Abstract: The actuator includes two piston motors interconnected in opposed driving relation with a fixed axis rotary shaft, and fluid pressure control means for controlling the piston motors so that they rotate the shaft bi-directionally at constant rotational velocity with constant resultant torque. The two piston motors preferably are of different effective cross sectional areas, the smaller motor being continuously pressurized with fluid composed solely of fluid from a fluid pressure source, and the larger motor being selectively pressurized with fluid made up of fluid from the fluid pressure source together with fluid exhausted from the smaller motor. A single valve controls fluid flow to and from the piston motors to effect bi-directional shaft rotation, or maintain the shaft in a fixed position. The valve may be operated automatically by servo control means responsive to the positions of the piston motors.

Abstract: The cellular structure is made up of a series of interengaged cell segments which form a series of triangular cells. The cell segments each include an equilateral generally triangular main body portion and a flat leg portion projecting from one tip of the main body portion. The outer surface of each leg portion is parallel to the outer surface of the main body portion wall opposite the tip from which the leg portion projects. Each leg portion extends to and engages a groove formed in the tip of an adjacent cell segment to provide a continuous outer surface to which a panel facing sheet may be secured. Another panel facing sheet may be secured to the outer surface of the main body portion opposite wall.