The Auto-

Anyone seriously considering autonomous freight transport, should also be thinking about automatic coupling and uncoupling for tractors and trailers. An international team of SAF-HOLLAND engineers from Germany, the US and China has developed an automatic coupling system and already presented their first prototype at the IAA Commercial Vehicles 2018 in Hannover. Now, this system is being further developed for series production.

However, there are still several unanswered questions before the first driverless trucks take to the streets. How would autonomous systems deal with complex inner-city traffic situations, for example, when traffic consists of both networked and conventional road users? There is not yet a clear regulatory framework in place to govern the autonomous transportation of goods on the road. There is one aspect that people usually fail to consider, and that is if there is no driver on board, how should a tractor change a trailer?

“Anyone seriously considering autonomous driving for commercial vehicles should also be thinking about automating the coupling and uncoupling processes.”

Teamwork: Sebastian Köster, Alan Feltham and Randy Kübler (from left to right) automate the coupling process.

Alan Feltham, Director R&D Fifth Wheel, Kingpin & Coupler EMEA

Until now, this has been done manually, with the coupling and uncoupling of tractors and trailers representing an everyday event in logistics operations. “Anyone seriously considering autonomous driving for commercial vehicles should also be thinking about automating the coupling and uncoupling processes,” points out Alan Feltham, who works at SAF-HOLLAND on the development of coupling systems in ­Europe, the Middle East and Africa (the EMEA region). This ­issue is what prompted a global team of SAF-HOLLAND engineers to launch the “Automatic Coupling System” project in April 2017. The first prototype of the system was presented at the 2018 IAA Commercial Vehicles trade show.

Coupling a trailer to the tractor is still a manual process that has a certain number of possible errors built in and takes a skilled driver about five minutes to complete. The driver first sets the tractor back with the fifth wheel open until the coupling under the trailer is slightly ahead of the kingpin. Then the rear axle of the tractor is raised with the help of air springs to allow the coupling plate to rest directly on the ­trailer’s skid plate. The fifth wheel must be in direct contact with the skid plate, otherwise there is a risk of so-called “high coupling,” where the kingpin does not enter and lock into the fifth wheel lock but rather on the coupling plate or the lock. Another possible error can occur during the manual connection of the electrical and pneumatic supply lines. To avoid this, the driver climbs into the space between the cab and trailer and puts the connections together by hand. EBS and pneumatic control lines are particularly crucial for the semitrailer’s braking system. Any faults can lead to a failure in the brake’s function.

Ready for coupling

The fifth wheel needs to be operated and monitored from the driver’s cab to make automatic coupling and uncoupling possible. The developers are also working on several pneumatic and electrical solutions. Inductive proximity sensors then monitor the distance ­between the fifth wheel and the skid plate and check the mechanical ­connection between the kingpin and the fifth wheel.

IAA prototype to be further developed for series production

“When automating the coupling process, we analyzed previous solutions but ultimately decided to take a different approach,” explains Sebastian Köster, head of the Automatic Coupling System Project at SAF-HOLLAND. “Right now, we are looking into a variety of possible solutions using pneumatic and electric drives to automatically open the fifth wheel.” Engineers are relying on inductive proximity sensors to monitor the distance between the fifth wheel and the skid plate, as well as the mechanical connection of the kingpin and fifth wheel. They pay close attention to the connection between the supply lines. A turntable is mounted to the kingpin of the trailer to which a boom is attached with a plug-in element. Now, when the fifth wheel with a connector approaches the kingpin, the turntable automatically aligns with the fifth wheel, and the connectors connect ­positively. This also enables the tractor and trailer to be coupled at an angle to each other. Another important point is the electrical retraction and extension of the landing gear, which supports the trailer when it is parked. Initially, the project team ­accomplished this with an electric drive that can be operated directly from the driver’s cab. “For highly automated coupling, this function can also be performed automatically in the future using the tractor control,” Köster explains.

The development of the prototype shown at the 2018 IAA Commercial Vehicles trade show will continue until it is ready for series production. The focus now is on reliability and durability when coming up against mechanical strain. “The system also needs to operate safely under the prevailing environmental conditions, such as high and low temperatures, moisture and dirt,” adds Köster. SAF-HOLLAND has the best prerequisite to succeed: the expertise of the global project team, which includes not only SAF-HOLLAND’s German locations in Singen and Bessenbach, but also co-workers in the US at the Muskegon and Holland (Michigan) sites. There is also a colleague contributing the know-how of the Chinese site in Xiamen, where parts of the automated landing gear were developed and manufactured. By cooperating ­internationally, the various requirements in the individual world markets can be best taken into account.