These worm gear screw jacks are very precision and reliability, it can meet all the necessary protection, cost-efficiency, and strength mandates of the application. High strength bronze worm gear is used, the payloads from 0.5T to 100T . A total of 11 sizes can be found, each in a traveling nut version and a basic version.
Worm equipment drive screw jack
Translating(traveling screw) and rotating (traveling nut) configurations
Electrical Driven and Manual Operated both are available
Trapezoidal spindle (self-locking) and Ball Screw spindle (high efficiency) version
Design option: Regular, Anti-rotation, Anti-backlash or Protection nut
Standard and custom end fittings, installation options, and drive shaft
Worm Equipment Screw Jack systems are ruggedly designed and produced in standard models with load handling capacities from 1/4 ton to 100 tons. They may 
be used separately or in multiple plans. There are no “standard” travel lengths and all Worm Gear Screw Jack systems are designed to specification.
The jack housings are made of ductile iron and proportioned to aid the rated capacity of the unit. MJ, 1/4 ton, and 1/2 ton models have aluminium housings.
Each Worm Gear Screw Jack incorporates an alloy steel worm which drives a higher strength bronze worm gear (drive sleeve). The worm shaft is supported on antifriction tapered roller bearings with external seals provided to prevent lack of lubrication (sealed Worm Gear Jack radial bearings on the MJ, 1/4 , 1/2, and 1 ton devices). The drive sleeve is definitely supported on antifriction tapered roller or ball thrust bearings. Rotation of the drive sleeve causes the lifting screw to translate or rotate, dependant on jack configuration.
The Inch and Metric Worm Gear Machine Screw Jacks incorporate an alloy or stainless worm which drives a high strength bronze worm gear (drive sleeve). The worm shaft is backed on anti-friction tapered roller bearings with external seals provided to prevent loss of lubrication. The drive sleeve is usually supported on anti-friction tapered roller or ball thrust bearings. Rotation of the drive sleeve causes the thread lifting screw to translate or rotate, depending upon jack configuration.
The threads are precision formed, typically using Class 2-C (Centralizing) tolerances. Jack lift shaft business lead tolerance is approximately ±0.004″ per foot.