What’s in Print

SAE's Trailer Committee finalized and publish J2807

Long road reaches its destination with Performance Requirements for Determining Tow-Vehicle GCWR and Trailer Weight Rating

The Society of Automotive Engineers’ (SAE) Trailer Committee has finalized and published J2807 (Performance Requirements for Determining Tow-Vehicle Gross Combination Weight Rating and Trailer Weight Rating), ending a long—and sometimes controversial—process.

J2807, first published in 2008 and then revised in September 2010, was expected to be adopted by truck manufacturers for the 2013 model year, but it wasn’t until 2014 that all of them agreed to adopt it for the 2015 model year.

The purpose of J2807 is to rate tow vehicles for maximum trailer weight to be towed, with a secondary purpose of evaluating trailer dynamic performance. It incorporates J684, J2638, J2664, and many other documents.

It was a controversial issue because manufacturers were just raising their ratings, and it became a marketing game.

“In 2003, General Motors approached SAE and said GM would like to look into trying to establish a standard that would level the playing field for developing tow ratings for tow vehicles,” said James Fait, director of engineering services for U-Haul International Inc. “Engineers in that industry realized there wasn’t an industry-standardized method of setting those tow ratings and it wasn’t a level playing field. That was the impetus to go forward, so we could have uniform tow ratings and the market would compare apples to apples.

Jim Fait, U-Haul International Inc

“The first official document arrived in 2008. In 2012, we had minor changes, and also in 2013. There were still some comments to revise. Finally, it got published in the past few weeks, with only some minor changes.”

Describing the performance requirements of J2807, Fait said:

“All of testing and performance requirements are set at GCWR for the tow vehicle and trailer. Fundamentally, you’ve got a towing weight rating for the tow vehicle. What’s the maximum trailer weight that would be allowed? So all tests are set with the maximum trailer weight with an empty tow vehicle as the fundamental purpose.

“When we were developing this between 2003 and 2008, in 2005, we took six tow vehicles and the same amount of trailers and went to the Chrysler Proving Grounds in Arizona and hooked the trailers up and did a series of dynamic handling and stability and braking tests. Weight stability and understeer were a big part of that because we did what I’ll call blind tests. We didn’t test at first to see performances. A well-rounded group went out and test-drove these trailers and basically used their own evaluation, their own interpretation, of how they performed. In sway stability, we would move the speed up gradually and sway stability would decrease slightly. We did that with each trailer. We said, ‘What’s acceptable from our own experience, our own judgement, our own comfort level?’ After we did that, we went back and tested vehicles and saw that the sway ratio came out at .07 to .08.

“There’s nowhere else in the world where you have a consensus group that used it as a process to help set that standard. That whole philosophy was used in all areas of the standard. It gives us as manufacturers and people responsible for product a clear level to look at what’s acceptable in the industry.” ♦

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TAGS: Chassis
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