Now available from Techdrives is a range of Servomech heavy-duty screw jacks with rated forces from 5kN to 350kN, plus new models rated at up to 700kN will be launched in 2010. Fourteen variants of travelling nut and travelling screw designs offer a comprehensive range of speeds and loads together with many configuration options.
These screw jacks are produced by linear motion specialist Servomech, which has 20 years' design and manufacturing experience. Screw jacks are used to deliver medium to high forces at strokes that can be short (typically 100mm) or very long (up to 6000mm) subject to the mounting configuration. They usually give outputs at low linear speeds but speeds of up to 150mm/s are possible. Although simple in concept, being based on worm gearbox technology, screw jacks have a wide range of variables and should be considered as engineered products to match individual customer needs. Input can be via a free shaft or the screw jack can be motorised to give output speeds from 1-150mm/s. Screw jacks are often combined in groups with mechanical connection via spacer couplings.
A typical screw jack application is lifting stage scenery, lids or platforms, where it is common to have four screw jacks arranged in an 'H' or 'U' formation, with one motor and multiple coupling connections. It is equally possible to motorise each screw jack and run them with synchronisation achieved electrically. Other example applications are on container cranes for trimming, positioning of radio telescopes, silo lifting and in steelmaking.
Servomech offers two different mechanical configurations. Travelling nut designs have the screw in a fixed position while a bronze nut runs up and down it. Travelling screw designs have the screw rising and falling as it passes through the body of the screw jack. The choice between the two designs is made by the mounting dimensions available. Normally acme threads are used but ball screws can be specified for increased duty cycles and high efficiency. Motors can be AC asynchronous, DC or servo for positioning. Other options include mechanical safety - for example, stroke limits and wear control of the travelling nut.
Follow the link for details of the full range of Servomech screw jacks, including catalogue downloads and enquiry sheets. Product engineers are available to provide technical support.