Driving downhill; trailer brake failure

A little while ago I read a post about someone who’d picked up a brand new, top of the line off road caravan and towed it through some hilly areas, using the trailer brakes extensively and only to find that he was up for new bearings and various other components as they’d overheated and cooked everything.

He was asking whether it was reasonable to expect this sort of behaviour, and it got me thinking, because there is a right way to descend hills with a caravan, and a wrong way.

One bay to pull over on Glenelg River Road
If you’re using your trailer brakes extensively it can end very badly

Electric brakes are pretty standard on Caravans and Camper Trailers these days, and you need an electric brake controller in the vehicle to make them function.

The Redarc Towpro uses a gyro, so the more you brake in the vehicle, the stronger it applies the brakes to the trailer being towed. However, they all have an adjustment level too, and the more you wind them up, the more sensitive they are.

Dmax tow controller
The Redarc Tow Pro Elite uses a gyro to detect how hard it needs to apply the trailer brakes

I’ll never forget pulling into a fuel station with our old camper trailer and slowing down gently, only to hear the camper trailer wheels lock up and skid. I was absolutely horrified, but that’s exactly what happens when the trailer brakes are up too high for the surface they are on.

A well set up 4WD towing a big trailer should be able to stop pretty quickly on bitumen even towing a big van, if the brakes are well adjusted and being used. They can pull your vehicle up really well, but they are most certainly not intended for long, extensive braking.

Trailer brakes
Trailer brakes are there to aid, not to do extensive braking down huge, endless hills

Feel the slop

In our setup, I can feel when the trailer is braking, and how much work its doing. There’s a bit of slop in the tow hitch, and when I brake, a split second later you can feel the slop knock and the trailer start to do its job.

Likewise, when I take my foot off the brakes, you have a delay before you hear the slop loosen again.

Trailer brakes should not be used excessively downhill

In the same way that trucks make sure they do a very slow speed down hill to avoid using their brakes extensively, you should be doing the same thing.

By all means, use them when you need to, but you should be reducing your speed and using engine braking to the absolute maximum, and taking breaks as needed. Extensive use of the brakes will result in them overheating, and the end result is pretty simple; you no longer have brakes!

We smelt some seriously bad brake smells from those towing on the Alpine Way, and its all due to inexperience and over use of brakes.

Dmax in the Hills
Victoria is the perfect place to test your trailer brakes out!

Using engine braking

If you aren’t familiar with using engine braking, it’s the practice of using a smaller gear to slow your speed down. If you are coming down a hill in 5th and the revs allow, drop it to 4th and you’ll feel the vehicle slow down.

You can use this in combination with the brakes to give them a bit of a break. If you have an auto you can still do this by flicking it to manual mode, and dropping down a gear (pull back in some vehicles, and push up in others – check the sticker!).

There are times where you will have to slow down, and let the gearing do its thing. There’s a reason big trucks go so slowly down a hill; if you let them speed up they run away to the point where your brakes would have an almost impossible job to slow you down again.

Look after your brakes

Above all, just have some respect for your brakes. When you’ve been doing hilly conditions, stop and let them cool, and touch the hubs to see how warm they’ve been getting. If you have to use your brakes, they will get hot, and you need to let them have a break!

Big Hills in Victoria
Trailer brakes can work pretty hard

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