In spherical and plane wheel suspensions, a torsional equilibrium of the components of forces acting around the point of intersection (penetration point) of the instantaneous axis of rotation can be established by the respective planes of projection (instantaneous center/velocity pole) separately for longitudinal and transverse views.
In three-dimensional wheel suspensions, the points of intersection are not identical to the longitudinal or transverse center, because the displacement in axial direction must also be considered.
"Equivalent poles" can be determined if the velocity components of suspension movement are known in the respective views from two points on the wheel carrier. The instantaneous center to be determined then corresponds to the intersecting point of the perpendiculars to the velocity directions in these two points (polar projections)