On Mon, 9 Apr 2012 16:38:44 -0400, "Arny Krueger"
wrote:


"Steve Thackery" wrote in message
...
Arny Krueger wrote:

the torsion bar suspension was highly nonlinear

That's interesting. How did they achieve a non-linear torsion bar spring?

Nonlinearity is inherent in the action of a lever arm that pivots on the bar
and accepts a vertical force. At zero displacement the spring has a long
horizontal lever arm for vertical travel. As you rotate the arm, the lever
arm shortens in the plan view and increases the effective spring rate. If
you actually rotate the arm 90 degrees, spring rate approaches infinity and
pushing harder will result in no additional rotation, but you may break the
whole thing lose from its mountings.

Automotive suspensions are among those things that generally work better if
highly nonlinear. One alternative to torsion bars is additional springs that
engage and resist travel as the displacement increases. A common example is
called a "jounce bumper". the bumper is usually made out of rubber and may
include voids and/or be pyramid-shaped to add nonlinearity.

http://www.gasgoo.com/auto-products/...14.html#img400


Today's formula 1 cars use torsion bar suspension. As you say the
non-linearity is valuable. A rising rate spring is exactly what you
want - far better than the linear spring plus bump rubber. Issigonis
designed the "dry" mini with rising rate rubber cone suspension.

d