US Patent 7827951 Gas exchange valve actuating apparatus

In a gas exchange valve operating apparatus with at least one overhead camshaft for actuating the gas exchange valves, with a hydraulic medium supply passage extending through the camshaft and with at least one hydraulic switchable support unit cooperating with a lever-like cam follower which is disposed on a switchable support unit and on a gas exchange valve and is furthermore in contact with the overhead camshaft, the support unit is disposed in communication with at least one pressure medium supplied via the hydraulic medium supply passage of the camshaft.