A challenge for all the Technic minds out here

[shimon]

Hello everyone.

While working on my new project i came across a need in a mechanism that will do the following things:

Having only 1 motor it will operate 2 functions. while the first function has a limited angle (like a lever switch) and the other one that can spin continuously.

For example an auto-valve: when operating the motor the first movement when the motor turns clockwise will be moving the pneumatic switch and right after it moves the switch it will spin and activate the compressor, same thing when right after you switch to counter clockwise: first the lever of the witch will go to the other side and then the compressor. eventually i ended up with Sariel's auto-valve modifying it for Technic and making it smaller. but then such a mechanism as mentioned will allow us many useful functions like having advanced crane outriggers that will first extend and then deploy: all with 1 motor and when motor activated other side it will lift the outriggers and then they go inside.. such mechanism cannot rely on a differential because it doesn't determine the sequence of the functions and each function can be activated any time without any sequence..

so here is the challenge: a solid mechanism that will have 1 output that is in 1st priority, it must be activated first and it's spin angle is limited and the second output that will be activated only when the 1st reached to its end and the same backwards. everything with 1 pf motor.

Thanks everyone in advance!

Also if such mechanism was invented please share it because i have never seen one that works by this method.

[Hopey]

You could use a differential with some added friction on the one you want to happen second, which won't be overcome until the first one hits a stop. Trouble is, the second function has to always work against this.

You could again use a differential and create some kind of fancy linkage that stops the second function from turning until the first one has reached its full extent.

I think you might also be able to use a sliding worm gear, although I can't quite wrap my brain around it at the moment.

[Alasdair Ryan]

You can use a clutch gear by having the drive axle going through the centre of a clutch gear and have first function coming of it with a 6 tooth gear, the second function should then come off after the first function put on the same axle.

Edited December 21, 2012 by Alasdair Ryan

[shimon]

Thanks for the replies guys.

Hopey: the point is it is not 100% that it will work if it includes friction and secondly it will give the motor a big power loss... if the preference between functions is depend on friction.

Alasdair Ryan: theoretically it might work but imagine the power loss due to the clutch friction... or if the function has more friction than the clutch it will never get activated..

The mechanism shouldn't be depend on friction or gravity it should be pure mechanism that will work 100% and it is hard to think about something like that

[Alasdair Ryan]

The only way you could then do it is by having a gear box that was on constantly and have the motor also switch the functions,you could then add a differential as a limiter to power the second function once the first function is as it's max.

Since you only want to use one motor you are always going to face using some sort of friction powered device,especially since you want to add a limiter on one of these which will power the second one.

Edited December 21, 2012 by Alasdair Ryan

[camaudio]

if you are having it power a compressor, wouldnt the friction of the compressor itself be enough?

[Alasdair Ryan]

if you are having it power a compressor, wouldnt the friction of the compressor itself be enough?

Ha yes,you could have it power a pressure valve.Once the pressure is high enough it could cut of the compressor and then power the other function.

[Hopey]

Hang on, how do you expect it to work in reverse?

From what I understand, you want to do something like extend stabilisers and run a PTO.

With the stabilisers retracted, you turn the motor on in the "forwards direction". The PTO doesn't move and the stabilisers extend. When they're fully extended, the PTO is then driven indefinitely.

But what's supposed to happen when you reverse the motor? Should the stabilisers retract immediately? What happens when they're fully retracted?

Edited December 21, 2012 by Hopey

[Saberwing40k]

*snip*

but then such a mechanism as mentioned will allow us many useful functions like having advanced crane outriggers that will first extend and then deploy: all with 1 motor and when motor activated other side it will lift the outriggers and then they go inside.. such mechanism cannot rely on a differential because it doesn't determine the sequence of the functions and each function can be activated any time without any sequence..

so here is the challenge: a solid mechanism that will have 1 output that is in 1st priority, it must be activated first and it's spin angle is limited and the second output that will be activated only when the 1st reached to its end and the same backwards. everything with 1 pf motor.

Thanks everyone in advance!

Also if such mechanism was invented please share it because i have never seen one that works by this method.

well, I actually have made a mechanism like this, and have seen a similar one in a Lego book, and contrary to what you have said, they can rely on a differential. you just have to add some, not a lot, just some on the mechanism you don't want prioritized. for instance, with outriggers, the initial rotation out gets first priority, then the valve to extend them.

I'll see if I can get something banged out, then we can really talk.

[Alasdair Ryan]

If it is for outriggers you might be able to use some thread like on 3 section booms that will pull down the outriggers as they are deployed and the opposite when they are retracted.