Abstract: Apparatus for moving a load, particularly a stack of panels, along a roof structure, including a plurality of spaced-apart roof rafters and transverse purlins comprising: a roof-mounted rail for mounting on said roof in vertical alignment with a purlin, a load-carrying cart comprising a carriage having rollers movable along the rail, and a load-carrying platform mounted on the carriage for longitudinal and vertical movement relative thereto including an inverted U-shaped elongate channel member. Mechanism is provided for relatively longitudinally moving the load-carrying platform and the carriage between rest positions and longitudinally displaced positions. The carriage and load-carrying platform include cooperating camming rollers and cam receiving slots which upwardly guide the platform relative to the carriage as the carriage and platform are relatively longitudinally moved, to lift the load relative to the roof structure for subsequent rolling movement via the carriage on the track.