GB592472A - Improvements in and relating to the control of tabs on aircraft control surfaces - Google Patents

Abstract

592,472. Control means for tabs on aircraft control surfaces. AIR-EQUIPEMENT. May 18, 1945, No. 12517. Convention date, Jan. 7, 1943. [Class 4] A tab on a movable aircraft control surface is controlled by driving means and reduction gearing also mounted on the control surface. As shown, a reversible electric motor 14 controlled from the pilot's cockpit by a switch 24, spring-urged to the off position, drives a non-reversible screw 5 secured against axial movement by a thrust bearing 6 by means of reduction gearing 12, torque-limiting clutch 13 and a bevelwheel 11 in a casing 1 secured to the control surface. An internally-threaded sleeve 3 meshing with the screw 5 and secured against rotation by a stud 7 in the casing 1 engaging a groove 8 in the sleeve is linked to the tab so that the tab is turned by axial movement of the sleeve 3. The motor 14 is fed for either direction of rotation from a battery 21 through two separate circuits, either of which may be closed by the two-way switch 24. Within the same casing 23 (shown twice in the drawing) as the switch 24 is a press-button switch 26 which when depressed completes through a switch 29 operated by the sleeve 3 whichever of two circuits will run the motor in a direction to return the tab to its normal position. Locking means secure the switch 26 in its depressed position if it is pressed while the switch 24 is central. A device 31, 32 indicating the position of the tab on a dial 31 in the cockpit is provided. The electric motor may be replaced by a hydraulic or compressed air motor, the switches 24, 26, 29 being replaced by valves.