Hydraulic bowthruster RPM

Discussion in 'OnBoard Electronics & Controls' started by Stillbuilding, Jan 25, 2011.

  1. Stillbuilding
    Joined: Dec 2008
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    Stillbuilding Junior Member

    Does anyone know usual RPM for a 12" bowthruster? Just curious.
     
  2. Lurvio
    Joined: Jul 2009
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    Location: Mid of Finland

    Lurvio Mad scientist

    http://www.usthrusters.com/hthrusters.asp

    Hard to say, what the prop shaft rpm is, as the gear ratio is not specified, but hydr.motor rpm is around 3000 rpm (57 liters/min, 19.5 ccm).

    Edit: Model SP 300 Hyd

    Lurvio
     
  3. Stillbuilding
    Joined: Dec 2008
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    Stillbuilding Junior Member

    Presumably a geroter motor is used in most cases providing some sort of reduction gearing. No guesses for the thruster prop RPM?
     
  4. Adler
    Joined: Jan 2010
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    Adler Senior Member

    Dear,

    More or less a 12" Dia-Ducted propeller(eff 0.65-0.67) of a thruster absorbs 25kW Hyd.Power at 1350-1450 rpm. (more speed , reduces the propeller's efficiency when the cavitation appears on blades' tip).
    Most of these systems use piston motors (because of the better efficeincy than the orbit or gerotor type motors) and reduce the motor's speed through the L drive gears by a ratio 1.3 to 1.5.
    If you consider all these above you need a Hyd.Motor to operate at 250 bars (continuous mode - able to achieve 350 bars) with a displacement 40-45 cm3/rev. and top speed never less than 2500rpm.

    I hope all these help you regarding the case.
     

  5. Stillbuilding
    Joined: Dec 2008
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    Stillbuilding Junior Member

    Adler, Thanks very much for that. All very clear. Will help with my plans.
     
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