worm screw lift; Safely self locking, Positioning Precision, Heavy Duty, Uniform Lifting Speed, Low Efficiency, Use Infrequentl worm screw liftConfiguration: Worm ... Worm Shaft, Taper Roll Bearings, Seals, Housing, Self-locking Trapezoidal Screw,etc.* Model: RN-0.5ton, RN-1 ton, ... their applied loads without needing any brakes or other locking systems.* Three reduction ratio are available for each ...