I am wondering what mechanism for a design could trigger one after the other a sequence of cams with followers on the same axis in a loop : follower cam 1 - follower cam 2 - follower cam 3 - follower cam 1 -follower cam 2 - follower cam 3 etc...

I don't want any electronic device,just a mechanical system(springs,cogs etc..).

Thank you.

 

I'm not sure exactly what you want, but it sounds like you could just put the cams on a common shaft and have them angled slightly out of alignment. Then, as the shaft spins, the cam most tilted forward will 'act' first, followed by the next and then the next, with the delay determined by the angles and the speed of rotation.

 

Thank you for your answer,I mean that after a 360 degree rotation only the follower for the first cam is in use then the second follower on the next rotation then the third ...etc in a loop.I know it's not easy to describe in text.

 

I'll give it a bit more thought when I have some time, but my first inclination is basically what I said before, only modified.
Change your cam profile so that it covers the same motion in 1/3 of the rotation (may be limited by geometric constraints - e.g. diameter of your followers), leave the other 2/3 at a constant radius for each cam.
Set each cam 120 degrees apart.
Then rotate your shaft at 1/3 of the speed.
The effect will be that your cam motion will apply in sequence, and when the other cams are active, the followers will stay stationary.

 

I am asking this question because I am wondering how Jacquet-Droz and Maillardet made their automata cycle through cams to write sentences by switching back and forth between letters.

 

In that specific case, my 5 minute google search suggests that the cams were moved back and forth so that different cams were in line with the cam followers. Likely the back and forth was driven by other cams, that gave the automata their memory.

 

A quick search of written materials only leads to superficial articles on these items. Now I feel the compulsion to find a treatise on the actual design and operation of automata...