Hydraulic drive for electric switch operating device has cylinder for inner piston and outer cylinder ring for outer annulkar piston formed in one piece

摘要

The hydraulic drive has a cylinder (2) defining an inner cylinder space containing a hydraulic drive piston and formed in one piece with an outer cylinder ring (5), cooperating with the outer surface of the cylinder for defining an outer annular pressure space (14), receiving an outer annular piston (13), acted on by a spring device (16) and provided with respective seals (9,15) cooperating with the outer wall of the cylinder and the inner wall of the cylinder ring.