US Patent 7694368 Positive lock for height adjustable ambulance cot

A positive lock for an ambulance cot and method thereof which requires lifting an upper frame of the ambulance cot, in order to permit a spring actuator to clear an interference fit of the positive lock, are provided. If the upper frame is not lifted, then the spring force used to pull on the positive lock is insufficient to overcome the interference fit. Clearing the interference fit permits the cot to be height adjusted. Optionally, a light indicator may be provided which illuminates if the cot has not been positively locked in a height adjusted position.