... Duty, Uniform Lifting Speed, Low Efficiency, Use Infrequentl worm screw liftConfiguration: Worm Gear, Worm Shaft, Taper Roll Bearings, Seals ... , Housing, Self-locking Trapezoidal Screw,etc.* Model: RN-0.5ton, RN-1 ton, RN ... are available.* Multiple Screw Jack Systems are availbale and fully synchronized.* Absolutely irreversible, they can support their applied loads ...