Hill descents towing a caravan; how to do it safely

There are some mechanical smells that instantly mean trouble, and the smell of brakes overheating is one you don’t forget in a hurry. On our recent drive across the Alpine Way, we went up and down some massive hills, and on one particular climb we had a relatively small caravan and 4WD go past the other way, leaving us breathing in the distinctive stench of brakes cooking themselves.

I tried to call the driver up on the UHF to let them know, but got no response, and after reading countless people say they had brakes smoking on the Alpine Way, I thought it was worth while writing a post about how you descend a hill when towing a caravan or heavy trailer safely. The first tip is this; there is zero reason to have your brakes smelling, or smoking when you come down a hill if you do it correctly.

Trucks and buses must use low gear
Do you know how to tow a caravan or heavy trailer down a hill safely?

Why can hill descents be a problem when towing a caravan?

If you take a typical 4WD that is fully loaded, it might come in at around 3 tonnes. That amount of weight rolling down a big hill takes a fair bit of energy to stop, but if you were to add another 2.5 – 3.5 tonnes of caravan behind the 4WD, it takes around twice the energy to stop.

If you run down a steep hill and try to stop, it takes a lot of effort, and you’re only around 100kg. Imagine trying to pull up something that weighs 50 times your body weight?!

Yes, caravans should have working trailer brakes that engage and take their fair share of the load, but that doesn’t always happen and if you come down a big hill relying only on your brakes things are going to go bad real fast.

In simple terms, the more weight you are moving, and the faster you’re going, the more chance there is that your brakes will have to work beyond what they are able to do.

Alpine way with a caravan
A lot of energy is required to stop a 5 or 6 tonne 4WD and trailer, and relying on your brakes down a hill is a bad idea

What’s the risk?

Car and Caravan brakes are pretty decent these days, and will pull a vehicle up quite quickly when in good condition. However, if you’ve been on the brakes, trying to slow a 6 tonne combination down a steep hill for the last two kilometres, the brakes are going to get hot.

When I say hot, I mean absolutely cooking, to the point that a tiny touch of the rotor or drum brake with your finger is going to make you howl. When brakes get hot, they start to fade, and become less effective.

Many of you may have experienced this in the past, and its quite a scary feeling. One minute your braking as you come down a hill, and the next minute you have to put your foot down harder to achieve the same braking force, and then you have to push harder, and harder to make the vehicle brake, until your braking force is extremely limited.

If this happens, you’re in a world of pain. You can use your hand brake to slow yourself down in some instances, drop gears as fast as you can, but stopping several tonnes from rolling down a hill without working brakes is very, very difficult. You might make a decision to bin your whole setup into a tree, or the edge of the road to stop yourself, before you pick up so much speed that it happens anyway, and that’s an even worse feeling.

Isuzu Dmax brakes being serviced
Caravan brakes are good, but they have their limitations!

Truck arrestor bays

I have no doubt that most of you would have seen truck arrestor bays, on the side of roads with huge hills. We have a couple in Perth, where trucks that completely lose their brakes can roll into, and the soft gravel sucks them in and pulls them up, stopping them from ploughing through an intersection at the bottom of the hill and killing dozens of people (like what happened a few decades ago).

If you lose your brakes, you are in a very, very bad position.

Trucks and Buses use low gears

Next up, is the most common sign you’ll see at the top of a big hill. ‘Truck and Buses must use low gears’. What exactly does this mean? It’s actually really simple. It’s advising any heavy vehicle (and in my opinion that absolutely covers 4WD’s towing caravans) to start at the top of the hill in a low gear, and to go down the hill as slowly as possible.

You have two choices; you can roll down the hill and within a few kilometres you’ll be flying and in top gear, and then you risk not making a turn, getting a speeding fine and not being able to stop due to your brakes not being able to exert enough energy to stop you.

Alternatively, you can start the drive in first or second gear, and use the brakes only to stop the revs from going too high. This reduces their use by a huge amount, and then they are still available when you really need them.

The Alpine Way is stunning
The whole idea of using a low gear is to keep your speed down and maximise engine braking

Are you prepared?

Before you take off down a hill, you need to make sure that your setup is adequate, and everything is working properly. That means that you need to be compliant with the 7 towing weights, that your braking system is working correctly (on the vehicle and trailer), tyres are in good condition and properly inflated, trailer lights are working properly and having a mapping app live that shows you the corners is hugely helpful.

What’s the right way to descend a hill towing a caravan?

The correct, and safest way to come down a steep hill towing a caravan (like what you’d find on the Alpine Way, or the Snowy Mountain Highway) is to use the engine braking to its absolute maximum, and to descend slowly, and carefully.

The higher gear you choose, the faster you go, the more brakes you’ll have to use and it becomes a balancing act. Coming down a big hill in our Isuzu Dmax, I’ll have it in first gear, and when the revs get to around 3500 – 3800 RPM, I’ll brake gently, bringing them back down to around 3000 RPM, and I continue this until we get to the bottom of the hill.

Driving the Alpine Way with a Caravan
Maximise your engine braking, and stay off the brakes unless you really need them

If I can see it levelling out, I’ll occasionally flick it into second gear, and then if it gets steep again, I’ll use the brakes to slow down below 40km/h and flick it back into first gear.

You can try it in second gear, but you’ll find on really steep hills that you end up going too fast, and have to use the brakes excessively to slow down, which makes them get hot, and potentially fade away.

Patience and care

If you’re in a hurry, or think you can go a bit quicker, it can bite you in the backside big time. Put it in first gear, and take it slowly, and carefully all the way down steep hills. Those on the road around you deserve it, and you’re a goose for going too quickly and relying on your brakes to pull you up.

Have you had any bad experiences with towing a caravan down a steep hill? What happened?

Steep sign at Blencoe Falls
The East Coast of Australia has a huge number of steep hills

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2 Comments

  1. Hey Gary,

    Yep, I think a good, and respectful driver is aware of those around them, and tries to let people pass when its safe. That said, those behind also need patience and an understanding of what is going on, and when its intelligent to pass!

    All the best
    Aaron

  2. Gary Couchman says:

    I do exactly what you have described when descending steep hills. The thing I find most frustrating are those uneducated people driving a vehicle behind you not understanding what I am doing and trying to overtake where it is either too dangerous or illegal to do so. If the opportunity arises I will always pull over & let those following past.