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BHS Planetary Gear Units

BHS planetary (also called ‘epicyclic’) gear units convert torque reliably and effi­ciently in turbo drive trains. Two gear unit series cover a power range from 400 kW to 45 000 kW. Gear ratios range from 1:1 to 80:1.

We customize our BHS planetary gear units to fit your application and meet your needs. This means that the driving and driven rotational direction, the toothing design, and the shape and material of the housing are all optimized to your equipment. The so-called ‘Stoeckicht principle’ ensures an ideal load balance between the sun pinion, the planet gears, and the ring gears.

These features enable a reliable and safe service life of over 250 000 operational hours. Unit efficiency can reach levels of up to 99.4 percent. This means that, as a user, you achieve a very high level of productivity and increase the effciency of your system. Planetary gear units deliver an efficiency advantage, particularly in applications where gear ratios greater than 6:1 are required.

Our customers have been placing their trust in BHS epicyclic gear units since 1932. More than 8 000 gear units of this type are in use reliably around the world, in many cases under very harsh conditions.

Beside this Voith offers also other types of turbo gear units.




Voith GmbH & Co. KGaA
Hans-Böckler-Straße 7
87527 Sonthofen, Germany

Tel. +49 8321 802-825

Service Sales
Tel. + 49 8321 802-826

24/7 Emergency Contact
Tel. +49 8321 802-555

Technical data

Power transmission 0.5 – 45 MW
Speeds 500 – 60 000 rpm
Rated output torque 150 – 570 000 Nm
Efficiency up to 99.4%
Gear ratio
  • compound star: 1:11 to 1:18
  • two-stage: 1:18 to 1:35
Housing design cast (standard), welded
Toothing double-helical (standard), spur
Noise emissions between 75 and 88 dB(A) at full load and rated speed
Design variants
  • integrated couplings (including on the low speed side)
  • built-in pumps
  • built-in starter drive
  • built-in rotor turning gear unit
  • with oil supply system

Advantages and Benefits

BHS planetary gear units from Voith

  • are customized to the operator's technical needs and deliver a very good price-performance ratio.
  • feature high reliability, preventing unscheduled downtime. This increases the productivity of your system.
  • achieve a very high level of efficiency (up to 99.4%), particularly at higher gear ratios. This saves you energy and reduces CO2 emissions.
  • exhibit optimal rotordynamics, thanks to the Stoeckicht load equalization principle. This increases lifetime and operational safety.
  • make compact, low-weight and space-saving drive trains a reality, thanks to special design and construction practices. This particularly reduces investment costs in places where space is especially expensive, e.g., offshore.
  • exhibit high gear toothing quality and special tooth profiles. This minimizes the noise level, often rendering additional investments for noise abatement unnecessary.

Typical applications

Driving machine:

  • Steam turbine
  • Gas turbine
  • Electric motor

Driven machine:

  • Generator
  • Compressor (axial, radial)
  • Pumps (centrifugal)
  • Fans / blowers


  • Power generation (power plants)
  • Oil & gas (upstream, midstream, downstream)
  • Petrochemicals
  • Chemicals
  • Steel
  • Test beds

Technical information

Design and function

A BHS planetary gear unit consists of a gear set and a housing that is very rigid and resistant to flex. The gear set consists of a central sun pinion shaft, mostly three planet gears, and two flexibly suspended ring gears. Spindles support the planet gears on hydrodynamic film bearings. Through the planetary wheels there is a power split, like it is applied at the BHS power distribution gears.

BHS planetary gear units increase or reduce the input speed. Speed-increasing gear units are typically used between electric motors and compressors, for example, whereas speed-reduction gear units are used between gas turbines and gener­ators. BHS planetary gear units are designed in accordance with a wide variety of standards: DIN 3990, ISO 6336, ISO 13691, AGMA 6011 or the corresponding Voith Standard that in part exceeds the quality requirements of these standards.