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As Quiet As Possible


Sep 18, 2019 - 2 months ago

By Supply Post

Electric bicycles promise effortlessly driving experience without annoying background noises. Gear technology from Liebherr makes it possible.

E-bikes and e-scooters are all the rage nowadays because they are so much fun and easy to ride. Modern versions have done away with noticeable judder and annoying extraneous noise thanks to compact high-precision gear technology.

Compact precision engineering

Norbert Ambros rarely lets anything throw him off course. This is also true when he sees the bemused faces of his colleagues as he whizzes across the factory floor at Liebherr-Verzahntechnik GmbH in Kempten on a futuristic electric vehicle that looks like a cross between a scooter and a bike. “This scooter has been designed to be used at trade fairs where Liebherr staff continually have to make their way across the large exhibition halls,” explains the seasoned e-bike enthusiast. “The gear technology in the motor determines how comfortable the journey will be – it should ideally facilitate powerful acceleration with as little noise from the motor as possible.”

Gear hobbing and gear grinding machines produced by Liebherr for customers all over the world make all this possible. Norbert describes the plant’s machinery as, “Cutting-edge technology at its best, providing high-precision gear mechanics for applications where space is a premium”. In his role as senior mechanical engineer, he coordinates machine acceptance tests, test runs and any fine tuning that needs to be carried out before the machines are delivered for use in various production processes.

Microgeometry makes the difference

But does this mean that e-mobility is redefining drivetrain technology and increasingly making gear wheels redundant? “Lower volumes are needed to fulfil e-mobility requirements,” says Norbert Ambros. “As it’s becoming increasingly important for the gears to function more cleanly and quietly, the gear wheels need to be of an exceptional quality.”

Ambros emphasises that this is why it is even more important to use innovative machinery which can deliver an excellent surface finish and maximum precision. The machines should also run exceptionally smoothly and ensure the geometry of the tooth flanks is absolutely perfect. It is especially important to get the microgeometry right to ensure that the teeth engage correctly under stress. And this is particularly critical since the gear wheels are specially designed in accordance with the natural frequencies of the drivetrain and to dampen drivetrain vibration.

The moment of truth at Eschacher Lake

Norbert Ambros is a passionate cyclist and nature lover. He is also a tech freak. Norbert switched to riding e-bikes years ago so that he could embark on as many varied and long cycling trips with his wife as possible. The fruitful partnership between Liebherr and Morat Swoboda Motion may also benefit him in the future.

The 58-year-old senior mechanical engineer has worked at Liebherr-Verzahntechnik GmbH for 43 years. He loves the fact he can experience the benefits of a technology he has worked with his entire working life during his leisure time. “I am reminded every day how important our work is.” Ascending the mountainous terrain above Eschacher Lake is a good example. He describes the way the small high-tech gear wheels come into their own here and deliver such strong torque. He also notes how the noise of the motor is only perceptible from its very quiet hum.

Better to be on the road than in the bicycle repair shop

“When I am out enjoying nature, I just want to enjoy the scenery, feel the wind in my face and hear the birds singing. Nothing else,” he says emphatically. “Drive wheels that have been ground with microscopic precision are a critical factor. They make the vehicles reliable, durable and comfortable to ride. I would rather avoid trips to the bicycle repair shop or having to continually carry out maintenance on my bike.”

From his experience as a senior mechanical engineer and keen cyclist Norbert Ambros is certain: “I can see so much potential in e-mobility and not just for e-bikes and e-scooters. I want to be among the pioneers through my role at Liebherr. The fact that these kinds of innovations allow me to have so much fun outdoors in the beautiful Allgäu countryside is a good enough reason alone.”


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