A hydraulic transmission comprising a variable displacement pump and motor, at least one having cylinders having valves which are controllable on each cycle of cylinder working volume to determine the net displacement of working fluid by the cylinder. The transmission has a valve control module which determines a displacement of the pump and the motor by specifying a displacement demand. The pump and/or motor valve control module determine the frequency of intensity peaks in the frequency spectrum of the pattern of cylinders carrying out active and inactive cycles of cylinder working volume using a first procedure and, if these will fall within disallowed frequency bands including the resonant frequency of components with which the transmission is in mechanical communication, the displacement demand, or another input, is periodically modified to suppress generation of those frequencies. The hydraulic transmission is useful for example in a wind turbine generator, or a vehicle.

A hydraulic transmission comprising a variable displacement pump and motor, at least one having cylinders having valves which are controllable on each cycle of cylinder working volume to determine the net displacement of working fluid by the cylinder. The transmission has a valve control module which determines a displacement of the pump and the motor by specifying a displacement demand. The pump and/or motor valve control module determine the frequency of intensity peaks in the frequency spectrum of the pattern of cylinders carrying out active and inactive cycles of cylinder working volume using a first procedure and, if these will fall within disallowed frequency bands including the resonant frequency of components with which the transmission is in mechanical communication, the displacement demand, or another input, is periodically modified to suppress generation of those frequencies. The hydraulic transmission is useful for example in a wind turbine generator, or a vehicle.

A system for supplementing the electric power needed by a pump jack electric motor, thereby reducing the electric power purchased from the local utility or power supplier. The system comprises a solar photovoltaic system, or other forms of renewable energy, and regenerated power from the electric motor or drive. The system can be both on-grid and off-grid. Battery banks and capacitor banks may be used to store energy.

A system for supplementing the electric power needed by a pump jack electric motor, thereby reducing the electric power purchased from the local utility or power supplier. The system comprises a solar photovoltaic system, or other forms of renewable energy, and regenerated power from the electric motor or drive. The system can be both on-grid and off-grid. Battery banks and capacitor banks may be used to store energy.

A modular pump system permits combining multiple discrete pump assemblies in serial and/or parallel configurations to tailor system output to user needs. The assemblies may be combined by hand quickly, without the needs for tools, to permit use in remote areas.

A modular pump system permits combining multiple discrete pump assemblies in serial and/or parallel configurations to tailor system output to user needs. The assemblies may be combined by hand quickly, without the needs for tools, to permit use in remote areas.

A system for supplementing the electric power needed by a pump jack electric motor, thereby reducing the electric power purchased from the local utility or power supplier. The system comprises a solar photovoltaic system, or other forms of renewable energy, and regenerated power from the electric motor or drive. The system can be both on-grid and off-grid. Battery banks and capacitor banks may be used to store energy.

A system for supplementing the electric power needed by a pump jack electric motor, thereby reducing the electric power purchased from the local utility or power supplier. The system comprises a solar photovoltaic system, or other forms of renewable energy, and regenerated power from the electric motor or drive. The system can be both on-grid and off-grid. Battery banks and capacitor banks may be used to store energy.

A turbine, wherein a propeller is mounted to said turbine, rotatable around a propeller axis, wherein a multi piston pump is provided, said multi piston pump being drivable by said propeller for pressurizing a pumping fluid, wherein the multi piston pump comprises a central part and a drive ring extending around the central part, wherein the central part comprises a series of piston-cylinder assemblies which are each compressible and extendible in a respective radial direction with respect to a common central axis, wherein each of the piston-cylinder assemblies is directly or indirectly engageable by the drive ring for radial compression thereof, in particular for pressurizing said pumping fluid, wherein at least one of the piston-cylinder assemblies is provided with a hydraulic and/or pneumatic biasing means for biasing, at least selectively biasing, at least part of that piston-cylinder assembly towards engagement with the drive ring, in particular substantially independent of and/or complementary to a biasing by a pressure of pumping fluid at that piston-cylinder assembly.

A system for supplementing the electric power needed by a pump jack electric motor, thereby reducing the electric power purchased from the local utility or power supplier. The system comprises a solar photovoltaic system, or other forms of renewable energy, and regenerated power from the electric motor or drive. The system can be both on-grid and off-grid. Battery banks and capacitor banks may be used to store energy.