LOAD RATING
The load rating of coil suspension is based on
the ultimate strength of the suspension arms,
bearing capacity, spring rates and dampening
characteristics.
Remember: the suspension does not just hold
up the van, it has to control the body in
dynamic conditions.
It must be rated to support the fully loaded van
when it is coupled to the tow vehicle (GTM).
For trailers with multiple axles, the suspension
load rating should meet the VSB1 Light Trailer
requirements for non-load-sharing axles in an
axle group, Jibu John said.
What about the stub axle’s load rating? After
all, the stub axle is subjected to extreme loads
in multiple directions. But in truth, it’s not
about the rating of any one component.
“A properly designed suspension looks at the
arm as an entire system,” Cruisemaster’s
Andrew Goddard said. “It may not be the
bearing capacity or the stub axle capacity
that is the deciding factor. However, as a rule
of thumb the bearings typically carry a higher
rating than the arm. Suspension is rated as an
overall system.”
And yes, a serious suspension system will have
been tested thoroughly. AL-KO, for example,
uses computer simulations and conducts tests
at the the Australian Automotive Research
Centre proving ground to validate the strength
requirements of stub axles and other
suspension components, which help its
engineers to optimise the geometry of the stub
axle and selection of the material.
“In most (AL-KO) suspension applications, the
stub axle material grade is higher than other
components,” Jibu said.
Cruisemaster, too, famously conducts
remote-area testing of its products known as
RAT Runs, torture-testing its suspension and
other components in serious offroad
conditions anywhere from Cape York to the
Birdsville Track.
Cruisemaster is famous for torture-testing its products.