Patent ID: 9643579
Date: 2017-05-09
CPC Classifications: B60T

Claim:
1. A tandem master-cylinder primary piston, comprising: a skirt equipped with a wall in an intermediary position between extremities of the skirt, the wall including a rear face to support a servobrake thrust rod and a forward face to receive a telescoping rod and a compression spring acting on a secondary piston, wherein: the skirt includes a forward extremity equipped with passages cooperating with a supply chamber to connect the supply chamber with a pressure chamber delimited in a body of a master cylinder by a forward part of the primary piston, the passages cooperate with a resupply seal housed in a groove of the body of the master cylinder to allow passage of a hydraulic fluid in an ESP mode, the wall includes a plastic material, the forward extremity of the skirt includes a ribbed crown delimiting grooves closed in a rear and emerging toward a front to ensure passage between the supply chamber and the pressure chamber when the primary piston is in a supply position, and to enable passage of the hydraulic fluid beneath the resupply seal when the primary piston is in a rest position and a brake system is operating in the ESP mode, and the skirt includes ribs delimiting the grooves, each rib including a first cylindrical portion extending from a front transverse face of the skirt, a conical portion connected to the first cylindrical portion, and a second cylindrical portion connected to the conical portion.