GB408044A - Improvements in and relating to roller shutters - Google Patents

Abstract

408,044. Preventing fires. BOOTH, J., BOOTH, T., and BOOTH, C. H., Hulton Steelworks, Bolton. Nov. 8, 1932, No. 31555. [Class 47 (ii).] A roller shutter of the kind associated with I a heat-sensitive device which is arranged to allow the shutter to descend in case of fire, is associated with mechanism which comes into operation automatically to facilitate the raising of the shutter and its retention in a raised position, after an emergency closure has occurred. As shown, a cable 1 embodying a fusible link, failure of which releases the tension of the counterbalancing springs of the shutter, is connected at its free end to a lever 5 one arm 7 of which holds a rod 8 in raised position. The lower end of the rod 8 is connected to a cam 13 keyed to a shaft 14 on which a pawl 20 is secured. The latter is adapted to co-operate with a ratchet 21 on a shaft 22 which carries a handle 26 and a bevel gear 28 adapted to drive a re-winding shaft 30 which, at its upper end, is operatively connected to the barrel of the shutter. A sleeve 34 threaded on the shaft 30 carries a striker 35. When the fusible link fails in case of fire, the shutter falls and the lever 5 is released. The consequent release of the rod 8 leaves the cam 13 free to turn. Descent of the shutter rotates the shaft 30, causing the striker 35 to engage and move the cam 13 and, consequently, the pawl 20 to engage the ratchet 21. A spring detent 36 prevents rotation of the shaft 14 except under the positive action of the striker 35. Thereafter, the shutter can be raised by rotation of the hand wheel 26, and is held at any desired position by the engagement of the pawl 20 with the ratchet 21. The connection between the pawl 20 and shaft 14 allows the pawl to ride over the ratchet during rewinding. The ratchet is loose on the shaft 22, and is locked to it, when rewinding of the shutter is desired, by means of a sleeve 23 and thread 27 on the shaft.