exhaust brake

[ironeddie]

Gembo:

IronEddie:
This is all very interesting to me. I’m learning the theory currently and the DVSA theory book talks about use of the retarder only in relation to going downhill as a means to avoid brake fade.

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Which is bollox.
What does it cost to use it all the time?
Nothing.
As most here, I use it as my primary means of slowing all the time and the brakes come last.
It saves on brake wear and heat and when you really do need the brakes in anger, like descending a steep hill, they will be cooler instead of already hot and so increasing the risk of brake fade and a potential acident!
It really is a no brainer.
Its abit like car drivers who drive around in ■■■■■■■ rain with side lights on, why?
It costs no more to use dipped headlights so why not use the bloody things!

Yes. Well. Not surprised the official theory differs to the ‘real’ world. Guess I shall learn it the DVSA way to pass the theory test. Ask my instructor and learn it their way to pass my practical and then decide what’s best for myself when in a job.

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[blue_estate]

I use the retarder in my Actros all the time

[punchy_dan]

cav551:
This is difficult to explain and easily misunderstood.

Over-reliance upon the exhaust brake or retarder will have the same effect as driving the vehicle around unladen the whole time. The friction material needs to reach the lower end of its operating temperature to be in its most effective working zone. Warm brakes will be better than cold ones. So almost coming to a halt on the auxiliary brake as a matter of habit will result in brakes which do not perform as well as intended. This will be more noticeable when the brakes are cold. In short, if the friction material does not get heat cycled then its stone cold performance suffers as will its ultimate ability as well. Habitual very light braking is not a good thing.

For level roads the 20 MPH advice seems just about right.

Yes I’ve noticed this . I took the exhaust brake off and binned it , they’re like a chocolate fire guard, I leave the jake on auto full ,the brake drums are still painted gloss black .

[slowlane]

I’m learning to use the useless single stage exhaust “brake” in an XF at the moment, and it does kind-of work if you give it a bit of time to build up the back pressure and are hot on downshifting as soon as it will let you, and snub the brakes once or twice too.

As for the operating temperature of brakes, the whole “brakes need to be at a couple of hundred degrees for optimal performance” thing has always mystified me. Somewhere in that temp range is where the pads will provide the greatest friction against the rotor… well whoop-de-do, it’s not the peak friction that stops you in an emergency, the peak friction that may only be there for a fraction of a second as the temperature hits the sweet spot and then rises through it… it’s the heat potential of the rotor and pads - how much can you raise their temperature by, from their current, before the temp of the pads and the rotor reaches the maximum temperature that the amount of friction they can provide can generate. When you can’t create more heat, you can’t have any stopping power. The amount of pressure the brake system can apply more than compensates for the slight difference between peak friction and the lowest amount.

When you’re trying to stop from “Heavy pedal for the boat” to 0 as quickly as possible, you need the biggest possible difference between the current temp in the rotors and the maximum temp. Dragging the brakes to hold you back down a hill is just reducing the heat potential you’ve got available to use, instead of knocking a few k’s off at the top and holding it on the retarder, topping that up with snubbing the service brakes as and when needed.

[own_account_driver]

The truck crash history books are filled with far, far more bad accidents from the brakes being too hot than too cold (if you could even find any for the latter).

[santa]

I used to drive an auto MAN with a bog standard exhaust brake. I use it all the time and took pride in using the service brakes as little as possible.

On my usual way back to the yard, there is a steepish hill - dual track with a single lane 40 limit at the bottom. I would hit the top at 56 with the CC on and just reduce the cc speed limit all the way down. This made the gearbox change down and apply the exhaust brake. I usually managed to not light up the little 40 warning sign at the bottom.

[jimbo47]

where I’m at its policy to use the “jakes” engine /exhaust brake as much as possible due to the work I’m on ,before I never much used them only when on hills or coming up to junctions . and yup there is a time to much engine/jake brake is not good and that’s on ice or heavy rain…from personal experience knocking your jake by accident on when decending a iced up single track going intae a valley is NOT good.

[pat_hasler]

As I drive the engine / exhaust brake is turned off, I do press the switch when I need to slow the vehicle and save brake wear, also to hold the speed on down grades. As with most of the newer models over here the switch is a button on the steering wheel so it is easy to just press the button when required. I see so many comments about not using it in snow over the years but I totally disagree with that. I have been in transport since 1975 and under no circumstances will the foot brake slow any vehicle in snow if the engine brake doesn’t work. I just lower the power of the engine brake and it slows me up far safer than the foot brake, you have to remember that the foot brake will lock all the wheels in snow causing complete loss of control, the engine brake only effects one driving wheel and allows the others to turn freely so you still have control.

