Actuating device having automatic adjustment for a vehicle hydraulic disk brake

Abstract

The invention relates to an actuating apparatus ( ) with automatic clearance adjustment for a vehicle hydraulic disk brake and includes a housing ( ) having a base ( ) and a shell ( ) in which an open cylinder bore ( ) is provided. For actuating the brake, a piston ( ) is hydraulically displaceable in the bore. A mechanical actuating device for displacing the piston in the bore and for compensating lining wear comprises an expanding device ( ) acting axially in a brake actuating direction and a length adjustable strut between the expanding device and the piston. The strut is formed by a first strut part ( ) having a bolt shaped end, which is screwed into a second, substantially sleeve shaped strut part ( ), which rests with a conical flange ( ) against the piston. Between the bolt shaped end of the first strut part and the second strut part there is a cavity ( ) which is to be filled with brake fluid and closed off in a fluid tight manner at one end. To ensure trouble free filling of the latter, the second strut part has in the region of the cavity a plurality of radial bores ( ) which connect the cavity to an outer peripheral surface of the second strut part and in the conical flange a plurality of axial through bores ( ) are provided which are disposed relative to the radial bores in such a way that in any rotational position of the second strut part relative to the housing shell at least one radial bore is situated above a horizontal reference plane extending through the longitudinal center line of the length adjustable strut and its radially outer bore end lies below at least one part of at least one axial through bore.