ADVANCED ABS WITH STABILITY CONTROL STARTING AND OPERATING THE VEHICLE
– 120 – Y53-6033
Regional Haul (R05/10)
RSP Example
Yaw Stability
Yaw stability counteracts the tendency of a vehicle to spin
about its vertical axis. During operation, if the friction
between the road surface and the tires is not sufficient to
oppose lateral (side) forces, one or more of the tires can
slide, causing the truck/tractor to spin.
These yaw events are referred to as either “under-steer”
(where there is a lack of vehicle response to steering input
due to tire slide on the steer axle) or “over-steer” (where
the tractor's rear end slides out due to tire slide on the rear
axle) situation. Generally, shorter wheelbase vehicles
(tractors, for instance) have less natural yaw stability,
while longer wheelbase vehicles (straight trucks, for
instance) have greater natural yaw stability. Factors that
influence yaw stability are: wheelbase, suspension, steer-
ing geometry, weight distribution front to rear, and vehicle
track width.
Yaw Control
Yaw Control responds to a wide range of low- to high-fric-
tion surface scenarios including rollover, jackknife and
loss of control. In the case of vehicle slide (over-steer or
understeer situations), the system will reduce the throttle
and then brake one or more of the “four corners” of the
A Real World Example
Of How The RSP
System Operates:
Excessive speed for road
conditions creates forces
that exceed the threshold at
which a vehicle is likely to
rollover on a higher-friction
surface.
The system automatically
reduces engine torque and
applies the service brakes
(based on the projected rollover
risk) to reduce the vehicle
speed, thereby reducing the
tendency to roll over.
