A lightweight car-on-track system having a pair of spaced-apart rails and an associated rotatable drive tube with a captive carrier movable along the rails and having a drive wheel in driving engagement with the rotatable drive tube. The drive wheel is spring-loaded against the rotatable drive tube and the capture of the carrier to the rails results in a controlled drive force achieved regardless of the weight of the carrier or of a load supported thereon. The system is made up of a selected number of modular units, each having adjustably mounted frame members supporting opposite ends of a rail section and a drive tube section. Adjustable mounting of frame members to an alignment plate assures alignment between rail and drive tube sections when assembling the system. A transfer device is utilized for transferring a carrier from the end of one track section to the spaced-apart end of another track section with the transfer device being oscillatable about a pivot axis. A drive tube for each track section has a generally frusto-conical end extending beyond an end thereof which coact with the drive wheel of a carrier to impart motion of a carrier onto and off the transfer device.