Devices built into automotive lifts to protect workers in event the system’s hydraulic system should fail. 

As auto mechanics work beneath cars elevated on lifts the lifts are raised through a hydraulic system that operates on air pressure. A sudden malfunction might cause the lift to drop. In such event, safety legs-installed in the bottom portion of the superstructure and engaged each time the lift rises high enough-prevent the car-laden lift from dropping to floor level.