kalle11

1 hour ago, AndyB said:

Hi, the smaller the small pulley is, the higher the belt tension needs to be to prevent slipping. Assume the belt contacts the small pulley for 1/3 of its circumference. For 5 cm pulley this contact length is 65 mm and for a 3.75 cm pulley is 37 mm. ie only 56% Thus you would need nearly double the belt tension to prevent slipping.....and the belt would not last very long. It is even worse than this if you keep the pulley centre distance the same as the smaller pulley reduces the angle the belt contacts the pulley even further.

Thank you! So even this small detail about contact area ruins the idea I guess?

  By "not last very long" you mean lasting a really short time like a couple of hours ?

Oh well, is there anywhere online where one could purchase a custom made reduction drive of 1:4 in this case, or do one know a higher reduction ratio of some paramotor unit other than this one? It seems near impossible to find any reduction drive suppliers anywhere.. custom made or not. 

Thanks

Regards

Hi!

I am looking for  a unit around 30hp with an as big belt reduction as possible and found that the black bull corsair fits the bell in weight, cost and power.  However the reduction ratio of 1:3 is a little less than I would really want. I am in need of a big reduction ratio to turn the a slightly bigger propeller slower.  Realizing  that designing, building installing a whole new belt reduction unit to a para motor unit is no small feat I thought of another possibility:

Can I just replace the engine pully with a smaller one to get a 1:4 reduction ratio?  

Obviously it maybe depends on the bearing size of the original pully and other things..hence my question if it is feasable?

Any home-/real engineers or DIY´ers here?:)

If I am correct, the big pulley is 15cm and the smaller one is 5cm which means that I would need a 3.75 cm to get  a 1:4 reduction

Or perhaps there are some  paramotor units with a  high reduction ratios around 30hp of 1:4 or more?

Thanks for taking your time to reading my post

Best Regards

/Kalle