Specialist in Drive Train

Hydrautrans BV is a Dutch drive train developer for offshore wind turbines, founded in May 2013. Being a specialist in Drive Trains for offshore wind turbines, we develop a dedicated mechanical-hydraulic drive train solution, fit for the next generation of offshore windfarms.

Our mission

Hydrautrans strives to contribute to cost reduction in the offshore wind market, by developing an innovative drive train by combining existing proven technologies. The Hydrautrans Drive Train has a modular mechanical-hydraulic power of 12+ MW, low head mass and aims to reduce the LCoE.

Our vision

At Hydrautrans, we believe in innovation by combining existing proven technologies into a realistic, competitive product. The outside of the box approach in the design of the Hydrautrans Drive Train concept is the core driver of our colleagues and partners. Therefore, Hydrautrans is a unique group where traditional status-quo is challenged and questioned. We envision a next generation Drive Train to lower the cost of offshore wind and thus, the Levelized Cost of Energy (LCoE) for the societyThe offshore wind market is developing rapidly, the call for ever larger, more powerful wind turbines, to reduce the LCoE is getting louder and louder. This puts the traditional drive trains (direct drive, mechanical transmission) under serious pressure. The Hydraulic-Mechanical Drive Train of Hydrautrans is part of the next generation wind turbines. The Hydrautrans Drive Train is designed with a modular power of 12+ MW, drastically lower weight and significant lower cost. It is our belief it is perfectly suited for the offshore wind market.


Hydrautrans has patented a mechanical-hydraulic-electrical wind turbine drivetrain solution, which is unique in offering superior lower LCoE performance through multiple technology-related and other benefits for next-generation offshore wind turbines.

Hydrautrans was awarded a European and PCT patent for its mechanical-hydraulic drive system in 2012 (European) and 2017 (PCT). An additional European,US, Chinese and Japanese patent covering different technology aspects was filed in 2013 and awarded.

The HDT is a hydraulic mechanical transmission where the turbine rotor drives multiple pumps through a ring gear and planetary gears. The pumps drive a hydraulic motor which is directly coupled to a generator. The generators are mounted on an extension of the machine housing (bedplate). The drive train consists of modules of 3 (+) MWe each and are coupled by said ring gear which is directly driven by the turbine rotor via the shaft. Four pumps drive 1 motor of identical design hence the speed ratio is 1:4.


Hydrautrans has developed a hydraulic drive train (HDT) with a higher power to weight ratio (kW/kg) and comparable cost per kg can make a new step in development possible. A solution is a hydraulic transmission. High power density for hydraulics is long time known but the efficiency of hydraulic pumps and motors is too low. HDT makes use of floating cup technology (FCT) what due to absence of metal to metal contact in pumps and motors lead to a high efficiency and absence of wear and tear.

FCT technology is proven for small pumps and motors. The components HDT uses have a ca 100 times bigger volume per rotation.

The HDT ring gear is directly coupled to the shaft. No introduction of bending moments in the ring gear due to external loads or misalignment between components.

The hydraulic transmission is flexible and thus damping peak loads and limitation of cascade effects meaning one pump influencing the others.

Long lifetime of the hydraulic components.

The HDT uses a cylindrical gear with an individual pinion per pump for torque splitting which allows the use of multiple pumps (modules of ca 3 MW), motors and generators.

Compact drive train hence reduced overall nacelle dimensions.

The HDT obtains a top mass reduction of around 40% in comparison its Direct Drive competitors.

Modular installation is possible with a maximum hoisting weight of 250 tons.