For controlling supply priorities, a hydraulic system includes several loads, a pump, and a tank. One load has a first-level supply priority, and optionally a second load has a second-level supply priority subordinate to the first level. A third load has a third-level supply priority subordinate to the second level. Each load can be connected to the pump by a separate supply line. The supply lines for the first and the optional second load are connected to the pump by a common load-pressure-controlled priority valve and the supply line for the third load is connected to the pump by an additional load-pressure-controlled priority valve. A first load-pressure line leading to the pump is connected to a load-pressure line of the third hydraulic load and to a second load-pressure line.