NASHVILLE, Tenn. — Truck driver seating comfort is a major concern at any time but never more so than at present, with the driver shortage and recruitment and retention top of mind for any fleet. To showcase the thought behind – and to get to the bottom of – seat comfort, a panel at the spring meeting of the Technology & Maintenance Council (of the American Trucking Associations) was assembled to gain insights from vehicle and seating manufacturers and end-users.
Cab and seating
As program manager for the newly introduced Peterbilt Model 579 and vocational 567, product manager Anthony Gansle is responsible for one of the newest and most driver-friendly trucks currently available. He explained that in deciding on the basic configuration for the new cab and interior, drivers were invited to sit in a four-way expandable cab, nicknamed “Gumby.” Then these 400 drivers were interviewed to test the interior buck for optimal seat positioning to be able to reach and operate controls.
He explained that not only is the seat developed for comfort and control but for safety as well. It has to have sufficient travel and support, it has to be adjustable by the driver without taking eyes off the road and many other considerations.
To ease entry and egress, the Peterbilt seat is designed to quickly drop to its lowest position but is equipped with a memory function. With a single switch it returns to the driver’s pre-selected, preferred position.
Gansle said that comfort development of the seat overlaps with safety, and ergonomic research to keep posture correct while providing a range of adjustments to allow a driver to shift position from time to time.
“Drivers want to feel the limits of the truck going down the road, so we widened cab mounts then widened the seat mounts as well, then used a scissor suspension to keep the driver connected to the truck,” he said.
Part of the comfort process is mapping pressure points for even support across the seat and to pull any load off the tailbone. During the development process, engineers were surprised by drivers’ different preferences for comfort, he said. In the end, there had to be a balance between the soft “showroom” cushion that drivers initially preferred and long-day firmer support.
“One size doesn’t fit all. And bolsters and backrest are important to reduce fatigue,” he added.
In the near term, seating must address driver retention, he said, to keep drivers healthy and accommodate different-sized drivers. Different health-related technologies have to be incorporated: massage, heated and cooled surfaces, adjustable cushions for different preferences and being able to “wiggle around.”
In the longer term, driver interaction with the truck may be cause for a rethink of the traditional driver’s seat. The autonomous truck that effectively drives itself while the driver takes care of other tasks may mean a different, more flexible environment, Gansle concluded.
Representing the seating manufacturers, Gordon Cooley, director of seat engineering at Commercial Vehicle Group summed up seating targets at CVG’s Bostrom and National brands.Obviously, he said, safety, initial and long-term comfort, and durability are the drivers in developing seat designs. Also, mountings, seatbelts and attachments must meet federal requirements.
Pressure maps relate to blood flow through the drivers’ body capillaries. Short- versus long-term comfort has to be considered. So work goes into developing foam shapes, what controls are to be included and where they are placed on the seat. Foam choice is a key element, he said, and it takes a lot of experience. You need comfort and long life. A digital model is constructed to check eye tracking to make sure the driver can adjust the seat without looking away.
Durability is also vital and long periods without seat deterioration means greater vehicle uptime. So does the ability to get in and maintain the seat mechanisms. To test for durability, data is gathered in field studies and used to build accelerated durability rigs. The shake tables can duplicate the conditions the seat would see in a million miles in just 84 hours, said Cooley. Components each have specific tests: seat slides for instance are cycled 25,000 times.
New features being incorporated in the seats include a back massager, adjustable ride characteristic, air adjustable lumbar and bolster, and map pockets. Wider cushions are offered up to 22 inches. In the future, seats will have to accommodate bigger drivers but at the same time a lot of women and smaller statured drivers are coming into the industry, so greater seat operability must be considered along with reduced buzz, squeak and rattle. And at the same time we must maintain durability, Cooley said.
One of the greatest innovations in truck seat design is the Bose Ride System. Based on the same technology used in noise-cancelling headphones, the seat suspension actively detects the vibrations and applies an opposite force to cancel them.
Jim Parison, principal systems engineer at Bose, explained why seat suspensions are so necessary. He said back injuries are a significant problem in the truck driving career and whole-body vibration is a major contributor to back pain and injury.
Long-term exposure to lower vibration results in truck drivers having two to three times the incidence of back pain than other industries. Musculoskeletal disorder (MSD) accounts for 41% of injuries in trucking and because the focus of safety professionals is on crashes, no one knows the real costs of MSD.Whole body vibration at low frequency causes motion sickness. But vibration in the range of two to 20 or 30 cycles per second are the frequencies at which body parts and organs are affected.
In the short term, exposure to this vibration causes nausea and back pains. But over the long term it results in herniated discs and other injuries. To avoid this, he said that seat manufacturers must strive to improve posture and reduce the vibration through the seat bottom and through the backrest.
And exposure is cumulative over time, leading to back damage.
Daily limits to the amplitudes of whole-body vibrations show a driver can survive with no injury only if they spend less than 6.8 hours per day in a conventional spring seat. But with the active cancellation this stretches out to 11.6 hours with a suspension like the Bose Ride, said Parison.
The end user
Titan Transfer is a 450-tractor fleet with seven locations in the eastern and Midwestern US. Wayne Finchum oversees maintenance in all locations and says good seating and the retention of drivers go together.
“Our driver turnover is about half the national average, but we saw it increase over 2011 to 2014,” he said at the panel meeting. So it was time to address it with some new policy decisions.
Finchum says Titan has a completely open door policy to encourage driver recruitment and retention. Driver feedback is welcomed. A guiding principle is that drivers are treated with respect. So they are encouraged to talk about and bring seating concerns to support staff: lower back pain, shoulder blade area pain, blood flow to legs, chronic fatigue, etc.
Cab ergonomics are important for drivers. Finchum says the company makes sure all options and components are tested before they’re included in a spec’. A driver panel is recommended in all cases but especially where seating is concerned.
“Most things are conducted under a panel situation,” he said.
Driver safety, through online safety training, is essential, he says. You have to use all tools at your disposal, he says, and online is essential. Drivers have to be addressed with every type of training and safety. Titan has a policy of addressing workers’ comp. “All employees are encouraged to assume good posture – it’s essential to a healthy back so it’s part of training,” he said.