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A vehicle's roll stability
is determined by i ability to resist rollover. A vehicle loses i
ability to resist rollover when the tires on one side of the vehicle
lift off the ground. Many elements of a vehicle's design are used to
determine i roll stability.
Roll stability for a trailer can largely be determined by the
height of the centre of mass of the trailer and the wheel base or axle
track. These factors can have the greatest impact on the roll stability
of the trailer. For example, changing the trailer's axle track from 71.5
to 77.5 inches can improve roll stability by eight percent.
While the chassis flexibility must also be considered, the
suspension, tire and axle deflections actually rate as minor factors in
determining a trailer's roll stability. Hendrickson trailer suspensions
provide the cargo protection of an air suspension along with the roll
stability performance equal to a steel leaf-spring suspension.
| The
Hendrickson Advantage |
Hendrickson
air-ride trailer suspensions provide a soft ride for driver comfort,
cargo and equipment protection. At the same time, a Hendrickson air-ride
suspension provides roll stability equivalent to a leaf-spring
suspension. This is evident in the accompanying chart, which shows that
while air and leaf-spring suspensions exhibit different degrees of roll,
both suspensions reach tire lift-off at approximately the same cornering
speed. (In addressing this phenomenon, we considered a Hendrickson
air-ride system and a typical leaf-spring suspension).
Since both suspensions reach roll stability limit at approximately
the same cornering speed, both suspensions are considered to provide the
same roll stability performance. However, suspension vertical stiffness
can be quite different, especially between air and leaf-spring
suspensions. The vertical stiffness of a leaf-spring suspension can be
four to five times stiffer than a Hendrickson air-ride suspension. While
a soft ride seems to be in conflict with roll stability, in reality it
is not. The answer lies in the fundamental difference between the
suspension types. Since air suspensions provide a considerably
softer ride than leaf-spring suspensions, they must rely on other means
to achieve roll stiffness. This other means, commonly referred to as
"auxiliary roll stiffness", usually comes from the axle.
Hendrickson
air-ride suspensions resist trailer roll by utilising the axle in a
manner similar to a torsion bar. The axle tube provides the necessary
trailer roll resistance that is equal to or greater than what can be
provided by a leaf-spring suspension. At the same time, the air
suspension eliminates the spring lash of a mechanical suspension
resulting in a lower roll angle. This allows Hendrickson's air
suspensions to have similar roll stability characteristics, while
providing a ride that is significantly superior to a leaf-spring
suspension.
What this brings to the Flee and owner operator is the ideal
combination of ride softness and roll stability, in other words, the
ultimate in cargo protection, comfort and safety.
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