Hydraulic actuation device in motor vehicles

A pressure cylinder for a hydraulic actuation device in motor vehicles comprising:

• a housing including an inside wall and an end surface defining an internal cylinder;
• a piston axially displaceable in the internal cylinder for forming a pressure space for hydraulic fluid, the piston including a hemispherical socket and an interior bounded by an outer conical surface facing said pressure space;
• a filling piece in the interior forming an annular space between the filling piece and the outer conical surface;
• a spring arranged in the pressure space and received in the annular space in a compressed state when the piston is fully displaced toward the end surface;
• a tappet including a transmission part with a hemispherical cap pivotable in the socket;
• and
• a pressure medium line opening on said inside wall at said end surface, whereby said outer conical surface can exhaust air bubbles from the pressure space via the pressure medium line when the cylinder is horizontally oriented with the pressure medium line on top and the piston is fully displaced toward the end surface.