Patent GB-290392-A (GB)
Title: Improvements relating to gyroscopic compasses
IPC: G01C19/38
Filed: 1927-03-02
Abstract: 290,392. Farmer, C. D., and Hight, W. R. March 2, 1927. Gyroscopic compasses.-Deviations due to the action of changes of speed or course of the vessel on the damping means of a compass are avoided by providing means for exerting on the compass during such changes, a force, which counteracts the force tending to produce the deviations, without affecting the normal action of the damping means. The Figures show the application of the invention to a compass of the Sperry liquidcontrol type wherein a spider 2 supports the follow-up ring 1 in which is mounted on vertical pivots the vertical ring 3 supporting the gyroc scope casing 4 on horizontal pivots 5. Gravity control is provided by liquid-containing vessels 6, 7 supported by a frame 8 pivoted to the ring 1, and connected by a tube 9, the frame 8 being connected to the casing 4 at a point 6<1> which is displaced laterally from the vertical axis of the casing so that tilting of the casing results in the production of both an orienting torque about the horizontal axis, and a damping torque about the vertical. Acceleration of the vessel produces a flow of liquid and a consequent false damping moment. Fig. 6 shows one form according to the invention of means for counteracting this effect. The vertical ring 3' is provided with a mass 10 near the horizontal axis 5<1>, this mass being preferably detachable so that different masses can be used in different latitudes. Under the influence of acceleration forces this mass exerts on the ring 3<1> a pressure opposed to that caused by the flow of mercury. To preserve the vertical balance of the compass a counterbalance weight 11 is attached to the ring 1<1>. Figs. 1 and 2 show a form in which the usual compensating weights 17, 18 carried by brackets 19, 20 secured to the ring 3 are, made use of for the purposes of the invention. One or each of the weights is carried by an arm 21 pivoted at 22 to the bracket and normally held vertical by a spring 23 and stop 24. When a change of course or speed occurs a solenoid 25 carried by the bracket is energized and, through a connection 26, deflects the arm 21 carrying the weight,. The movement of the arm is limited by a stop 27 adjusted according to the latitude. The means for energizing the solenoid is of the kind described in Specification 275,182, comprising step-up gearing 28 operated by the large gear 29 on the follow-up member 1 and actuating, through a lost-motion device 30, a governor 31 arranged to close a switch 32, which excites an electromagnetic clutch 33 and causes the upper part thereof to be turned by a gear 34. This rotation closes one or other of the contacts 35, 36, see Fig. 8, after a predetermined rotation, to energize the solenoid 25. The delay action prevents closing of the contacts except in response to a substantial change of course. A switch 37 is also provided and is closed when a change of speed occurs. In another form of the invention the correcting torque is applied by masses pendulously mounted on opposite sides of the ring 3 so as to be normally balanced, these masses being both adapted to be deflected in the same direction by solenoids which are energized as above described. Specification 215,594 also is referred to.