An ambulance cot loading and unloading apparatus includes a base for mounting to an emergency vehicle deck and an arm mounted for linear movement along the base, which is configured for engaging an ambulance cot. A drive mechanism is provided for raising the arm, which is configured in the presence of an applied force with a first magnitude on the arm to raise the arm at a first speed and in the presence of an applied force on the arm with a second magnitude greater than the first magnitude to raise the arm at another speed or speeds lower than the first speed.