Link Digital Suspension Uses Sensors, ECU to Keep Cabs Stable

October 1, 2019

Terry Costlow

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

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.

Link will offer aftermarket versions starting next year. (Link)

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.

ROI test systems are the same as equipment used by OEMs. (Terry Costlow)

“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 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. “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-year-old 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 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.”