Comfort is a Measurable Standard
January 11th, 2014
North American bus and coach seating manufacturers speak to comfort, safety, health and durability
By David Hubbard
Talk to any of the major manufacturers of bus and coach seating and the foundation for their unique, proprietary products rings the same. Each will speak to the challenges of designing, constructing and testing seating systems that meet or surpass all established safety standards; provide comfort for drivers and passengers; incorporate sound ergonomics; protect against health threats; and last as long or even outlive the vehicle lifecycle — all at cost effective price points for operators.
BUSRide recently spoke with executives and engineers from these major U.S. bus and coach seating manufacturing companies.
USSC Group, Exton, PA — USSC Group incorporates in-depth engineering that includes 3-D modeling to develop premium, durable and ergonomically-sound driver seats for many types of vehicles. The company builds passenger seating under its 4One brand with manufacturing partner, Freedman Seating.
Freedman Seating, Chicago, IL — In addition to its joint venture with USSC Group, Freedman Seating manufactures seats and seating-related products for small-to-midsize buses and heavy-duty transit and paratransit vehicles.
Commercial Vehicle Group, New Albany, OH — Three separate manufacturers comprise Commercial Vehicle Group (CVG), a seating provider for heavy-duty class-8 vehicles in a wide range of applications.
• National builds passenger and driver seats for small buses
• Bostrom produces seating for the small and midsize bus market, as well as school buses
• KAB builds primarily for construction vehicles
HSM, Hickory, NC — Formerly known as Hickory Springs Manufacturing, HSM has expanded by bringing in other companies to fully integrate its manufacturing of seating products for school buses, and push further into the small bus and transit markets.
RECARO Automotive Seating, Auburn Hills, MI — A division of the global Johnson Controls group, RECARO manufactures premium driver and passenger seating for every type of commercial bus.
Focus on critical areas
The companies commented on the regulations and procedures they adhere to, and the standards they establish themselves that allow their products to perform satisfactorily in these critical areas. Here are the key takeaways from our conversations.
Much of the focus on bus safety currently points to seatbelts. Though not mandated as yet, three-point seat belts are closer to a standard than an option in today’s motorcoach market.
HSM has incorporated a dual retractor system with a restraint length up to 100 inches, to restrain the smallest to largest driver without having to rely on an independent belt extender.
The HSM Driver seat, featuring Maximum Driver Protection (MDP), evolves from research on driver incidents, such as the driver doing something to slip or fall out of the seat and cause the vehicle to swerve. In this case, the armrest lowers and slides back into a full lock position to keep the driver from leaving the seat.
Seat vibration is a source of driver fatigue and can become a safety issue.
Jonathan Sieber, director of sales, RECARO Automotive Seating, says seats must not cause bodily harm or damage the health of the lower back, the shoulders and entire spine.
“They must be comfortable and offer improved concentration on the road,” Sieber says. “High-spine alignment is something we consider with all of our designs.”
This key fatigue factor typically requires a suspension seat mounted to an oscillating suspension that can absorb road vibrations through its own built-in air spring and shock absorber.
“This is less of an issue in motorcoaches, as those vehicles ride on much softer suspension systems typically over smooth highways,” says Dan Cohen, vice president of sales and marketing for Freedman Seating. “Motorcoach drivers will often opt for a static seat with a height adjustment over a suspension driver seat that costs 30 to 40 percent more.”
Cohen says the landscape changed when Ford and Chevrolet adopted 202A, a FMVSS standard 202A for passenger seating which establishes criteria for the height of the seatback. The standard provides for greater head and neck support.
“The 202A standard is law for any vehicle under 10,000 pounds GVW,” Cohen says. “From our work with Ford and Chevrolet, we have adopted 202A as the standard for the small and medium duty bus markets — even though it is not required.”
COMFORT and ERGONOMICS
The significant challenge in the design of driver seats is to arrive at a safe and comfortable solution that can accommodate a wide variety of body types.
“Comfort is a measurable standard, as opposed to a subjective judgment of what may constitute comfortable seating,” says Ray Melleady, managing director, USSC North America. “We create comfort through static pressure mapping for a variety of body types in a pure seating position.”
