Abstract: The invention relates to a sequential control system for two-cylinder thick medium pumps whose delivery cylinders (1, 1′) are actuated hydraulically by two drive cylinders (5, 5′) in opposing cycles. A pipe shunt (3) is provided inside a material feed container and is connected at the inlet side alternatively to the apertures (2, 2′) of the delivery cylinders (1, 1′) and at the outlet side to a pump line (4). The drive cylinders (5, 5′) are each connected at one end to a different connection pint of a reversing pump (6) to form a closed hydraulic circuit (11, 11′) and at their outer ends via an oscillating oil line (12) hydraulically to one another. To effect switching of the pipe shunt (3), pressure oil is taken off directly from the hydraulic lines (11, 11′) leading from the reversing pump (6) to the drive cylinders (5, 5′).