HWH Active Air

[David Brady]

For those interested,

I spoke with an HWH engineer today regarding their Active Air
suspension. For the uninitiated, Active Air provides dynamic
suspension height adjustment. Enter a turn or change a lane and
the outboard airbags are inflated and the inboard bags deflated to
maintain a level chassis attitude. HWH uses their own technology:
high flow air valves, electronic height control sensors, and computer
mother boards. They link it all together with a CAN, J1939, bus
know as RV-CAN, and have been active in the standards committees
to formalize the RV protocol. The system consists of three height
control sensors, pressure sensors for each air bag, high flow air
manifolds with solenoids, a transmission speed sensor, an accelerometer,
and a steering wheel angle sensor, along with associated wiring and
plumbing. Integrated with the Active Air is an Air Leveling System.
Control is also provided to the operator to allow raising the coach
at each end to clear obstacles and to allow lowering the coach to
clear obstacles. While en route the operator can raise or lower sides
or ends of the coach to low, medium, or high to suit his needs; i.e, crowned
roads, side wind, or front wind, etc. Air bag inflation takes time. While
on a cloverleaf HWH instrumentation can show an increase in outboard
air bag pressure of 20 to 30 psi and a reduction of inboard air pressure
of 30 to 40 psi. The high flow valves use orifices of .25 inch and hoses
can range from 1/2 inch to 5/8 inch. The required pressure changes may
require .5s or more to attain. To help eliminate delays, HWH uses the
accelerometer, vehicle speed, and steering wheel angle to "anticipate"
changes in direction and to get a head start on inducing bag pressure
changes. When pressed, I was unable to pin HWH down on actual air
bag response rates, but the engineer did cite and improvement in ride
and handling of from 30 to 50%. The test mule at HWH is an 1988 BB
PT40 and is available for test drives. The system comes with monitoring
and diagnostics tools and air bag pressure displays. There are 2 modes of
operation plus disabled. Below 15 mph the air in an axles air bags are
pressure
equalized and the system is disabled, above 15 mph the system can be in
"economy" mode or "active" mode. In economy mode the bus is leveled and
the system is basically put in standby, this eliminates load on the air
compressor
and is said to improve fuel mileage. In "active" mode, the system is sensing
air bag pressure, accelerometer, steering, and speed inputs, and is
poised to
dynamically pulse air into airbags as needed. The overall goal in
"active" mode
is to keep the coach level. This is done by anticipating roll and acting
quickly
to circumvent it. A perfectly level coach under all circumstances is the
goal
of the "active" mode. I apologize to HWH for any inaccuracies in this
report.
NFI.

David Brady
'02 LXi, Smokey
NC

David Brady wrote:
>
> Folks,
>
> Seems HWH is offering a product called Active Air. It consists of
> electronic height sensors and an electronic control module which together
> automatically (or manually) sense road conditions and steering input
> and sends air to the appropriate air bags. I think Hadley has a similar
> system. The HWH system's price is about $5500 and is reported to
> greatly improve handling and ride. Is this the same system used on the
> 450LXi? Any comments?
>
> Thanks,
> David Brady
> '02 LXi, Smokey
> NC
>
>



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