According to RECARO, while its driver seats accommodate the fifth percentile female to the 95th percentile male, product testing focuses more on those drivers who push the upper end of the limit.
“The hips, shoulders and spine all align to the best of a person’s physical build,” RECARO’s Sieber says. “As much as you can try to put someone into an ideal position, there are a lot of outside factors. The best we can do is set up the core structure of the seat to put a person in proper alignment to allow a feature matrix that can adjust for an individual’s size and build.”
CVG has developed the Back Cycler lumbar support that provides continuous air-driven spinal motion rather than a vibrating motion.
“This device keeps the fluids in the spine moving and the muscles supple,” says Ray Miller, CVG vice president, Sales. “The continuous passive motion has been shown to prevent and alleviate back pain, and also increase driver alertness.”
These companies say they see bus operators doing all they can to extend the life of their present fleets. This becomes their challenge, to build durability into a seating product that holds up for the life-cycle of
“The average life of a cutaway bus was once seven years,” says Tony Everett, HSM vice president, Transportation Solutions. “Today, vehicle life expectancies are increasing upward to 10 and 12 years.”
This challenge is no different the transit industry.
“Our mission is to make an aesthetically pleasing, vandal-proof and comfortable transit seat that will last 12 to 18 years,” says USSC Group’s Melleady. “In many respects, this is like trying to achieve conflicting objectives.”
According to USSC, its driver seats carry a 650-pound weight rating, the heaviest in the commercial vehicle market. USSC says that because seat adjustments must be easy, its driver seats feature pneumatic push-button adjustments to move the seat vertically, fore and aft, recline, and make adjustments in the lumbar support.
“We use much heavier-gauge steel and 100-percent steel structural components,” Melleady says. “Our driver seats are durable enough to meet the typical 12-year life cycle.”
CVG tests for life-cycle durability on a fixed-axis shake axis, using a program to simulate one million miles on a test track. CVG says this test takes about two weeks to complete.
HEALTH and SANITATION
The seat must be capable of easy cleaning by maintenance crews, and the design has to give the impression of cleanliness to the passenger.
Freedman reports a trend in the bus industry toward a greater use of antimicrobial fabrics, a shift back to once-shunned vinyl materials.
“The ‘icky factor’ is lower for vinyl,” Cohen says. “A passenger can walk onto a bus, take out a wet wipe and wipe down the seat and know it is clean for use.”
He says recent improvements have led to vinyl and plastic materials embedded with inherent properties that are antibacterial and antimicrobial. Cohen says the killing effect lasts up to 15 years.
In an outsourced process, Freedman treats the grab handles for its transit seats with specified antibacterial chemicals that be integrated during the product’s foam injection procedure. The grab handles bear the sanitized logo, authorizing Freedman to use the product and inform passengers that the handles are safe to touch. “The chemical company we use for this requires us to submit a sample of our grab handles annually for testing,” Cohen says. “It wants to be certain we are using their product as specified.”
Most component manufacturers conduct their own product testing in conjunction with NHSTA test labs. They will typically test to a maximum weight, follow government standards established for safety purposes, and set their own quality criteria and standards with aim of exceeding federal mandates.
“The old way was to take our products to NHTSA and ask how they measure up,” HSM’s Everett says. “We now tell NHTSA beforehand that we are exploring a particular concept or product for a school bus, and ask what they would like to see.”
CVG says it does not do crash testing internally, but will conduct its own FMVSS 210 pull tests and 222 impact tests to simulate crash forces and dynamics. The company says it works with bus OEMS to crash-test its seats with the actual vehicle.
USSC Group says it puts a seat through a series of 40 separate tests for safety, fit and comfort before it qualifies for production. This testing takes several months.
“There are established thresholds that manufacturers must maintain,” Melleady says. “For example, one test we conduct specifies the maximum stress on a body over an eight-hour drive before crossing over the threshold that causes muscle fatigue. For this, we conduct extensive testing using extreme load data to not only ensure we meet those thresholds, but are well within the limits on the positive side.”
Original URL: http://busride.com/2013/11/comfort-is-a-measurable-standard/