Abstract: An upper sealed reservoir and a lower vented reservoir are connected by a conduit and tube extending into the lower reservoir. A shroud forms a chamber around the end of the tube within the lower reservoir and is vented at its upper end. Openings are provided in the tube and the shroud and are indexed in diametrically opposite relation, with the opening in the tube pointing in the direction of the center of the lower reservoir. The arrangement maintains proper hydraulic fluid level balance between the two reservoirs under a wide range of vehicle attitudes and accelerations. When either the vehicle attitudes or acceleration, or both, momentarily reorients the actual fluid level in the lower reservoir and the shroud, trapped fluid within the shroud chamber prevents air from entering the upper reservoir through the tube and conduit so that excess fluid cannot flow into the lower reservoir from the upper reservoir.