Roller-shutter opening mechanism - has dogs on endless belt parallel to direction of slat movement

摘要

The mechanism opens and shuts a roller shutter comprising slats (22) joined (50) together and engaged by moving dogs (48). The dogs are on an endless driven belt, running part of the way parallel to the direction of movement of the slats. The belt can be arranged to run round two drums. These maintain tension in it at a predetermined value, one of them being driven. ADVANTAGE - Even movement even when starting with no jamming of dogs into engagement with slats.