Pic. 2.187. Diagram of the valve drive mechanism: 1 - inlet valves; 2 – a cam-shaft of a drive of final valves; 3 - camshafts of the intake valve drive; 4 – a cam-shaft of a drive of final valves; 5 - exhaust valves
Valves are opened and closed directly by four camshafts (see fig. 2.187). The exhaust camshafts are driven by a toothed belt, while the intake camshafts are driven by gears on the exhaust camshafts.