At some point in your life, you’ll likely have to tow a trailer. Be it moving house, going on holiday, or for your line of work, chances are it will happen. But how many of us really know how to tow a trailer correctly? There are actually many nuances to learning how to tow a trailer correctly and safely, ranging from the tow vehicle itself to the trailer, the trailer linkage, and crucially how you load the trailer before setting off. On a small trailer, incorrect loading might not have too much of an effect on the overall safety, but as the size, weight, and load capacity of the trailer increases, how you pile up your cargo is increasingly more important. The video below, provided by U-Haul, shows the dangers of incorrect weight distribution on a trailer:
Though the video might make use of a model Mustang (no crowds were harmed in the making of that video) on a treadmill, it accurately displays what happens when towing should you need to swerve for any reason. In South Africa, that could be to avoid a pothole or minibus taxi, and where road surfaces are at best uneven, you want to be as safe as possible.
When the weight is distributed evenly or slightly toward the front of the trailer (it’s important not to load everything too far forward), the bulk of it rests upon the axle of the trailer itself, with support from the tow hitch. Not only does this transfer the bulk of the carrying forces to the vehicle itself, but the extra weight over the rear axle actually improves grip. On a front-wheel drive vehicle, a heavy load might not aid towing ability, but it will increase overall stability and prevent the rear from stepping out. In a rear-wheel drive application, the extra weight on the rear axle will not only improve grip and stability, but it’ll improve towing ability and capacity as well.
However, if for some reason you load your cargo with the bulk of the weight to the rear of the trailer, the dangers increase hugely, for a number of reasons. First of all, on a single axle trailer, the lever effect lifts the weight off the rear axle, reducing towing capacity and grip. Crucially though, the weight hanging so far back is potentially fatal in the event of a sudden emergency manoeuvre – as depicted in the video above. The rearward weight distribution results in a pendulum effect that amplifies minor steering inputs. Because of the reduced weight on the rear axle and the lower levels of grip, this destabilises the vehicle and trailer immensely. As the trailer swings back and as the driver tries to correct with steering inputs, the fishtailing effect gets worse and can lead to running off the road, jack-knifing, or in the worst case scenario, rolling the vehicle and trailer.
It might seem trivial at a standstill, but once the ball gets rolling, loading your trailer with the correct weight balance could be the difference between arriving at your destination safely or having to make a very expensive insurance claim.