GB593175A - Improvements relating to door-operating and like mechanism - Google Patents

Abstract

593,175. Door-operating mechanism. GENERAL MOTORS CORPORATION. June 12, 1945, No. 14848. Convention date, July 19, 1944. [Classes 44 and 65 (i)] [Also in Group XXXVII] Door-operating mechanism comprises a latch-held spring forming part of a telescopic link, and a motor-operated screw and nut device, the nut of which is adapted to move in one direction to release the spring and effect a quick movement of the door and to move in the return direction and effect a slow reverse movement of the door. A tubular member 60 while telescoping within a casing 81 stresses a coil spring 78 which is held in the stressed condition by a spring- loaded pivoted latch 71 engaging the outer race of a ball bearing 50 mounted on a screw shaft 25. A recess 64 in the link pivotally engages a lug mounted on a bomb-bay door of an aircraft. A nut 52 having a bevelled portion 73 which in the closed position of the door as shown, abuts the latch, is adapted to slide within the link, the nut and shaft co-operating by means of travelling balls 53 which are contained within a channel defined by coincident helical grooves. An electric motor 20, pivotally connected to the fuselage of the aircraft by an apertured lug 21, is adapted to rotate the shaft through a magnetic clutch which drives a spindle 23, on an eccentric portion 40 of which is rotatably mounted a hypocylic gear member 43 having two sets of teeth which mesh respectively with internal teeth on gears 28 and 32. The former is secured to the screw-shaft and the latter is held stationary by the meshing of external teeth with a worm 35. The gear 28 has a flange 100 formed with a worm tooth which meshes with a gear 101 coupled by a train of reduction gearing to a switch control cam. To open the door a selector switch is moved to the " down " position, closing circuits for operating the motor to move the nut downwards, thereby tripping the latch and releasing the spring which projects the link out of the casing, a collar 61 on the link then resting on an upper flange 152 of the nut. The cam operates switches arranged to stop the motor after the latch is tripped. When the door is fully open a signal lamp becomes illuminated. The selector switch when moved to the " up " position closes further circuits which energize a reversing field winding in the motor. The nut then ascends carrying with it the link until the latch becomes re-engaged. The cam is arranged to reverse the direction of rotation of the motor at this point, causing the nut to descend until it abuts the latch, when the motor is stopped by the cam. A second signal lamp then becomes illuminated to indicate that the door is fully closed.