returns in reducing steering effort, as well as exaggerating the
effects of road shocks felt at the steering wheel.
the advantage claimed for negative , as opposed to positive,
steering offset is that tyre drag forces acting about the moment arm created
by the offset promote toe-in, rather than toe-out, of the wheels .
Therefore in the event of the tyre deflation or uneven braking,the wheel turning-in
effect of negative offset tend to counteract any veering off course of the vehicle.
This feature is also relevant to modern diagonal split dual-circuit safety braking
systems, since if either circuit misbehaves one front brake will develop much more
drag force than the other.
Centre point steering is obtained when the swivel axis of the wheel intersects ground level
at the centre of the tyre footprint area, instead of being laterally offset from it
as in conventional practice . True centre point steering implies a vertical swivel axis
that is contained within the centre plane of the wheel, but this has seldom been
found practicable except in the case of some earlier front- wheel-drive cars
with brakes mounted inboard on the final drive unit. Otherwise,
an apparent centre point steering geometry is obtained by resorting to
a fairly generous swivel axis inclination, usually in the region of 10度 or more,
An important advantage of centre point steering is that in the presence of braking forces
and also traction forces in the case of driven front wheels, acting through the centre
of the tyre footprint area, the wheels experience no turning moment or disturbance about
their swivel axes. A disadvantage of centre point steering is,of course, the earlier
mentioned increased scrubbing effect on the tyres, which demands greater steering
effort during parking manoeuvres unless power- assisted steering is used.