A tachograph's a device that combines the functions of a clock and a speedometer. Fitted to a motor vehicle, a tachograph records the vehicle's speed and whether it's moving or stationary. The mechanical tachograph writes on a round piece of paper which constantly turns throughout the work day. The marker moves further from the center the faster the vehicle's moving. An entire rotation encompasses 24 hours. Analogue tachographs record the driver’s periods of duty on a waxed paper disc. How… (More on Tachograph)