TMC council members seek consensus on next generation tractor-trailer interface

It’s served the trucking industry well, but most industry experts agree the time has come for the venerable SAE J560 seven-pin tractor-trailer connector to be replaced with a new solution that will better accommodate the growing power and data needs of 21st century trucking. The tough question is, what’s next?

While this robust, tried-and-true 12-volt connector is utilized ubiquitously throughout the North American market, the power and data demands of each generation of technology advancement have pushed the limits of what can be done with this connection. Multi-voltage requirements, solar installations, electric drive and regenerative braking axles, advanced driver assistance systems (ADAS) and automated driving systems’ (ADS) —and the host of sensors, emitters, and cameras that support them — mean the need for a new connector standard is increasingly necessary and urgent.

ATA’s Technology & Maintenance Council (TMC) recently released a position paper from its S.7 Trailers, Bodies & Material Handling Study Group regarding the tractor-trailer electrical architecture of the future. The paper, TMC  P 2023-1: Design Recommendations for Next Generation Trailer Electrical Architecture, has several recommendations for smart trailers and hopes that trailer manufacturers will use these as a road map for the development of technology that will access the robustness of suppliers’ offerings. TMC specifically wants to ensure that new interface solution will be backward compatible as well.

S.7’s Next Generation Trailer Electrical Architecture Task Force identified several principles that guided their research. First, that the current electrical architecture is inadequate for the future. Second, that trailer tracking is well established in the industry and is only growing. Third, that electric-powered refrigeration may require off-board charging of trailers. Fourth, that new and safer vehicles pursued by OEMs require additional information and control. Fifth, that many companies have proposed new architecture for trailers. Sixth, TMC established similar issues regarding tractor data networks in the 1980s. Seventh, fleet input is critical for more efficient and reliable electrical and information on trailers. Finally, that collaboration is anticipated with other TMC Study Groups.

Based on these principles, the Task Force is working with TMCs S.1 Electrical Study Group and its Next Generation Tractor-Trailer Interface Task Force to obtain input from tractor manufacturers on future needs for safer vehicles; obtain input from fleet/equipment users on the future of electrical wiring; review proposals from manufacturers; and develop initial expectations for a recommended practice from TMC.

TMC has its own thoughts on how the industry could improve the safety, efficiency, and reliability of freight. Smart trailer expectations include the right for users to repair their own equipment; the preference of patentfree solutions from industry groups; the preference of global non-proprietary solutions; the consideration of forward/backward compatibility; the importance of safety; the need to standardize on a single telematics device when untethered; better support for doubles and triples; the need for upgradable software; the fair sharing of data ownership and electronic documentation; the necessity of highspeed connections for smart trailers; the focus on cybersecurity due to increasing connectivity of devices; the consideration of future power connections; and the consideration of installation, maintenance, and inspection in factories and in the aftermarket.

During TMC’s 2023 Annual Meeting in Orlando earlier this year, the S.1 Task Force presented eight competing designs for what the future tractor-trailer interface could be. The intention of the construction of the recommendations was to describe an “ideal” interface and to not be constrained by existing art.

However, significant consideration was given both to available and yet-to-be available technology, and the interface is expected to be backwards compatible, yet expandable.

The more than 50 technical criteria identified by S.1 falls into the following categories:

1. Compatibility;
2. CAN networks and related ABS/EBS databus recommendations;
3. Ethernet network recommendations;
4. Recommendations for additional pins and pin assignments;
5. Intellectual property discussions and recommendations.

Council fleet members continued to study these design proposals during a series of webinars in April and May and soon will provide feedback through a detailed survey that TMC staff will administer.

Following this, task force members will be asked to evaluate how well each prototype would provide for the trailer support needs of the “guiding principles” as well as the desired technical performance criteria. The Task Force’s findings will then be presented at TMC’s 2023 Fall Meeting in Cleveland, Ohio in September.

Soon after, TMC would then likely begin the process of developing a Recommended Engineering Practice to finalize the criteria for a new standard design.

Electronics are going to become increasingly prevalent on smart trailers and OEMs and others need to take note. The recommendations from TMC’s S.1 and S.7 Task Forces and other organizations will ensure that effective future standards are set as trucks and trailers become more autonomous, self-diagnosing, and integrated with other devices. The sheer volume of multi-megabyte cybersecure dataflows and the bi-directional power flows between tractors, trailers, and dollies will require multi-voltage systems for future 24- and 48-volt, with even high voltages where electric supplemental drive axles and regenerative braking on trailers may come into play. Trailers are ever more a global commodity, and the one potential of the TMC effort may well be to identify a worldwide solution that still is able to meet the unique needs of the North American market.

TMC recognizes that the challenges facing future combination-vehicle connectivity are not easy. With millions of trailers in use with as much as 20 years of expected service life in many duty cycles, protecting the investments in these legacy assets is paramount, and the reality of fleet operations will require a “mixing and matching” of multiple generations of units and technologies on an ongoing basis. While adoption of a new tractor/ trailer connection will be organic and market driven, TMC is engaged in this process to provide transparency and objectivity so that the transition can be rational, driven by practicality, and ultimately best meet the needs of fleets.