U-shaped strips 47, 48 and 49, 50, Fig. 4. The lever 45 is balanced at one end by a member 54 and at its other end is bifurcated into two arms 55, 56, Fig. 5, between which is stretched a thin wire 58. A member 85 connects the wire 58 to the offset centre part 73 of a vertical wire 70, 75 threaded through apertures in the arms 61, 62 of a U-shaped supporting strip 60, 61, 62 and clamped by wires 71, 76. The U-shaped strip carries a rod 63 bent at right angles to have a horizontal portion 64 terminating in a pointer 65 which moves over a scale 67. The arms 61, 62 carry a pair of damping vanes 81, 81 arranged to swing in a box 82. In another embodiment, Fig. 6, the pointer-supporting frame comprises a strip of metal having a rearwardly extending loop 90 and a forwardly extending loop 91 which carries a pointer rod 92, 94. The frame is mounted on a vertical shaft 97 freely rotatable in bearings 98, 99. The embodiment shown in Fig. 7 is similar to that of Fig. 1, but the shaft 197 which carries the pointer-supporting frame is provided with a small drum 205, Fig. 11, fixed to and round which is partially wound a wire 206 fastened to the outer end of the resiliently supported lever 145. Another wire also fastened to the drum 205 extends round it in the opposite direction and is secured to one end of a long coil spring 208, the other end of which is secured to an arm 215 of a U-shaped spring strip. The tension of the spring 208 may be varied by turning a cam 218 which abuts the arm 215. When the lever 145 is displaced in one direction, the wire 206 rotates the drum 205 so displacing the pointer 164 and when the lever 145 is displaced in the other direction the spring 208 reverses the.rotation of the drum 205 and consequently the pointer 164 moves in the opposite direction.