... Shaft, Taper Roll Bearings, Seals, Housing, Self-locking Trapezoidal Screw,etc.* Model: RN-0.5ton, RN-1 ton, RN-2 ton, ... ,Rolling.* Manual Operation and Electrical Operation are available.* Multiple Screw Jack Systems are availbale and fully synchronized.* Absolutely irreversible, ... other locking systems.* Three reduction ratio are available for each model. Fast ratio,1 turn shaft,1 mm stroke; Medium ...