Fluid reservoir for a master cylinder in a hydraulic force transmission system

The overflow container (12) has a hydraulic fluid chamber (50) defined between a container base (46) and a flexible container cover (52), displaced relative to the base in dependence on the container filling level and coupled to the atmosphere via a vent connection (64) for pressure equalisation between the air volume in the container and the atmosphere. The hydraulic connection (62) for the source cylinder, provided in the container base, has a projection (66) extending into the fluid chamber, defining a given volume (V) which is greater than the air volume in the filled fluid chamber.