[andyauger]

That term has been tossed about a good deal around here. Some aspects of this topic are clearly not understood by many posters.

http://docs.google.com/Doc?id=dfjcvtc2_91hk7s2gfx

There's an example of a simple mechanism with equal distance input and output, varying, non-linear input force requirements. I can't make it any more simple.

 

[Mudsurfer1234]

This term comes up alot in the RC airplane world. Setting up servos, linkages, and control arms does wonders for the mind. Good find.

 

[tcl]

Andy,
The movement MA in the system you illustrated system IS progressive.
Aside from its function as a "red herring", second lever halfway down the string is totally irrelevant.

 

[Veee]

just to save on searching time

 

[swiest152]

Andy, just stop.

All these "look at me I know everything threads" are getting really old, especially since you are WRONG 95% of the time. Please, stop trying to show off your "knowledge" and stop trying to protect your ego.

Although me and many others are getting a good laugh out of it.

 

[andyauger]

The input force acts on one end of the lever. The end of the lever moves through the identical arc that the wheel moves through, and travels the same distance along the arc. The motive force moves through the same arc the same distance. The input motion is identical to the output motion. Definitely not progressive.

The only purpose of the weight is to provide a constant torque for the example. Still, even the weight providing the torque moves identically the same distance as the input and output (but in a straight line).

There is a constant 1 foot pound of torque on the wheel. To rotate the wheel from the starting position requires more and more force as the wheel rotates (torque/cos(angle of rotation).

I can provide others, I just wanted to start with the simplest one I could think of. It's not simple enough?

If you read the entire example I state at the end that the mechanism works the same without the lever. I put it there to make the motion of the input force easier to visualize.

 

[tcl]

Definitely not progressive.
.

It is only the LIFTING movement that counts.

When your pivot is at 3:00, one bucket is lifting the other an equal amount; there is neither force nor movement MA. As the pivot approaches 6 (or 12), the second bucket is barely being lifted compared to the vertical drop of the first bucket; this is the point of the greatest MA (force and movement).

I thank you for posting this document. Before this, I held that there was a tiny possibility that I was missing something in the other thread and you were fact correct. Now, here, you have made a nice, simple diagram that illustrates the fundamental error you were making all along and I'm finally certain that I was never missing anything.

It's not simple enough?

plenty simple, thanks

 

[andyauger]

I posted this because of a comment in another thread.

The example didn't involve lifting the weight. The weight just provides a constant torque on the wheel, nothing more. Still, the weight travels the same distance as the input and output. The constant torque makes it easier to see what's happening with the input force. What I am pointing out is that the input and output are moving exactly the same distance and arc, but the force required is increasing.

When I tried to explain why the SV suspension was progressive one of the main counter arguments was "you can't have equal mechanical motion and increasing force". I tried to give a couple of simple examples of what I was talking about, but no one understood (and in a couple of cases wouldn't even look at the simplified examples). Here's one simple example that shows you can have linear input and output, non-linear increasing force. It illustrates the concept of effective torque or lever arm, which is a simplified version of resolution of force vectors.

I'm not always right (like I assumed that there was an oil spray from the top of the connecting rod the other day. Guilty of ignorance and making a bad assumption), and I don't pretend to know everything (like I didn't know I had an erroneous circuit diagram for the 2nd gen bikes until someone posted a correct one), but this is simple mechanical geometry. Just like the rear suspension on the SV.

Let's set the record straight. You tell me where I was wrong in the past, and if I was I'll admit it in print on this site, line by line. BUT, if I disagree with a particular item I'll present my data supporting my position, you tell me why my data is bad. That's how we learn.

 

[swiest152]

When I tried

stop trying and go ride.

 

[andy438]

Regardless of the mechanical advantage, work in equals work out, and power in equals power out.

Just sayin'...

 

[andyauger]

I was out twice yesterday and out again this morning. It's great riding weather.

Andy438, yep, energy is conserved, power is conserved. Conservation of power is why the horsepower of an engine is the same at the rear wheel regardless of gear reduction.

Force is a bit different. Put a scale on the wheel in my example. Hold it tangent to the wheel and hold the scale so the wheel doesn't rotate. It will read 1 pound force. Now rotate the scale so it's 60 degrees from the tangent line (rotate up or down, it doesn't matter). It now reads 2 pounds force. Let's call the angle between the scale and the tangent line to the wheel "a". Just like in the example the scale will read (1 pound force/cos(a)).

 

[iron dragon]

That is all.

 

[Coop]

That is all.

If it wasn't for nerds you wouldn't have a bike to ride ;D.

 

[BossMan]

That is all.

Is that you in your avatar?