Patent GB-757678-A (GB)
Abstract: 757,678. Gyroscopic apparatus. GENERAL ELECTRIC CO. Oct. 11, 1954 [Oct. 16, 1953], No. 29260/54. Class 97 (3). In gyroscopic apparatus, means permitting its disconnection from an indicating member prior to its connection to. an adjusting mechanism comprises an axially fixed clutch, member connected to the indicating member, an axially movable clutch member urged toward the axially fixed member for co-operation with it by a resilient spring member, the movable member being held in fixed angular relation with the output shaft of the gyroscope by the said resilient spring member, and a clutch throw-out plate freely rotatable with respect to the axially movable clutch member. As shown in Fig. 2, a cup-gear 13 has a shaft 16 journalled in a hub 14 supported by spacers 15 in the casing 11 of a directional gyroscope. The cup-gear 13 is geared to a gimbal (not shown) supporting the gyroscope rotor casing in the usual manner. A pointer 18 is mounted on a shaft 25 journalled in a bushing 30 supported by a bracket 22 near the front end of casing 11, which is closed by a glass plate 21. The rear end of shaft 25 carries a permanently magnetized disc 26 forming part of a clutch, the other member of which comprises a plate 27 carried by a shaft 36 slidable in a bore in shaft 16. A cup-shaped member 35, fast with shaft 16, has slots which receive the ends of a flat spring 33 which urges plate 27 into contact with disc 26, and also transmits movement of shaft 16 to plate 27. The contacting faces of members 26, 27 may be roughened to give greater friction. The engagement of the clutch thus enables shaft 16 to drive pointer 18 in accordance with the movement of the gyroscope rotor case relative to the craft, so that the direction of heading is indicated on a dial 19. The dial 19 end a setting gear 31 are fixed on opposite sides of the bushing 30, which is rotatable in bracket 22; such rotation being, however, normally restrained by a spring member 32 between gear 31 and bracket 22. A clutch member 28 is keyed to bushing 30 by a pin 42 in such manner that member 28 is movable axially with bushing 30, but rotates therewith. When it is desired to reset pointer 18 and dial 19 together, a knob 23 is pushed in, causing a sleeve 46, wherein the shaft 43 of the knob is journalled, to move from one position to another, with snap action of a spring-pressed ball 47. An arm 49 fixed to sleeve 46 has two projections. One projection 50 engages a clutch throw-out plate 40 rotatably mounted on shaft 36, moving the shaft against action of spring 33 to disengage clutch plates 26, 27. The other projection 51 enters an annular groove in clutch member 28, and so moves it into contact with the magnetic plate 26. At the same time a gear-wheel 52 is moved into mesh with a gearwheel 53 on the same shaft as a gear-wheel 54 in permanent mesh with setting gear 31. This gear can now be turned by knob 23, and with it hub 30 and dial 19, and, through clutch members 28, 26, the pointer 18. After resetting, knob 23 is pulled out, and the parts return to their previous positions. To reset the pointer only, knob 24 is pressed in, moving a sleeve 57 from one position to another with snap action of a spring-pressed ball 59. An arm 64 attached to the sleeve engages the clutch throw-out plate 40 to separate clutch plates 26, 27. A bevel gear 60 on the shaft 55 of knob 24 is in permanent mesh with a bevel gear 61 on a shaft 62, held in a skew position by a sleeve 63 fast with sleeve 57. Movement of the sleeves brings a bevelled wheel 65 into frictional driving engagement with a bevelled part of plate 26, through which rotation of shaft 62 and shaft 55 is transmitted to the pointer 18. In modifications, only one member (either the dial or the pointer) may be adjustable, the knob 23 and associated mechanism being omitted; the magnetic clutch may operate by friction only; and an extension of shaft 36 may extend through a bore in shaft 25 beyond the end thereof and may carry a needle indicating the orientation of the gyroscope spin axis. Specifications 718,484 and 740,796 are referred to.