.A positive lock (70) for an ambulance cot and method thereof which requires liftingan upper frame (22) of the ambulance cot, in order to permit a spring actuator (74)to clear an interference fit (98) of the positive lock, are provided. If the upperframe is not lifted, then the spring force used to pull on the positive lock (70)is insufficient to overcome the interference fit. Clearing the interferencefit permits the cot to be height adjusted. Optionally, a light indicator (81)may be provided which illuminates if the cot has not been positively locked ina height adjusted position.
