Patent GB-622185-A (GB)
Abstract: 622,185. Gyroscopic apparatus. SPERRY GYROSCOPE CO., Inc. Aug. 12, 1943, No. 13080. Convention date, Feb. 20, 1942. [Class 97 (iii)] A directional gyroscope is provided with means for rotating its direction-indicating member independently of the gyroscope whilst the gyroscope is locked against azimuthal rotation. Locking about the vertical axis may also lock the rotor bearing frame about its horizontal axis. The inner and outer gimbals 15, 6, Fig. 1, of the gyro may be locked by pressing in a knob 42, thereby causing a rack 56 (operating through a pin and inclined slot arrangement) to raise a ring 63. The ring lifts a pin 66 slidable in the vertical gimbal 6, and the pin resiliently raises a pivoted rack 68 into gear with a sector 69 to lock the inner gimbal, the outer gimbal 6 being locked by the contact of the ring 63 and pin 66. The inward movement of the knob 42 also brings a pinion resiliently into engagement with teeth on the azimuth indicating dial 40 which is driven by gearing 46, 47 from the vertical gimbal 6 through a slip friction coupling on a shaft 44. By rotating the knob, the dial 40 may (owing to the presence of the friction coupling) be reset independently of the locked gyro. A course indicator in the form of a transparent disc with radial markings, or of a disc with spoke-like members 70 is attached to the dial 40 by a. slip friction connection which permits the course indicator to be set relative to the dial by means of a disconnectible knob 71, Fig. 5. The indicating dial 40 is partially covered by a mask 79 with two concentric openings 77, 78, each displaying a course reading, the arrangement facilitating course readings when the aircraft is turned through 180 degrees. In a modified setting means, the dial 80, Fig. 6, is made of magnetic material and is attracted into driving engagement with a non-magnetic disc 81 by a permanent or electric magnet 82 secured to the driving shaft 44<SP>1</SP>. By pulling out a knob 86, a pinion 84 is engaged with an internal gear 83 and the dial is disengaged from the disc 81. The dial may then be set by rotating the knob. The gyro rotor 10, Fig. 4, is attached to a shaft 17 mounted in ball bearings 11, 12 which are urged apart by a spring 19 in order to take up play. The rotor is provided with a recess at each end accommodating respectively the stator 13 of the driving motor and the bearings 11, 12 together with their shaft. Polyphase current to drive the rotor is supplied through the gimbal trunnions by means of insulated concentric sleeves and axial pins as described in Specification 622,270. If the gyroscope is to be controlled by a magnetic compass, a coil 92<SP>1</SP> excited in one direction or the other from the magnetic compass co-operates with permanent magnets 90, 91 on the rotor casing to produce the necessary torques for orienting the gyro in azimuth. The Specification as open to inspection under Sect. 91 describes a modification wherein the gear-driven dial 40 is replaced by a ring-shaped indicator attached to the vertical gimbal 6, the two sets of readings being displayed through rectangular openings. This subject-matter does not appear in the Specification as accepted.