A multi-cylinder hydraulic actuator system comprising multiple hydraulic actuators, with each of the multiple hydraulic actuators being linked via a simultaneous transmission line that is joined to or integral with a synchronisation connection; wherein each hydraulic actuator comprises: a hydraulic cylinder ; a piston within the hydraulic cylinder and movable in response to movement of hydraulic fluid in a hydraulic circuit coupled to the hydraulic cylinder; the synchronisation connection for receiving an input from the simultaneous transmission line ; and a valve for controlling the flow of hydraulic fluid in the hydraulic circuit; wherein the valve is a rotary valve comprising: a first valve section arranged to rotate in either a first rotational direction or a second rotational direction in response to input from the simultaneous transmission line in order to open a hydraulic flow path to the cylinder and urge the piston to move along the hydraulic cylinder in a corresponding first linear direction or second linear direction; and a second valve section arranged to rotate in either the first rotational direction or the second rotational direction; wherein the second valve section is coupled to the piston such that movement of the piston results in movement of the second valve section to follow the first valve section and to close the hydraulic flow path when the rotation of the first valve section is stopped. a hydraulic cylinder ; a piston within the hydraulic cylinder and movable in response to movement of hydraulic fluid in a hydraulic circuit coupled to the hydraulic cylinder; the synchronisation connection for receiving an input from the simultaneous transmission line ; and a valve for controlling the flow of hydraulic fluid in the hydraulic circuit; wherein the valve is a rotary valve comprising: a first valve section arranged to rotate in either a first rotational direction or a second rotational direction in response to input from the simultaneous transmission line in order to open a hydraulic flow path to the cylinder and urge the piston to move along the hydraulic cylinder in a corresponding first linear direction or second linear direction; and a second valve section arranged to rotate in either the first rotational direction or the second rotational direction; wherein the second valve section is coupled to the piston such that movement of the piston results in movement of the second valve section to follow the first valve section and to close the hydraulic flow path when the rotation of the first valve section is stopped. a first valve section arranged to rotate in either a first rotational direction or a second rotational direction in response to input from the simultaneous transmission line in order to open a hydraulic flow path to the cylinder and urge the piston to move along the hydraulic cylinder in a corresponding first linear direction or second linear direction; and a second valve section arranged to rotate in either the first rotational direction or the second rotational direction; wherein the second valve section is coupled to the piston such that movement of the piston results in movement of the second valve section to follow the first valve section and to close the hydraulic flow path when the rotation of the first valve section is stopped. <EOS>