GB222936A - Improved means for securing and mounting spiral springs as used with revolving shutters and the like - Google Patents

Abstract

222,936. Hartley, J., and Thornborough, G. R. July 7, 1923. Roller-blinds, spring. - Spring roller shutters, of the kind in which a rotating roller carrying the shutter is mounted upon a divided spindle, one part of which is fixed against rotation and carries within the roller a spring normally acting to counterbalance the weight of the shutter, and in which a second tensioned spring mounted within the roller on the other part of the spindle is normally inoperative but releasable in emergency by hand-controlled, thermostatic, or electrically-operated means to positively raise or lower the shutter, are characterized by a sliding clutch member adapted to clutch the spindle to a fixed bracket or to the roller to put the second spring into or out of action, and by special means for securing the ends of the springs. Fig. 1 shows a roller b mounted on a divided axle a<1>, a<2> and carrying a shutter that is balanced by the concentric springs f. One end of each spring f is secured to the boss g, pinned to the axle part a<1>, while the other ends are secured to the loosely-mounted end boss e<1> of the roller. The additional spring h is connected to the boss i pinned to the axle part a<2>, while the other end is secured to the loosely-mounted end boss e<2> of the roller. When the clutch member j is moved axially against the action of the spring m until it engages the member e<2>, the axle part a<2> and the roller b will rotate in unison, leaving the spring h unaffected during the ordinary use of the shutter. When the operating handle n is released, for example by the rupture of a thermostatic link m<1> in case of fire, or by hand operated or electrical means, the spring m frees the roller from the axle part a<2> and fixes the axle by engagement of the clutch with teeth r<1>, thus allowing the spring h to assist or overcome the springs f as the case may be. To adjust the springs h initially, the bracket n<2> is disconnected from the framework d<2> and the handle and bracket oscillated about the shaft a<2> as a centre. The fixed ratchet r<1> acts as a detent during this process.