GB769814A - Improvements in or relating to gauges having a dial and cooperating pointer - Google Patents

Abstract

769,814. indicating-apparatus. MANNING, MAXWELL & MOORE, Inc. May 12, 1955 [Dec. 27, 1954], No. 13731/55. Class 106 (4). [Also in Group XXIV] A temperature or pressure gauge having a case 12 containing a dial 20 and pointer 24 and a stem 26 containing a sensitive element 25 is provided with a flexible torque transmitting spring 38 connecting the element 25 and pointer 24 and a tube 42 connecting the case 12 and stem 26 which can bend through a right angle in any direction. The element 25, Fig. 3, which may be a flat bi-metallic coil or a Bourdon tube, effects rotation of a shaft 32, which rotation is transmitted to the pointer 24 by the spring 38, without introducing any parasitic movement provided the axial length of the spring 38 is maintained constant and provided the case 12 does not rotate about the axis of the stem 26. The latter condition is satisfied by forming the tube 42 as a hollow bellows, flexible longitudinally, but rigid in torque. The tube 42 is preferably of stainless steel or other corrosionresistant material, e.g. nylon, and since the tube protects the driving elements they may be made of cheaper materials, e.g. copper. The former condition may be satisfied approximately by introducing crossed links 44, Fig. 1, of suitable length, pivoted to brackets 46, 48 which are mounted for rotation respectively on the case 12 and a nipple 30 supporting the stem 26. The bracket 48 is a split sleeve whose clamping bolt 57 engages a peripheral groove 60 round the nipple 30 to prevent axial movement. A more accurate alternative is to provide parallel links 144, Fig. 8, pivoted on brackets which are formed with intermeshing gear sectors 147, 149 in the ratio 3 to 2. In either embodiment, when the case has been adjusted so that the dial faces in a desired direction, it may be locked by tightening the clamping bolt 57 and the pivot screws 56 (156), the holes in the links 44 (144) being unthreaded.