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What is Engine Braking?

Bradley Jando | Friday 25th June 2021 10:26am

Cross Section of an Engine and it's Component

Youíll have noticed when driving that if you take your foot off the accelerator pedal, your car starts slowing down, even without braking. If you shift down the gears, you will slow down even more - but youíll have probably also noticed the loud noise from the engine that happens if you do this too soon (i.e. if the revs are still too high for that gear).

Engine braking will only work when your car is in gear, and not when the clutch is engaged.

How it Works

When you disengage the accelerator pedal, you close the air intake valve and create a vacuum which restricts air flow to the cylinders. This vacuum, by restricting airflow, provides a lot of resistance to the pistons, which in turn slows down the engine.

How to Engine Brake

Engine braking is a fairly simple process, and youíve probably done it before, if unintentionally.

Imagine there is a traffic light up ahead of you and you are travelling at 40mph. If you want to slow down gradually, stop accelerating and switch down in the gears one at a time.

Be sure to match your revs as you downshift, slowly and smoothly removing your foot from the clutch each time - this will save you the uncomfortable jolt that happens when jumping down the gears too quickly.

Engine braking wonít bring you to a full stop, so youíll want to then use the clutch and brake to stop fully. This way, you will have limited wear on your brakes but will come safely to a stop!

Benefits of Engine Braking

Wear and Tear

Caliper brakes and drum brakes work by using friction, so as you might imagine, less strain on your braking components translates to less wear.

But this does not mean that you should always rely on engine braking, and you should instead use a mix of this and traditional braking.

Downhill Driving

Engine braking can be helpful for driving downhill. When driving downhill, staying in a lower gear allows you to maintain a safe speed, whereas going up in the gears will mean you speed up rather quickly - without even engaging the accelerator - which could potentially be dangerous.

Driving In Icy Conditions

You might also want to consider using engine braking in icy conditions. Slamming on the brakes on ice physically slows your wheels themselves, which creates a risk of skidding, while engine braking allows for a more controlled slow-down via the engine.

Brake Failure

Engine braking can also be used in the (worst case) scenario that your manual brakes fail. In this case, you would have to do your best not to panic and utilise these steps for engine braking. Remember: donít keep your foot on the clutch.

When NOT to Engine Brake

In some cases, engine braking might unnecessarily take your focus away from the steering wheel and road ahead as you use your hand to change gears.

Keep in mind that you donít have brake lights when engine braking. You largely wonít need to worry about this, as youíll be slowing down gradually anyway. But this is partially why you shouldnít use 1st gear to engine brake from high speeds - itíll slow you down harshly with no warning to other drivers. This will also put strain on your gears and synchromesh.

Overall, engine braking can be a safe way to come to a stop and can save you some wear and tear to your braking components, but should not be thought of as a replacement for using the brake pedal.

To find out more about how a car engine works, check out our article that explores just that! And if youíre concerned about your clutch or brakes, do call in to one of your local centres.




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