US Patent 7543656 Breathing for single acting hydraulic cylinders

A single acting hydraulic cylinder apparatus includes a mechanism operated by a single acting hydraulic cylinder, the mechanism including a hollow member. A breathing chamber is provided by sealing at least a portion of the hollow member such that outside air is prevented from entering the breathing chamber. A pressurized port of the hydraulic cylinder is adapted for connection to a pressurized hydraulic fluid source, and an un-pressurized breathing port of the hydraulic cylinder is connected to the breathing chamber such that air can flow between the breathing port and the breathing chamber.