A sensor system for monitoring a condition of a piston rod includes an interrogator system having a first coil winding coupled to a housing and radially spaced from the piston rod such that a gap is defined between the first coil winding and the piston rod. A second coil winding is coupled to the piston rod and is inductively coupled to the first coil winding. The second coil winding is configured to communicate with the first coil winding through a range of linear movement of the piston rod relative to the housing. A sensor is coupled to the second coil winding. The sensor is configured to measure a characteristic associated with the piston rod and generate a current in the second coil winding to transmit, via the inductive coupling with the first coil winding, an electrical output signal associated with the characteristic to the interrogator system.

Systems are provided comprising at least one driving cylinder comprising a driving chamber and a driving piston within the driving chamber. The driving piston separates the driving chamber into a driving fluid zone for receiving a driving fluid and a buffer zone for receiving a buffer fluid. The driving piston is movable in the driving chamber by the driving fluid. The systems may also comprise a driven cylinder comprising a driven chamber and a driven piston moveable in the driven chamber. The driven piston is connected to and driven by the driving piston to move within the driven chamber. The driven chamber comprises an input port configured to receive a driven fluid at a first, lower pressure into the driven chamber and an output port configured to expel the driven fluid at a second, higher pressure from the driven chamber when the driven fluid is pressurized by the driven piston. The buffer fluid is different from the driving fluid and the driven fluid, and the buffer fluid in the buffer zone separates the driving fluid from the driven fluid.

Methods and systems are provided to adaptively control a hydraulic fluid supply to supply a driving fluid for applying a driving force on a piston in a gas compressor, the driving force being cyclically reversed between a first direction and a second direction to cause the piston to reciprocate in strokes. During a first stroke of the piston, a speed of the piston, a temperature of the driving fluid, and a load pressure applied to the piston is monitored. Reversal of the driving force after the first stroke is controlled based on the speed, load pressure, and temperature.

Methods and systems are provided to adaptively control a hydraulic fluid supply to supply a driving fluid for applying a driving force on a piston in a gas compressor, the driving force being cyclically reversed between a first direction and a second direction to cause the piston to reciprocate in strokes. During a first stroke of the piston, a speed of the piston, a temperature of the driving fluid, and a load pressure applied to the piston is monitored. Reversal of the driving force after the first stroke is controlled based on the speed, load pressure, and temperature.

A method of differentially steering a hydraulically driven vehicle includes measuring left and right swash plate angles of pumps which drive left and right wheels of the vehicle and if the angles are different from one another and the larger swash plate angle is equal to or exceeds a threshold value then reducing the larger swash plate angle. If the larger swash plate angle is between the threshold value and a lower limit, or below the lower limit the swash plate angle is increased. Control systems and vehicles include swash plate angle sensors and actuators in communication with a controller which effects the steering control method.

Methods and systems are provided to adaptively control a hydraulic fluid supply to supply a driving fluid for applying a driving force on a piston in a gas compressor, the driving force being cyclically reversed between a first direction and a second direction to cause the piston to reciprocate in strokes. During a first stroke of the piston, a speed of the piston, a temperature of the driving fluid, and a load pressure applied to the piston is monitored. Reversal of the driving force after the first stroke is controlled based on the speed, load pressure, and temperature.

Systems are provided comprising at least one driving cylinder comprising a driving chamber and a driving piston within the driving chamber. The driving piston separates the driving chamber into a driving fluid zone for receiving a driving fluid and a buffer zone for receiving a buffer fluid. The driving piston is movable in the driving chamber by the driving fluid. The systems may also comprise a driven cylinder comprising a driven chamber and a driven piston moveable in the driven chamber. The driven piston is connected to and driven by the driving piston to move within the driven chamber. The driven chamber comprises an input port configured to receive a driven fluid at a first, lower pressure into the driven chamber and an output port configured to expel the driven fluid at a second, higher pressure from the driven chamber when the driven fluid is pressurized by the driven piston. The buffer fluid is different from the driving fluid and the driven fluid, and the buffer fluid in the buffer zone separates the driving fluid from the driven fluid.

A linear compressor includes: a piston configured to reciprocate along an axial direction of the linear compressor; a resonance spring configured to elastically support the piston along the axial direction; a motor assembly configured to provide a driving force to the piston, the motor assembly including a magnet that is disposed radially outside the piston; and a supporter configured to be coupled to the piston, the magnet, and the resonance spring. The supporter includes: a piston coupler coupled with the piston; a magnet coupler coupled with the magnet; and a spring coupler coupled with the resonance spring. The piston coupler, the magnet coupler, and the spring coupler are integrally formed by aluminum die casting.

A sensor system for monitoring a condition of a piston rod includes an interrogator system having a first coil winding coupled to a housing and radially spaced from the piston rod such that a gap is defined between the first coil winding and the piston rod. A second coil winding is coupled to the piston rod and is inductively coupled to the first coil winding. The second coil winding is configured to communicate with the first coil winding through a range of linear movement of the piston rod relative to the housing. A sensor is coupled to the second coil winding. The sensor is configured to measure a characteristic associated with the piston rod and generate a current in the second coil winding to transmit, via the inductive coupling with the first coil winding, an electrical output signal associated with the characteristic to the interrogator system.

A method of differentially steering a hydraulically driven vehicle includes measuring left and right swash plate angles of pumps which drive left and right wheels of the vehicle and if the angles are different from one another and the larger swash plate angle is equal to or exceeds a threshold value then reducing the larger swash plate angle. If the larger swash plate angle is between the threshold value and a lower limit, or below the lower limit the swash plate angle is increased. Control systems and vehicles include swash plate angle sensors and actuators in communication with a controller which effects the steering control method.