Moving wind forward
Wind first emerged as a marketable technology a quarter-century ago – and Rexroth was on the scene.
Helmut Wagener vividly recalls the revelation that promised not only enormous market potential but a green technology for the future. “When we took our first look at the 300 to 400 wind turbines in Tehachapi, California, at the start of the eighties, we knew it right away: there’s a gearbox in every one of those nacelles.” So Rexroth embarked on supporting the development of this renewable energy source, becoming a valuable partner in innovation at a very early stage.
Wagener, today head of the Hydraulics Division, started his career in 1974 at Lohmann & Stolterfoht GmbH in Witten, Germany. Around ten years later, he represented that gearbox specialist, which was acquired by Rexroth in 1977, at the Windpower exhibition in San Francisco – the first major trade show for wind energy. “On display there were systems that since then have disappeared without a trace: virtually historic ‘windmills’, Darrieus rotors reminiscent of wire whips, and even set sails,” recalls Wagener. Today’s standard turbine designs were also represented – in the 150 kilowatt power class. The present norm is twenty times that.
A tale of spurs and planets
One major factor in this development is that the spur gear units once standard in wind turbines have increasingly been replaced by planetary gearboxes built in Witten. They are lighter and more compact – but they’re more expensive, too. And reducing costs was not the only task to be faced at the outset. Constant vibration in the nacelles of the wind turbines caused gearbox leaks – a challenge that initially stumped the engineers. But after just a short time they came up with a solution that has since become accepted as the state of the art: “We were the first to use to use non-contact labyrinth seals,” recalls key account manager Ulrich Vieth, who joined the team at Witten in 1982. These were initially used in so-called turbo transmissions because of their exceptional dependability at high speeds. And later they proved to be the ideal solution for the low speeds associated with wind turbine gearboxes.
Harvesting the wind
The commitment started bearing fruit economically as well in 1985. Additionally, following the first Windpower show in San Francisco, Helmut Wagener, at that time head of sales, defined the objective: “We need to move wind forward!” This conviction was key in helping to build the strong position this company holds today in the continually growing market for wind energy systems. Over time, Rexroth evolved into a single-source provider for the drive and control technologies used in wind turbines, with an extensive gearbox program and automation solutions. For example, the enterprise developed hydraulic pitch drives for optimal alignment of the rotor blades with the wind. The undiminished viability of this technically and economically foresighted process is now being documented by a new factory for large wind energy gearboxes in Nürnberg and the acquisition of Igus ITS GmbH in Dresden. This company’s unique condition monitoring systems track the status of the rotor blades and ensure that the turbines face directly into the wind.