Why trailers weave, yaw or snake
If you’ve driven behind a caravan on a motorway, you’ll have seen weaving, yawing or snaking at close quarters. Many people think that it’s part of towing, but it’s not.
If you load the trailer correctly, so the front is slightly heavier than the rear, you can virtually eliminate all the usual snags in towing a trailer.
The three laws of towing physics
- When a trailer turns, it will naturally want to rotate about its own centre of gravity (CG).
- You can reduce the yaw during the swing by setting the CG towards the front of the combined vehicle and trailer.
- Altering the position of the CG alters the handling characteristics of your trailer.
The physics of successful towing
Properly finding and positioning the centre of gravity (CG) of the trailer is the secret of successful towing.
- The CG is important in towing because a motor vehicle or trailer naturally wants to turn around its centre of gravity. It acts as a kind of hinge and where this ‘hinge’ is placed has a significant effect on towing.
- When towing a trailer, the CG needs to be just in front of the trailer’s wheels, so that the trailer follows perfectly behind it.
- When the CG is just ahead of the trailer’s wheels (about 10 – 20cm is best), the trailer can be towed securely in a straight line and you will turn corners safely.
- If the CG is too far forward, the trailer won’t want to turn and the driver will feel that the car is oversteering.
How to calculate the centre of gravity
You need to know the trailer’s gross weight (use weighbridge), axle to hitch distance (drawbar length), and nose weight (weighbridge).
Then: CG position = (in cm ahead of trailer axle) noseload in kg x drawbar length in cm by trailer gross weight in kg.
How to load and drive a trailer
Here are a few handy tips for loading and driving with your trailer.
How to load a trailer
- Always check the owner’s manual to discover the towing capacity of your Land Rover vehicle.
- Ensure that the centre of gravity (CG) is towards the front of the trailer, usually around 10 – 20cm ahead of the axle. You can do this by loading slightly more weight in the front half of the trailer than in the rear.
- Adjust the rear tow hitch to ensure trailer is level, or slightly down at the front, but never at the rear.
- Check the maximum gross weight of the trailer – it should be clearly marked.
- Secure loads to the trailer tie-downs.
- Load carefully both side to side and front to back.
How to drive with a trailer
- Anticipate stops and brake early.
- Allow a gap of at least four seconds between your vehicle and the one in front.
- Allow yourself extra turning and manoeuvring room.
- On hot days, beware of engine overheating on long climbs.
- Using a lower gear will keep the engine cooler.
Here are some tips for handling certain situations.
Move trailer CG forward, reduce trailer weight, increase trailer and towing vehicle tyre pressures according to manufacturer’s specification, fit a hitch yaw damper, reduce speed.
- Oversteer cornering
Move trailer CG further towards the rear of the vehicle.
- Tucks in when cornering
Increase towing vehicle rear tyre pressures, reduce trailer weight.
Trailers and braking
Land Rover’s Trailer Stability Assist (TSA)
Our new system helps make towing safer by detecting trailer oscillations and then using selective braking to help correct a potentially hazardous situation.
TSA is a groundbreaking safety feature that should be use in conjunction with proactive driving techniques. Here are some additional tips for braking while you drive:
- Checking brakes
Whatever trailer type you have on tow, it’s important to check overall braking action as soon as possible. Ensure you do so when it is safe and with due consideration to other road users. Even light unbraked trailers may affect the overall braking action. Testing coupled brakes is also necessary as the trailer may not be proportionally braked and this can result in forces acting on the tow vehicle during braking.
- Excessive braking
Avoid harsh braking as this can produce download on the vehicle-towing hitch and in wet or slippery conditions can lead to front-wheel lock-up. Although ABS can help prevent this, moderate braking is always preferable. If your vehicle is not fitted with ABS, we suggest cadence braking (feathering the brake pedal with your foot).
- Safer braking in braked trailers
Braked trailers are inherently more stable than their unbraked counterparts. However, braking can accentuate even a minor instability.
To ensure safe braking in a braked trailer, make sure you:
- Always brake in a straight line for maximum safety and control.
- Leave a reasonable distance between your vehicle and the one in front.
- Consider the load you’re towing and drive accordingly.
Here are some key points to consider in regard to hitches:
- The standard 50mm ball hitch is suitable for on-road towing of a trailer with a gross weight up to 3,500kg.
- Trailers with a gross weight above 3,500kg should have a ring hitch and close-coupled brakes – a special vehicle modification.
- Allow extra room for braking and use cadence braking if you do not have ABS.
Tips for the gentle art of reversing
- Start reversing with vehicle and trailer in the same straight line.
- Slowly reverse the trailer, turning the vehicle in the opposite direction to the one in which you wish the trailer to turn.
- As the rear of your vehicle turns away from the direction you want the trailer to travel, the rear of the trailer will turn in the direction you wanted.
- Do not, however, continue too far or the vehicles will jack-knife.
- Once the trailer is moving in the right direction, reverse the steering on the vehicle and follow the trailer into the turn and finally straighten it up when you reach the correct direction.
- Note that generally, frames that are long compared to the wheelbase of the towing vehicle are easier to reverse than those that are short.
- Comprising of 5 cameras located around the vehicle, the Surround Camera System provides a near 360 degree view of the world outside. The cameras are mounted in the front bumper (x2), the underside of the door mirrors (x2) and tailgate lift handle (x1) and the images from each are viewed through the infotainment screen in the vehicle’s cabin.
- Utilising the camera system, Tow Assist is an innovative new function that predicts the direction of a trailer when reversing. Guidelines can be set to the trailer width and when reversing these are displayed on the screen to show trailer trajectory.
- Additionally the Tow Hitch Assist function helps the driver to precisely couple the tow bar with a tow hitch. A coloured dot graphic is displayed on the screen representing the tow ball together with a guide line showing the predicted reversing path of the vehicle towards the trailer tow hitch.
Tips for the safety lighting on your trailer
- Before setting off, make sure the lighting equipment on your trailer is fitted, working correctly and meets the latest lighting regulations.
- At the very least, you should have two good tail and stop lamps, direction indicators, number plate illumination, and two triangular, red rear reflectors.
- Make sure your trailer has at least one red, rear fog lamp (something you may need to add if your trailer was manufactured after 31 March 1980).
Additional lights may be required on larger trailers, as well as horseboxes and caravans.
Jaguar Land Rover Limited: Registered Office: Abbey Road, Whitley, Coventry CV3 4LF Registered in England No: 1672070