engine retarders

[colcestrian]

Hi, can somebody please explain about engine retarders. I start my practical C training after Christmas and would like to know if you are taught about this braking system on your training or not. I have seen youtube videos about this subject but when I watch the new pass videos nobody seems to mention this on their tests. As it is a type of braking procedure I am guessing this must be on your test somewhere.....cheers.

[Monkey241]

I wasnt shown it on mine

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[MegaHips]

You can ask but they'll probably tell you not to worry about it during test/training.

It's something you'll pick up when you start working, but for now i wouldn't bother with it.

[Juddian]

The most common retarders were simple exhaust brakes, literally a solenoid controlled flap in the exhaust pipe just after the manifold, often controlled by a foot operated valve but these foot operated sort are vanishing fast, almost always go hand in hand with manual gearboxes, also vanishing fast.

Newer vehicles tend to have a manual switch for the retarder on the end of the RH steering column switch, this can either be a push button on/off, or a trigger type switch with up to 3 settings for the retarder, with an automatic pressing that manual switch (or switching the three position lever to max) automatically engages the exhauster and also automatically changes gears down to keep the revs in a suitable band for efficient engine braking, circa 2000/2200 rpm is quite common...note the efficient band on the rev counter changes during retarding, both its preferred rev band and sometime colour too.
You can of course select Manual on the auto box and control the gears and revs yourself to maximise exhaust braking, but all of this is best left until you pass your test.

To brake like this is getting quite advanced and is how old school drivers operate, indeed many experienced drivers don't or won't brake like this because they aren't interested in lorry driving so never bothered to learn how to drive a lorry properly, and some trainers insist on gears to go brakes to slow, which is how cars not lorries are driven, you do whatever you want once you've passed.

The other and better sort of common engine brake is found on some Volvos and Daf's as standard, and that is an engine brake, in Dafs i believe its a licence built version of the Jacob Brake, which alters the exhaust valve operation and timing when the retarder is operating effectively turning the engine into a compressor, these are really good systems providing powerful retarding, other sorts operate some sort of retarder fitted to the gearbox, hydraulic and/or electric, some are special order only and unlikely to be found on standard fleets.

In almost all cases there will be switch on the dash which allows the retarder to help the normal foot operated service brakes when they are applied, this is a good way to be going on when you pass the test and go out on your own until you get the feel for your vehicle, i expect this is how some training schools set their vehicles up so the retarder is working all the time whenever you brake, course its been a lifetime since i took my test and for all i know they've disconnected the thing, hopefully the ever helpful Peter Smythe will be along shortly to give it chapter and verse.

Using the retarder properly is sensible driving practice, its saves brake wear and if you use it well you can drive for many miles on all sorts of roads without ever touching the brakes once, this saves a fortune in fuel because you are driving by planning far ahead slowing gradually for junctions, which if you plan and execute well you don't have to actually stop at many junctions at all.

During slippery conditions you need to exercise a bit of care**, remember the retarder is only operating on the driven wheels, so as the gears drop especially if you are empty it is possible to end up locking the drive axle momentarily as the retarder on a high setting provides too much effort, hence why many now have a three position switch, but generally if you leave the retarder alone for the time being till you've sussed your vehicle out and allow it to help the brakes in auto setting during normal braking then the chances of a lock up are minimal, best compromise in other words.

All makes have slightly different operating systems and switches for these things.

As said, don't worry about it too much till after you've passed your test.

Good question though, sorry the answer is a clear as mud.

** slippery conditions, hah.
only about 10 years ago i got caught out by a full engine brake retarder, i got going down the road in an empty FM12 tractor unit and trailer one morning, unbeknown to me the last driver had left the retarder on auto and max, as i approached the seriously icy first roundabout on the industrial estate the lorry suddenly downchanged about 3 gears and the retarder clocked straight in, resulting in one locked drive axle just entering an icy roundabout , luckily i managed to bring the thing back under control and no damage done but it sure put the wind up me.
So something to keep in mind, doesn't matter how many years you've been doing the job, a strange motor and the right or wrong circs and things can easily go pear shaped.

[Peter Smythe]

Juddian has got it spot on. I cant speak for other trainers but we have our vehicles set up to make use of retarders where this is helpful. Some vehicles simply make a lot of noise and achieve little whilst others will virtually eliminate the use of the footbrake if driven correctly.

The use, or otherwise, has no bearing on the driving test.

As Juddian said, a lot of this is best left until the new driver is in a position to experiment with different loads and vehicles following the test pass.

Personally, I dont spend more than a few seconds on the topic as there are so many variations a little knowledge could be less than useful.

Pete

[Hyh]

I can't add anything to the post above, however you may find this video helpful. Around 1 minute in, they cover the exhaust brake on a Daf LF - Which I've found is one of the most common smaller class 2 vehicles (Up to and including 18T) on the roads
https://www.youtube.com/watch?v=iroumPleTNA

You don't need to know how to use the exhaust brake on test from memory. When you do driving assessments with companies after passing, they will look for you to use the exhaust brake in my albeit experience with driving assessments

[grumpyken52]

The system on the smaller DAFs, when set , engages as soon as you are fully off the throttle . It's only gentle but will stop over runs when going downhill .
I used to enjoy driving the length of the country without using the brake pedal.
I'm out of touch with all the new auto box models as I never drove them. I did drive those god awful Isuzu heaps twice and refused point blank to ever drive them ever again .

