Jacking Forces

[traindriver]

I am researching (trying to understand) jacking forces produced by SLA suspension systems. I think that jacking forces can be produced by both elastic (through the springs)and geometric (through the linkages) lateral force inputs. Can anyone help me plow through this stuff. Any help is most appreciated.

Thanks

 

[GregLocock]

Can you define what you mean by jacking?

One of the simplest is just via castor. As you steer the front wheels typically the car rolls.

The there is bad swing arm geometry, etc etc

Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[traindriver]

Thanks for replying Greg.

My defination of jacking would be, through lateral force inputs at the contact patch, raising or lowering the sprung mass and increasing or decreasing the vertical force at the contact patch.

I am interested in the jacking forces produced by lateral force inputs when high speed cornering. There are vertical and horizonal components of these lateral forces being transmitted through the links. If the vertical component is upward, would this not tend to lift the body and/or reduce the load on the contact patch and vise versa?

Also I think there would be an elsatic jacking force if the RC is asyemtrical with the CG location. But then should we look at forced based RC's or kinamatically constructed RC's?

 

[GregLocock]

"My defination of jacking would be, through lateral force inputs at the contact patch, raising or lowering the sprung mass and increasing or decreasing the vertical force at the contact patch."

That's a /useful/ force based definition of roll centre height. In fact that is how we physically measure the FBRC.

"if the RC is asyemtrical with the CG location"

Hmm, I've just read a paper that says that RC is only really a meaningful concept if it is on the centreline, otherwise you might as well work it all out properly!





Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.