Innovative hydraulic engineering has revolutionised scenery management
at the Royal Opera House in London
Scenery moving at the Royal Opera House, Covent Garden will never be the
same again. Since Parker Hannifin distributor, Hedley Hydraulics
completed its £1m contract to install what is probably the most
sophisticated stage scenery management system in the world, heavy and
complex scene changes can now be executed silently and smoothly at the
touch of a button. At the heart of this hydraulically operated system are
four 37kW motors driving four dual pump sets, each pump capable of
delivering 100 litre/min. These are housed in an acoustically isolated
plant room and maintain a constant 115bar pressure in an hydraulic
circuit that approaches 8km in length!
The stage scenery management system comprises 27 mobile rectangular floor
sections called 'wagons', on which the sets are built. Measuring 15x5m,
each wagon has a set of castoring wheels that allows easy orthogonal
movement. They are driven by a system of 'cassettes', which incorporate a
spring loaded, hydraulically retracted drive unit carrying a 1.5kW
gearmotor. The latter drives a toothed belt, which engages with a toothed
belt fixed to the edge of the wagon. In order to move the wagons, one
above another, an ingenious hydraulically operated elevator system has
been installed (the structure of which is shown here) which moves a
vertical distance of 300mm to position the fixed and driven toothed belts
opposite one another.
When the elevator hydraulics are de-energised, the cassette cylinders are
released, allowing the toothed belts to mesh. when a wagon arrives at its
new location, hydraulically operated locating cylinders are raised to
prevent further movement. A two-speed, two-load system is employed in the
elevator by using two sets of four Parker cylinders. In the normal mode,
four cylinders raise/lower the elevator in seven seconds and have a
lifting capacity of 8 tonnes. In the 'boost' mode, eight cylinders carry
out the same function, but in 14 seconds and with a lifting capacity of
16 tonnes The elevators can be synchronised to raise/lower up to six
wagons (an area of 450m2) simultaneously. A special control valve was
developed to achieve this, and ensures synchronisation within 5mm during
movement.
2000