Three innovative products are now being marketed by a German wind turbine maintenance company, Wind Turbine Service (WTS) of Ibbenbüren. The first is a bypass oil filter system aimed at keeping gear box oil clean and thus avoiding bearing damage. The oil in gearboxes of older turbines can contain more than eight million particles in every 100 millilitres of oil, Harenkamp says. Over time these can cause pitting on the surface of the bearings and the gear teeth and lead to gear box failure. "The WTS bypass oil filter system was developed to prevent this," he explains. WTS's second innovation is a soft braking option designed to reduce the stress on gear boxes. Dubbed "Sobo," the braking system consists of hydraulic and electronic elements and works in a similar way to ABS car brakes, says the company's Bernd Harenkamp. Sobo has been developed in exclusive co-operation with Svendborg Brakes of Sweden and has been tested on a Tacke Windenergie TW 600 kW machine operated by the Emden municipal utility. The third product is a warning light for installation on wind turbines that blinks 20 to 60 times a minute to alert low flying aircraft of an aerial obstacle. The eight kilogram light was certified in April by the transport ministry. WTS particularly hopes to find a market for it in offshore turbine installations. The company, which employs 16 people, has been servicing wind turbines for three years.