Trick is not to try to economise on fuel by driving between 55 and 60mph in the inside lane of Motorways.
Instead make it exactly 50mph and tailgating ceases to exist as, a) they can actually overtake and b) If they don`t they lose momentum and they don`t do that.
Of course if its a car transporter coming up behind, I clear off into the distance and give it some space ;);)
Regards ;)
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On the M1 through the 50mph SPECS controlled roadworks I quite regularly see lorries tailgating, and in the majority of cases I take note of, it is due to car drivers doing 45mph in lane 2 when lane 1 is clear, and it doesnt enter their heads to move over. The lorry behind knows he could be going 5-6mph faster but can't use lane 3 to overtake.
This is not the cause in all cases, and I dont condone tailgating, but in these particular circumstances I can imagine how frustrating it must be for the lorry drivers. Tailgating is not clever and neither is lane hogging.
If I get tailgated I either: speed up, move out of the way, or if those options are not possible, stop looking in mirrors and ignore them until I can do one of the first two.
By using good lane discipline I find I very rarely get tailgated. (That and setting cruise control to an indicated 53mph).
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Oilrag, you line em and i have to respond....nice one.
I'm not giving you the pleasure this time so nurrh. With nobs on!
No i can't resist, up in Yorkshire there are many, usually Italian, vehicles cruising around the roads for almost free, carrying mainly pigeons and ferretts, using the truck in front as their windbreak, subsequently broadcasting their amazing fuel figures to those of us maybe not quite so thoughtful (tight) with our car buying choices.
These same Italian but Yorkshire piloted vehicles upon sighting a car transporter will often go into super economy mode, looking for a chance to nip a quick piggy back for as many miles as they can.
Other counties, though probably not as nice as the aforersaid Yorks, have their own version of the mobile veterinary vehicle, but none so clever, as a van load of flapping pigeons sufficiently disturbed (as are we) must aid the progress of said vehicle further.
All the best, and to other Yorkshire dwellers, please don't take any of this seriously.
;) ;)
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what confused me a bit in HJ's answer was the comment that "your speedometer is over-reading and the truck driver's isn't" are truck speedometers more accurate than car ones and if so why?
Yes they are more accurate.
I get the same issue with muppets who block average speed specs areas doing 5 MPH less than the posted limit & with the naff lane discipline they normally manage.
If the speed limit is artificially low (which most specs type limits are) & also I'm not allowed to use my discretion at what speed I can travel then I'll travel at the limit + what margin I'll not get nicked at. So typically in a 50MPH spec limit I'll be at 55MPH on the GPS, which on the Jag is 60MPH speedo speed.
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I tend to do the same, travel at a speed I'll not get nicked at, an indicated 54 will get you going quicker than most in a 50 posted.
Technical query why are truck speedos more accurate and why, if it can be done are car speedos not similarly accurate?
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I simply don't understand why car drivers want to mix it with HGVs on the motorway. It seems perverse to me to waddle along the inside lane being menaced by 44-ton monsters, or slowly overtaken by an endless stream of them, just for a theoretical few more mpg.
Generally speaking cars are much faster and much more manoeuvrable than lorries, and generally almost as economical at 65 as they are at 55. If I was a truck driver I imagine by now I would have a deadly hatred for these boring, passively aggressive mimsers. If you just nip past lorries they don't menace you. Try to stay out of their way and everyone will be happier.
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Can`t do that Lud ;) I`m hard-wired to save cash, (I suspect it was in the Bios at initial boot) even if it only buys a newspaper after a trip down to Meadowhall and back... ;)
All The Best ;)
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To you too oilrag... I don't think I can remember you complaining of being frightened on the motorway though, so obviously you can look after yourself...
:o}
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>>Technical query why are truck speedos more accurate and why, if it can be done are car speedos not similarly accurate?
Among other things, trucks are subject to a 2 yearly tachograph calibration, where the drive axle is motored on rollers, and the calibration of the tacho checked and adjusted.
Add to that the fact that tachographs are expensive instruments, the evidence from which is good enough to be put before a court, and you can see that they are a world apart from the dashboard mounted gimmick in a car.
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thanks NC I've learned something today
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"I don't think I can remember you complaining of being frightened on the motorway though"
I`m near the M1/M62 interchange Lud. So I`m used to being terrorised by foreign trucks whichever way I go ;)
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"All the best, and to other Yorkshire dwellers, please don't take any of this seriously."
