A method of raising a wheelchair compartment from a non-horizontal ramp position to an approximately horizontal safe position comprises providing a lift mechanism comprising an elevator structure, a wheelchair compartment configured to hold a wheelchair and rotatable from the ramp position to the safe position, a cam connected to the compartment and comprising a cam contact surface, a cam arm connected to the elevator structure and rotatable about a pivot pin, an actuator connected between the elevator structure and the cam arm and configured to rotate the cam arm relative to the pivot pin, and a cam arm bearing connected to the cam arm and configured to press against the cam contact surface of the cam. The method includes operating the actuator when the wheelchair compartment is in the ramp position so as to cause the wheelchair compartment to rise to the safe position.