Systems that convert lateral preassure into torque HELP

[mcpp]

I am not an ME but I have a problem I am working on.


I am looking for a mechanical system that would convert a short distance of heavy downward preassure into a strong amount of rotational torque on a wheel. For instance, 150lbs downward preasure over 2" distance converting to 50+ ftlbs torque. What would this type of system be called in the engineering world?

I know a system like this has been designed with a short pulled trigger on a toy gun powering a small electric motor to spin a flint very quickly. http://www.ehow.com/how-does_5421719_toy-spark-guns-work.html

I am wondering what options I have.
Thank you in advance for all your hard earned knowledge

 

[xxChrisxx]

I am not an ME but I have a problem I am working on.


I am looking for a mechanical system that would convert a short distance of heavy downward preassure into a strong amount of rotational torque on a wheel. For instance, 150lbs downward preasure over 2" distance converting to 50+ ftlbs torque. What would this type of system be called in the engineering world?

A piston. Or more generically a crank-slider mechanism.

 

[Unrest]

A piston. Or more generically a crank-slider mechanism.

Or just a wrench.

 

[xxChrisxx]

Or just a wrench.

Indeed.

It's strange how our minds become optimised to think in certain ways. I saw the words linear pressure and rotational torque, and piston was the first thing into my brain.

 

[wsabol]

Or just a wrench.

Well, the driving force for a wrench isn't purely lateral. You could get away with it for very short distances, but there will be motion in two directions rather than just one.

A wrench isn't incorrect per se, but the crank slider is a more correct.

 

[mcpp]

I am not sure a crank slider will work though.

I need to spin this wheel about 50-60 mph. At the same time I need to be able to apply energy to it in intervals not constantly. I need some kind of system that will allow me not to add energy except for when I want to. Almost like blowing a baffle into hot coals. I don't want the energy supplying system to be tied into the moving wheel. How do you get a wheel to spin like this?

One of the problems I see happening is the rotation of the wheel becoming too great and when more energy is applied it would strip gears or something off of the energy applying system.

I apologize for my ignorance in advance.. :) It would be kind of like the system a bmx bike uses to add rotational speed to the rear tier without the pedals having to move all the time. What is this called and can it be designed without the use of a chain?

 

[wsabol]

The first thing I thought of when I read the post actually will fit this pretty well. I'm not sure of the techinal name, but its a centrifugal pump, but in reverse.

You have an impeller on the end of your shaft that you want spun. Then just as you said you can force air into the impeller chamber, onto the impeller blades, to drive the impeller around, just like using a baffle on hot coals. However, I imagine start up could potenially take a while depending on the intertia of the shaft. Friction/air resistance could also be a big issue. You'd be using your baffle pretty regularly...

 

[xxChrisxx]

I apologize for my ignorance in advance.. :) It would be kind of like the system a bmx bike uses to add rotational speed to the rear tier without the pedals having to move all the time. What is this called and can it be designed without the use of a chain?

Ratchet if you only want to go in one direction or some kind of overruning clutch.


You are being a bit vague in what you are trying to achieve so it's hard to give specific advice, there is always more than one way to skin a cat.

 

[Unrest]

This is really quite confusing. mcpp could you clarify these things?

Do you want to apply fluid pressure or transmit force mechanically?
What kind of motion does the applied force/pressure have to have? Reciprocating?
How fast does the wheel have to spin?
Does it have to keep applying the same 50ft-lb torque at all speeds?
What's the application?
Does the applied force have to provide the required torque immediately, or can you use several cycles to spin up a flywheel, which I suspect is what those spark guns might be doing?

Sounds like a ratchet or overrunning clutch as Chris suggested might be what you're after.

There are these hand squeeze powered flashlights that have an overrunning clutch. When you squeeze the lever, it acts like a centrifugal clutch with teeth engaging the generator. Then when you release, it reverses direction and slips past like a ratchet.