 Wheels - Driving dynamics 2
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Having looked at the movements around the vertical axis extensively so far, we now take care of the longitudinal axis through the entire car from front to back. The corresponding movement is the 'vehicle roll'.
While the front and rear wheels were loaded differently, now they are concerned the wheels inside and ouside of the turn. Sometimes the former are even hanging in the air as rear wheels, some artists even manage to do
this with both wheels inside of the turn.
But be careful, then there is an acute danger of tipping over. The question remains as to why a car tips over. First cheeky answer, least of all on black ice if it has neither borders nor edges. So it must have something to do
with the friction. Somehow it's then too good.
But that would actually mean that the risk of tipping increases with wide tires. Is correct. Of course we are still talking about the wheels outside of the turn. The car is being pushed outwards off the track by centrifugal forces
and the tires are trying to keep it on the respective track.
Now even the height of the center of gravity comes into play, which is always felt to be so pleasantly low in electric cars. That's also true, but the centrifugal force is also higher in these cars because of the disproportionately
larger empty mass.
So the rally car has to be light, the center of gravity low, then the tipping moment is lower despite wider tires. Incidentally, the other racing classes are more likely to have really wide tires, because here the structure is
designed lighter or almost completely omitted.
Now you can perhaps also guess where the stabilizer got its name from. It distributes the mass of an axle even more than it already does on the outside of the curve. As a result, the tires there tend to be overwhelmed when
it
comes to transferring of friction to the road surface.
No, they only stabilize the car in the curve with a view to reducing the risk of tipping over. Rather, they reduce the lateral forces of the axle on which they are located. You can get through the corners faster without stabilizers,
but
you have to pay more attention to the lateral inclination.
That is also the reason why we almost always find them at the truck (picture above), often almost as thick as an arm. Here, of course, the risk of tipping is much greater due to the high structure (and thus center of gravity).
Note: The thicker the stabilizer, the more effective it is, because it works as a torsion bar spring.
This is even integrated as an option in the ESP system. Let's assume you took the corner so quickly and suddenly that ESP didn't stand a chance either, then it provides at least by much use of the brakes to ensure that you
fly off on the wheels into the botany and preferably not roll over.
Together with adjustment of damper and even spring hardness in milliseconds, you don't really need stabilizers anymore. From a certain inclined position, you simply harden the suspension of the wheels on the outside of
the curve.
This also avoids the undesirable effect of the rigid connection between the suspensions of an axle, e.g. if the road is uneven on one side. Or you use active stabilizers (picture above), the effect of which can be partially
switched off.
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