US Patent 7549370 Actuator means to accomplish a linear movement

A regulating unit for accomplishing a linear movement includes a cylindrical frame part (1) having a cylinder part (11) and cylinder head (12), which define a piston space (131, 132), and a piston unit (2) to be moved by a pressurized medium in the piston space. The height of a first space (131), in which a piston part (22) is moveable, is bigger than the height of a piston part, the cross section area is bigger than a cross section area of a piston rod. A cross section area of a second space (132) is smaller that the cross section area of the piston part. Pressurized medium may be fed into a cavity space (15), which is between the facing surfaces of the piston part and the piston space, for moving the piston unit towards the cylinder head (12) or vice versa.