I'm a final year mechanical eng student, I'm working on designing a prototype of a 'Hybrid vertical axis wind turbine (VAWT)". This hybrid turbine consists of two types of VAWTs Savonius & Darrieus, one providing good 'starting torque' at 'low wind speed' another, needs 'high starting torque' and ' high wind speeds' but, can spin faster than Savonius turbine (no limiting drag). So I want to combine both of these to enjoy both of these turbines' advantages, thus trying to nullify each others' disadvantages. To do this I'll be needing a switching OR engage/disengage mechanism which can switch between both turbines' shafts... Savonius turbine shaft engaged with Darrieus's shaft until Savonius assists Darrieus in starting & speeding up and after reaching its drag-limiting speed, Savonius's shaft has to disengage from the Darrieus's thereby letting it spin independently with Savonius's shaft disengaged. Here the engaging & disengaging are going to happen at a wind speed of 7 m/s. Please suggest to me if there's a mechanism that can do this switching AND if there's a mechanism that doesn't use electrical power or servo motors for the switching actuation mechanism. Any suggestion is appreciated. Thanks in advance! :) Diagram of Savonius-Darrieus turbine, notice above's Savonius & below's Darrieus


1 Answer 1


You are looking for a one-way clutch or freewheel. You will be familiar with these from a bicycle wheel chain-drive cassette. The chain drives the wheel until the wheel's rotational speed exceeds that of the driving sprocket.

  • $\begingroup$ Hi Transistor, thanks so much for the suggestion. IG so far from what I've researched, one-way clutches will be the best choice for the mechanism I want to achieve. I'll be researching more about it, and reverting back to you if I get stuck somewhere. If you're fine with it. If I can DM you? $\endgroup$ Jul 26, 2023 at 17:46
  • $\begingroup$ All communications need to be done through the site. That way everyone benefits (if anyone benefits!). SE sites don't have a direct messaging system anyway. Meanwhile, do a search for "sprag clutch". $\endgroup$
    – Transistor
    Jul 26, 2023 at 18:40
  • $\begingroup$ Oh alright! Sure everyone will benefit... at least I am! Haha I'll read more on the sprag clutch. Thanks! $\endgroup$ Aug 6, 2023 at 9:14

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