the hydraulic actuator includes a control piston that is coupled with the at least one gas exchange valve, that limits {HEAD ~ a hydraulic working chamber}, and that is able to be displaced against {TAIL ~ a valve closing spring} by the pressure medium introduced into the hydraulic working chamber, and 
the hydraulic actuator includes a control piston that is coupled with the at least one gas exchange valve , that limits { HEAD ~ a hydraulic working chamber } , and that is able to be displaced against { TAIL ~ a valve closing spring } by the pressure medium introduced into the hydraulic working chamber , and
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH