Here are some pictures of the old UM7-MOCON unit as it existed. The track and dolly arrangement is based upon a guy named Ron Dexter who's an old hat in the US film industry. It uses off the shelf bearings that contact with the track which is aluminium tubing strengthened with wood down the centre of the tubes. The motor is a hobby stepper motor attached to a 200:1 Tamiya gearbox and Tamiya wheel. The more recent system the UM11-Dolly2 uses thicker walled rails for the tracks and is now propelled by a micro stepper motor with a cam belt. For the best view hit the full screen button below right. This has now been "raided" for components and the UM11 and 12 combination is the current tracks and dolly system.