At 01:03 PM 10/16/2001 -0400, you wrote:
>I read the article on the fulcrum pin fix, then I read it again. I just don't
>see how it works. Now, I'm just a plain old EE trying to work out a ME type
>problem, but I think I have some valid questions here.
>
>The extra forces that cause the breakage are largely parallel to the ground,
>correct? I would think that the non-Ackerman business would create more forces
>inward or outward, as the tires scrub or grab. Wouldn't a force directly
>inward cause the links to want to ROTATE around the bolts that attach them to
>the square tubes? What prevents them from turning, just the friction of the
>tightened bolts?
>
> I could see it working better if the links were horizontal, in the same
> plane
>as the force. But that, of course, would require some major crossmember
>mods.
>
>Anyone out there want to comment?
>
>Stu
The pins are loaded in several directions due to normal suspension
travel and brake torque transferal in addition to the stresses caused by
the Ackerman situation. The historical evidence says that the cracks tend
to form on the horizontal plane on the inside and outside surfaces of the
reduced diameter at the change in 5/8" diameter to the 7/8" base pin. This
says that this particular Ackerman loading is the highest or most
predominant of the applied loads. If you consider the loads in vector
format, any form of locational "fixing" or attachment at the extreme ends
which reduces the cantilever effect will tend to substantially reduce the
stress at the typical point of crack propagation.
Even if the tolerances of the installed system were so loose as to
be ineffective in this stress reduction goal, the effect of the secondary
"capture" of the outer end of the pin would still allow less freedom in the
event of pin failure. Mind you, I'm not advocating this solution over
other alternatives, simply offering the explanation to your question.
Tom
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