Patent GB-552554-A (GB)
Title: Improvements relating to gyro-verticals or artificial horizons
IPC: G01C19/44
Filed: 1941-06-05
Abstract: 552,554. Gyroscopic apparatus. SPERRY GYROSCOPE CO., Inc. June 5, 1941, No. 7144. Convention date, June 5, 1940. [Class 97 (iii)] A gyro-vertical comprising a gyroscopically stabilized element defining a vertical axis and a horizontal reference plane normal thereto is universally mounted in an outer frame by means of a Cardan suspension having two horizontal gimbal axes (the frame being supported on a platform, ship or other vehicle liable to turn in azimuth and thereby to change the orientation of the gimbal axes with respect to the North), gravity responsive means (a pendulum) for controlling the application of a torque to cause the stabilized element to seek the vertical, and means for applying a latitude-error correcting torque in two components applied about the two gimbal axes respectively. Manual means are provided for setting the correcting means according to latitude; and the component torque about each gimbal axis is controlled to be proportional to the cosine of the angle made by that axis with the E-W direction. The gyroscope 25, Fig. 1, is mounted universally by a gimbal ring 63 supported on trunnions 62 within a follow-up frame 16, 20 which in turn is universally mounted by an outer gimbal ring 6. The follow-up frame carries a five-pole inductive pick-off 24 the armature 29 of which is mounted on the gyro casing. A follow-up motor 2, Fig. 5, adjusts the outer gimbal 6, and consequently the follow-up frame, about an axis 7, 71. The motor also drives coarse and fine transmitters 5, 5<SP>1</SP> for transmitting the position of the gyro-vertical to a distance. a second follow-up motor 3 similarly adjusts the follow-up frame about an axis 17, 171 through the intermediary of a bail 18 and rollers 21, and simultaneously drives coarse and fine transmitters 4, 4<SP>1</SP>. Any relative tilting of the follow-up frame 20 and the gyroscope casing generates a signal in the pole windings of the pick-off 24 in the plane of tilt and actuates the appropriate followup motor to drive the follow-up frame to follow the gyroscope as is explained in Specification 378,148. A pendulous U-shaped frame is universally mounted on the follow-up frame 20 by means of a gimbal ring 30 and carries an armature 34 co-operating with a second inductive pick-off 35 mounted on the follow-up frame. Relative tilt between the pendulum and the follow-up frame generates in the transformer windings of the pick-off a signal which after amplification energizes a torque applying device 36 operating on a copper stator 39 as described in Specification 545,284 to erect the gyroscope. During turns or other acceleration of the ship, the erecting force may be eliminated by a switch in the supply to the windings 45, the switch being operated either manually or automatically as shown in U.S.A. Specification 2,093,503. The pendulum is damped by an oil bath 38. In order continually to correct for latitude, the torqueapplying device 36 is provided with additional windings 50, 50<SP>1</SP> and 51, 51<SP>1</SP>, Fig. 3, connected to a controller 52 which may be set in accordance with the latitude. The correcting torque provided by the additional windings is applied in two components through the windings of a midtapped potentiometer resolving mechanism 53 the contact arm of which is rotated from the repeater motor 54 of a gyro-compass or other azimuth indicator, the E.M.F. components being distributed between the poles of the torque-applying device 36 so that the resultant torque is kept constant in the E-W plane.