A couple weeks ago Gigglepin 4x4, a UK company that specializes in high-quality 4x4 recovery gear, especially for competition, posted a video on Facebook that showed someone attaching one of their rapid-deployment Hook Link recovery hooks to . . . a hitch ball.
The reaction was swift. Several people, including me, posted replies saying any suggestion to use a tow ball for recovery was inconceivably irresponsible. One of the first inviolable lessons any 4x4 training school with which I’m familiar teaches is to never, ever use a tow ball as a recovery point.
The next day the company responded . . . by reporting my post (and, I presume, others as well) as spam and having it removed.
Then something interesting happened. The original video, as far as I can tell, was taken down. Instead, the company posted another video on their website explaining “what we actually meant” in the first one. In it, the spokesman first demonstrates attaching a Hook Link and strap to a proper recovery point on a Discovery, and notes that it is, “Much safer than placing the strap or rope over the tow ball.” He then says that using the Hook Link and strap on a tow ball is “ideal for recoveries on the road and light duties around the workshop,” and adds that it’s “not ideal” for extreme recovery situations. Confused yet? He then says, even more confusingly, that the MSA (Motorsports South Africa) rule book allows some UK-style tow balls—which, unlike typical U.S. versions, are usually flanged and fastened with two M16 bolts—to be used for recovery in racing.
Contradictions aside, let’s look at this. First, as far as I recall (since I can no longer find it), the original video contained no such explanations or caveats; it simply showed the Hook-Link being snapped over a hitch ball, quite clearly as a suggested application. The opportunities for this to be interpreted as a universally acceptable practice by inexperienced 4x4 drivers/Facebook users are rife.
Second, a friend who called my attention to the first video followed up and contacted a well-known supplier of this type of tow ball in England, to ask for their stance on the use of such balls for recovery.
The response:
“Towbars are designed to pull the safe rated load that they were tested and type-approved at in a smooth and controlled manner. They are not designed to be subjected to any sharp impact or snatch, using them for this purpose is most likely to overload and cause damage, possibly invisible to the naked eye, that may not become immediately apparent but weeks or months later may cause failure and pose a danger to other road users. Using a towbar in this manner would be classed as outside of their intended use and would invalidate any warranties.”
There’s another potential factor at work in such a scenario. I couldn’t find any specs of the Hook-Link that listed the width of the neck of the hook. It appears to be around two inches or more. If the neck is larger than the tow ball over which one hooks it, a sudden jolt and slack could pop the hook off the top of the ball. In the U.S. standard tow balls start at 1 7/8 inches in diameter.
I noticed one more confusing aspect to the Hook Link. The spokesman noted there are two versions of the product, identical in size but employing different aluminum alloys in construction. The model made from 6082 is rated at 4.5 tons, the one in 7075 to 6.5 tons. I assumed he was referring to a metric ton (2,204 pounds) and, indeed, the Hook-Link shown on the website is stamped “Break strain 4500kg”—which is 9,920 pounds, and 4.5 times 2,204 equals 9,918 pounds. But . . . “break strain?” That doesn’t sound like our familiar working load limit (WLL) with a 2X or 3X (or greater) safety factor; that sounds like the point at which things might come apart precipitously. Perhaps it’s a matter of cross-Atlantic nomenclature, but here we like to see both a WLL and a separate minimum breaking strength (MBS).
I’m going to restate the rule: Don’t use a tow ball—any tow ball—as a recovery point. Period.
What about alternative methods for employing a receiver hitch as a recovery point? Many articles and trainers suggest inserting the loop of a recovery strap into the receiver tube and fastening it with the hitch pin. This has the advantage of securely anchoring the end of the strap or rope.
However, look at the diagram below, from Dougal Hiscock, a mechanical engineer at at Engen Consulting in New Zealand, which shows the relative stresses exerted on a tow ball and a hitch pin subjected to a 5,096 kilogram (11,235 pound) steady pull. The stress is three times higher on the pin due to its smaller diameter. The pin is also subjected to a three-point bending load, from the strap in the middle of the pin and the through-points on the side of the receiver. When towing a trailer using a hitch insert the pin is subject only to sheer loads, as the square receiver insert rides closely against the wall of the tube. A wide strap or rope, such as the one illustrated, might reduce the focus of this bending stress, but it will still be much higher than that exerted by a receiver tube under the same load.
The only acceptable way to employ a receiver for recovery is to use a receiver shackle insert and shackle to attach the kinetic strap or rope. Even then, I much prefer a dedicated shackle mount on a bumper designed for recovery duty, or a chassis-mounted recovery ring.
