In one embodiment, a conveyor comprises identical carriages and apparatus for connecting the carriages end. The carriages each include first wheel pairs supported for a rotation about spaced apart parallel axes and a second wheel pair supported for rotation about a perpendicular axis. The first and second wheel pairs are rotatably supported by self-lubricated bearings. The connection apparatus may comprise either connection rods or a wire rope. In another embodiment, the conveyor comprises identical links each including first and second link portions. The link portions are pivotally interconnected by a first connecting pin which also supports a first pair of wheels. Adjacent links are interconnected by a second connecting pin which also supports a second wheel pair. The first and second wheel pairs are rotatably supported by self-lubricated bearings.