By Anke Henrich
Climb aboard and take a deep breath: It's going to be a fast ride! A Multi cabin catapults eight people upwards at up to 6 mph. There are faster elevators - but the Multi also moves the cabins left and right. This means it can do something that architects in the past could only dream of: not only transport people and goods vertically, but also horizontally and with multiple cabins moving independently of one another in a single shaft. The development has been a long time coming, and not just for the manufacturer, thyssenkrupp Elevator from Essen.
There was astonishment when the first hydraulic lift was presented at the World Exhibition in Paris in 1867. Not long after came the installation of the first paternoster: cabins that traveled up and down and were pushed sideways by rollers in the basement and on the top floor. 150 years on, elevators are a means of mass transportation. Statistically speaking, every person on earth travels in an elevator every 72 hours. Germany alone has around 750,000 of them rushing from floor to floor. But the system behind them has changed little since that day in Paris. A single cabin hangs on huge cables in a narrow shaft, while a motor is used to convert power into vertical movement.
It is a proven technology, but one that is considered impractical by many architects, landlords and office users. After all, the construction limits the construction height. From a height of 500 meters, the cables begin to swing so significantly in high winds that the interior walls of the shafts can be damaged. Architects of skyscrapers therefore usually install multiple elevator shafts and sometimes additional escalators, meaning getting from A to B can take a while.
Multi aims to change all that for residents and staff in skyscrapers over 150 meters - the height at which the investment begins to pay off. As the cabins move rapidly in a rectangular cycle, they are scheduled to arrive every 15 to 30 seconds. It is hoped that the Multi will also benefit real estate operators. By requiring fewer shafts than conventional elevators, the construction will enable around 25 percent more space per floor to be utilized and rented. As a result, the investment costs for the Multi – which are higher than for conventional elevators - can be redeemed more quickly. Architects benefit from greater design freedom, as the Multi makes it easier to connect horizontal and vertical construction elements and entire buildings.
The tower of Rottweil
High above the Swabian mountains and valleys, a 246-meter tower suddenly protrudes from the landscape near Rottweil. As thin as a finger, it looks very futuristic and has won several architectural prizes. With it, or rather in it, stands and falls the Multi. This is where thyssenkrupp Elevator develops and tests all its new elevator models, including the Multi. Its cabins can also be moved sideways, as three of the 12 shafts in the test tower are reserved solely for the Multi. The tower is also home to Germany's highest public visitor platform, which offers a magnificent bird's eye view. However, the technology for express and high-speed elevators found inside is even more interesting. The tower is also the first building that allows wind loads to be realistically simulated. An oscillating pendulum inside the tower makes it move.
Visitors can take a close look at how the 70-strong core team of component manufacturers and experts in elevators, drive technology, magnet technology and production plants built their masterpiece. thyssenkrupp Elevator also contributed the necessary expertise in magnetic levitation technology gained from the development of the maglev train it once tested in the Emsland region. The corporation still holds around 120 patents from that period. The use of artificial intelligence also provides new options for controlling the elevator. Electric linear motors move the cabins - which have an energy-saving lightweight construction made from carbon fiber composite material – without wear. Multi technology can be used in skyscrapers up to a dizzying height of 1,000 meters. For comparison, the Burj Khalifa, currently the tallest building in the world, measures an incredible 828 meters.
Although elevators are statistically the safest means of transport for people, some are sure to be a little nervous when they think that there are no more cables preventing the cabin from crashing to the ground. However, should the power fail, a four-stage braking system and mechanical catching arms would keep the machine in position. According to thyssenkrupp Elevator, the linear motors are safe because they need to be energized before they move. That means that, without energy, the cabins cannot move. That is why the cabins include batteries in case of energy breakdown. The Multi cabins can also be maintained in the company’s own repair shops, while data from digital twins makes predictive maintenance easier.
But the technology is not yet ready for series production. "We aim to gain global approval by the end of 2021," says Andreas Schmidt, Head of Consulting & Pricing Multi at thyssenkrupp Elevator. "We have had 20 to 30 serious project inquiries." The company is of particular interest for prestige projects in the Middle East, he says. International competitors are therefore watching the first mover closely to see how demand for its Multi in its current enhanced prototype status develops.
Global interest in elevators is growing with each new skyscraper. This benefits the entire German elevator sector - one of the most innovative segments of German mechanical engineering.