Where's the roll axis?.... Triangulated 4-link

[-DA]

The roll axis of a triangulated 4-link (in plan view: one set of triangulated links, one set of parallel links) is created by drawing a line through the intersection point of the triangulated links with the slope equaling that of the parallel links in the side view. But...

How would you determine the roll axis if the slopes of the triangulated links varied from side to side? i.e. they technically never intersect in 3 dimensions, only the plan view. Do you simply use the plan-view intersection point projected into the the side view? You'd still have to pick a vertical point in the side view between the projected slopes of the links though.

Or let's say you built a Satchel Link but the upper links (parallel in plan view) have different slopes in the side view. Which slope from the parallel links becomes the slope of your roll axis? Perhaps you just split the difference...?

An inverted example of this is Billy Shope's triangulated 4-link being set up to dynamically cancel driveshaft torque by differing the slopes of the lower parallel links and, therefore, changing the anti-squat from side to side.



-Dave