The Lug_Nut View. Trailer hitches, we all have them, most of us use them. Today’s trailer hitches, or Hidden Hitch like assemblies, are found on pretty well all SUV’s, pickups, vans, cross-over’s, trucks and motor coaches. They are out of sight, reliable and are not the shin bangers of yesterday’s design. At least as long as you remove the ball shank when not in use.
Fortunately these covert mounted assemblies require little or no maintenance, as they are out of sight, and out of mind. While they do not require maintenance, adjustments or tweaking, they do require to be used within their specifications and have periodic inspections. Abuse and environmental conditions can render them unsafe and in some cases, outright dangerous. Age, rust and decaying welds and metal over time can reduce their original bond and strength. Abuse, whether by accident or neglect, may eventually lead to a total failure and possible separation from the vehicle. This in turn can result in not only losing the towed vehicle or trailer, but even the safety chains which are also fastened to the severed assembly. This, unfortunately, does occur.
Most hitch assembly failures are caused by physical damage. Damage caused by impact, such as backing into a solid obstruction or over stressing by exceeding the design limitations.
Today, we will look at one of the most common ways that people overload their hitch capacity, exceeding the tongue weight. Hitches are rated in pound capacity. That is, the total loaded weight of the vehicle or trailer. This can be anywhere from 2,000 to 20,000 lbs. It is important to realize that all component capacity ratings, like the ball and shank, are equal or higher, otherwise the rating will be that of the lowest. The next consideration is the bumper point tongue weight (Not applicable to flat four down vehicle towing). That is, the actual weight at the tongue, ball, or contact point. As a general rule this will be 10 to 15% of the total weight of the trailer. Too light at this point can cause vehicle handling issues such as trailer sway or light end at the rear of the tow vehicle. Too heavy can cause hitch assembly over stress and light front steering axle on the tow vehicle. The tongue weight is set by the weight and load distribution within, or on. the trailer. The more the load is moved forward, the heavier the tongue weight will be.
So, exactly how do people determine the correct loading distribution? Well, this is where the problem begins. Many people load their trailer with what they believe is about right, noting the amount the tow vehicle sinks when the tongue is lowered onto the hitch. This, of course, is not a safe method. Take a stacker trailer, a unit that can carry two cars, one above the other. Their gross vehicle weight may be 15,000 lbs. This would require positioning of the two vehicles and other cargo to apply about 1,500 lbs. on the hitch ball. This can not be done by just observing the hitch sink. A large diesel class A may sink only slightly with twice that weight or more. Definitely not a safe practice.
The only correct way to verify the tongue weight is to weigh it. Once the correct weight is accomplished, stops and markings can be made inside the trailer for future similar loading. If one of the carried vehicles are replaced with a new one, a re-weighing is needed to assure the correct weight balance. Don’t forget also to check the total trailer weight to avoid an over gross weight issue.
The picture to the left shows an actual hitch failure on a motor home. Fortunately, the driver of this rig had pulled over for a break and then spotted it. The hitch assembly would have probably separated from the coach within a short time. As the safety chains are connected to the assembly’s frame, the trailer would have took off on its own. Certainly a very dangerous situation was averted. (Note: This failure was reported to be caused by incomplete hitch assembly installation.) Again, an inspection would have found this issue.
Regular inspections should be done, and can be carried out by the owner. This may be particularly important if you believe your hitch could have been overloaded at an earlier date. Verifying that all bolts are tight and in good condition is relatively easy. Checking that no cracks are present in the hitch assembly, frame fastenings and related welds may require cleaning first. This will allow you to see the physical condition of the metal surface better. If you have never inspected a hitch assembly before, have a mechanic or like expert check it out. By observing what he does and looks for, may allow you to be able to do it yourself in the future.
In addition to the aforementioned, you should always visually check your hitch and trailer any time you stop. Make sure everything looks good, safety chains in place, wiring harness secure, trailer tires fully inflated, etc.
So, if you are towing a heavy trailer, or have plans to, don’t forget to use your hitch within its designed specifications and to inspect it regularly. If you do, your hitch will give you years of safe service.
Pulling For You – Lug_Nut – Peter Mercer