Nowt there to offend us lad ;);) Pigeons are a long term memory, Yorkshire changed, everywhere is now `middle class` and much as I would like to tailgate trucks in taking a newly aquired brood out.... It really would be `a pigeon coming home to roost` in more ways than one in our neighbourhood. A good hobby aged 12, I found amongst a few local upturned noses.
All The Best !
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So many of us saw HJ's response to that as a refreshing change. He told it as it is, not as it should or shouldn't be.
He wasn't condoning it, just explaining why it happens.
Surely a greater understanding of the situation is to the good of everyone as has been shown by many on here who travel at 60MPH as opposed to 54MPH and never seem to get near a lorry.
And just think, at 65MPH your actual speed is more like 59ish anyway!
Remember when you feel threatened by a tailgating lorry, we feel just as threatened when a car pulls in front and promptly brakes to exit the slip road or join the queue.
It's the same thing, someone encroaching on our safety cushions be it car or lorry.
Pat
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a point fairly made Pat, but it just seemed to me the reply was laying the blame on the poor bloke being followed.
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the reply was laying the blame on the poor bloke being followed.
Quite rightly too. If you drive at a speed slower than the HGV wants to go in the inside lane, but not slowly enough for its driver to be able easily to overtake, you are in fact quite simply getting in its way. Its driver may succumb to the temptation to drive closer, in the hope that you will see the light and make yourself scarce, as you so easily could.
'Why should I?' I can hear people thinking, 'There's no legal minimum speed. I've got as much right to go at my chosen speed as anyone else, etc.'
Yes, you have. You can creep about getting in the way and holding up better drivers than you as much as you like. Lots of people do it. But just think: if you didn't get in their way, and become drearily resentful when they tailgated you, we wouldn't have to be thinking about this subject at all. We could talk about motoring, not car use by people who don't deserve cars.
Why not go by bus, or waddle about getting in the way on ordinary A roads?
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As an HGV driver,I'm not going to say what I think on here,as the last time I made objections about 'lorry bashing' I got banned.
What I will say,is I have photographic evidence of a car on the M6 this morning,in the new roadworks near J5,a specs lined 50 mph route,doing about 40 mph in the middle lane,and a truck wanting to be by,right up his jacksie.
So let's not go tarnishing every truck driver with the same brush here,some car drivers are as big as,if not bigger culprits,of danger within camera lined routes.
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So let's not go tarnishing every truck driver with the same brush here some car drivers are as big as if not bigger culprits of danger within camera lined routes.
No mate for once I'm on your side. It seems to be slightly worse these days I suspect because people are slowing down because of fuel costs me I just want to get where I'm going.
Don't these muppets understand three in a bed, nah probably too advanced driving for them.
Same as T & T.
I see stupid driving around lorries, living in Kent I see dozy people sitting by the side of lorries UK & foreign for mile after mile, just because they don't put their foot down.
Echoed by the supervisor at Godstone Highways Agency the other week when we did a tour.
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I`m sure all are as bad as each other. Then there are bikes and cyclists with their own antics.
My guess is that technology will eventually enforce no tailgating from engine management and sensors. That will then be that, but being what we are as a species there will be outrage about that too.
Edited by oilrag on 29/05/2008 at 19:42
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I personally, would go easy on the "muppets" "Dozy people" and "stupid" comments too. No call for that.
I sometimes wonder if a `Walled Garden` with well meaning swear filters and moderation, allows or actually encourages a culture to develop which would be given short thrift on the Usenet.
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I personally would go easy on the "muppets" "Dozy people" and "stupid" comments too. No call for that. I sometimes wonder if a `Walled Garden` with well meaning swear filters and moderation allows or actually encourages a culture to develop which would be given short thrift on the Usenet.
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Sorry what else do you call people whom are desperate to prove Darwinism is alive and well.
And I'm quite happy to support these opinions face to face!
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Lud,
I was trying to think of a way of putting over my thoughts..and then there it was...your entry.
If some people weren't so damned selfish and actually thought of others, they wouldn't hold up lorries at all.
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"If some people weren't so damned selfish and actually thought of others, they wouldn't hold up lorries at all."
Perhaps some sort of Gentlemans agreement, where cars keep out of the way of trucks and trucks don`t pull out to do a five mile overtake on dual carriageways just as you are about to overtake.
It can`t all be one way. There has to be some reciprocity and you can see how much there is of that from largely foreign trucks.
Unless we are saying that one category of road user has a certain right or priority over others.
If we started with that, there would be an argument for further ` priority`grading.
