Yunlong_Xu
08-26-2009, 09:04 AM
Hey guys, my first post here.
It’s a very basic question about camber change in roll but I just can’t get around it. I’ve looked through RCVD and Fundamentals of Vehicle Dynamics but can’t seem to find a detailed explanation about it.
Suppose we have a car with upper and lower suspension pick-up points on the chassis parallel to each other (hence no anti-dive? Well I’m just trying to make the simplest scenario in front view), then we will see a simple four bar mechanism in the front view. When the sprung mass rolls about the roll axis, the motion of the link between the upper and lower pick-up points is set. But I don’t see how the rest three bars are restrained so there’s only one way they can relocate themselves and therefore I cannot get the new suspension geometry in that roll condition and hence can’t get find the camber change. It seems to me there must be some restraint that I’ve missed.
But can anyone tell me what is it that I’m missing? My guesses are:
1) The pull/push rod. The amount of length change combined with the installation ratio gives the relative position change of the upper/lower ball joint on the upright, and this adds on one more restraint for the geometry to be settled.
2) The instantaneous centre/axis of rotation for the two suspension control arms, this gives restrains on the possible route of travel of the upper and lower ball joints and hence also gives an extra restraint on the geometry.
Any help will be really appreciated!
Cheers
Yunlong
It’s a very basic question about camber change in roll but I just can’t get around it. I’ve looked through RCVD and Fundamentals of Vehicle Dynamics but can’t seem to find a detailed explanation about it.
Suppose we have a car with upper and lower suspension pick-up points on the chassis parallel to each other (hence no anti-dive? Well I’m just trying to make the simplest scenario in front view), then we will see a simple four bar mechanism in the front view. When the sprung mass rolls about the roll axis, the motion of the link between the upper and lower pick-up points is set. But I don’t see how the rest three bars are restrained so there’s only one way they can relocate themselves and therefore I cannot get the new suspension geometry in that roll condition and hence can’t get find the camber change. It seems to me there must be some restraint that I’ve missed.
But can anyone tell me what is it that I’m missing? My guesses are:
1) The pull/push rod. The amount of length change combined with the installation ratio gives the relative position change of the upper/lower ball joint on the upright, and this adds on one more restraint for the geometry to be settled.
2) The instantaneous centre/axis of rotation for the two suspension control arms, this gives restrains on the possible route of travel of the upper and lower ball joints and hence also gives an extra restraint on the geometry.
Any help will be really appreciated!
Cheers
Yunlong