Abstract: The invention relates to a master cylinder with a pressure chamber formed in a housing of the master cylinder and a reservoir bore for accommodating a pressure fluid reservoir, a valve with a closing element being provided which due to a pressure difference prevailing between the pressure chamber and the pressure fluid reservoir can be moved into an opening position or a closing position, the valve in its opening position allowing a pressure fluid flow from the pressure fluid reservoir into the pressure chamber and throttling or preventing, in its closing position, a pressure fluid flow from the pressure chamber into the pressure fluid reservoir. Means are provided which maintain the closing body in its opening position when it is acted upon by a closing pressure difference during vacuum filling of the brake system.

Abstract: The invention relates to a master cylinder, in particular for a hydraulic brake system, with at least one pressure chamber formed in a housing of the master cylinder and at least one reservoir bore for accommodating a pressure fluid reservoir, a valve with a closing element being provided which due to a pressure difference prevailing between the pressure chamber and the pressure fluid reservoir can be moved into an opening position or a closing position, the valve in its opening position allowing a pressure fluid flow from the pressure fluid reservoir into the pressure chamber and throttling or preventing, in its closing position, a pressure fluid flow in the opposite direction to the pressure fluid flow from the pressure chamber into the pressure fluid reservoir.