At that point I would buy another big bike and everything would be standing still ;)
(written tongue in cheek as usual, with not an atom of emotion invested ;)
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"And I'm quite happy to support these opinions face to face!"
Why not the usenet? Anyway, my Dads bigger than yours. :):):)
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There's one other good reason not to tailgate a lightly-loaded truck; on a dry road it can stop in the blink of an eye.
Even around town, if the driver stamps on the air-brakes; it can come to a dead halt in only eight feet from 20mph.
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if the driver stamps on the air-brakes; it can come to a dead halt in only eight feet from 20mph.
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Hold on a sec, while I check my reference books on the laws of physics................
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drbe
I may have to re-write them for you then. To be allowed out on to the road to take your HGV test; you must first prove that you can bring your vehicle to a, controlled, halt from 20 mph in 20 feet or less - even if the test lane is wet and greasy like mine was.
The 8 ft braking distance was measured on a drum-braked Ford D1614 fitted with a chalk gun; Wymeswold airfield, Leicestershire; dry tarmac - the best of many tries, admittedly.
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I would have to agree with Screwloose, though i couldn't possibly quote figures, but be assured there aren't many vehicles can stop as instantly as a (drum braked funnily enough IMO) truck from about 20 mph in the dry, i wouldn't try to outstop one in most cars.
In the wet though, or loaded from 40 or above and a whole different story
I always thought leylands had the edge over everything else stopping power wise, but memory fades.
Just anecdotal, many years ago when i worked driving a skip type tipper, a motorbike overtook me on a regular run, some 2 miles up the road, biker (tiddly) had dropped bike on corner and slid across road stright in front of my mate Alec (another good one passed), who had a leyland, well Alec's skid marks from 30 mph were unbelievably short, and the bike and rider stopped under the front bumper of the truck. If it had been me in my seddon atki, the biker would not have survived. And abs would not have allowed the instant lock stop either.
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>>from 20 mph in 20 feet or less
It's OK SL, physics does not need to be revised!
;-)
% First convert 20mph into metres per second V=20*1609.3/3600; % Convert 20 feet into metres D=20*12*25.4e-3; % acceleration due to gravity (m/s^2) g=9.81; % estimate co-efficient of friction required to perform the stop mu=(V^2)/(2*g*D)
mu =
0.6683
This is an entirely reasonable value of mu, and should be attained in dry conditions. I can imagine that you might struggle a bit in the wet though.
Thankfully, I had a (rare in the pennines!) dry day when I took my HGV test.
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NC
Thanks for the calculations; I'd no idea all that was going on - I was just relieved that none of the wheels locked and the examiner said; "In your own time, proceed to the main gate and turn to the right."
Two-and-a-half hours round the centre of Nottingham at 8.30 on a Friday morning - every idiot and his dog was out to get me; I was shattered when I finally got back to Watnall and it felt like my head was about to drop off.
[They don't do 19 mirror checks on a roundabout now, either. Back then; miss just one in the whole test and you'd failed.]
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eight feet from 20mph. >> Hold on a sec while I check my reference books on the laws of physics................
Before you all get too involved in proving that 20 feet from 20 mph is perfectly feasible, may I remind you that my chin stroking was prompted by the figure of "eight feet from 20mph".
See the extract above.
Now if you would care to prove to me that a stopping distance of eight feet from 20mph is attainable in everyday circumstances by a road going lorry, I will issue an apology.
: - )
Edited by drbe on 30/05/2008 at 08:17
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This may be relevant.
www.honestjohn.co.uk/forum/post/index.htm?t=59143
Scroll down to the ROSPA link, then scroll down to the actual stopping distances.
From 30mph, 15 metres is the norm for a lorry. A mondeo stops in 7 metres.
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>>>>Now if you would care to prove to me that a stopping distance of eight feet from 20mph is attainable in everyday circumstances by a road going lorry, I will issue an apology.<<<<
Only if I can duck when my load comes through the headboard and lands on top of me in the cab!
Pat
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In similar situations I (try to if safe) get the reg and company name, date time and place and email a complaint to the company. Sometimes I get a nice email back thanking me. More often than not I get no response. It might or might not stop it happening again but it makes me feel better.
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>>"eight feet from 20mph"
Yes, unless geared to the road, that's a bit unlikely. For some reason, I misread that part of SL's post, and didn't see (or didn't register!) that piece of info. Sorry.
18 feet would be more likely, or perhaps 8 yards.
Edited by Number_Cruncher on 30/05/2008 at 18:44
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NC
I know that it's possible, as I was the one that measured it - the pink blob wasn't even half way to axle 2.
