That model of actuator is actually direct-drive onto the leadscrew and so the motor will stall when it reaches maximum load or the ends of travel (unless you have a limit switched variation on the model, mine purchased from ebay did not have any). Shouldnt worry about stalling though as the currents involved are very unlikely to cause lasting damage.

Might be worth looking here if you ever consider a future actuator upgrade http://firgelliauto.co.uk/default.phphttp://firgelliauto.co.uk/default.php