[gembo]

Own Account Driver:
The truck crash history books are filled with far, far more bad accidents from the brakes being too hot than too cold (if you could even find any for the latter).

Aye.
Ive never known any brake perform badly when cold. Load of old bollox!!!
If anything, the drum brakes on trucks from way back when, would put you through the windscreen until they got warm!

[slowlane]

IronEddie:
This is all very interesting to me. I’m learning the theory currently and the DVSA theory book talks about use of the retarder only in relation to going downhill as a means to avoid brake fade.

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This was nagging me, so I got my arse in gear and pulled my own DVSA Driving Goods Vehicles off my bookshelf, and they absolutely don’t say it’s only in relation to going down hill. I thought they dealt with retarders very well, including talking about how they don’t use any fuel, to be cautious in very wet/icy conditions as it is possible for them to lock the drive wheels… the book even mentions that the retarder might be linked into the trucks ABS system - this book covers a hell of a lot of bases.

From P82, in the “understanding LGVs” section…

Endurance braking systems, commonly referred to as retarders, provide a way of controlling a vehicle’s speed without using the wheel-mounted brakes. This is particularly useful when descending long or steep hills. Using this system instead of the footbrake also extends the life of the vehicle’s brake linings.

“Particularly useful” means that it’s always useful, but most useful in relation to long downhills.

and from P310 and 311

Plan ahead while driving, be aware of the risk of brake fade, and use engine braking when it’s safe to do so. Always be aware of the traffic situation behind you and how it may be affected by your actions.

You should brake - in good time, - smoothly, - progressively

If your vehicle has a retarder/endurance braking system fitted, use it, where appropriate, to control the speed of your vehicle.

I’d say that the DVSA have done a pretty decent job of explaining that drivers should be using the retarder!

[ironeddie]

slowlane:

IronEddie:
This is all very interesting to me. I’m learning the theory currently and the DVSA theory book talks about use of the retarder only in relation to going downhill as a means to avoid brake fade.

Sent from my E6653 using Tapatalk

This was nagging me, so I got my arse in gear and pulled my own DVSA Driving Goods Vehicles off my bookshelf, and they absolutely don’t say it’s only in relation to going down hill. I thought they dealt with retarders very well, including talking about how they don’t use any fuel, to be cautious in very wet/icy conditions as it is possible for them to lock the drive wheels… the book even mentions that the retarder might be linked into the trucks ABS system - this book covers a hell of a lot of bases.

From P82, in the “understanding LGVs” section…

Endurance braking systems, commonly referred to as retarders, provide a way of controlling a vehicle’s speed without using the wheel-mounted brakes. This is particularly useful when descending long or steep hills. Using this system instead of the footbrake also extends the life of the vehicle’s brake linings.

“Particularly useful” means that it’s always useful, but most useful in relation to long downhills.

and from P310 and 311

Plan ahead while driving, be aware of the risk of brake fade, and use engine braking when it’s safe to do so. Always be aware of the traffic situation behind you and how it may be affected by your actions.

You should brake - in good time, - smoothly, - progressively

If your vehicle has a retarder/endurance braking system fitted, use it, where appropriate, to control the speed of your vehicle.

I’d say that the DVSA have done a pretty decent job of explaining that drivers should be using the retarder!

Ah ok. I’m obviously being to specific in that first bit and just relating it to going downhill. There’s several questions in that section worded differently that relate to downhill, the retarder and brake fade. So I guess that’s the impression I wrongly gained.

In my defence I’ve also not yet reached page 310. The book is pretty good I think. I only got confused as what I read here didn’t match my current knowledge as I’d understood it. Glad to have the clarification and learn.

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[juddian]

Well found and quoted Slowlane, has that been updated in the last 6 years i wonder?

In my very first DCPC module, so roughly 6 years ago, the (claimed to be) HGV instructor taking the class went on and on like a stuck bloody record about brakes to slow gears to go and how wonderful modern lorry brakes are (no arguments from me about that, they are vastly better) so to just stay in gear right down to the junction, then select gear for carrying on, just as they teach people to drive cars then.