20 feet from 20 is the maximum allowed - under all conditions - for a learner under test conditions; lock a wheel, or take 21 ft and you have failed your test before even leaving the test centre. In reality; 17-18ft is easily attainable in the wet; 13-15ft in the dry.
Playing with the chalk gun [borrowed from the Drive magazine guys] showed that stamping hard on the shoe gave about a 10 ft skid distance with all the wheels locked. I was determined to win this little contest and finally got the perfect stop to record the 8ft distance. [Hey; they weren't my tyres...]
On the billiard-smooth, very grippy, hot-rolled asphalt, [around 5pm, in the hot July of '82] the deceleration was vicious - a passenger would have been flung through the screen. The forces were so violent, a brutal twisting moment was generated in the ladder chassis which slammed into the cab just after it came to rest, nearly snapping your head off.
If someone would like to lend me a 3-axle truck and a test-track on a nice warm day, I'd be more than happy to have another go - just to put any doubts to rest....
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I have to agree with you Screwloose, having spent a long time driving 6 wheelers (multilift rolonoff equipped) especially with a leyland constructor chassis, the brakes could only be described as deadly. If you had to stop suddenly you always expected the bang.
Up to probably maximum speed in the dry empty, probably 5 tons of fixed equipment, the stopping power could shake your whole body up, leaving you feel quite ill for some time.
I'd be very surprised if a modern disc braked truck could match it, certainly nothing i've driven.
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What were they like freewheeling at 75 down an endless hill with a full load and sharpening curves coming into sight though gb and Screwloose? I bet there would have been moments then when discs would have seemed an improvement.
After all making a dotted black line on the tarmac or even gouging lumps out of it if it has been recently laid isn't the be-all and end-all of trucking...
:o}
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Lud
To survive any time in the haulage game you had to be very, very, good at anticipation and reading the road far ahead - the level of unremitting concentration needed was often physically draining.
The situation you describe would never arise; [free-wheeling?? 75...!!] as you'd already be engine-braking in a low gear [retarders - what are they?] and not even touching the brakes all the way down until you maybe just needed them to balance the wagon before applying power for the corner.
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Putting 8 feet into the previous sums gives
% First convert 20mph into metres per second V=20*1609.3/3600; % Convert 8 feet into metres D=8*12*25.4e-3; % acceleration due to gravity (m/s^2) g=9.81; % estimate co-efficient of friction mu=(V^2)/(2*g*D)
mu =
1.6708
That's a value that is way beyond that normally attainable between tyre and tarmac.
If one were to swap the positions of mu and D in the equation, braking distances may be estimated. The parameter in the equation which is most sensitive is V, the initial velocity. How accurately was the 20mph recorded? Even a small error in the speed measurement would give a large change in stopping distance.
I can beleive that values of mu over 1 are acheivable, especially when the tarmac is softened, and is acting as an adhesive, but, 1.67 is really exceptional.
Under stops of that deceleration in unladen short wheelbase trucks, it's entirely possible to lift the rear wheels - very early Ford Transcontinentals with their high mounted Cummins engines would do this, scraping their bumpers along, before a front axle load sensing valve was specified to prevent it!
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NC
The, not very scientific, method was to accelerate until the tacho read 20 and then immediately hit the brakes.
Allowing for cumulative drag and engine braking in the half-second that the brake chambers took to fill and the gun to fire; maybe 16-17mph, as an absolute minimum, as the brakes activated?
It wasn't a short-chassis unit; front bumper to axle 2 was approx 20ft. The surface was very grippy, fine-grit, warm asphalt; but not a resin-bonded Shellgrip-type anti-skid compound. [Factor-in the ten 37" tyre footprints - that's a lot of rubber on the road, even with 4-5 tons to stop.]
Comparing the sensation with that of braking in a performance car, which can generate 1G+ under braking, I'd estimate that it achieved at least 1.5G. I was a lot younger then, but it still hurt.
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I did get lifts in trucks in the 38mph fifties and early sixties which freewheeled like anything getting up to those sort of speeds, or jolly nearly. Of course the drivers knew very well what they were doing, and anticipation was first not second nature to them. However a very long hard demand on those initially very effective drum brakes would have put them to the test in no uncertain fashion. Anyway a 38 ton 12 wheeler with all wheels locked in the middle of a small town in a dip on a straight East Anglian road is a fairly terrible thought.
Of course the situation in my post, full load at 75 down a steep hill with sharpening curves, is just a nightmare fantasy. The point being that with drum brakes it really might be a nightmare, but with proper discs perhaps a recoverable situation.
