A fluid system includes a controllable first pump unit for supplying fluid pressure to at least one implement; a prime mover arranged to supply a driving torque to the first pump The first pump unit is arranged to supply fluid pressure to the implement. The fluid system further includes a controllable second pump unit connected to a fluid accumulator. The prime mover is arranged to supply a driving torque to the second pump unit in order to accumulate fluid pressure in the accumulator during periods of low demand. Fluid pressure from the accumulator is arranged to drive the second pump unit to assist the prime mover during periods of high demand in order to supply an additional driving torque in excess of the available driving torque from the prime mover.