Time-Delay or Proportional Brake Controller Blog Guide

How to Choose: Time-Delay vs. Proportional Brake Controllers

Shopping for a brake controller? If so, you’ve probably come across the terms "time-delay" and "proportional." No doubt you’re wondering what these two terms actually mean.

In this article, we'll compare the two basic types of brake controllers, specifically time-delay vs. proportional brake controllers. We’ll cover how they work, what the pros and cons are of each, as well as how to decide which one you need.

What is a Brake Controller?

First, let’s define what we mean when we say brake controller. A brake controller (or trailer brake controller) is a device that works with your tow vehicle to activate and monitor your trailer’s electric brakes during a braking event. In other words, when you’re towing a trailer and you press the brake pedal to slow down your vehicle, your brake controller is the thing that tells your trailer brakes to activate as well.

The point is to assist your vehicle in bringing all that weight to a stop. Large, heavy trailers come with electric brakes for a reason, and it’s a brake controller that allows them to function properly in sync with your vehicle.

Trailer Brake Controller Mounted Under Dash CURTTrailer Brake Controller Mounted Under Dash CURT

Two Basic Types of Brake Controllers

There are many trailer brake controller options on the market, each with its own bells and whistles – from smart wireless controllers to integrated OE-style models. But, virtually all of them can be placed into two basic categories: time-delay and proportional.

These categories have to do with how the brake controller operates and their respective approaches to trailer braking activity.

Time-Based & Proportional Brake Controller Examples:

Time-delay and proportional brake controllers don’t need to look different from each other on the outside. The difference has to do with their internal workings.

Time-Delay Brake Controller CURT Discovery NEXT 51126Time-Delay Brake Controller CURT Discovery NEXT 51126
CURT Discovery NEXT Time-Delay Brake Controller #51126
Proportional Brake Controller CURT TriFlex NEXT 51146Proportional Brake Controller CURT TriFlex NEXT 51146
CURT TriFlex NEXT Proportional Brake Controller #51146

What is a Time-Delay Brake Controller?

A time-delay brake controller actuates the trailer brakes based on (you guessed it) timing. From the moment you press the brake pedal, a time-based unit is designed to actuate the electric trailer brakes by an increasing amount over a certain period of time. It ramps up braking power to a maximum amount based on the settings you choose.

On most timed brake controllers, power can be adjusted to accommodate different trailer load sizes, and the ramp-up time can even be adjusted to longer or shorter increments.

Time-Delay Brake Controller Activation DiagramTime-Delay Brake Controller Activation Diagram

What is Gain Control?

Gain in a brake controller establishes the maximum amount of power available to the trailer brakes when braking. If we were to take the example of pressing the brake pedal in your car, the gain control would be how hard you’re pressing down on the pedal.

The gain control can typically be adjusted in a brake controller during the initial setup or any time when the trailer load changes and adjustment is needed for different driving conditions.

What about Load Control?

Load refers to the trailer brake aggressiveness. How aggressively will the brake controller apply the trailer brakes? If we take our car example again, load would be how quickly you press down the brake pedal. Is it immediate, or do you slowly depress it over several seconds?

The load control can typically be adjusted for trailer load changes, changing road conditions and individual driver preferences.

What is a Proportional Brake Controller?

A proportional brake controller or inertia-based brake controller operates using a sensor called an accelerometer. This integrated circuit is designed to detect inertia and translate physical forces into electrical signals.

When you press the brake pedal, a proportional brake controller actuates the trailer brakes based on input from the accelerometer. This means proportional brake controllers are adaptive. In other words, the heavier or faster the trailer is moving, the more braking power is applied. If the trailer is lighter or you're driving up a hill, less braking power is needed. The result is smooth, prompt braking tailored exactly to your current driving situation.

Proporational Brake Controller Activation DiagramProporational Brake Controller Activation Diagram

Proportional Controllers Adapt to Their Surroundings

Proportional Brake Controller Power Adjustment DiagramProportional Brake Controller Power Adjustment Diagram

Proportional Control Explained

Different Activation Methods: Time-Based vs. Inertia-Based

Notice again the difference between time-delay brake controllers and proportional. Both work to bring the vehicle-trailer combination to a stop, but they each take a different path to accomplish that goal through different activation methods.

Proporational Versus Time-Delay Brake Controller DiagramProporational Versus Time-Delay Brake Controller Diagram

Pros & Cons of Time-Delay vs. Proportional

Now that you have a basic understanding of the differences between time-delay and proportional brake control, which one is better? Let’s go through pros and cons of each type.



