Japanese aerospace industry relies on turbo transmission from BHS Getriebe GmbH

There are not so many companies in the world that are able to build turbo gearboxes. And when the customer needs a high-end solution that approaches the boundaries of what is actually possible, BHS Getriebe GmbH from Sonthofen, Germany is usually involved somewhere along the line.

The latest example of BHS’s technical expertise is a two-stage epicyclic gearbox with a transmission ratio of over 20, an output speed of 62,000 rpm and a power rating of 1,400 kW, which was recently supplied to Japanese contractor Kobe Steel Aerospace Division. The order comprised two different gearboxes, both of which will be used by the end-user NAL (National Aerospace Laboratories, Japan) in Japan for testing pumps for liquid oxygen and hydrogen in non-military rockets.

The aim of NAL’s research is to prevent cavitation damage to the pump impellers. Cavitation, which happens when bubbles of liquid form and collapse within the liquid being pumped, creates very high local pressures and temperatures that can seriously damage the surfaces of the pump.

The pumps being tested are used in the current generation of Japanese rockets for civilian space applications, and must satisfy extremely stringent technical requirements. The pumps will also be tested with BHS epicyclic turbo transmissions in future generations of the rockets.

Stefan Burkart, who is responsible for the project at BHS Getriebe, explains: “We have built ourselves a reputation in this field of technology with other projects in the past, and since no Japanese companies were able to meet the requirements, we were selected. In fact there are probably only two companies in the world that are capable of building these transmissions, and that makes me very proud.”

Gearboxes of this type are used in the aerospace sector and are primarily in demand in areas such as the USA, Japan and the European Union, including Germany, where they are used by the German space agency DLR (Deutsche Luft- und Raumfahrttechnik) based in Göttingen. BHS has been building these transmissions for over 20 years. Other companies, such as Daimler-Benz, Volkswagen and KHD, and universities operate similar high-performance transmissions supplied by BHS for their motor, engine or compressor test beds.

The special epicyclic gear unit supplied to Japan surpasses all previous models in terms of speed and power.