Patent GB-377262-A (GB)
Title: Improvements relating to direction indicators for moving craft
Filed: 1931-04-16
Abstract: 377,262. Automatic steering gear- SPERRY GYROSCOPE CO., Inc., Manhattan Bridge Plaza, Brooklyn, New York, U.S.A.-(Assignees of Sperry, E. A., ; 115, Ocean Avenue, Brooklyn, New York, and Thompson, H. H. ; 73, Pollard Road, Mountain Lakes, New Jersey, both in U.S.A.) April 16, 1931, No. 11310. Convention date, May 7, 1930. [Classes 4 and 114.] Means, controlled by the relative position of a magnetic compass and a free gyroscope, are provided for exerting a torque to correct the position in azimuth of the gyroscope. In the form shown gimbals 5 support a casing 4 containing a pivoted magnetic element 6 on the stem 7<1> of which is eccentrically mounted a circular disc 8 serving differentially to cover nozzles 9, 10. Flexible pipes 9<1>, 10<1> connect the nozzles 9, 10 to opposite ends of a cylinder 11, further pipes 15, 16 connectfng the cylinder 11 to a chamber 2 from which air is evacuated by the Venturi tube 1. The arrangement is such that a piston 12 in the cylinder 11 tends to move when the nozzles 9, 10 are differentially covered by the disc 8. A gyroscope 18 mounted to rotate about its centre of gravity is supported on a horizontal axis 20 in a vertical ring 21 having a stem 25 carrying a compass card C and an eccentrically mounted circular disc 8<1> serving differentially to cover nozzles 26, 27. The latter are connected to opposite ends of a cylinder 11<1> connected by the pipes 15, 16 to the chamber 2. A piston 12<1> in the cylinder 11<1> is connected by a rod 13<1> to a slide valve 29 connected at the other end to the piston 12 by a rod 13. When the nozzles 26, 27 and 9, 10 are similarly uncovered, i.e. when the gyro axis and magnetic element have the same direction in azimuth the tendency of the piston 12 to move is opposed by the tendency of the piston 12<1> and the slide valve rests in its central position where it covers equally the ports connected to the pipes 33, 34. The latter lead through hollow trunnions and the hollow ring 21 to opposed cylinders 35 fixed to the ring 21 and containing pistons fixed to a crank arm 37 on the horizontal trunnion of the gyro. When the gyro and magnetic element have different directions in azimuth the slide valve 29 moves causing a difference in pressure in the pipes 33, 34 and cylinders 35 giving rise to a torque precessing the gyro into the direction of the magnetic element. The rate of precession of the gyro is slow so that it does not react to the short period oscillations of the magnetic element. Means for preventing inclination of the gyro axis comprise air jets issuing from each end of an aperture 40 the ends of which are differently covered as the gyro tilts by curved arms 41, 42 as described in Specification 366,764, [Group XX]. When used for automatic steering the ring 21 carries a shield 42<1> normally covering equally a pair of nozzles (only one 43 shown) mounted on a rotatable base 45 and connected by pipes 43<1>, 441 to a cylinder 48<1> communicating by pipes 46, 47 with the chamber 2. Displacement of the nozzles 43 relative to the shield 42<1> causes a piston 48 in the cylinder 48<1> to move carrying with it a slide valve 49 controlling the ports of pipes 50, 51 leading to cylinders the positions of which are connected to a rudder bar 56<1>. The course may be changed by operating a hand crank turning a worm 58 for rotating the base 45. The frame 57 of the worm 58 may be connected by a link to the rudder bar so that when the rudder is turned the base 45 will be revolved by axial displacement of the worm. Specification 366,058 is referred to.