[net.auto] Suspension myths, and myths of my own making

guido@twitch.UUCP ( G.Bertocci) (05/31/85)

In my recent analysis of suspension and weight transfer, I have
left out a rather important element, which doesn't
totally invalidate my previous results, however, they should
be presented in a new light.

I have stated that you can't transfer weight from side to side
of a car, and that you can't transfer weight from front to rear.
These are both true enough, if you take side to side to mean the 
SUM of left tires and the SUM of the right tires, or that
front to rear means the SUM of the front tires and the 
SUM of the rear tires.
However, there is another way that weight can be transferred 
that doesn't violate either of the two previous statements 
and that is diagonally.

Picture a perfectly square table.

		A   Front     B
		_______________
		|             |
		|             |
		|             |
		|             |
		|             |
		|             |
		|             |
		---------------

		C  Rear	      D

If the table is square and uniform  and A,B,C,D represent the forces at the
four corners, then

		A + B = C + D  (no transfer from front to rear)
		A + C = B + D  (no transfer from side to side)

Solving these two equations you get:
		A = D and B = C

If you cut one of the legs slightly, you change the weight distribution
dramatically without moving the CG or exerting any external force.

Therefore, on a car the weight can be transferred because you
can increase B and C while at the same time decreasing A and D.
This can be controlled by the stiffness of the suspension.

(Nothing like taking a shower to get a new perspective on the world:-) )

I hope that everyone isn't totally confused.  
-- 
Guido Bertocci
AT&T Bell Labs
Holmdel, NJ

...!ihnp4!houxm!twitch!guido