A fluid-working machine has a plurality of working chambers, e.g. cylinders (11), of cyclically changing volume, a high-pressure fluid manifold (14) and a low-pressure fluid manifold (16), at least one valve (13, 15) linking each working chamber to each manifold, and electronic sequencing means (20) for operating said valves in timed relationship with the changing volume of each chamber (11), wherein the electronic sequencing means is arranged to operate the valves of each chamber in one of an idling mode, a partial mode in which only part of the usable volume of the chamber is used, and a full mode in which all of the usable volume of the chamber (11) is used, and the electronic sequencing means (20) is arranged to select the mode of each chamber on successive cycles so as to infinitely vary the time averaged effective flow rate of fluid through the machine.