The silent revolution

A cable-free MULTI elevator successfully completed its maiden voyage in the Rottweil testing tower. The developer team now wants to bring it quickly to market – and a customer is already waiting.

A silent revolution has occurred: One moment, the elevator cabin was floating down the shaft – vertically, as elevators have been doing for more than 150 years. Then it paused at the exchanger, stayed there until said exchanger had rotated 90 degrees, and started riding horizontally through the shaft, as if that were the most normal thing in the world.

Markus Jetter is standing at a large screen in front of the shaft, keenly following the elevator’s ride. Each time the cabin here in the Rottweil testing tower rotates without difficulty, the tension dissolves from his face. After all, this revolutionary elevator is slated for presentation in front of an international crowd of specialists in just a few days, marking an important milestone. Jetter is Head of Development on the thyssenkrupp Elevator MULTI team. He spent five years working with 20 engineers on the cable-free elevator powered by linear magnet technology, which transports people along one axis (up and down) as well as two-dimensionally (up, down, and sideways). This new technology is called MULTI. Compared to conventional elevators, MULTI ones take up less room in buildings, allow taller buildings to be built and transport more people in a shorter period of time.

Presentation. The first MULTI operating in Berlin On June 22, Elevator CEO Andreas Schierenbeck ­symbolically pressed the MULTI’s “start” button in front of 300 guests in Rottweil. A customer is already waiting for the cable-free elevator ­system: the real estate ­developer OVG Real Estate, which aims to install the MULTI in the East Side Tower that will open in 2020.

Lovely outlook – from a height of 232 meters

Jetter’s team set up camp in the testing tower, which stands 246 meters tall just beyond Rottweil city limits, to put the finishing touches on MULTI. About half their offices are occupied by engineers in ­sparsely equipped rooms, following on six screens every ride taken by the MULTI elevator. A menu for a restaurant in Rottweil is lying on a table, and since these men don’t currently have time to drive a few ­kilometers into town to have lunch, they order in.

Let’s go up to the 232-meter viewing platform, the tallest of its kind in Germany. Jetter describes MULTI’s origins: “At the beginning, we just had a blank piece of paper.” Everything is different with MULTI technology: the drive, the controls, the safety solutions and the construction. Matthias Glück, who is responsible for all of the system’s electronics, electric components and software, recalls how, at the beginning, Jetter asked him which components from existing elevator control systems they could use. In response, Glück took out a piece of a board on a control element and said, “This is the only thing we can use.” Together with his team, Glück programmed the control software and ensured that the control elements communicate via WLAN, which has been set up practically through three slotted hollow conductors.

"At the beginning, we just had a blank piece of paper.”

Markus Jetter, Head of Development on the MULTI team

MULTI technology also poses new challenges for safety systems since, in contrast to conventional systems, it does not offer any possibility to “monitor the ­elevator ride using mechanical measures,” says Eduard Steinhauer. The usual safety concepts, according to the Team Leader for Functional Security, cannot be applied to MULTI. Instead, safety is guaranteed through a functional chain of sensors, data analysis and the resulting reaction. “Thankfully,” says ­Steinhauer, “­elevators only crash in the movies.” MULTI elevators are just as safe as conventional ones, even though they use magnetic technology instead of cables. The systems also react more quickly and precisely than those in an elevator with cables.

At the heart of these systems lie the electromagnetically powered motor and the exchanger. Thousands of components had to be fixed inside the shaft to set these up, says Thomas Kuczera, who is responsible for the MULTI’s mechanical systems. Each exchanger alone weighs five metric tons. Meanwhile, the cabins as well as the supporting structure by which they are connected to the shaft were made using lightweight construction. MULTI elevators ride on high-end tracks, Kuczera explains, which have been meticulously made from premium materials. “During the next phase of development, we will tailor the track geometry even more precisely to our needs,” says Kuczera. That way, the cabins will ride even more smoothly and quietly through the shaft.

The team stands to face a few more challenges ­before the first system is commissioned as planned in the East Side Tower in Berlin, Germany, in 2020. For example, acceleration and braking along the horizontal axis must be made comfortable and risk-free for passengers, which requires the precise coordination of all components. Further testing will also continue to eliminate noises and vibrations and thereby make the ride more comfortable.

As things stand, the revolution has only just begun.

1 Functional security

“We take charge when things suddenly go awry,” says Eduard Steinhauer. The safety engineer worked with his team to develop and program the safety systems. All relevant components are redundantly arranged, meaning that if one of them fails, another will jump in to take its place. For instance, alongside four brakes, a safety also ensures stabilization. Moreover, thanks to software and constant communication, the system can also react quickly. “That’s absolutely key,” says Steinhauer, who studied robotics and mechanical engineering.

Eduard Steinhauer Head of Functional Security

2 Controls

Matthias Glück knows that reprogramming three control systems with a total of eight units and attaching an entire electrical supply system to the shaft wall calls for a strong team, one whose members have ideas that “not everyone can understand at first glance,” as he puts it. His team had to solve problems quickly. “We always had a Plan B up our sleeve,” Glück says. The technical IT specialist has been working on MULTI since 2012.

Matthias Glück Head of Electric Components, ­Controls, and ­Software

Up and down, from right to left. The cabin has paused at an exchanger in the testing tower. The exchanger rotates 90 degrees so that the ride can continue horizontally.

3 Mechanics

For Thomas Kuczera and his team, the greatest challenge was space. How could they construct the system to accommodate the components, tracks, exchanger, and cables? And how to construct the system so that these components wouldn’t deform under the weight of the cabin? Kuczera, who holds a doctorate in mechanical engineering, spent a year answering these questions, simulating loads on the model, testing lightweight construction materials, and finally attaching suitable pieces in the testing tower.

Thomas Kuczera Head of Mechanical Development