A hydraulic system for an aircraft, the hydraulic system comprising: a hydraulic rotary actuator assembly rotationally coupled to a road wheel of the aircraft, the hydraulic rotary actuator assembly having a first operating mode comprising a braking operation, wherein a rotation of the road wheel causes the hydraulic rotary actuator assembly to pump a fluid from a fluid supply system; a variable restrictor assembly coupled to the hydraulic rotary actuator assembly in the aircraft, the variable restrictor assembly controlling a flow of the fluid flowing from the hydraulic rotary actuator assembly, to brake the rotation of the road wheel on a ground surface; and a variable restrictor controller coupled to the variable restrictor assembly, the variable restrictor controller controlling the variable restrictor assembly, so as to enable a variation of a rate of braking of the road wheel on the ground surface; the hydraulic rotary actuator assembly having a second operating mode comprising a taxiing operation, wherein the fluid is pumped through the hydraulic rotary actuator assembly, and causes the road wheel to rotate on the ground surface; an auxiliary pump coupled between the variable restrictor assembly and the fluid supply system in the aircraft, the auxiliary pump pumping the fluid through the hydraulic rotary actuator assembly, via the variable restrictor assembly; and a taxiing controller coupled to the variable restrictor assembly, the taxiing controller controlling an output of the auxiliary pump, so as to enable the variation of a rate of the rotation of the road wheel on the ground surface; the hydraulic rotary actuator assembly having a third operating mode comprising a wheel spin-up operation, wherein the fluid is pumped by the auxiliary pump through the hydraulic rotary actuator assembly, via the variable restrictor assembly, and causes the road wheel to rotate during a flight mode of the aircraft, prior to the aircraft landing on the ground surface; and a wheel spin-up controller coupled to the variable restrictor assembly, the wheel spin-up controller controlling the output of the auxiliary pump, so as to enable the variation of the rate of the rotation of the road wheel during the flight mode. a hydraulic rotary actuator assembly rotationally coupled to a road wheel of the aircraft, the hydraulic rotary actuator assembly having a first operating mode comprising a braking operation, wherein a rotation of the road wheel causes the hydraulic rotary actuator assembly to pump a fluid from a fluid supply system; a variable restrictor assembly coupled to the hydraulic rotary actuator assembly in the aircraft, the variable restrictor assembly controlling a flow of the fluid flowing from the hydraulic rotary actuator assembly, to brake the rotation of the road wheel on a ground surface; and a variable restrictor controller coupled to the variable restrictor assembly, the variable restrictor controller controlling the variable restrictor assembly, so as to enable a variation of a rate of braking of the road wheel on the ground surface; the hydraulic rotary actuator assembly having a second operating mode comprising a taxiing operation, wherein the fluid is pumped through the hydraulic rotary actuator assembly, and causes the road wheel to rotate on the ground surface; an auxiliary pump coupled between the variable restrictor assembly and the fluid supply system in the aircraft, the auxiliary pump pumping the fluid through the hydraulic rotary actuator assembly, via the variable restrictor assembly; and a taxiing controller coupled to the variable restrictor assembly, the taxiing controller controlling an output of the auxiliary pump, so as to enable the variation of a rate of the rotation of the road wheel on the ground surface; the hydraulic rotary actuator assembly having a third operating mode comprising a wheel spin-up operation, wherein the fluid is pumped by the auxiliary pump through the hydraulic rotary actuator assembly, via the variable restrictor assembly, and causes the road wheel to rotate during a flight mode of the aircraft, prior to the aircraft landing on the ground surface; and a wheel spin-up controller coupled to the variable restrictor assembly, the wheel spin-up controller controlling the output of the auxiliary pump, so as to enable the variation of the rate of the rotation of the road wheel during the flight mode.