RN-0.5ton, RN-1 ton, RN-2 ton, RN-3 ton, RN-5 ton, ... , RN-30 ton, RN-40 ton, RN-50 ton, RN-100 ton. Worm Gear Screw Jack Application Notices:* Screw jack must ... prevent radial forces on the lifting screw.When jack,shafts,gearboxes etc. have been connected it should be possible to turn ...