Patent ID: 6894447

Claim:
An electrically operated system for extending and retracting a room relative to an exterior containment wall, the room having structure that forms an outside vertical wall, an interior vertical wall and an upper wall and a lower wall joined by side walls, said system comprising: a plurality of guide tracks combined with the interior wall at the upper and lower walls of the room and extending around the side walls where the side walls join with the upper and lower walls; a plurality of compressive load bearing chains, one moveable in each of said tracks, each of said chains having a plurality of connected links that terminate in a first end and a second end, said chain first ends being fixed to said exterior containment wall; a plurality of linear actuators, one for each of said chains and having an operating rod connected to a respective one of said chain second ends, the linear actuators being positioned along the interior vertical wall and mounted transversely to the direction of movement of the room; an electrical motor operatively connected to and powering each of the linear actuators; a sensor combined with each chain for detecting movement of each chain by counting the links as they pass the sensor to provide a signal related to the number of links passing the sensor; and a control system combined with the motors for processing the signals from the sensors to control operation of each motor and thereby synchronize movement of the chains.