GB818090A - Improvements in or relating to control spring mechanism for a pivoted arm or lever - Google Patents

Abstract

818,090. Door operating appliances. HENDERSON Ltd., P. C. Sept. 17, 1957 [June 28, 1956], No. 20009/56. Class 65(1) [Also in Group XXXII] A spring mechanism for controlling a pivoted lever comprising an extension or compression spring having one end fixed to a point remote from the pivot of the lever has the other end of the-spring connected to a point on the lever other than its pivotal point through a roller capable of moving along the lever and being pivotally mounted on one end of a link, the other end of which is pivoted at a point spaced from the pivot of the lever such that the roller moves towards or away from the pivot of the lever as the latter rotates through its arc of movement. Lever 10, Figs. 3, 4, pivoted at 11 is connected to door 15 by bracket 14 and to spring 22 via a roller which moves in groove 16 and turns on pin 20. Pin 20 is carried by member 18 pivoted at 19. When the door is closed arms 10, 10<SP>1</SP> of the lever are substantially vertical, spring 22 is fully extended and the roller is at the minimum distance from pivot 11. Since pins 11, 19 are not coaxial spring 22 is at an angle to the vertical and tends to swing the door into open position; a catch prevents this. On release of the catch the door swings outwards and upwards, arm 10<SP>1</SP> moves down and the roller moves away from pivot 11 so that increased leverage tends to compensate for decreased spring force. When the door is fully open arms 10, 10' are again vertical but spring 22 is fully contracted. On closing the door the above sequence is reversed. In a modification pins 11, 19 are in alignment and a pin 26 on link 18 holds part of spring 22 at an angle to the vertical when the door is closed so that opening of the door is spring assisted. Two or more positions may be provided for the attachment of the roller and spring to the link so that adjustments may be made for doors of different weights.