MAN EVB engine brake system

High engine braking power at low design complexity characterises the EVB (Exhaust Valve Brake) engine brake. Brief opening of the exhaust valves increases the engine's braking power significantly. When the exhaust flap is closed, waves of pressure build up in the exhaust duct which causes the exhaust valves to briefly open. A piston subjected to engine oil pressure in the exhaust valve block holds the valve slightly open during the compression and the subsequent expansion stroke. By throttling exhaust gases at this gap, the upwards and downwards movement of the piston can be utilised for braking purposes.