TILTING VEHICLE SUSPENSION SYSTEMS
A tilting vehicle cant work properly unless it has correct suspension action.
A motorcycle has correct suspension movement. In a motorcycle the wheel
always moves in the plane of its inclination. This system can be called "in the
plane suspension" .
Many people fit laterally running parallel wishbones to tilting vehicles because
they have observed this style on racing cars but this can result in a less than ideal
suspension when applied to a tilting vehicle.
TvA has experimented with all forms of suspension and has reached clear
conclusions that the parallel wishbone types are flawed.
When parallel wishbones move while inclined they cause the wheel to move
dramatically out of its inclined plane.
Imagine a wheel rolling from a flat surface then onto an undulation/bump. There is
a "natural rolling path" that this wheel will follow and this path is only possible if the
suspension of the wheel is arranged to move in the inclined plane.
We have a simple visual aid to assist you so click on the picture below[1Mb]
Notice in the 2 examples the way the wheel moves on a different path because in
one example[ parallel wishbones] it is forced off the natural rolling path. The N.R.P.
is the path on the surface of the bump/hollow that shows when a cut is made
through the profile of the irregular surface at the inclined angle of the rolling wheel
that is passing over it.
IF the N.R.P. is not maintained then the slip angle of the wheel will be
instantaneously loaded as the wheel is scrubbed across the surface sideways. In
a real event the mass of the vehicle has inertia that wants to resist any sideways
displacement so the wheel is forced to scrub sideways across the surface and so
causes loss of traction and poor feedback characteristics.
On the other hand if the suspension is performed properly "in the inclined plane"
then this does not occur. Many large corporations who are ignorant of tilting
vehicle requirements have proposed tilting vehicles with parallel wishbones and
many individuals have built such vehicles [ as has TvA]
There is only one way to do it and thats the right way. In this regard the Piaggio
Mp3 has done the correct thing and no doubt this is why the suspension on this
vehicle works so well.
Like many things its easy to see but its not obvious unless it is pointed