GB689509A - Improvements in or relating to instruments operated by capsules - Google Patents

Abstract

689,509. Pressure gauges. KELVIN & HUGHES, Ltd. Oct. 19, 1951 [Oct. 24, 1950], No. 25865/50. Class 106 (ii). An instrument having one or more main pressure-actuated capsules 13, 14, Fig. 1 actuating indicator means 63, Fig. 2, comprises at least one additional capsule 15 which operatively controls the movement of the indicator means over only a part of its range. For example, as shown, up to about 50,000 feet the main capsules 13, 14 may operate the pointer 63 through a bridge-piece 32 to 37, a spring 40 secured to the bridge, a linkage 44, 47 and a rock-shaft 48, the rock-shaft 48 being connected through toothed sectors and pinions with the pointer 63. The additional capsule 15 is carried to the left with the main capsules 13, 14 until at about 50,000 feet a disc 28 on the free end of the additional capsule 15 contacts an adjustable screw 42 on the spring 40 to move the free end of the latter away from the bridge-piece. and thereby apply additional movement through the linkage, rock-shaft and pointer to maintain the required characteristic of the instrument at the extreme end of its range. The spring 40 and linkage 44, 47 form a three-bar linkage, the relative lengths of which are selected to achieve a close approximation to the required characteristics of the instrument. An inertia compensator arm 55 is pivotally mounted at 56 on a main frame 10 and is connected by a link 57 and pin 58 to the rock-shaft 48. A bimetallic temperature compensating device 20 has arms 22, 23 that act through toggle links 26, 27 on the disc 28 on the free end of the additional capsule 15. The screw 42 may be used to set the altitude at which the additional capsule 15 will become effective. Specification 481,941 is referred to.