Changes coming in SAE standards

May 1, 2009
J2807 to define trailer weight rating of all tow vehicles, removing the ‘marketing game’ and leveling the playing field

The Society of Automotive Engineers (SAE) International is recommending that SAE standard J2807 — which defines performance requirements for measuring a vehicle's gross combination weight rating (GCWR) and trailer weight rating (TWR) — be adopted for all vehicles with a model year of 2011 or later.

The towing capacity of a truck can be a major selling point for consumers, so to maintain fair competition among manufacturers, SAE has set this standard to determine the trailer weight rating of all tow vehicles. The guidelines of J2807 require vehicles to be tested under consistent conditions and parameters, giving consumers accurate information when comparing the towing capacities of similar models.

The standard, which can be applied to passenger cars, multi-purpose passenger vehicles, and trucks with a GCWR of up to 16,000 lb, was developed by SAE International's Tow Vehicle Trailer Rating Committee, which includes representatives from leading original equipment manufacturers and suppliers.

“The whole purpose of this from the OEM vehicle-manufacturing side was to level the playing field,” said Jim Fait, U-Haul director of engineering services and chairman of the SAE Trailer Committee, in the SAE Standards Update Workshop at the NATM Convention.

“They were just raising the ratings, and there was no rhyme or reason to that. It just became a marketing game. General Motors promoted and spearheaded this (standard). There are parts of this where there are minimum performance requirements, and even though it doesn't apply directly to trailers, it will be used as a benchmark in litigation.”

Said Clint Lancaster, the NATM's technical director, “This will bring all vehicle manufacturers in line so that they have the same testing for their tow-vehicle rating. The issue is going to be that it will probably reduce the tow capacity of the vehicle. That's why there has been some hesitation … (on the) side of manufacturers. It will pull down their towing capacity. What does that mean to us as trailer manufacturers? We have to be keenly aware of what trucks can pull. There will be some effects.”

Other revisions

Fait said SAE also is looking at revising test procedures for J684 (Trailer Coupling, Hitches, and Safety Chains — Automotive Type), which includes couplings, hitches, and safety chains used in conjunction with all types of trailers or towed vehicles whose Gross Vehicle Weight Rating (GVWR) does not exceed 10,000 lb. This includes such types as utility, boat, camping, travel, and special-purpose trailers that are normally towed by conventional passenger cars, light-duty commercial vehicles, light trucks, and multipurpose passenger vehicles.

This document is intended primarily for ball-and-socket type of couplings and hitches. It should not be construed as a limitation to this type alone but should apply where appropriate to ring-and-pintle, clevis-and-pin, or any other draft means designed to serve this purpose.

“I believe part of vision is that conventional towing systems up to 20,000 lb probably just cover the hitch, coupler, and ball, and not the safety chain,” Lancaster said. “A whole new standard might be developed just for the safety chain. We'll have to see what happens on that.”

Fait said J2664 (Trailer Sway Response Test Procedure), which was published in 2006, is currently an information report but might eventually become a recommended practice.

It establishes a consistent procedure for measuring and analyzing the natural sway response of a particular trailer when attached to a particular vehicle under specific loading and operating conditions.

This test procedure applies, but is not limited to, passenger cars, vans, light trucks, and medium-duty trucks as tow vehicles, and semitrailers with a GVWR of 26,000 lb or less.

Other applications include full trailers, tow dollies, tow bars, and the like. Other articulated vehicles can utilize this test procedure as long as the test does not exceed the linear response range of the tires.

Fait said SAE is trying to upgrade J2638 (Fifth Wheel and Gooseneck Attachment Performance Up to 30,000 lb Trailer GVW) into a recommended practice.

First published in October 2003, it establishes minimum performance criteria and definition of terms for the towing interface between a towing vehicle and fifth wheel or gooseneck trailer at or below 30,000 lb gross trailer weight. This establishes criteria for the hitch, tow-vehicle attachment structure, trailer-attachment structure, and coupling.

The document is intended as a guide for manufacturers of fifth wheel and/or gooseneck trailers at or below 30,000 lb gross trailer weight and of tow vehicles and of components necessary to tow these trailers. Regulatory authorities desiring to formulate regulations may use this standard as a guide. This document is also intended for voluntary use by others associated with manufacturing of these products.

“In the past few years, as I've been doing compliance visits, I've talked about this standard and found a lot of people really weren't aware of it,” Lancaster said. “There are some issues from consumers that had goosenecks breaking away from the chassis of the trailer. This is to address those issues. It's not just a gooseneck coupler standard. It's actually the whole structure of the gooseneck itself, back to the frame.”

Coming soon

They said future initiatives include possibly coming up with an:

  • Axle Performance Standard

    “A lot of you guys are using an axle of 3500 or 5000 lb, and there's not a standard test,” Lancaster said.

  • Brake Performance Standard

    “There's a Canadian standard for the undercarriage that really doesn't address the axle; it addresses brakes,” Lancaster said. “A lot of manufacturers tested that standard as far as brake performance. We may look at some issues of brake performance.”

Fait said J134, published in September 1993, is a recommended practice that establishes a uniform procedure for the level road test of the brake systems of all combinations of new multipurpose passenger vehicles, new light-duty trucks up to and including 10,000 lb, and new passenger cars when coupled with new trailers (braked or unbraked).

And there's also J135, which presents service brake performance requirements for brake systems of all combinations of new passenger cars and new trailers (braked or unbraked) intended for roadway use (excluding special-purpose vehicles such as ambulances, hearses, etc).

He said they are combination vehicle braking tests, and “the focus is as much or more on the towing vehicle. I view it more as a durability standard. Performance requirements are not actually required; they are the maximum levels you test. There's a lot of interpretation in the industry and litigation as to what the standard means. We need a more specific standard.”

Lancaster said many jack manufacturers are adopting the American Society of Agricultural and Biological Engineers' (ASABE) S485, which defines terms, establishes test procedures, and creates minimum performance requirements for telescopic mechanical screw-type jacks mounted on agricultural implements. These jacks are used specifically for: supporting the hitch points of towed agricultural implements during storage, lifting and lowering of implement tongues to facilitate attaching to or disconnecting from an agricultural tractor, and leveling of machinery for stationary use.

“If you're a trailer manufacturer and put a certification label on, that trailer all becomes yours,” Lancaster said. “You need to ensure that the items on there are meeting the guidelines or specifications they should. A lot of jack manufacturers are testing the standard, but some aren't. They're not required to, as they are with couplers.”