Duff Norton, USA, manufactures machine screw actuators. They offer positive mechanical action, uniform lifting speeds and precise positioning. These actuators are supplied in various configurations to suit every need of the industry. They include position upright or inverted with translating or rotating lifting screws and top plate, threaded or clevis end. These actuators can be tied together mechanically to lift and lower in unison. This typical arrangement involves actuator units, meter, gearboxes, motors, reducer, shafting and couplings. These actuators are produced in many standard models in a wide range of capacities. There is a standard model for every requirement. They are available in capacities from 0.25 to 250 tonnes, and in worm gear ratios from 5:1 to 50:1. More than 200 standard combinations are covered in the range. Operated manually or with air, hydraulic or electric motors, machine screw actuators can be used individually, in tandem or in multiple arrangements. Actuators of most capacities have similar gear ratios. Users can realise added economy by using different capacities in the union to raise unevenly distributed loads. Actuators with anti-backlash features can also be supplied.