How Is "Engine Braking" Applied in an Automatic Car?

The concept of "engine braking" is interesting, whether in a car with a manual or automatic gearbox. If you're trying to slow down your car and have plenty of room and time to work with (ie, there's no need to stop immediately), slowing down using this method is a smart way to brake.

However, you can't go too far with this technique, as, as a general rule, "engine braking" helps to use the brakes less, but never replaces them . Doing this isn't necessarily bad for the engine or gearbox, but it can be if you do it incorrectly. You need to weigh the benefits of engine braking against a few other factors, as well as knowing how it works and in what situations.

What is "engine braking"?

When you take your foot off the accelerator , that's when the phenomenon we refer to as " engine braking " occurs. Most people confuse this term with other types of braking, but it has a different mechanism than other braking systems.

Most of the engine kicks in, the case where the gas pedal closes the throttle valve. This valve is the engine's air intake source, and it works with the help of another throttle valve to create a vacuum and reciprocate the pistons in the engine. As a result, the motor slows down and ultimately slows down the wheels as well. Therefore, the "engine brake", when going down a slope, has a fundamental role when you want to reduce speed .

How does "engine braking" work in an automatic car?

In this case, it depends on the automatic car it is. Until not long ago, gear selectors featured various number positions beyond the indentations for “P” , “R” , “N” and “D” . We are talking about options “1” , “2” , “3” and, in some cases, “4” . In those vehicles that are hybrid or electric, together with the four immovable ones, the “B” function has been integrated .

When riding downhill, you can shift the automatic transmission ratios to a lower gear using the gear lever. Generally, when shifting into one of the numbered gears (ie from “D” to “3”, for example), the vehicle will stay in a higher gear without upshifting . This will rev the engine up more and slow the car down as you go down a hill or want to help keep your brakes down.

It's perfectly fine to do this to the engine and transmission, although if you've never done it before, you probably thought it couldn't be good for the car . If you use the brakes hard downhill, as most drivers do, you will most likely overheat them . This will cause them to lose their effective power and can cause the brakes to “chatter” or “squeak” . In extreme conditions, the brake system could even fail.

In the case of a hybrid or electric car, the "B" position on the gear selector is responsible for performing the "engine brake" function, in some cases programmable in different retention modes to act as a recovery of Energy. Remember that the energy wasted in the form of heat when braking is always wasted, but thanks to regenerative braking systems , this source of friction is used to recharge the car's battery.

In contrast, downshifting an automatic transmission while going downhill may not be the best practice to do on a regular basis . Most transmissions are not programmed to do constant manual shifting. Unless they have that way of selecting a gear or paddles (or the like), manually controlling gear selection is a recipe for an overheated transmission. In a nutshell, if you have an automatic car, use “engine braking”, but don't abuse it .

What are the benefits of “engine braking”?

You may be wondering, "Is 'engine braking' bad for my engine?" While the process does generate some heat, this is less of an issue as it has little or no negative effect on the vehicle in practice if used sparingly. If the downshift is done correctly, the transmission should remain healthy. There are several benefits to "engine braking," including:

  • Lower associated maintenance costs:the reduction in the application of our foot on the brake pedal causes less wear on the components of the braking system, which prolongs the useful life of those components.
  • Safer driving downhill:prevents excessive friction that can cause the brakes to fatigue and fail, which may result in the driver being unable to stop the car safely.
  • Improved fuel efficiency:Since the car's ECU cuts off the fuel supply to the injectors of the cylinders used during compression braking, this process actually helps slightly with the fuel efficiency of the engine.