  • No internal moving parts
  • No leveling required
  • No mount angle requirements
  • Less expensive



  • No automatic adjustment
  • Less sensitive to fragile cargo



  • Smoother, more precise braking, customized to load
  • Adapts to driving conditions automatically
  • Dynamic power adjustments when going up or down a hill
  • Gentler stops for less stress and strain on passengers, cargo and systems



  • More expensive

Advantages of Time-Based Controllers

The advantage of a time-based brake controller is in its simplicity. The simple design has no internal moving parts, meaning there’s no leveling required and no mounting angle requirements. You can install the brake controller virtually anywhere you want on the dash or below it, without having to worry about its physical orientation being exactly right.

A simpler design also means time-delay brake controllers are generally cheaper than their proportional counterparts. If you’re on a strict budget, a time-based unit may be the preferred option.

Time-Based Brake Controller CURT 51116 Venturer Under DashTime-Based Brake Controller CURT 51116 Venturer Under Dash

Advantages of Proportional Brake Controllers

The greatest advantage that a proportional brake controller has over time-based units is the concept of “customized” braking or “adaptive” braking. Instead of a one-size-fits-all-conditions approach, proportional models sense the conditions of each stopping event, applying the exact amount of braking power needed to achieve a smooth stop for your particular load.

If you’re going down a hill and towing a trailer full of heavy cargo, a proportional controller will increase the brake power to accommodate more weight and inertia. If you’re driving up a hill with an empty trailer, less brake power is required, so the controller will reduce power proportionally.

The drawback of this precision approach is that because of its more complicated design, the price for a proportional brake controller tends to be higher. That said, the difference is fairly minimal.

CURT 51146 Triflex Inertia-Based Brake Control Under DashCURT 51146 Triflex Inertia-Based Brake Control Under Dash

Which Brake Controller is Right for Me?

Now that we’ve laid out the differences between time-delay and proportional brake controllers, let’s consider which one makes more sense for your situation and towing setup. Review the following situations to make an informed buying decision:

1. Types of Cargo

The types of trailers and cargo you’re planning to haul can play a significant role in which brake controller you choose. If you’re only hauling relatively light loads or raw materials, a time-delay brake controller might be the way to go. Time-based units don’t stop as smoothly as proportional units, but perfectly smooth braking might not be necessary for the type of cargo you’re pulling.

If you’re towing heavy loads or fragile cargo, such as sensitive equipment or livestock, you’ll want the smooth, adaptive braking of a proportional unit.

Also, if you’re planning to change load sizes often, going from lightweight to heavy-duty, or fragile to durable and back again, a proportional controller is well worth the investment, able to be quickly adjusted to each situation.

2. Frequency of Towing

If you don’t plan on towing very often, it may be wiser to purchase a time-delay controller. The slightly lower cost can be friendlier to strict budgets, and you might not need the more sophisticated, dynamic approach of a proportional model. That said, towing frequency should be a secondary consideration to cargo type. If you’re pulling livestock, even infrequently, do right by your animals and give them a smoother, safer ride.

Obviously if you’re planning to tow quite often, a proportional unit makes more sense. The automatic power adjustment optimizes your braking, putting less strain on your vehicle, trailer and towing equipment over time.

3. Geography

Another consideration is where you’ll be towing. If you live in a relatively flat area, a time-based brake controller may be sufficient. You won’t need the auto-adjustment of brake power for driving up or down a hill because there really aren’t any hills.

However, if you live in a mountainous area or a place with hilly roads where you’ll be stopping on different grades, a proportional brake controller is much better suited for the job. Proportional control responds to the environment and applies more or less braking power, depending on each situation.

Chevrolet Truck Towing Travel Trailer RV Camping WoodsChevrolet Truck Towing Travel Trailer RV Camping Woods

4. Overall Cost

Although the cost difference between time-delay brake controllers and proportional brake controllers is relatively small, it can play a role in your buying decision.

In general, time-based units are less expensive. They have simpler parts and components, allowing manufacturers to keep costs down. Conversely, proportional brake controllers are more complex, requiring more sophisticated circuits and internal components. For that reason, they tend to be higher in price.

If you’re trying to hit a budget, a time-delay brake controller may be the right choice. However, the factors listed above shouldn’t be ignored or sacrificed for the sake of saving a buck. When push comes to shove, you need to select equipment that’s rated and qualified for the job at hand.

Disclaimer: These photographs, recommendations, and approximations are intended for demonstration purposes only and do not reflect the specifications of any particular tow vehicle, recreational vehicle, or trailer. Always consult the manufacturer’s Owner's Manual.