I gonna dispute the "Friction controls are worthless" comments.
I have used them in the past and would have no problem using one again.
Friction controls are the oldest design out there, and there arte more of them than any other. It is a very simple system. So simple that even when not setup right,,,it still works to some extent. I truly can be a hook up and tow type of deal.
Most of wht I see are not setup right, but theier owners are happy with the improvement it gave them.
While there are some advantages of the higher end hitches, setup is the key with them.
Most that use higher end hitches are more into setup, so they are OK with dialing a hitch in.
Huntindog
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Uncle Wiggly wrote: So my question is, "How could a tapered bar NOT be progressive?"
Before responding to your question, I need to know -- How do you define "progressive"?
Quote: Although I have not recorded detailed data (I am now re-setting and calibrating my WD hitch) it appears that my EZ-Lift 800# bars (tapered, trunnion) are exponential in their progressive increase, at least in the range of adjustment needed to equalize my rig. The difference between 2 links loose and 3 loose is monumental.
Please post details of your experimental procedure and your data and analysis. Then we will have a good basis for a meaningful discussion.
Ron Gratz wrote: How do you define "progressive"?
Ron
Increasing in a nonlinear fashion.
It'll be a while before I have anything meaningful to post. My weeks tend to be 80 hours.
As I said, I haven't been able to obtain repeatable data with my Sherline, but the seemingly large difference between two links loose and three ought to be measurable.
There may be too many variables to consider without constraining the pieces. If that's what it takes, I sure won't get to it until fall....
Mike
Ron Gratz wrote: How do you define "progressive"?
Ron
Increasing in a nonlinear fashion.
It'll be a while before I have anything meaningful to post. My weeks tend to be 80 hours.
As I said, I haven't been able to obtain repeatable data with my Sherline, but the seemingly large difference between two links loose and three ought to be measurable.
There may be too many variables to consider without constraining the pieces. If that's what it takes, I sure won't get to it until fall....
Mike
Glad to see you join this discussion, Mike. I don't think it is easy for many people to visualize Andy's theory, and it's nice to see an understanding and interest in such things besides Ron and I.
When Ron and I were talking of progressive spring loading, I took it to mean more tension for each additional successive unit of delection. In other words, the first deflected inch might take 10 pounds (total of 10), the second inch might take 11 more pounds (total of 21) etc. This should occur until the stage of plastic deformation is reached. My intuition dictates that a tapered "equalizer" bar should behave this way, but I could be wrong. However, if I remember right, one of the engineering reference formulas Ron provided also seemed to indicate a progressive rate to me, as I think I said in an above post.
I still have some intentions to do some weight measurements later this spring, but it will require getting my former camper out of winter storage and making measurements on the most level parking lot that I can find. I'll have to make do with an ordinary bath scale set up either in a lever/ratio apparatus for out of range scale weights, or direct for lesser weights within the bath scale range.
For lesser weights, I may be able to place a small hydraulic jack on the bath scale and lift the "chain end" of the bar in both straight ahead and turned towing positions, with a tilted head of course. If Andy's theory works, the ends of the bars may change tension as he describes between a turn and straight ahead position. All I need measure, is to lift enough tension to note a slight chain slack. When the slack just occurs, the scale should indicate present bar tension.
I note your legitimate concern with the Sherline shaft friction. If my ordinary jack suffers a slight "stiction", I believe it should not matter as the combined resistance of hydraulic pressure and piston friction should always weight the scale equally well regardless of pressure/friction ratio.
Wes
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Wes Tausend wrote: ---However, if I remember right, one of the engineering reference formulas Ron provided also seemed to indicate a progressive rate to me, as I think I said in an above post.
Wes,
The tapered cantilever beam equation which I referenced in this post does NOT show a "progressive rate".
The equation shows that the ratio of tip load divided by tip deflection is constant for a given beam . And, that is a definition for a linear relationship.
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