A camshaft is a mechanical component of an internal combustion engine that is responsible for opening and closing the inlet and exhaust valves of the engine at the right time, with the exact stroke and in a precisely defined sequence. It is a cylindrical rod running the length of the cylinder bank with a number of cams (discs with protruding cam lobes) along its length, one for each valve. The camshaft is driven by the crankshaft by way of gearwheels, a toothed belt, or a timing chain. The task of the cams is to convert the rotary motion of the camshaft into a lifting motion in order to be able to press on the exhaust valves and intake valves. If the cam presses down on the exhaust valve or intake valve via a hydraulic tappet or cup tappet, the valve is opened. If the cam no longer presses on the hydraulic tappet or cup tappet, the valve is pushed up again by the valve spring. Accurate control of the position and speed of the camshaft is critically important in allowing the engine to operate correctly. The shape of the cams greatly affects the engines characteristics. Camshafts are usually made from steel or cast iron, and their bearings and the cam tracks are usually surface-hardened. There are various designs as well as different materials and production processes. The most commonly used type is the cast or hollow cast camshaft. Forged steel camshafts are also used in high-performance engines. A relatively new type is a so-called “tubular steel camshaft”, which is also known as a “built” camshaft. The big advantage here is the weight saving because here 20-40% of weight can be saved.