When the flat drive belt drives, the belt is sleeved on the smooth wheel surface and is driven by the friction between the belt and the wheel surface. The transmission types include open drive, cross drive and semi-cross drive, which are respectively suitable for different relative positions and different rotation directions of the driving shaft and the driven shaft. The flat belt drive has simple structure, but is easy to slip, and is usually used for transmission with a transmission ratio of about 3.

Belt drive is a kind of mechanical transmission that uses the flexible belt tensioned on the pulley to carry out movement or power transmission. According to the different transmission principles, there are friction belt drives driven by the friction between the belt and the pulley, and there are synchronous belt drives driven by the meshing of the teeth on the belt and the pulley.