Patent GB-397654-A (GB)
Title: Improvements in or relating to gyroscopic compasses
IPC: G01C19/38
Filed: 1932-07-16
Abstract: 397,654. Gyroscopic compasses. SPERRY PRODUCTS, Inc., Manhattan Bridge Plaza, Brooklyn, New York, U.S.A.- (Assignees of Carter, L. F. ; 129, Woodridge Place, Leonia, New Jersey, U.S.A.) July 16, 1932, No. 20186. Convention date, July 16, 1931. [Class 97 (iii).] A gyro compass utilizing the W-E component of the earth's rotation and having a rapid rate of orientation comprises a preferably non-pendulous gyroscope supported with its spinning axis in and maintained at a predetermined inclination to the vertical in an E-W plane. In the form shown, the gyro casing 10 is mounted in neutral equilibrium about an axis 11 in a ring 12 pivoting about an axis 16 in a frame 15 which is suspended by a pivot 17 from a plate 24, the latter having a spindle 23 carrying a compass card 25 and journaled in a plate 22 supported by springs 21 from the binnacle 20. The plate 24 has an annular gear 26 connected by pinions 27, 28, to an azimuth motor 31 fixed on the plate 22. The axis of the gyro is maintained slightly inclined to the vertical in an E-W plane by a pair of solenoids 35 mounted on the frame 15 and having cores 37 fixed to the ring 12. The current to the solenoids 35 is controlled by a trolley fixed to the gyro casing and co-operating with contact segments on a pendulous bail 30. An outer ring 13 pivots on the axis 16 and is stabilized by a pendulum or preferably has a bail 50 carrying a stabilizing gyroscope 52, the precession of which moves a trolley fixed to the gyro over contacts carried by the bail 50. Solenoids 65 carried by ring 13 are then energized and coact with cores 67 fixed to the frame 15 so that a torque is applied to restore the gyro 52 to its central position. To ensure that the ring 13 is not maintained in an inclined position a trolley 74 fixed to the ring 13 coacts with contact segments 71, 72 on a pendulous element 70 and controls solenoids 75, 76 carried by the bail 50 and co-operating with a core 77 fixed to the vertical axis of the gyro 52 so that torques are applied to retain the trolley 74 in contact with both segments 71, 72. The circuit is wired so that during accelerations the movement of the trolley fixed to the gyro 52 due to the resultant precession of this gyro breaks the circuit to the solenoids 75, 76 and renders them ineffective during accelerations. In operation the axis 11 is normally in the meridian but if it is not in the meridian the action of the earth in rotating will tilt the gyro axis in a N-S plane causing a relative displacement of the rings 12, 13. A trolley 40 fixed to the ring 12 co-operates with contact segments 41, 42 fixed to the ring 13 and, when there is relative inclination between the rings 12, 13, brings into operation through a relay the azimuth motor 31 which then brings the axis 11 back into the meridian. The motor 31 is brought into operation when the vehicle turns and a switch lying in the circuit of the tilt control magnets 35 may be opened by the relay so that the operation of the bail 30 is suspended during turning. In a modification the apparatus is supported from the base of the binnacle and the gyro casing 10 carries an upstanding pointer which in conjunction with a transparent graduated dome or plate serves as an inclination indicator. Alternatively the pointer may be replaced by a small light source projecting a spot of light on a ground glass screen.