Ravigneaux Gear planning

[Philip_Il]

Hi hope someone here can help me or at least guide me to a sensible approach to calculating this problem I have.

I need to calculate a Ravigneaux Gear I'm aiming to get 4 gears + reverse with the following ratios:
1st gear: 3.00 ratio
2nd gear: 1.67 ratio
3rd gear: 1.00 ratio
4th gear: 0.75 ratio
Reverse gear: (-3.00) ratio.

I tried using the formulas from this page:

https://www.mathworks.com/help/physmod/sdl/ref/ravigneauxgear.html

but since it is based on radius and not teeth count I'm getting really confused.
Anyone has experience with it and can help with a "best practice" for how to approach this issue?

Thanks!

 

[waross]

Radius times 2Pi equals circumference.
Circumference divided by tooth pitch equals number of teeth.
Vary the tooth pitch and radii until you get an even number of teeth.
You may not be able to get exactly the gear ratios that you want with a reasonable tooth pitch or reasonable radii..
Close enough is often good enough.
You can always state the desired ratio in a footnote, "Subject to rounding errors".
eg: 2nd gear: 1.67 ratio (Subject to rounding error)

Bill
--------------------
Ohm's law
Not just a good idea;
It's the LAW!