GB791876A - Improvements in or relating to indicating instruments - Google Patents

Abstract

791,876. Indicating-apparatus; pressure gauges. BENDIX AVIATION CORPORATION. Dec. 29, 1955 [Jan. 3, 1955], No. 37304/55. Classes 106 (2) and 106 (4). Indicating-apparatus has mechanism for deriving an output motion which is a desired function of two input factors comprising two capsules 17, 16 sensing the factors and acting jointly on a common link 39 having two degrees of freedom for movement along two different directions in response to the capsules and a cam 52 transmitting the motion of the link 39 to an output shaft 45, the cam 52 being so shaped as to impart to the shaft 45 a motion which is the desired function of the inputs. As shown in a Machmeter, Fig. 2, a cam link 39 moves under the influence of two capsules 17, 16, one an evacuated capsule 17 exposed to static pressure, acting through a link 19, pivoted to an arm 25 on a rock-shaft 21 with another arm 32 connected to the link 39 by a spring 43, and the other exposed internally to impart pressure and externally to static pressure and acting through a pin 37 pivoted to the link 39. The link 39 is urged into contact with a cam wire 52 through which it rocks a shaft 45 and rotates a pointer 14 through sector 53 and pinion 55. The transmission ratios may be adjusted by changing the effective lengths of the pin 38 where it is clamped by screw 61 and of the arm 25 where it is clamped by screw 60 and also by a fine adjustment screw 31 in a split block 24. The effect of the spring 43 may be varied by adjusting the collar 33. The cam 52 is formed of spring wire secured directly to the shaft 45 or to a collar rotatably adjustable on the shaft 45 and its other end bears on a cam pin 51 secured to a cam arm 48 secured on the shaft 45 in a desired angular position to give the cam 52 an appropriate shape. The cam link 39 is given a curvature suitable to the particular capsules used and the appropriate curves are blended at the transonic interval.