Abstract: A linear actuator is disclosed. The linear actuator comprises a cylinder portion and a base portion. The cylinder portion comprises a housing defining internally a compression chamber for containing a fluid and comprising a piston assembly that can reciprocate within the compression chamber. The housing further defines a cylinder port in fluid communication with said compression chamber. The base portion defines a first base port and a second base port and a passage extending therebetween fluidly communicating the first base port with the second base port, and comprises valve means operable to control the flow of fluid through the second base port, in which the valve means is actuatable between an open condition in which the flow of fluid through the second base port is permitted, and a closed condition in which the flow of fluid through the second base port is substantially prevented.