PUSH-PULL CHAIN AND ACTUATOR

A push-pull chain that can bend in one direction only, and is provided with at least two rollers on each of the driving pins, one of the rollers engages a drive sprocket and the other of said at least two rollers engages a chain guide surface. An actuator for e.g. opening and closing a window that uses this dual-roller push-pull chain. A link driven push-pull chain that can bend in one direction only, with links that is shaped as an engagement surface for engaging a drive sprocket. An actuator for e.g. opening and closing a window that uses the link driven push-pull chain.