Three-position pneumatic or hydraulic power cylinder

A three-position pneumatic or hydraulic cylinder comprising:

• a housing provided with two end caps and an annular protuberance, wherein the two end caps are provided at two end portions of the housing, and the annular protuberance is formed on an inside surface of the housing and located between the two end portions of the housing;
• a rod arranged inside the housing and configured to perform limited movement within the housing;
• wherein the rod is provided with two peripheral protuberances at its two end portions and a central protuberance located between the two peripheral protuberances;
• wherein the central protuberance is configured in a form of a cylindrical bushing, and sleeved in the annular protuberance to form, with the annular protuberance, a hermetic moveable coupling of the shaft/opening type;
• working fluid supply channels formed in the housing or in the housing and the rod;
• and
• two pistons sleeved on the rod and perform limited movement along the rod due to the peripheral protuberances on the rod;
• wherein the central protuberance is configured to separate the two pistons;
• wherein each piston, a corresponding end of the housing, and a corresponding end cap cooperate to form a first chamber;
• each piston, the housing, the annular protuberance, and the bushing cooperate to form a second chamber;
• each of the first chamber and the second chamber communicates with one of the working fluid supply channels.