A linear web accumulator is provided wherein a web is threaded alternately between two sets of movable rollers. Each set of movable rollers is connected to the other through a mechanical connection, so that relative motion of the sets is always simultaneously toward each other or away from each other....http://www.google.es/patents/US6050517?utm_source=gb-gplus-sharePatente US6050517 - Counterbalanced web accumulator
