A patient transport apparatus for use with a vehicle, comprising a lift mechanism between a base and a support frame to move between an extended configuration defining a first distance and a retracted configuration defining a second distance. An interface generates a user signal. A sensor generates a sensor signal corresponding to force acting on the base relative to the support frame. A controller determines if the user signal corresponds to an extend or retract command； determines if the force acting on the base has exceeded a predetermined threshold value based on the sensor signal； drives the lift mechanism toward the extended configuration where the user signal corresponds to the extend command and toward the retracted configuration where the user signal corresponds to the retract command； and interrupts driving the lift mechanism to stop motion of the lift mechanism in response to the sensor signal exceeding the predetermined threshold value.
