A Simplified Look at Trailer Brakes

Trailer brakes don’t get a lot of attention – until you really need them. Whether you’re hauling tools, timber or a full load of gravel, having the right braking system means your trailer pulls up steadily without putting extra strain on your tow vehicle.

There are a couple of main types you’ll come across: electric trailer brakes and surge brakes. Each has its place depending on what you’re towing, how often you’re on the road, and what sort of maintenance you’re willing to stay on top of. This article runs through the basics, what makes each system different, and which trailers on our site come fitted with which brakes.

What Are Trailer Brakes and When Are They Required?

Depending on the size and weight of your trailer, having working brakes may be a legal requirement. In most states, anything over 750kg needs brakes of some kind, and trailers over 2,000kg ATM usually require electric brakes on all wheels with a breakaway system. Check your local laws and the specs on your trailer.

But aside from ticking the legal boxes, brakes are about safety and control. If you’re towing tools, machinery, landscaping materials or livestock, you want to know you can stop when it counts.

Types of Trailer Brakes

There’s a lot of debate in the trailer braking world about which braking system is better, but the answer really depends on how you tow, what you’re hauling, and how much control you want behind the wheel. Here’s a quick look at the main types of trailer brakes you can find in Australia.

Electric Trailer Brakes

Electric trailer brakes are extremely common on Australian roads, especially for dual axle trailers over 2,000kg, and are essential if you’re regularly towing heavy loads. They’re powered by an electric brake controller mounted inside your tow vehicle, which sends a signal to electromagnets on the trailer’s axles.

With an electric setup, the brakes activate automatically as soon as the controller detects you’re braking, adjusting force based on your settings to help keep things steady and controlled, especially on hills or when towing heavier loads.

Electric brakes do require the right wiring, with a special pin setup like a 7-pin or 12-pin plug. If your trailer’s plug only has four pins, it’s likely running without brakes altogether.

Here at Big Man, we have several models that come fitted with electric brakes, including our 8×5 Tandem Electric Brake Trailer, 10×5 Tandem Trailer with Electric Brakes, 10×6 Cage Trailer, and 12×6 Cage Trailer. These trailers are perfect for safely hauling everything from furniture to building and landscaping materials.

Surge Brakes

Hydraulic surge brakes (also called override brakes) are most commonly found on smaller trailers and boat trailers. Unlike electric systems, surge brakes work using inertia and hydraulic pressure that kicks in when the driver slows down. As the trailer pushes forward, the coupling compresses and a rod pushes against the master cylinder, building pressure and sending it to the brakes.

There’s no wiring or brake controller needed, as all the functions are mechanical. This simplicity makes surge brakes a popular choice for boat trailers and leisure trailers where loads are lighter and braking demands are a bit more relaxed.

While they’re a breeze to use, they do have some drawbacks. You lose the fine control that electric systems offer, and they can feel delayed when braking hard or reversing unless they’re fitted with a lockout or override. Still, for lighter jobs, they operate reliably and are legal across the country.

Mechanical Overrun Brakes

Mechanical overrun brakes are a close cousin to surge brakes but with a few European upgrades. Instead of relying on hydraulics, the brake kits use a cable system that connects the drawbar to the brake drums. As the trailer begins to overrun the vehicle, tension on the cable applies the brakes. These systems are mounted directly to the drawbar and axles, making them sturdy and low-maintenance.

Brands like AL-KO and Knott have refined these systems with shock absorbers and auto-reverse mechanisms that make them smoother to use. You’ll find them more commonly on European trailers or in fleet setups where simplicity and durability are key.

Trust Big Man Trailers for Safer Hauling

It comes down to what you’re towing and how often. If you’re moving heavy loads regularly or want full control over braking, electric trailer brakes are hard to beat. For lighter gear or simple weekend jobs, surge or mechanical overrun brakes might be all you need.

At Big Man Trailers, our range of galvanised trailers is built with your safety and hauling in mind. From tandem trailers to heavy-duty hydraulic tipper trailers, plant trailers, flat top trailers and more, you can trust that your load is secure when you’re towing a Big Man.