Given the vast number of trailers and towable equipment leaving rental yards every day, it makes sense that the American Rental Association (ARA) and ARA Insurance Services have made safe hitching and towing one of their risk management focuses. Products such as the Winning with Towable Safety DVD and the Trailer Hitch Gauge have been available for years and though they’ve helped, the number of accidents involving towables remains high.

Almost a third of all property damage claims received by ARA Insurance Services involve towables and more than half of those are due to the towable detaching from the towing vehicle.

For example, an all-too-common accident occurs when, at the point equipment is driven onto a trailer, the coupler detaches and strikes the vehicle’s tailgate. Similarly, disconnects account for about a quarter of the claims filed for rental equipment damaged in transit as usually the equipment and trailer end up in a ditch.

“Disconnects continue to be a problem. Most of the losses are property-related but problems come when disconnects happen in traffic and injure or kill people,” says Rick Ream of Northwest Insurance Services, Gig Harbor, Wash., an ARA Insurance Services preferred agent since 1999.

So, why do all these disconnects happen? Most are due to misidentification of the coupler to hitch ball size. Says Ream, “This has been one of the most talked about issues with trailer hook-up, but it continues to be a significant problem at rental stores. People either get too busy or don’t pay enough attention to detail, thus failing to notice the incorrect ball size while hooking up to the towing vehicle.”

Dean Eklund, president of Lew Rents in Olympia, Wash., agrees. “Attaching a trailer to an undersized ball is always something that must be guarded against as it will virtually always end up in a trailer disconnect, either while towing or while loading,” he says.

Another reason for disconnects, says Ream, is that “hitch balls are not all created equal.” The most frequently used sizes in the rental industry are 2- and 25/16-in. hitch balls, but both can vary wildly in their gross trailer weight rating (GTWR). The average rating is 5,000 to 6,000 lbs. for 2-in. balls, but if they’re made with small diameter shanks, it can reduce their towing capacity significantly. The same goes for 25/16-in. balls, says Ream.

“Most construction vehicles are equipped with 25/16-in. hitch balls that have 1¼-in. shanks rated at 10,000 lbs. It’s not unusual to see 25/16-in. balls with 1-in. shanks rated at 5,000 GTWR, and recently I saw a 25/16-in. ball with a ¾-in. shank rated at only 3,500 lbs.,” he says.

The broad range of ratings is a problem because the rating stamps on the balls are often covered by dirt, grease or rust, and the person connecting the coupler to the hitch assumes the ball’s rating based on its size.

Adding to hitch ball inequality is the emergence of inside thread balls in which the shank, rather than being permanently attached to the ball, is bolted up through the drawbar into the ball head.

Ream says that he has heard of specific accidents involving such a ball. In one, he says, “the vehicle owner had installed the ball with a bolt too short for the application. Only two or three threads secured the ball to its shank and it easily broke off while towing rented equipment.”

A similar problem occurs when an inferior grade bolt is used, says Ream. “For example, an inside thread ball with a 5,000-lb. GTWR improperly installed with a Grade 2 bolt would have its actual capacity significantly reduced,” he says, adding that this can result in the bolt shearing off.

Shearing also can occur when the shank of a ball is smaller than the hole in the drawbar, as with a ¾-in. shank in a 1-in. hole, which is exactly what happened to a renter towing a concrete trailer. The shank sheared off in transit, resulting in severe damage to the trailer. Discrepancies such as too-short or low-grade bolts and the wrong size shank for the drawbar are usually missed because they are not visible at a glance.

Yet a third reason for continued towable disconnects is that drawbars have differences, too. Like hitch balls, the stamped GTWR is often obscured. In addition, many drawbars are homemade and have no known rating at all.

“It’s easier than you think to have something go wrong when you hitch up a towable,” says Doug Hansen, owner of A-1 Rentals in Billings, Mont. “Employees get in a hurry and they don’t double check to see if they have taken all the precautions and have hooked it up correctly,” he says, adding this is understandable given all the components to check.

To address the various ways a towable connection can fail, Ream has worked with rental store owners to devise a color-coded solution that can help make it easier for anyone to match couplers and hitch balls, avoid mistakes and better prevent towable accidents. For more details about how this solution works, read this column in the upcoming August 2009 issue.