At first glance it doesn’t look like much – a flat piece of black licorice, perhaps. But the super-light KONE UltraRope is a completely new take on elevator hoisting. Made of a carbon fiber core surrounded by a unique high-friction coating, the new rope weighs only about 19% of a similar strength conventional steel rope.
“You wouldn’t think it, but rope weight impacts everything,” says Tomio Pihkala, who heads one of KONE’s global research and development units in Hyvinkää, Finland. “If you have a lighter rope, you can have a smaller and lighter elevator counterweight and sling. This means the overall moving masses are reduced.”
Put simply, the new technology enables massive cuts in the deadweight that is moved up or down every time someone hops into a high-rise elevator. Less deadweight means smaller energy consumption and operating costs.
“When components are smaller, the logistics are easier,” says Pihkala, adding that installing huge components inside relatively cramped skyscrapers is always a challenge. “The environmental impact is also smaller when materials are lighter.”
Reinventing the Elevator
Traveling more than 500 meters, or 100-odd floors in a continuous elevator trip is challenging and doesn’t really make sense using conventional technology. At that point, the weight of the several kilometers of rope needed to hoist the elevator becomes an obstacle. More ropes are needed just to lift the weight of the ropes.
In a building this tall, the moving masses of a single elevator hoisted with steel ropes can be some 27,000kg. This is equal to fitting ten off-road vehicles inside the shaft and shifting them along with the elevator. Using KONE UltraRope for hoisting in a similar shaft, the moving masses are roughly 13,000kg, or about the weight of four off-road vehicles.
Limits set by ropes are a major reason why most very tall buildings have sky lobbies served by shuttle elevators from the ground. Separate elevators take people higher from these lobbies in the sky. In the future, KONE UltraRope will enable elevator travel all the way from ground floor to penthouse in a kilometer-high building in one continuous journey. “We are on the brink of something big. In a sense, we have reinvented the high-rise elevator,” says Pihkala.
KONE UltraRope is compatible with all other KONE high-rise solutions so it can be used to replace conventional ropes in old buildings. And with the new technology, the higher you go, the bigger the benefits. For example, the energy savings for a 500-meter elevator journey are around 15% versus conventional rope. For an 800-meter journey, the savings are over 40%.
In addition to being very light, carbon fiber is strong and durable. It has already revolutionized products in several other industries, including aviation and sporting equipment.
At KONE, the idea of creating a carbon fiber rope came in 2004. “The first prototypes were made by hand,” says Pihkala. Actual research and development began a few years later. It wasn’t long before the rope was fitted into a shaft at KONE’s Tytyri high-rise testing laboratory in Southern Finland.
“We were surprised by how problem-free it was,” says Pihkala. “Often, there are a lot of problems when you develop something completely new. But our faith in this started to grow very quickly.”
The rope has since been tested thoroughly both in real elevators and in laboratories. Properties like tensile strength, bending lifetime, material aging and the impact of extreme temperatures and humidity are just some of the qualities that have been measured.
No Rust, No Wear
Unlike steel, carbon fiber does not rust, stretch or wear. The special coating of the new rope makes lubrication unnecessary, meaning environmentally friendlier maintenance. Carbon fiber also resonates at a completely different frequency to most building materials. This means KONE UltraRope is less sensitive to building sway, and elevator downtime during strong winds and storms can be reduced.
While typical high-rise elevator ropes need to be changed at regular intervals – no easy task in a tall building – the new technology enables a rope lifetime twice that of conventional ropes. KONE has also developed a real-time rope condition monitoring system. “We have a rope that works, is reliable, and delivers on our promises,. This is a good place to move on from.”