A tracked, stair-climbing carrier for carrying loads up and down stairs and across floors. The carrier includes a frame mounting a pair of parallel endless tracks at its sides for moving the frame forwardly and rearwardly along a floor and up and down stairs. An upper, load-receiving deck is slideably...http://www.google.com/patents/US4027889?utm_source=gb-gplus-sharePatent US4027889 - Stair-climbing carrier
