Some days ago Thiago Bouzan wrote me about his improvements on a Geneva mechanism design, presented here at TBs long ago.
However, what I found most genius in his model, was not the Geneva mechanism implementation itself, but the application he found to command a functions switch box sequentially, with such indexing mechanism.
Who says it can command a switch box, may also say a sequential gearbox for a car transmission.
Here the Geneva mechanism is used to switch among functions the easy way, using a secondary selection motor. Ideal for remote operation of any 4-stage switch box or gearbox.
The mechanism allows for a larger 'window' to tune the secondary motor, as by conception it locks always in one of four positions.
Now it would be great if someone would manage to build a 6 or 8-station Geneva mechanism, out of LEGO parts, to command 5+R and 7+R car sequential gearboxes...
Probably an alternative way to build a remote controlled sequential like gearbox. A bit like doing the same as the one at Sheepo's Buggati Veyron.
Still regarding the Geneva mechanism, Thiago explains:
In this mechanism we have a driving wheel and a driven wheel (or star wheel). This document explains that in order to work properly, a Geneva mechanism should fulfill three conditions:
Consider the space between the centers of the holes in a Technic beam as a unit of measurement. In my design I have r equal to 4 in both wheels and a distance between then of 6.
- r is the distance between the center of the driving wheel to the center of its outer pin.
- The center distance of the two wheels should be the square root of 2 times r.
- r should also be the distance of the outer radius of the star wheel.
This fulfill conditions 1) and 3). Condition 2) could be match with r = 5 and distance between the wheels = 7., because 7 is a good approximation to square root 2 times 5. It looks like that the example from the original post meet these criteria.
The reason why I didn't choose this particular combination was to make full use of two (32249) 'Red Technic Beam Quarter Circle' and achieve a more compact size. But I intend to make a new model that will meet all these conditions.
Simply a brilliant idea on how to apply the Geneva mechanism into a LEGO model.