Linear actuator

A linear actuator arranged to convert rotary motion to linear motion, comprising:

• a linear shaft arrangement, comprising a first shaft portion and a second shaft portion, the linear shaft arrangement extending along a longitudinal axis of the linear actuator, wherein at least one of the first shaft portion and the second shaft portion of the linear shaft arrangement is arranged to be translated linearly along the longitudinal axis upon actuation of the linear actuator;
• a first drive system comprising a first rotary component arranged to extend at least partially around the longitudinal axis and arranged to rotate about the longitudinal axis to actuate the linear shaft arrangement;
• and
• a second drive system comprising a second rotary component arranged to extend at least partially around the longitudinal axis at a different axial position to the first drive system;
• wherein the linear actuator is arranged, when the first drive system fails, to effect rotation of the second rotary component about the longitudinal axis to actuate the linear shaft arrangement so that the second shaft portion moves relative to the first shaft portion;
• and
• wherein the first shaft portion comprises a screw shaft portion comprising helical grooves on an outer surface of the screw shaft portion.