A gear wheel is a machine element rotatable about an axis, consisting of the wheel body with its bearing surfaces and the teeth projecting from the wheel body. The teeth are evenly distributed around the circumference of the gear. In addition, chain and belt wheels are available. These are also machine elements used for power transmission with chains and belts. The range is supplemented, among other things, by toothed pulleys. These are ring-shaped washers with pointed teeth which are used to secure a screw. This ensures uncontrolled loosening of the connection.