Abstract: A reservoir tank includes a main portion and a storage chamber disposed in the main portion for storing operating fluid, with the storage chamber being surrounded by a side wall, a ceiling portion and a bottom portion. A float is disposed in the storage chamber and is adapted to move vertically corresponding to the height of the operating fluid level, and a reed switch is operatively associated with the float so as to operate in accordance with the height of the float. A partition member divides the storage chamber into an upper space and a lower space in which the operating fluid and the float are disposed.

Abstract: The hydraulic brake system for a vehicle which can perform anti-lock control includes a brake circuit for connecting a master cylinder to wheel brakes, a control valve circuit for decreasing hydraulic brake pressure in the wheel brake by discharging brake fluid from the wheel brake to a reservoir, a plunger pump driven by an electric motor for returning brake fluid from the reservoir to the brake circuit and a slit formed on at least the discharge valve seat or the suction valve seat of the pump unit for evacuating the pump chamber of the plunger pump. The hydraulic brake system can further include a one-way valve which permits communication between the pressure chamber of the pump with the reservoir for evacuation.