Why you need a Trailer Braking System

Asking your vehicle to produce twice as much stopping power as normal puts a lot of demand on the existing braking system and components. Even if the trailer is of a moderate size and weight compared to the tow vehicle, you are still asking more of your vehicle than it would normally deliver. Without assistance, this results in two problems:

  1. Accelerated wear of braking components in the tow vehicle
  2. Safety risk due to momentum of connected trailer

All trailers exceeding 1500 Ibs must be fitted with a towing brake controller system by law.

Two type of trailer brakes have been developed that provide braking power to the trailer to supplement tow vehicle brakes.

Types of Braking System

The two main braking systems available today are surge brake controllers and electric brakes.

Surge brakes work by hydraulic pressure activated by the momentum of the trailer as it pushes against a braking tow vehicle. The compression is taken by a hydraulic cylinder, which in turn transfers the pressure to the trailer’s brakes. The limitation being that the driver has no direct control over these braking systems, for that – you need to look at an electric brake controller.

A trailers electric brakes are activated by electricity supplied by the tow vehicle, to activate electromagnetic brake drums on the trailer. The driver controls the activation through normal braking, giving him total control over the braking, rather than the momentum based activation of surge brakes.

Electric brake controllers require a wiring loom to connect the control unit and towing brake, and there are two types to select from: inertia based and time based. Both systems offer in-cab control of the trailer braking system.

Inertia Brake Controls

These controllers are sometimes referred to as proportional braking systems and use an accelerometer to gauge the change in the inertia of a vehicle due to the driver pressing on the brake pedal. The controller then passes current to the trailer brakes in direct proportion to the change in inertia in order to activate the trailer brakes.

This type of system offers a very smooth braking experience as the control matches the change in inertia with the amount of braking effort applied to the trailer brakes. The accelerometer works in all conditions, i.e. on the level or on an incline (up or down), providing the driver with a consistent driving experience as the tow vehicle and trailer brake in unison.

For the very best braking, seek out an inertia brake controller that features a triple-axis accelerometer as these are capable of extreme braking precision.

Inertia systems provide good service for most needs, however they are especially suited to heavy loads or where there is a requirement for extremely smooth braking (for example transporting of livestock). Additionally, if you are a frequent tow’r, you will appreciate the braking comfort that these units deliver.

Time-Based Brake Controls

A time-based brake controller has no inertia gauge and relies only on the time that pressure is applied to the tow vehicles brakes. These units have a gain setting that can be set by the driver to determine the braking effort applied. In this way, the driver is responsible for setting the level of braking intensity and the rate at which it is applied. This requires a period of setting and testing until the driver feels comfortable with the braking effort being applied depending on the load being towed.

Time based brake controls are usually reserved for lighter loads such as a small boat or light trailer, or occasional use.

How to Select your Trailer Braking System

The benefits of an inertia (or proportional) braking system over a time based system are explained above, however there are other factors that you may wish to consider:

  • Expense: If cost is your deciding factor you may wish to start with a time delay system as these are typically less expensive than inertia controllers. However, considering the added benefits of inertia braking, the small additional outlay is usually more than worth it.
  • Ease of Installation: Due to the technology used, an inertia system does require greater setup time to ensure that the controller is installed correctly. Additionally, an inertia system may require calibrating before testing, not something that a time delay system usually requires.
  • Comfort: As mentioned earlier, an inertia controller wins the comfort factor hands down, with smooth progressive braking that a time-based controller cannot match.
  • Safety: While both systems offer safe braking, the inertia system offers additional stopping power in the case of an emergency stop.

Overall, an inertia system is usually recommended as the best trailer brake system.

Take a look at our extended guide on brake controllers here.

Trailer Brake Controller Installation

Brake controllers are connected to the tow vehicle’s wiring using a wiring harness described in the following section, however the actual controller is mounted in the vehicle cab using a supplied mounting bracket. This will usually require drilling to secure the unit in the vehicle within reach and eyesight of the driver. The manufacturers trailer brake controller installation instructions must be followed carefully and the unit levelled and centered to ensure proper operation.

Trailer Brake Wiring

Wiring trailer brakes to a modern electric trailer brake controller is achieved using one of two methods – a pigtail wiring harness included with the electronic trailer brake controller, or a OEM specific wiring harness that comes with a connector specifically for your vehicle. The harness connects the vehicles OEM socket and brake controller quickly and easily using a quick plug. A quick plug is basically plug and play, there is no wiring required. Allow as little as 10 minutes to install trailer brake wiring to a brake controller with a quick plug.

Final Preparation

With the control unit mounted in the cab, and the wiring connected there will be a brief calibration of the trailer brake system required, followed by a few low speed braking tests to ensure that the system is operational and providing proportional braking effort to the trailer.