Momentum - October 2019 - 18

TODAY'S

ENGINEERING

DIGITAL SUSPENSION KEEPS CABS
STABLE
LINK MANUFACTURING is beefing up
its usage of digital technologies with
an upgraded Cabmate, unveiling a cab
suspension system that smooths the ride
for both drivers and those in sleepers.
Link's Road Optimized Innovations (ROI)
system uses sensors and an electronic
control unit (ECU) to stabilize the entire
cab for roughly the cost of two advanced
comfort seats.
The suspension system levels the entire
cab, providing more stabilization than
advanced seating solutions. That can help
those in sleepers while also smoothing
out some of the jerkiness that plagues
most stop-start systems. Link plans to
keep ROI's cost premium relatively low
compared to conventional Cabmate
systems, which recently surpassed 2
million shipments.
"Cab equipment and a person in the
sleeper aren't protected by an improved
seat," said Michael Hof, Link's VP of new
business development. "We hope to have
this stay below $2,000. Standard upgrade
seats are around $1,000, so this is a wash."
Drivers present at an unveiling in
Sioux Center, Iowa, said their tests
showed significant benefits. Cabmate's
enhancements are most noticeable on
bumpy roads and events like railroad
tracks, while its key benefit on highways
may be to stabilize cabs on windy days.
"For in-city deliveries where the roads
are not always the best, this will have a
big impact in comfort," said Joel Morrow,
a fleet driver who's head of R&D at Ploger
Transportation. "Long-haul drivers won't
see as much benefit until you start talking
about wind shear. If the cab stays more
stable, it will be very helpful. The benefits
for someone in the sleeper are really nice;
drivers often wake up in an adrenaline
state when there's a sharp jolt to the cab."
The system's ECU runs proprietary
algorithms that interpret sensor
information in real time. It responds to
road events by continuously adjusting the
stiffness of shock absorbers and filling or
exhausting air from the air springs. The

18 October 2019

Photo credit: Terry Costlow

ROI system consumes less than
10 watts of power.
"We have one accelerometer
and one position sensor. They
monitor what the cab is doing
and what the suspension is
doing," said Tye Davis,
senior engineer at Link and
an SAE Member. "From
those two inputs, the
system can determine the
optimal response for the
shock. The ECU controls
the shock's solenoid
valve, which provides air
for the spring. We make
adjustments about 200
times per second."
That technology marks a major
turning point for Link, a 40-yearold company which to date has used
electronics for basic controls. President
Jim Huls said sensor and microcontroller
pricing and capabilities make it practical
to implement active controls. It's likely
that future systems will make additional
use of active control systems.
Link is testing ROI in a new lab that can
be customized for a range of systems.
Engineering VP Bill Ott noted that "we
have the same test systems used by
major OEMs, we just have fewer of them."
It will take OEMs a while to analyze
Cabmate and design it in, so Link plans

Link's Tye David
with test setup.

Link's Road
Optimized
Innovations (ROI)
suspensions are
mounted at the front
and rear of the cab.

Image credit: Link

to roll out an aftermarket system to help
spark interest in the technology. One
fleet owner noted that improved comfort
in cabs could help his company retain
drivers and attract new hires.
"For us, the biggest value is the safety
issue," said Fausto Velazquez, President
of TC Logistics of Mexico City. "This adds
value to our fleet, drivers reported less
pain in their back, and it reduces noise in
the cockpit, so drivers are less stressed
and can focus more on the road."

By Terry Costlow, freelance contributor

MOMENTUM
Momentum - October 2019

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