We originally wrote this piece in 2017 when Trailer Sway Control was still a relatively new feature on modern cars; 6 years on, Trailer Sway Control is found on most new cars and there are also advanced options on some models.
One such example is the Bosch trailer safety control system; this takes automatic control of the trailer brakes and detects situations where wheels may slip, sway or swerve. It works by combining hardware and its own driver assistance algorithms together to intervene faster than ever before.
Original 2017 piece
Heavy load?
If you often use your vehicle to tow then you’ll do doubt be interested in Trailer Sway Control, a safety feature on modern vehicles to correct sway and correct tow vehicle sag. Used in conjunction with Weight Distribution Kits, your driving will be made safer under heavy load pressure.
What is Trailer Sway?
Trailer sway is when the “tail wags the dog” – the load you are pulling literally starts to sway over the road as you’re driving. This can be caused by a number of reasons – incorrect load putting too much pressure on the tow hitch, high winds or even a poor road surface or road level, but whatever the reason, you’ll want to correct is ASAP, and safely. Trailer sway can lead to nasty – even fatal – accidents and these are extremely common, but yet so easily prevented. They are a leading cause of trailer accidents – and this also includes touring caravans.
Trailer sway is also known by other terms – ‘snaking’, ‘tail swing’, ‘fish tailing’, ‘shimmying’ and ‘trailer wobble’, to name a few.
Preventing Trailer Sway
Trailer safety is key, first and foremost. If your load is not balanced correctly before you start off you’re running a high risk of trailer sway even without any other adverse conditions playing their part (such as high winds). Make sure you’ve balanced the weight to both the forward and the rear of the load keeps an even trailer and goes a long way towards preventing sway.
In addition, make sure your vehicle is safe for towing the load you want to pull. Many drivers exceed the tow rating of their vehicle as they don’t appreciate the weight of the load vs the weight and torque of their towing vehicle. Simple research online will give you an idea of whether your vehicle is suitable – Go Caravanning have a great tool for working out towing weight and specs.
Also, you should know how to help stop trailer sway if it does happen. Try to curb your natural instinct to brake the tow vehicle as this will only aggravate the situation (unless of course you are about to hit something otherwise). Then apply the trailer brakes if you have a separate brake controller fitted – braking should be slow and gentle, not hard and sharp. Steer in a straight a line as possible without hitting anything until the trailer is under control. Once this is the case, stop in a safe place where you can exit the vehicle and check for any damage. You will also need to try and determine why the trailer started to sway – do you need to redistribute your load, are your tire pressures low or too high, is it too windy and should you wait to continue your journey?
Trailer Sway Control Safety Feature
Trailer Sway Control is fast becoming an integral aspect of newer cars and is part of the inbuilt ESP system which stabilises the vehicle. It works to monitor the “yaw rate” of the vehicle and compares this to the steering angle of the driver and the acceleration. If swaying becomes a risk, Trailer Sway Control will kick in to correct the instability and prevent the sway. Different vehicles offer different types of Trailer Sway Control, partly based on whether they are four wheel drive or two, but the overall function and end result is the same.