GB754452A - Improvements in or relating to apparatus for opening and closing doors - Google Patents

Abstract

754,452. Door-operating apparatus. NATIONAL PNEUMATIC CO., Inc. Feb. 8, 1954, No. 3626/54. Drawings to Specification. Class 65 (1). [Also in Group XXXVII] In a system for operating doors, particularly of public vehicles, by an electric motor, undesired movement of the doors from the open or closed position is prevented by an electrically-controlled brake which is controlled by a door-actuated switch and is energized only when the door is in one or other extreme position. In the system described, a second dooractuated switch energizes the brake when the doors are closed ; a resistance is connected in parallel with the motor by a third door-actuated switch when the door is nearly open, to reduce its speed, and a second resistance is connected in series with the motor during the whole of the closing movement so that this movement is slower than the opening. The motor circuits are controlled through relays by a hand selecting switch and limit switches. The motor drives, through spur and worm gearing, a shaft placed in the centre of the door lintel or sill, this shaft having opposed arms linked to arms on two vertical shafts placed at the sides of the doorway and carrying folding doors. In a system for controlling two sets of doors, a rotary switch is used, providing for one set to be opened when the switch is moved in one direction from a neutral (doors closed) position and the other set by opposite movement of the switch ; continued movement in either direction opens both sets of doors. When only one set is open, only the brake of that set is energized. Selective closing is not provided for.