Patent ID: 6996985

Claim:
An expansion reservoir for a master cylinder of a hydraulic force transmission system, the reservoir having a fluid chamber defined by a reservoir bottom and a flexible reservoir top which may be moved towards the reservoir bottom or away therefrom as a function of a filling level of the reservoir, wherein a hydraulic connection to the master cylinder is provided at the reservoir bottom while the reservoir top comprises a substantially liquid-tight but air-permeable connection to the atmosphere in order to allow pressure compensation between an air volume left in the fluid chamber when the force transmission system is in the filled state and the atmosphere, wherein the hydraulic connection to the master cylinder comprises an extension protruding into the fluid chamber, which extension defines a predetermined volume in the fluid chamber which is larger than the volume of air left in the fluid chamber when the force transmission system is in the filled state, and wherein the extension is constructed in one piece with the reservoir bottom and is preferably injection-molded from plastics material.