Heavy-duty screw jacks lift performance

Austria's annual Bregenz Festival on the eastern shore of Lake Constance is world renowned for its spectacular opera productions and is held in two lakeside theatres. Whereas the indoor theatre is home to more traditional performances, the floating stage on the lake - the Seebuhne - is known for its imaginative sets that require a high level of technical support. As all scene changes at this al fresco theatre are undertaken in full view of the audience there is little room for error.

Therefore when specifying mechanical lifting systems to effect set movement theatre engineers had to be especially careful in their selection.

It was vital that the chosen system should provide smooth, speedy, reliable and above all safe positioning of the high loads involved.

Furthermore it had to deliver a consistent performance in all weathers and require little or no maintenance.

Zimm lifting systems, available in the UK from HepcoMotion, have been used by the festival theatre complex since its inception in 1997.

Four Zimm 250kN screw jacks were initially specified to raise and lower the scenery platform a distance of 1790mm typically with a static load of 27t and a dynamic load of 17t.

The equipment is driven by a 22kW three-phase motor, the output of which is transmitted via connecting shafts to the four screw jacks equipped with bevel gears.

These heavy-duty screw jacks are supplied as standard with a safety nut with a sensor that detects wear in the thread in excess of 20% of the screw pitch.

It also has a rotation sensor that responds to the failure of any of the transmission components.

In the event of a problem the load is therefore brought safely to a standstill.

The success of this application led to four further Zimm screw jacks being ordered - size 50kN - for the connecting passageway between the floating stage and the festival theatre.

A lifting distance of 3450mm was required for this platform and the system had to withstand 12t of static load and 8t of dynamic load.

In view of the length of travel involved Zimm engineers suggested the load on the gearbox spindles should be applied under tension not pressure.

This allowed the dimensions of the lifting systems to be considerable smaller.

As a result the mechanism not only cost less to buy but also to install.

The proven performance and reliability of the permanently installed Zimm systems have led to them several units being kept for specific production tasks.

These 'extras' were used extensively in the highly acclaimed stage settings for La Boheme in the 2001-02 season.

Last year, in West Side Story, they were also responsible for lifting a stage flat weighing 22t along a 50m bridge against a substantial wind force that can occur at any time across the lake.

The current production, Verdi's Il Trovatore, has also benefited from this technology.

Zimm screw jacks are available in a range of capacities from 500N to 500kN complete with gearboxes, motors and connecting shafts