when to use retarder and when to use engine brake?

[MaximB]

when to use retarder and when to use engine brake?
In real life and in game.

In the game all trucks can have both (if you choose),
In real life I've also seen trucks with both options.
When to use each in real life and in game?
What is the non-mechanical difference between them?

[zeeuwse_adonis]

https://www.youtube.com/watch?v=bXai8z99lUg

[zeeuwse_adonis]

https://www.youtube.com/watch?v=HkfjCJClWVA Jake brake

[Kenton]

Originally posted by Sandhill:

Originally posted by briannospam:

All engines have engine brake, it works when you don't feed the engine with energy.

Except diesels generally don't work that way...without an add on system (Jacobs brake) which turns the engine into a high resistance air pump diesels generally don't have much resistance when you lift the throttle, unlike a gasoline engine which has a lot of resistance.
I don't know about engine brake usage on European trucks, I do know that American trucks virtually never have retarders, those equipped with Allison automatic transmissions being the exception.

Diesel engines have waaaay more resistance than petrol (gasoline) engines - period. Mainly because of the way they combust.

[Hiro Protagonist]

Originally posted by killa_hertz911:

Originally posted by Sandhill:

Except diesels generally don't work that way...without an add on system (Jacobs brake) which turns the engine into a high resistance air pump diesels generally don't have much resistance when you lift the throttle, unlike a gasoline engine which has a lot of resistance.
I don't know about engine brake usage on European trucks, I do know that American trucks virtually never have retarders, those equipped with Allison automatic transmissions being the exception.

Diesel engines have waaaay more resistance than petrol (gasoline) engines - period. Mainly because of the way they combust.

Diesels may run much higher compression ratios, but they do not have a throttle butterfly like a petrol engine. The pumping of the engine creating a vacuum between the throttle butterfly and the intake valves is the real "resistance" found in engine-braking in a petrol engine, this does not happen in a diesel so other methods (exhaust brake, retarder etc) are needed to supplement.

[Sandhill]

^^^^^ this
because there is no resistance in the intake path (throttle butterfly in gasoline engines) the diesel gets its full charge of air on the intake stroke. This full charge is compressed on the compression stroke, and returns almost all of the energy of the compressed but not combusted air on the power stroke, so there is relatively little energy lost in the full cycle.

[Neil]

Originally posted by Adam Beckett:

... I am learning so much, reading this thread. Keep going, please.

Also worth being aware if you play ATS (yes, this is the ETS2 thread but many, me included play both games) that use of Jake Brake is prohibited in some urban areas - you will see signs to this effect at the roadside. Don't think you get fined in the game if you ignore it though?

[DynkH]

Originally posted by Hiro Protagonist:

Diesels may run much higher compression ratios, but they do not have a throttle butterfly like a petrol engine.

I'm pretty sure all diesel engines with EGR has a throttle system.

[Hiro Protagonist]

Originally posted by DynkH:

Originally posted by Hiro Protagonist:

Diesels may run much higher compression ratios, but they do not have a throttle butterfly like a petrol engine.

I'm pretty sure all diesel engines with EGR has a throttle system.

There may be some kind of butterfly in the system somewhere, but the Diesel Cycle does not use a throttle to meter airflow - they run full-flow and purely meter the fuel.

[MaximB]

I'm happy to see many replies here, but none of them answered the original question.

If I have a truck with both engine brake and retarder (in game and in real life),
How do I know when to use each? when to use retarder and when engine brake?

[Týr]

They have the same purpose, to assist you in slowing down the truck downhill and reduce wear on service breaks. What sets them apart is the technical solution to accomplish this.
IRL trucks usually only have one aux brake, volvo has the VEB (Volvo Engine Break) which is an exhaust brake. Scania has a retarder I believe.
What others have I don´t know.
So basically you use what´s your truck are outfitted with.

[Karlia]

VEB is NOT an exhaust brake, it is a CREB compression release engine brake operating on the same principle as the Jacobs, and exhaust brake on the EPG chamber. Volvo also have an option for a Fluid Retarder.
Scania run with a retarder and CREB.

To the OP original post.. Engine brakes are more common with those you need to keep your engine RPM up in the premium braking range which is around the 1500 to 2000rpm for them to be effective, engine braking usually produces around 50 to 60% of the engine output as Braking KW so as your rpm diminishes you need to change down to keep the braking effective.

The retarder is a more powerful aux braking system it will almost pop you through the windshield on a good day. The benefit of the retarder is it is not dependant on the transmission or the engine, you can slip your transmission in to neutral and the retarder will keep braking (Volvo now use this technique on their I-See range)

As with any supplemental braking system they are to be use in unison with the service brakes on heavy application (down hill), the reason the service or trailer brakes are still used is to stop the trailer pushing the rear of the prime over..

As per what is the prefered way to use the CREB or Retarder is purely up to the driver.. Me personally in real world and in ETS I use the retarder more over the EB..

Hope this helps
Happy trucking

[zeeuwse_adonis]

Originally posted by MaximB:

I'm happy to see many replies here, but none of them answered the original question.

If I have a truck with both engine brake and retarder (in game and in real life),
How do I know when to use each? when to use retarder and when engine brake?

Irl. If you are working on a long trip through the mountains driving (highway) delicious on cruise control at a constant speed and are working on a long major descent, (downhill), and your speed is increasing.
Then you use your retarder in steps to keep your speed constant, position 1 slow brake, position 2 more and heavy brake, positon 3 everything needed from the system, to come back to the right speed, here the brakes of the wheels do not have to brake too much and too long, no more brakes on warm drums / discs. some cruise control do this automatic.

When you have a descent style with hairpins with lots of brakes and and you need a lot of braking power then you use the engine brake, you can then see the oil pressure and temperature of the engine and keep it under control, too high than use the retarder and brakes of the wheels.
Dosing with al of the brakes, but then your speed was already too high for the descent.

The temperature of retarder and brakes can not be seen on the dashboard, only smell when it is too late.

[Kimmaz]

If you lift your gas pedal, you "use" engine break. I dont drive a semi truck irl so i dont know if you would use the retarder and maintain your throttle/pedal position while going downhill.

I my car, I just down shift to a lower gear and dont use my gas pedal to maintain speed downhill. I never use my break pedal unless i have to slow down.

[Neil]

Ah that smell of hot brake linings - fond memories of doing track days in my TVR-owning days!!

[Hiro Protagonist]

Originally posted by Kimmaz:

If you lift your gas pedal, you "use" engine break. I dont drive a semi truck irl so i dont know if you would use the retarder and maintain your throttle/pedal position while going downhill.

I my car, I just down shift to a lower gear and dont use my gas pedal to maintain speed downhill. I never use my break pedal unless i have to slow down.

As has been discussed in detail, truck/diesel engines don't work the same way and thus don't have the same off-throttle engine braking ability as petrol car engines do.

As for the retarder/engine/exhaust brake thing, as has been mentioned the engine/exhaust brakes work best at high rpm (often there will be a marking on the tacho showing the ideal range) whilst retarders work best at higher road speeds - the more you slow down the less effective they become.