After the umpteenth time of reciting the GTGBTS prayer i could stand it no longer and challenged him that what was the poor young driver who he trained supposed to do when he got his first job on a 44 ton artic tipper in the Derbyshire Dales (Bath tragedy thoughts anyone?), was he supposed to stay in top gear going down 2 mile hills ending in villages on the brakes alone with them nearly alight then something goes wrong, such as a red line burst?, he had no answer for this other than some ■■■■■■■■ about how companies like eddie stobrat would train new drivers their way…whatever the f that might mean.

Maybe he thought he was teaching new recruits (badly), or has the official method been updated recently following Bath?

[slowlane]

Juddian:
Well found and quoted Slowlane, has that been updated in the last 6 years i wonder?

In my very first DCPC module, so roughly 6 years ago, the (claimed to be) HGV instructor taking the class went on and on like a stuck bloody record about brakes to slow gears to go and how wonderful modern lorry brakes are (no arguments from me about that, they are vastly better) so to just stay in gear right down to the junction, then select gear for carrying on, just as they teach people to drive cars then.

After the umpteenth time of reciting the GTGBTS prayer i could stand it no longer and challenged him that what was the poor young driver who he trained supposed to do when he got his first job on a 44 ton artic tipper in the Derbyshire Dales (Bath tragedy thoughts anyone?), was he supposed to stay in top gear going down 2 mile hills ending in villages on the brakes alone with them nearly alight then something goes wrong, such as a red line burst?, he had no answer for this other than some ■■■■■■■■ about how companies like eddie stobrat would train new drivers their way…whatever the f that might mean.

Maybe he thought he was teaching new recruits (badly), or has the official method been updated recently following Bath?

Thank you, mine’s the current version, so I don’t know if it’s changed since your instructor - but I bought the book pre-Bath.

The whole GTGBTS thing is endemic of the way that everything is going - data data data - you can’t do anything without a tick in a box, a form or a pass mark. Driving instructors need to stay in business by getting people to pass the test, if you make it more simple to pass the test, you get to have a higher pass mark and you stay in business.

I did my class 1 & 2 with Stobart, and the instructor showed us where the exhaust brake was and said that we could use it if we wanted, but it wasn’t necessary for the test, but is necessary in real life. Personally, I don’t agree with the idea of training someone one way, and then expecting them to operate in a different way once they’ve got their tick in the box.

Now, I’ve always been fascinated by lorries, so I’ve always had a thirst for knowledge about driving them. But this whole tick-box thing comes back to bite again like further up in this thread about brakes needing to be warm commonly found over on performance car forums, mostly espoused by members who wish their car had race spec carbon disks that do actually have to be hot to work properly, instead of accepting the reality of steel disks on their Corsa, big exhaust or not. Once you get this tick-box mentality ingrained in a culture, people stop thinking and wondering why things happen. You can just tell people “don’t worry about using the exhaust brake, you only need to use the foot brake to get this tick” and they’ll never think about it again. Just take a look to see how many, especially big fleet - Tesco, Morrissons, Wincanton and the like drag the footbrake all the way down inclines. Or, if you knock a few k’s off at the crest of the hill so that the ■■■■ poor exhaust brake stands half a change on the way down, how many trucks will fly past you and then drag the brakes on the way down.

I must have watched this classic video back in the earliest days of youtube and this thread made me head out and find it again: youtube.com/watch?v=AbtUdgbg0Nk So simple! Why don’t we get taught this when we’re learning now? Why is it that we have to go looking on youtube to find an american video from probably before I was born to learn about this kind of thing?

As for big companies, I can only speak for my experience with Downton, but when I got taken out by the driver trainer when I started this job, he watched me using the exhaust brake and did give me pointers on using it better and more often than I was - he definitely wanted it using properly. But how many drivers will stick to the advice vs how many will shrug their shoulders and think “It’s not my truck, why should I bother, I don’t have to”.

I don’t want to come across as a know-it-all, because let’s face it - I’ve been driving since March this year. I’m at the point now where I probably know just enough to be dangerous!!!

[juddian]

Ah but you want to do it right Slowlane, and have the nous to suss that lorries and cars ain’t the same and teaching people to drive lorries as cars is going to be fine for 99% of the time (albeit causing unecessary wear and tear to the braking system) but it’s that 1% when it all goes ■■■■ up is partly why the sensible try and do things the right way, but more importantly IMO taking a pride in your work gives back at least some of the job satisfaction that has been lost through increased automation.

