Wärtsilä Double Input Gear

Wärtsilä double input, single stage reduction gears connect two engines to a single propeller shaft and cover a power range from 2,000 to 25,000 kW.

The gears are available with a horizontal offset between the input shafts and output shaft to allow two (diesel) engines to be connected.


  • Clutches to disconnect the propeller from the main engine(s)
  • A primary driven PTO, rotating whenever the engine is running or a secondary driven PTO, which rotates whenever the propeller is rotating.
  • Combined power take-off / power take-in (PTO/PTI) 


    Double input gears are applied to combine the output power of 2 medium speed diesel engines on a single propeller shaft. Typical applications include:

    • Anchor handling tug supply (AHTS) vessels
    • Fast patrol vessels
    • High power cargo vessels with medium speed (dual fuel) engines
    • Ferries

    A key dimension of a double input gear is the horizontal offset, which is determined by the required service space between the two propulsion engines. Wärtsilä double input gears can be combined with Wärtsilä engines, as indicated in the table below, as well as with other engine brands.

    Technical Info

    Double input gear tech-information


    Power take-off (PTO)

    All Wärtsilä gears can be supplied with one or more PTOs for driving the shaft alternator, compressor or pump. For single vertical and horizontal gears, the standard PTO is primary driven. For double gears, the PTO is optionally primary or secondary driven.

    A primary driven PTO rotates whenever the engine is rotating.
    A secondary driven PTO rotates whenever the propeller shaft is rotating.

    Power take-in (PTI)

    Most Wärtsilä gears can be supplied with a combined PTO/PTI. In PTI mode the shaft alternator can also be used as an electric motor. PTI is normally used for the following operational modes:

    PTI “Booster” mode is used when the main power of the engine is insufficient in order to increase the total propulsion power. For this mode, no clutches are required on the gear.
    PTI “Take me home” mode is used in case of emergency should the prime mover be inoperable. For this mode a minimum of 2 clutches are required on the gear.

    Hydraulic power unit

    Most Wärtsilä gears are purpose-designed with an integrated hydraulic system for both the gear and the CP propeller. As a separate hydraulic power unit for the CP propeller is superfluous, both installation costs for the yard and operational costs for the owner are reduced. For safety reasons the gear mechanically drives the main pump for the propeller. All gears can also be interfaced with a separate hydraulic power unit.

    Special gears

    Based on the standard Wärtsilä gear types, customized solutions can be delivered upon request.


    • Combined vertical and horizontal offset
    • Multiple power take-off (PTO)
    • High power PTO
    • High power power take-in / dedicated hybrid propulsion gears​

    Related references


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