Double-cylinder buffer

Abstract

A buffer includes an actuation cylinder filled with oil, a piston rod extending through the upper end of the cylinder for vertical movement in the cylinder, a piston provided at the lower end of the piston rod in sliding contact with the inner wall of the cylinder and having a damping action producing mechanism. The piston divides the interior of the cylinder into upper and lower chambers. An outer cylinder is disposed about the cylinder in a peripherally spaced relationship therewith to define a reservoir chamber therebetween, the upper portion of the reservoir chamber being filled with gas and the lower portion of the reservoir chamber being filled with oil. A passage communicates the lower oil filled portion of the reservoir chamber with the lower chamber of the cylinder. A passage communicates the upper gas filled portion of the reservoir chamber with the upper chamber of the cylinder through the outer periphery of the piston rod. A valve is provided in the passage communicating the upper chamber of the cylinder with the gas filled portion of the reservoir chamber for only allowing the flow of oil from the upper chamber of the cylinder to the reservoir chamber. The valve includes a first seal for sealable engagement with a rod guide along which the piston rod is guided. The valve further includes a second seal for sealing the interior of the buffer.