Control device for volume stream of hydraulic working medium

A control device for a volume stream of a hydraulic working medium, comprising a blocking valve having a seat valve member cooperating with a stationary main valve seat;

• a pre-control valve member arranged in said seat valve member and cooperating with a valve seat provided in said seat valve member;
• an actuating device with which said pre-control valve member is in an operative cooperation;
• a spring providing a force with which said pre-control valve member cooperates with said valve seat and controls a pressure in a pressure chamber formed in said seat valve member and a valve housing, said seat valve member being pressed against said main valve seat under the action of said pressure;
• means forming a pressure chamber for working means;
• a throttle point with a constant cross-section through which said pressure chamber between said seat valve body and said valve housing constantly communicates with said pressure chamber of said working means;
• a variable throttle point through which said pressure chamber between said seat valve body and said valve housing is connectable with a container, said variable throttle point being spaced from said valve seat of said pre-control valve member and having a cross-section which is changeable of said pre-control valve member, said actuating means which cooperate with said pre-control valve member being formed as a proportional magnet mounted on said blocking valve, said seat valve member having a fine control slider, said main valve seat having an effective diameter which is equal to a diameter of said fine control slider.