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Lud, perish the thought, i couldn't imagine for a moment any truck travelling at 75 downhill, apparently they could be made to go better than that, so i'm led to believe.
Those sorts of speeds would only have been attainable in Irish overdrive -)
The brake balance and feel have been completely removed from the driver now anyway, abs, disc brakes, automatic retarding all designed very cleverly.
Progress? undoubtably, better than before? yes but not in all circumstances.
The scenario i described above, which occurred in Gayhurst near Newport Pagnell some 26 or so years ago, would have resulted in the death of the biker with a modern truck, IMO. (actually the poor bloke left quite a lot of the skin of his shoulder on the road as he sliced along, can't imagine what he thought as the front of a huge bin wagon slewed to a halt on top of him)
Anyway we like drawing pretty black lines all down the newly laid road. -:)
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So the conclusion from this is that if you have one of the "older" truck tailgating you its ok 'cause they can stop quicker than you.... but if its a new one.....
Lets just hope that the truck driver's reaction times are damn quick...
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So the conclusion from this is that if you have one of the "older" truck tailgating you its ok 'cause they can stop quicker than you....
How could you possibly assume thats what i meant from my post, i was talking about a particular set of circumstances with a very experienced 'old school' driver.
I don't tailgate other drivers anywhere....i've got a good record which i fully intend to keep that way, with a good dose of luck!
If you look at my post carefully, instead of reading into it a meaning that isn't there, you will find i have said that things have progressed, but not in every circumstance.
In other words as with most things, the more modern is better overall, but not ALL the time.
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Especially if there`s a banana on the road....;)
Edited by oilrag on 31/05/2008 at 11:42
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Sorry, GB, it was meant in jest, no offence m8.... sometimes I wish we had smilies on here!
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No problems B308, as usual i grabbed the wrong end etc.
Sorry for jumping down your throat.
Only excuse is that after 30 odd years of being a 'scum of the earth' lorry driver, you develops a persecution complex.
-;)
Bananas, wrong sort of leaves as well, or is that something else..;)
Edited by gordonbennet on 31/05/2008 at 12:13
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>>I'd be very surprised if a modern disc braked truck could match it, certainly nothing i've driven.
This is the trade off that most people simply don't "get" - particularly those who always slag off drum brakes. Disc brakes do not give more stopping power, or more braking force than drum brakes - what they do give is much greater thermal stability, and better heat dissipation.
In other words, there are situations where a drum brake is the correct engineering solution, even on a modern car - particularly the rear axle of front heavy front wheel drive cars, where the rear axle never does enough braking work to give a thermal problem.
I've never done any work on a full sized disc braked truck, but I would imagine that they are a lot easier and quicker to change the pads in than it was to reline the shoes in a drum braked truck.
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In other words there are situations where a drum brake is the correct engineering solution even on a modern car - ........
But doesn't ABS work better with disc brakes than drum brakes?
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>>But doesn't ABS work better with disc brakes than drum brakes?
Yes, there were some earlier generations of ABS which needed to work with disc brakes, because of the different fluid volumes and threshold pressure characteristics of a drum brake, but, it's no longer the case, a modern ABS controller/system can cope with drum brakes with no problems.
On many cars, rear disc brakes are a marketing gimmick rather than an engineering led solution.
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On many cars rear disc brakes are a marketing gimmick rather than an engineering led solution.
They are also, I suspect, considerably cheaper, and theoretically easier to maintain since they require no adjustment over their service life.
As an HGV driver I do try my best not to tailgate; it is immensely frustrating though when other drivers (car AND HGV) see your "safe zone" in front as a convenient gap, pull in to it and then force you to decelerate further to reinstate the gap.
If taken to it's theoretical (albeit illogical) conclusion you'd end up going backwards!
As for being tailgated myself; I find that the 3-ton demountable forklift strapped to the back of my current truck is a superb deterrent!
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>>I suspect, considerably cheaper
That would be true if were not for the need to incorporate a handbrake mechanism.
If you do it properly, like MB, Volvo, and older Vauxhalls, you have a seperate small drum brake in the "top hat" section of the disc. So, you have a disc brake and a drum brake - not cheap.
If you try to bodge, and use the pads as the handbrake device, you need to use a complex mechanism to apply the force to the pads AND to also compensate for the disc contraction as it cools. None of this is easy or cheap.
A full sized drum brake allows the easy incorporation of a handbrake mechanism, and, if well designed does not need to be disturbed too often, as wear rates are so small.
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