A rotating shaft drive system is configured to propel a load along a conveying path of an overhead conveyor system. A stationary frame extends along the conveying path and supports the rotating shaft drive system. A movable carriage is suspended from the stationary frame and engages with a rotating shaft of the shaft drive system to propel the carriage and the load. The rotating shaft comprises a plurality of shaft segments supported pillow blocks at each end of the rotating shaft segments, and the pillow blocks create a gap between adjacent shaft segments. The movable carriage has at least one canted driven roller configured to engage with adjacent rotating shaft segments and to create a helical loci of tractional engagement that provides sufficient drive force to propel the carriage and the load along the conveying path. The drive system is further configured to provide continuous propulsion as the canted driven roller moves across the gap between adjacent shaft segments.