As the gaps between tractors and trailers shrink through aerodynamic design, making connections safer is only one concern for standards-writing engineers who must account for autonomous trucking in the near future.
The Society of Automotive Engineers (SAE) is developing new standards for hookups that tackle two contentious issues: tractor-trailer interconnection that let the two units communicate, and the best way to electronically couple them to reduce driver injury.
“There is little consensus on a common connector system for the future,” said Dave Engelbert, chair of the SAE Truck and Bus Brake and Tractor-Trailer Interconnect group. “It is very political.”
For example, a global solution is needed to harmonize European trailers that connect with North American tractors sold in Australia, said Matthew Fry, an engineering manager Knorr-Bremse Group AG, the German industrial holding company and parent of Bendix Commercial Vehicle Systems.
“The amount of data is exploding and we need a system that can report back and forth,” said Wally Stegall, vice chairman of the future truck group of the Technology and Maintenance Council of the American Trucking Associations (ATA). Tire pressure monitoring systems, door sensors, solar panels, and wireless temperature sensors are just a few of the data sources.
Engelbert, Fry and Stegall spoke at the recent SAE COMVEC Technology Connection meeting in Indianapolis.
“Anytime you try to create standards, it’s hard to get everybody to agree,” said Mike Roeth, executive director of the North American Council for Freight Efficiency (NACFE). “But that’s not a reason not to do it.”
An SAE task force reviewing voltage systems used by North American heavy-duty truck manufacturers recommended in October 2018 that 12-volt direct current should be used with the interface governed by existing SAE standards. The task force said 24- or 48-volt DC connectors should be options based on demand.
With many truck makers pledging to offer high-voltage battery-electric trucks for sale early in the next decade, a new standard probably will be needed.
Kenworth Truck Co., which is working with Toyota Motor Corp. on an experimental fleet of 10 hydrogen-powered fuel cell electric heavy-duty trucks, is using 48-volt power systems to run cooling fans and pumps, said Brian Lindgren, Kenworth director of research and development.
Volvo Trucks North America has twin 12-volt battery systems on its retrofitted battery-electric VNR day cab model that it will sell in selected states beginning in 2021.
“With the continual buying and selling of equipment, fleet mergers and consolidations, and for the long service life expected, compatible electrical connections is a critical factor” in making trailers worth their investment, according to a position paper by the ATA’s maintenance council.
Truckers often are injured in slips, trips and falls when hooking or unhooking cables between tractor and trailer. As farings and other gap-closing technology become common to improve fuel efficiency, access to the space between the tractor and trailer is getting more difficult.
New fifth-wheel designs and trailer electric brakes could eliminate cable hookups because the tractor would allow electronic coupling, according to Chris Lee, vice president of engineering at Great Dane.
Great Dane and Jost International, a maker of fifth wheels and king pins that secure them, conducted a test with an autonomous tractor for Walmart in 2018. Lee said the nation’s largest traditional retailer wants its yards to operate with fully autonomous trucks.
Drop and hook
More immediately, the makers of gap-closing equipment need to consider the rise of drop-and-hook operations as dry van freight moves shorter distances and is pushed into hub-and-spoke distribution, Roeth said.
“The gap closure devices that are emerging mostly deploy at 50 mph and stow below that,” he said. “People creating those systems that close the gap need to design for drop and hook.”