You only have to look at lorries running along with you on the open road or different lorries in the same fleet, you’ll find the vast majority of steering wheels will be caked in brake dust, ingrained so deeply it can never be removed, and then the small minority of lorries where the front wheel edges are clean, in every case you’ll find the main driver of the clean wheeled to be one who uses the exhauster (or whatever) as the primary brake and only uses service brakes as back up.

Fair play to your Stobby instructor, he did say the exhauster was necessary in the real world, and the Downtons trainer sounds on the money too, that DCPC instructor i had words with was trying to make out they might as well be disconnected cos no longer needed…i’m sure in the back of my mind that in the case of the Bath tragedy that the exhauster on that tipper wasn’t working , but even if it had been unless that young driver knew to use it and in an appropriate gear (by taking control of the gears on such terrain) then it might not have made much of a difference to the outcome unless the auto downshifting was up to par, though that is only conjecture and something we shall never know…though i would like to see it tested out one way or the other as best one can on a suitable test track somewhere, so if anyone fancies setting it up■■?

Up to a point the Tescos and similar of the world will get away without using exhausters for ever, they simply don’t carry the full weight day in day out in severe terrain so are most unlikely to overcook already completely knackered brakes that the full weight carriers on adverse terrain have, though whatever the weight it’s always good practice to drive lorries properly cos then it becomes habit and when adverse conditions arise the driver can concentrate on those conditions because driving the lorry proper has become second nature.

‘’‘Now, I’ve always been fascinated by lorries, so I’ve always had a thirst for knowledge about driving them’‘’
that sentence alone speaks volumes mate , it’s why you give a toss when so many don’t.
PS good video that.

[gembo]

Juddian:
Well found and quoted Slowlane, has that been updated in the last 6 years i wonder?

In my very first DCPC module, so roughly 6 years ago, the (claimed to be) HGV instructor taking the class went on and on like a stuck bloody record about brakes to slow gears to go and how wonderful modern lorry brakes are (no arguments from me about that, they are vastly better) so to just stay in gear right down to the junction, then select gear for carrying on, just as they teach people to drive cars then.

After the umpteenth time of reciting the GTGBTS prayer i could stand it no longer and challenged him that what was the poor young driver who he trained supposed to do when he got his first job on a 44 ton artic tipper in the Derbyshire Dales (Bath tragedy thoughts anyone?), was he supposed to stay in top gear going down 2 mile hills ending in villages on the brakes alone with them nearly alight then something goes wrong, such as a red line burst?, he had no answer for this other than some ■■■■■■■■ about how companies like eddie stobrat would train new drivers their way…whatever the f that might mean.

Maybe he thought he was teaching new recruits (badly), or has the official method been updated recently following Bath?

A local firm to me has dozens of tippers and artics,/ They had a spate of them crashing into a bridge parapet that was at the bottom of a long descent on one particular run. One of their fitters whom I know well works on all their trucks. He said they were getting through brakes like nobody’s business and couldnt understand why. It transpired that alot of their younger drives were taught this “gears to go brakes to slow bollox” and so were screaming around like tippers tend to do and burning up brakes in the process like they were going out of fashion!
Since the management have had a word and changed their driving style to, shall we say, more conventional driving, things have settled down.

[juddian]

Gembo, i can’t understand why tippers and other vehicles on hard work like that arn’t specced with automatic retarders or Jacob brakes when new, and set up so that they need to be switched off deliberately and default to ‘on’ every time the vehicles is restarted, but what the hell do i know.

[gembo]

Juddian:
Gembo, i can’t understand why tippers and other vehicles on hard work like that arn’t specced with automatic retarders or Jacob brakes when new, and set up so that they need to be switched off deliberately and default to ‘on’ every time the vehicles is restarted, but what the hell do i know.

Thats a valid point but ■■■■ knows.

[juddian]

Gembo, love the pic of your hound in your sig.
Completely off topic but here’s George (the maggot) at around 9 months old have a well earned kip, he turned 1 year old last week, and gives his mum (who’s much smaller) and aunty a run for their money.

he turns all beds over and uses them as a pillow, dogs are bonkers.

[iomex]

Only time you can use it too much is when you leave it switched on around town - no benefit and shoves the truck around. As soon as I hit 30, I switch it on. I don’t see the reason in using your service brake first when going downhill. If you’re using 25% braking force on a hill, and some Honda Jazz pulls out from a side road, you’ve got 75% of total braking power available remaining, as opposed to 100% if you were on the engine brake.

On some of the trucks I drive, you can tell they’re never used from the burning smell after just 20 seconds at 2000rpm :L