Disc brake with automatic adjustment

Claim 1

A disc brake with automatic adjustment of the type including a caliper, a brake actuator which is adapted to act directly upon a first friction component and, by reaction through the caliper, upon a second friction component, the brake actuator including a mechanical control acting upon a hydraulic control piston by means of an automatic adjustment device, the automatic adjustment device formed by a screw and nut device with reversible pitch which is operable by the hydraulic control piston when the control piston travels beyond a predetermined distance defined by a clearance between an annular component and a thrust bearing, the thrust bearing adapted to act upon the screw and nut device and the clearance variable as a function of pressure applied to the control piston, characterized in that when a predetermined control pressure is reached said annular component is moved axially relative to said control piston by means of a monitoring piston slideably and sealingly mounted within said control piston, the annular component movable against a biasing force exerted by a resilient member engaging the annular component and the movement of the annular component neutralizing the automatic adjustment device, the monitoring piston engaging sealingly a surface of a bore in the control piston and within which the monitoring piston is disposed, and that for any control pressure which is less than said predetermined pressure, the predetermined distance is defined by said annular component coming to bear, by means of said resilient member, against the monitoring piston which bears axially against a bottom of the bore of the control piston and which houses said monitoring piston.