A patient transfer apparatus is provided and includes a frame, a seat assembly coupled to the frame, and a track assembly coupled to the frame. The track assembly includes a moveable track for traversing stairs and a motor configured to drive the track. The apparatus further includes a control system. The control system includes a controller configured to control the motor and to adjust a speed of the apparatus based on an occupancy of the seat assembly upon traversing the stairs based on a current to the motor upon traversing stairs.