Abstract: A hydraulic unit for a vehicle brake system that enables limiting wheel brake slip is known. To that end, the hydraulic unit has at least one piston pump, which is drivable by an electric motor and empties a reservoir that is filled on the occasion of the limitation of wheel brake slip. This reservoir comprises a cylinder, embodied in the manner of a blind bore, as well as a piston that divides a storage chamber from a spring chamber in the cylinder, a spring, and a closure element that prevents water from entering the cylinder if the hydraulic unit should become immersed in water. A pressure equalization conduit begins at the spring chamber and leads into the interior of the motor, so that a displacement of the piston for taking up pressure fluid in the storage chamber is effected essentially only by friction of the piston and forces of the spring. A conduit is also provided, by means of which pressure fluid that emerges from the piston pump at the eccentric can be carried away.

Abstract: A fastening screw is used to hold a hollow body against a base body. To assure that no dirt can get into the hollow body, sealing between the fastening screw and the hollow body is necessary. The fastening screw has a bevel (10s) coated with a relatively soft coating at the transition between the screw shaft and the screw head. When the fastening screw is tightened, one edge of the hollow body digs into the coating, thus assuring a secure seal. The fastening screw is intended in particular in a brake system for securing a motor housing to a pump housing.