GB664890A - Airspeed indicators - Google Patents

Abstract

664,890. Pressure gauges; indicating- apparatus. BENDIX AVIATION CORPORATION. Oct. 14, 1949 [March 28, 1949], No. 26485/49. Classes 106 (ii) and 106 (iv). An airspeed indicator comprising a fixed dial with airspeed designations thereon and a concentric pointer movable in response to airspeed is characterized by a concentric dial movable in accordance with ambient pressure having Mach number designations thereon. A pointer 15 fixed to a shaft 16 moves over a fixed scale 12 graduated in m.p.h. in accordance with a differential pressure responsive member 24 whose interior is connected to a pitot pressure source while its exterior is subjected to ambient pressure, transmission being through a link 23, pivoted to the member 24 and to a pin 22 in a collar 21 on a shaft 20 carrying a sector 19 meshing with a pinion 18 fixed to the shaft 16. A dial 36 graduated in Mach numbers is fixed to a sleeve 57 and is moved in accordance with ambient pressure by an aneroid capsule 30 through a link 31 pivoted to the capsule 30 and a pin 32 in a collar on a shaft 33 carrying a sector 34 meshing with a pinion 58 on the sleeve 57 so as to indicate through an aperture 14 in the dial 12 for speeds above say 260 m.p.h. against the pointer 15, the Mach number corresponding to the airspeed and ambient pressure. A pointer 60, fixed to a sleeve 61 which passes through the sleeve 57 and through which passes the shaft 16, is moved with the dial 36 through pinions 58, 68, double pinion 65, pinions 63, 62, the last being fixed to the sleeve 61. The pinions 68, 63 and 65 are mounted on shafts 64, 66 carried by a sector 56 pivoted on a bushing 55, which also journals the shaft 16, so that the Mach number which may be reached by the aircraft carrying the instrument may be set against the dial 36 by turning the pointer 60 relative thereto through a shaft 71 with pinion 70 meshing with the sector 56. In another embodiment, not shown, the pointer 60 and sector 56 with the shafts and pinions it supports are omitted and this embodiment may be modified by replacing the aperture 14 by a circular hole 42, Fig. 2, through which a Mach number scale 44 and altitude scale 45 appear, the former being read against a restricted part 51 of a pointer 50 and the latter against an index mark 46.