A range of Parker Hannifin products, including bespoke cylinders, accumulators, gas bottles, piston pumps and valves, are at the heart of an impressive hydraulics system that lifts and moves a cutting edge floating stage platform at the MGM Grand Hotel in Las Vegas.
The incredible 7.5 by 15 metres stage platform, called the Sand Cliff Deck, floats in the air above the Abyss, the MGM's basement, several floors below, where a traditional stage would normally be used as a sandy beach or cliff and even as a massive battleground. At almost two metres thick, the platform rises, drops, tilts and swirls with precision and is the focal feature of the Cirque du Soleil's latest production KA, an extravagant mix of acrobatics, theatre and circus, which is currently showing at the MGM Grand Hotel.
The lifting and moving of the platforms and performing areas used in the show require what are believed to be two of the largest and heaviest elements ever constructed for use in theatre: the Sand Cliff Deck and a massive free standing gantry crane that together weigh nearly 160 tonnes. Due to seismic building codes in Las Vegas, the crane could not be part of the actual building so it is a separate structure within the building and can itself withstand an earthquake.
Parker's system engineers worked closely with the designers of the Sand Cliff Deck to design a hydraulic system that provides 4,500 kilowatts and all of the necessary motion control. During the design stage it was determined that extremely long cylinders would be essential for raising and lowering the Sand Cliff Deck and Parker custom manufactured five 22 metre stroke cylinders, believed to be the longest stroke single rod cylinders ever manufactured. Four are being used with the gantry crane and the fifth one is held on site as a spare.
The cylinders are mounted vertically into two columns that support the Sand Cliff Deck. The columns are 18 metres apart and tower several stories above the audience, with the cylinders being mounted rod down, so that they are lifting the stage deck when they are retracting. If the cylinders were mounted rod up, they would have to push upward to lift the stage, putting too great a load on the piston rods. Retracting the cylinders to lift the stage keeps the rod in tension and eliminates the possibility of buckling damage, decreasing the risk of expensive downtime. In addition, the cylinders are coupled to carriages on linear guide bearings, to provide lateral as well as vertical movement.
To lift the stage deck, the four cylinders each require over 6,000 litres per minute of oil to achieve a speed of 0.6 metres per second. This flow is supplied by five power units, each comprising a single 180 kilowatt motor driving two Parker PE145 Series piston pumps, with each power unit delivering 5,000 litres per minute.
In addition to the five power units, the remaining flow requirements are fulfilled by 35 Parker accumulators that charge during the lengthy dwell times available between movements of the stage deck. The accumulators store energy under pressure, absorb hydraulic shocks within the system and minimise flow fluctuations. The 190 litre piston accumulators have a 280 bar maximum working pressure, with each accumulator weighing 1000 kilograms and measuring 5.2 metres in length.
In total, Parker supplied two racks of eight accumulators, one rack of nine, and one rack of ten accumulators. Each of the accompanying 18 gas bottles is 6 metres long and weighs 2.8 tonnes. There are two racks with four gas bottles and two racks with five gas bottles, each with a 1,320 litre capacity and 280 bar maximum working pressure rating. These are the largest capacity accumulators and gas bottles ever manufactured by Parker Hannifin and special rack and manifold designs had to be constructed to accommodate their massive size and weight.
When the stage deck is elevated, four Parker cylinders work in pairs with two hydraulic servo valves to tilt the stage. Incredibly, the stage can be tilted by 100º in less than 40 seconds, with the tilt axis controlled by Parker D81FH zero overlap proportional valves.