What is the simplest way if you have a shaft rotating clockwise for it to have an extension that rotates anti clockwise. Least loss of energy is best so i think a mechanical mechanism would be best.

I am thinking is there a way you could use the main shaft in a turbo fan engine to drive another fan in the opposing direction in front of the original fan.

  • $\begingroup$ Do you mean simple to build, or simple to maintain, or simple to calculate? Seems fairly straightforward to do with gears regardless. $\endgroup$
    – JMac
    Apr 3, 2017 at 11:27

1 Answer 1


Least loss of energy would be using one gear with adequate lubrication.

I prefer planetary gears because they last much longer and distribute the load better. Plus you can do it with a hollow shaft. The center shaft turns clockwise, the planet gears turn counterclockwise as does the outer shaft.

Here is a link that should show you a gif of the gear in action.


  • $\begingroup$ Why isn't this used in turbo fan engines to have a contrarotating fan? $\endgroup$
    – SRawes
    Apr 3, 2017 at 16:55
  • 1
    $\begingroup$ They have used counter-rotating blades on aircraft (see link below) and steam turbines use fixed blades that fit between the moving blades that kind-of do the same thing by forcing the steam to hit the next set of turning blades at an angle that will impart the most kinetic energy. en.wikipedia.org/wiki/Contra-rotating_propellers $\endgroup$ Apr 3, 2017 at 16:59

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.