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[Franglais]

The most common retarders were simple exhaust brakes, literally a solenoid controlled flap in the exhaust pipe just after the manifold, often controlled by a foot operated valve but these foot operated sort are vanishing fast, almost always go hand in hand with manual gearboxes, also vanishing fast.

Newer vehicles tend to have a manual switch for the retarder on the end of the RH steering column switch, this can either be a push button on/off, or a trigger type switch with up to 3 settings for the retarder, with an automatic pressing that manual switch (or switching the three position lever to max) automatically engages the exhauster and also automatically changes gears down to keep the revs in a suitable band for efficient engine braking, circa 2000/2200 rpm is quite common...note the efficient band on the rev counter changes during retarding, both its preferred rev band and sometime colour too.
You can of course select Manual on the auto box and control the gears and revs yourself to maximise exhaust braking, but all of this is best left until you pass your test.

To brake like this is getting quite advanced and is how old school drivers operate, indeed many experienced drivers don't or won't brake like this because they aren't interested in lorry driving so never bothered to learn how to drive a lorry properly, and some trainers insist on gears to go brakes to slow, which is how cars not lorries are driven, you do whatever you want once you've passed.

The other and better sort of common engine brake is found on some Volvos and Daf's as standard, and that is an engine brake, in Dafs i believe its a licence built version of the Jacob Brake, which alters the exhaust valve operation and timing when the retarder is operating effectively turning the engine into a compressor, these are really good systems providing powerful retarding, other sorts operate some sort of retarder fitted to the gearbox, hydraulic and/or electric, some are special order only and unlikely to be found on standard fleets.

In almost all cases there will be switch on the dash which allows the retarder to help the normal foot operated service brakes when they are applied, this is a good way to be going on when you pass the test and go out on your own until you get the feel for your vehicle, i expect this is how some training schools set their vehicles up so the retarder is working all the time whenever you brake, course its been a lifetime since i took my test and for all i know they've disconnected the thing, hopefully the ever helpful Peter Smythe will be along shortly to give it chapter and verse.

Using the retarder properly is sensible driving practice, its saves brake wear and if you use it well you can drive for many miles on all sorts of roads without ever touching the brakes once, this saves a fortune in fuel because you are driving by planning far ahead slowing gradually for junctions, which if you plan and execute well you don't have to actually stop at many junctions at all.

During slippery conditions you need to exercise a bit of care**, remember the retarder is only operating on the driven wheels, so as the gears drop especially if you are empty it is possible to end up locking the drive axle momentarily as the retarder on a high setting provides too much effort, hence why many now have a three position switch, but generally if you leave the retarder alone for the time being till you've sussed your vehicle out and allow it to help the brakes in auto setting during normal braking then the chances of a lock up are minimal, best compromise in other words.

All makes have slightly different operating systems and switches for these things.

As said, don't worry about it too much till after you've passed your test.

Good question though, sorry the answer is a clear as mud.

** slippery conditions, hah.
only about 10 years ago i got caught out by a full engine brake retarder, i got going down the road in an empty FM12 tractor unit and trailer one morning, unbeknown to me the last driver had left the retarder on auto and max, as i approached the seriously icy first roundabout on the industrial estate the lorry suddenly downchanged about 3 gears and the retarder clocked straight in, resulting in one locked drive axle just entering an icy roundabout , luckily i managed to bring the thing back under control and no damage done but it sure put the wind up me.
So something to keep in mind, doesn't matter how many years you've been doing the job, a strange motor and the right or wrong circs and things can easily go pear shaped.

It's rare for us to disagree (on driving and trucks anyhow!) but here I will pick you up on a couple of things.
Retarders are rare (in the UK) but do exist and are different than the two systems you've described: exhaust brakes and engine brakes.
I think you've fallen into the common mistake of calling an engine brake a retarder.
All you've posted about the method of using, and basic design of exhausters and engine brakes is sound, but you don't mention true retarders at all.
As I said they are rare in the UK but they are about.
A retarder is normally a fluid brake mounted on the rear of the gearbox. DAF call It an "intarder" I think. It operates independently of the engine, so doesn't matter what gear you're in or even if the clutch is in/out. It operates through the prop shaft to slow only the drive wheels, so is similar to the other methods in that respect. It is most effective when the prop is turning fastest: at high road speed. So I'm conjuction with a conventional exhaust brake, best in a low gear, at slower speed, it's great.
Always amusing to see the engine coolant temp rise as you spin down hill too!
Driving with a proper retarder, and exhauster, coupled to a manual box, is a joy.

[Gidders]

As Franglais said.I used to work for a Swiss outfit whose MANs had an intarder tagged onto their ZF gearboxes.Excellent in use.

[trevHCS]

On original point - don't worry too much about such stuff as exhaust brakes and the likes until you're comfortable driving.

For the first couple of months you'll be so focused on not hitting anything to have time to worry about saving the brakes. Don't think I ever used one in the rigids, DAF wouldn't go fast enough.

If you move to artics, then you need them! Especially going over the M62 fully loaded and trying to stay under 70mph.

On second point - someone should tell DAF as the "better driving" bollox thing on this one keeps saying "use exhaust brake / retarder" so even it doesn't know. (Its the one thats not a XF but too cold to get put and look at the door).

[colcestrian]

Thanks for replies everybody....much appreciated..