Braker controllers for trailers come in two basic designs: time-delayed and proportional. They operate differently and have cost/operational trade-offs.

Time-delayed Controller
Time-delayed brake controllers are cheaper and an older design. The driver sets a delay that determines how long it takes the trailer brakes to engage after he hits the brake pedal on the tow vehicle. The driver also sets the amount of trailer braking force and tries to match it to the weight of the trailer and payload he's hauling.

One problem is that a setting that works well when stopping gradually is too weak when you need hard braking. The result is that most of the stopping load must therefore be taken on by the tow vehicle and wears it's brakes much harder. Conversely, another problem occurs if you adjust the setting to use stronger braking because it will cause the wheels to lock up when attempting to brake gently. This results in the trailer slowing the tow vehicle with locked wheels as it gets dragged along and wears its tires away much more quickly. You can now see the limitations of this design.

Proportional Controller
Proportional brake controllers use a motion sensor to determine how quickly the tow vehicle and trailer are decelerating and adjusts the trailer braking force accordingly. So, if you're the driver and initially start slowing gradually, the trailer brakes will be applied gradually. If a dog runs across your path and you apply much more stopping power, the sensor will sense the greater deceleration forces and apply the trailer brakes harder. Proportional brake controllers used to require manual calibration, and some still do. But most of the newer models are self-calibrating, and therefore, very easy to install and put into operation. Proportional brake controllers are a more effective and recent design.

As for the differences:

• Time-delay controllers are cheaper, but the difference is getting smaller.
• Time delay controller force and delay settings are an estimate made by the driver and are almost always not optimal, especially as loads vary.
• Proportional brake controllers will vary the amount of braking as needed whereas a time-delay system always applies the same amount, even if it's too much or too little.
• Proportional controlled braking is safer because it adjusts to the immediate needs of stopping the load, including stronger braking if needed for an emergency stop.
• Time-delayed braking results in more wear and tear on either the tow vehicle, the trailer, or both because one of them will be doing most of the breaking regardless of the amount each should do. With proportionally controlled brakes, the tow vehicle will apply what it needs and the proportional controller will sense that and apply what is needed to stop the trailer.

Besides being an avid trail rider, Jerry Tardif is a technology consultant and a horse and nature photographer in SE Connecticut — see his work at: www.jerrytardif.com. He is also co-founder and President of QueryHorse.