Abstract: A fluid working machine, operable to carry out a motoring cycle under at least some circumstances, comprises a controller (12) and a working chamber (2) of cyclically varying volume. The working chamber has a high pressure valve (18) associated therewith to control the connection of the working chamber to a high pressure manifold (20), and an electronically controllable primary low pressure valve (14) to control the connection of the working chamber to a low pressure manifold. The controller is operable to actively control at least the primary low pressure valve, in phased relationship to cycles of working chamber volume, to determine the net displacement of fluid by the working chamber on a cycle by cycle basis. The fluid working machine is adapted to release pressurised fluid from the working chamber prior to the opening of the primary low-pressure valve, during a motoring cycle. This facilitates the opening of the primary low pressure valve.

Abstract: A fluid power system comprises a pump with multiple independently variable outlets (11, 12, 13, 14), each of which is capable of delivering fluid in individually controllable volume units and a plurality of hydraulic loads (15, 16, 18, 20). A system of switching valves is configured to create fluid connections between the pump outlets and the loads. A control system commands both the pump and the switching valves, so as to create valve state combinations to satisfy load conditions as demanded by an operator The number of pump outlets (11, 12, 13, 14) connected to one or more of the loads (15, 16, 18, 20) is changeable to satisfy the flow required of the load due to the operator demand, each pump outlet being commanded to produce a flow depending on the status of other outlets connected a load to which the outlet is connected and the operator demand for that load.

Abstract: The present invention provides a hydraulic pump for use in driving a load with a control modulation system which modulates a primary control signal in order to accommodate variations in secondary changeable parameters which require control at a higher frequency or have a lower latency.

Abstract: A variable transmission comprises a first fluid working machine (1) for connection to a prime mover (2), a second fluid working machine (5) for connection to a mechanical load (6) and a fluid system linking the first and second working machines, the fluid system having a high-pressure side (3) and a low-pressure side (4) each connected to both said first and said second fluid working machines (1, 5), a fluid accumulator (7) on the high-pressure side, a means to admit fluid from the reservoir to the low-pressure side and a pressure control valve to maintain the correct pressure in the low-pressure side, wherein the second fluid working machine (5) includes chambers of variable volume having electronically controllable valves such that each of said chambers has pumping, motoring and idling modes of operation, and the second fluid working machine (5) is operable to both source fluid to and sink fluid from each of said high-pressure side (3) and said low-pressure side (4).