A system for providing hydraulic power to a plurality of hydraulic circuits (160, 162, 164, 166, 168, 170) of a machine, comprising: a plurality of hydraulic pumps (132, 134, 136, 138, 140A, 140B) for supplying the plurality of hydraulic circuits (160, 162, 164, 166, 168, 170) with hydraulic fluid; a plurality of control valves (142, 144, 146A, 146B, 150A, 150B, 152A, 152B, 154A, 154B) operable to associate each of the plurality of hydraulic pumps (132, 134, 136, 138, 140A, 140B) with one of the plurality of hydraulic circuits (160, 162, 164, 166, 168, 170) for supplying hydraulic fluid exclusively to the associated hydraulic circuit (160, 162, 164, 166, 168, 170); and a control unit configured to: determine a hydraulic flow required by each of the plurality of hydraulic circuits (160, 162, 164, 166, 168, 170); determine a number of hydraulic pumps (132, 134, 136, 138, 140A, 140B) to be associated with each of the plurality of hydraulic circuits (160, 162, 164, 166, 168, 170) based on the hydraulic flows required by the plurality of hydraulic circuits (160, 162, 164, 166, 168, 170); operate the plurality of control valves (142, 144, 146A, 146B, 150A, 150B, 152A, 152B, 154A, 154B) to exclusively associate the determined number of hydraulic pumps (132, 134, 136, 138, 140A, 140B) with each of the plurality of hydraulic circuits (160, 162, 164, 166, 168, 170); and operate the plurality of hydraulic pumps (132, 134, 136, 138, 140A, 140B) to supply the required hydraulic flow to each of the plurality of hydraulic circuits (160, 162, 164, 166, 168, 170), wherein the system is characterised by a plurality of sensors for detecting an overrunning load condition in one or more of the plurality of hydraulic circuits (160, 162, 164, 166, 168, 170), and the control unit is configured to modify the hydraulic flow supplied to the one or more hydraulic circuits (160, 162, 164, 166, 168, 170) for which the overrunning load condition is detected. a plurality of hydraulic pumps (132, 134, 136, 138, 140A, 140B) for supplying the plurality of hydraulic circuits (160, 162, 164, 166, 168, 170) with hydraulic fluid; a plurality of control valves (142, 144, 146A, 146B, 150A, 150B, 152A, 152B, 154A, 154B) operable to associate each of the plurality of hydraulic pumps (132, 134, 136, 138, 140A, 140B) with one of the plurality of hydraulic circuits (160, 162, 164, 166, 168, 170) for supplying hydraulic fluid exclusively to the associated hydraulic circuit (160, 162, 164, 166, 168, 170); and a control unit configured to: determine a hydraulic flow required by each of the plurality of hydraulic circuits (160, 162, 164, 166, 168, 170); determine a number of hydraulic pumps (132, 134, 136, 138, 140A, 140B) to be associated with each of the plurality of hydraulic circuits (160, 162, 164, 166, 168, 170) based on the hydraulic flows required by the plurality of hydraulic circuits (160, 162, 164, 166, 168, 170); operate the plurality of control valves (142, 144, 146A, 146B, 150A, 150B, 152A, 152B, 154A, 154B) to exclusively associate the determined number of hydraulic pumps (132, 134, 136, 138, 140A, 140B) with each of the plurality of hydraulic circuits (160, 162, 164, 166, 168, 170); and operate the plurality of hydraulic pumps (132, 134, 136, 138, 140A, 140B) to supply the required hydraulic flow to each of the plurality of hydraulic circuits (160, 162, 164, 166, 168, 170), determine a hydraulic flow required by each of the plurality of hydraulic circuits (160, 162, 164, 166, 168, 170); determine a number of hydraulic pumps (132, 134, 136, 138, 140A, 140B) to be associated with each of the plurality of hydraulic circuits (160, 162, 164, 166, 168, 170) based on the hydraulic flows required by the plurality of hydraulic circuits (160, 162, 164, 166, 168, 170); operate the plurality of control valves (142, 144, 146A, 146B, 150A, 150B, 152A, 152B, 154A, 154B) to exclusively associate the determined number of hydraulic pumps (132, 134, 136, 138, 140A, 140B) with each of the plurality of hydraulic circuits (160, 162, 164, 166, 168, 170); and operate the plurality of hydraulic pumps (132, 134, 136, 138, 140A, 140B) to supply the required hydraulic flow to each of the plurality of hydraulic circuits (160, 162, 164, 166, 168, 170), wherein the system is characterised by a plurality of sensors for detecting an overrunning load condition in one or more of the plurality of hydraulic circuits (160, 162, 164, 166, 168, 170), and the control unit is configured to modify the hydraulic flow supplied to the one or more hydraulic circuits (160, 162, 164, 166, 168, 170) for which the overrunning load condition is detected.