Abstract: A counter weight door has a plurality of counter weights each associated with a respective one of the panels and an interconnecting spring connecting each of the weights to the next. At least one of the counter weights has a cradle which is arranged to receive a plurality of weighted members. The spring arrangement connecting one counter to the next is housed within the cradle and includes a shaft on which the spring is mounted. The door has a pulley system which has a first pulley on one side of the door, a second double pulley on the other side of the door, a first cable fixed at a first end to the door extending through the first pulley and a second cable fixed at a first end to the door extending through the second pulley to the counter weight system.

Abstract: An improved counter weight door comprises a guide means arranged to be located on respective sides of an opening on a building, a door which is arranged to be supported on respective side thereon by the guide means, the door has a plurality of panels each connected to the next one of the panels for common movement vertically in the guide means, a counter weight system coupled to the door for providing counter weight for the weight of the door, the counter weight system has a plurality of counter weights each associated with a respective one of the panels and an interconnecting means connecting each of the weights to the next. The counter weight system has a weight adjustment arrangement on at least one of the counter weights and the counter weights have a support means which is arranged to receive a plurality of weighted members. The interconnecting means provides a spring arrangement connecting one counter to the next.