Abstract: The invention describes an over-speed governor for a stairlift which not only triggers a safety gear or brake upon the carriage exceeding a pre-determined speed, but also triggers the safety gear in the event the carriage unexpectedly reverses its direction. In a preferred embodiment, the over-speed governor also triggers the safety gear in the event the chair departs from the horizontal by more than a predetermined angle. The speed determining function is preferably electronic and the safety gear operates in both directions without adaptation. Other aspects are described including setting the trip speed as a function of carriage position on the rail.