Before revision: After this initial description of Yan Su's device, the text continues to describe the work of Wu Deren, who crafted a wheeled device that would combine the odometer and south-pointing chariot: Chariots with differential gears Background and explanation An illustration of a differential between the drive shaft (at bottom right) and driving wheels of an automobile There is a widely believed hypothesis that most, if not all, south-pointing chariots worked by means of differential gears employed differential gears.Joseph Needham (1986).
After revision: After this initial description of Yan Su's device, the text continues to describe the work of Wu Deren, who crafted a wheeled device that would combine the odometer and south-pointing chariot: Chariots with differential gears Background and explanation An illustration of a differential between the drive shaft (at bottom right) and driving wheels of an automobile The English engineer George Lanchester proposed that some south-pointing chariots employed differential gears.Joseph Needham (1986).