A linear actuator assembly comprising: a linear actuator driven by rotation which has a housing and an output shaft, the output shaft defining an actuator axis and being movable along the actuator axis between an extended position and a retracted position relative to the housing; and a buffer carriage arranged in an active configuration in which it is mounted on either the housing or the output shaft, the buffer carriage having a rotary portion, wherein: the output shaft is rotationally coupled to the rotary portion of the buffer carriage such that rotation of the output shaft about the actuator axis requires corresponding rotation of the rotary portion; the rotary portion is rotationally restrained when the buffer carriage is in the active configuration; the one of the housing and output shaft on which the buffer carriage is not mounted has a first abutment surface; the first abutment surface is positioned to act directly or indirectly on the buffer carriage when the output shaft reaches one of the extended position and the retracted position, such that continued movement of the output shaft beyond said position moves the buffer carriage from the active configuration towards a first passive configuration; and the rotary portion is rotatable about the actuator axis when the buffer carriage is in the first passive configuration. a linear actuator driven by rotation which has a housing and an output shaft, the output shaft defining an actuator axis and being movable along the actuator axis between an extended position and a retracted position relative to the housing; and a buffer carriage arranged in an active configuration in which it is mounted on either the housing or the output shaft, the buffer carriage having a rotary portion, wherein: the output shaft is rotationally coupled to the rotary portion of the buffer carriage such that rotation of the output shaft about the actuator axis requires corresponding rotation of the rotary portion; the rotary portion is rotationally restrained when the buffer carriage is in the active configuration; the one of the housing and output shaft on which the buffer carriage is not mounted has a first abutment surface; the first abutment surface is positioned to act directly or indirectly on the buffer carriage when the output shaft reaches one of the extended position and the retracted position, such that continued movement of the output shaft beyond said position moves the buffer carriage from the active configuration towards a first passive configuration; and the rotary portion is rotatable about the actuator axis when the buffer carriage is in the first passive configuration. the output shaft is rotationally coupled to the rotary portion of the buffer carriage such that rotation of the output shaft about the actuator axis requires corresponding rotation of the rotary portion; the rotary portion is rotationally restrained when the buffer carriage is in the active configuration; the one of the housing and output shaft on which the buffer carriage is not mounted has a first abutment surface; the first abutment surface is positioned to act directly or indirectly on the buffer carriage when the output shaft reaches one of the extended position and the retracted position, such that continued movement of the output shaft beyond said position moves the buffer carriage from the active configuration towards a first passive configuration; and the rotary portion is rotatable about the actuator axis when the buffer carriage is in the first passive configuration.