... : Worm Gear, Worm Shaft, Taper Roll Bearings, Seals, Housing, Self-locking Trapezoidal Screw,etc.* Model: RN-0.5ton, RN-1 ton ... RN-40 ton, RN-50 ton, RN-100 ton.* Safely self locking, Positioning Precision, Heavy Duty, Uniform Lifting Speed, Low Efficiency, ... ,Hand Wheel,Electric Motor,Motor Flange,Frequency Inverter,Safety Nut,Steel Cover,Rubber Belllows,Limit Switches,Couplings,Flexible Linking ...