Multistage hydraulic systems and methods for converting the potential energy of a pressurized gas, particularly air, into mechanical work when operating in motor, and for producing compressed gas from the mechanical work of the rotating shaft when rotating when operating in compressor mode, by performing a successive expansioncompression of the said gas. Cook time is user selectable and varies from less than one minute to 4 minutes. An imaging device 22 for robot vision is supported on an upper end of the upper body 1 of the robot by an attachment 2 which is positioned forwardly of the center-of-gravity point A. Principals of the invention can be extended to isolation applications and push-pull forward converts, in particular. The core cross-section of the outer thread support has the shape of a rounded n-sided polygon, n being a prime number>3. The energy source connects to the stator at the proximal end and powers the transition device.