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Author Topic: Landing-Craft accident, Railway Street, Chatham - 1953  (Read 135550 times)

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Offline Sentinel S4

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Re: Landing-Craft accident, Railway Street, Chatham - 1953
« Reply #370 on: May 11, 2013, 23:12:57 »
I would hazard a guess that the engine would have been a direct descendant of that 1927 engine, if not an identical unit putting out the same horse power. Until recently, the last twenty years, 150 hp was thought to be enough for HGV's pulling 38 tonnes as standard. The HP only went up when 45 tonnes came into being as a standard weight. However what really precipitated the change was computer control and the common rail injection systems that are now run. Some trucks from the 1970's and 80's could barely put 100 hp into the gear box. Very often engines were and are down rated for the haulage industry, to give reliability and longevity, I have driven vehicles from the 1970's with well over a 1,000,000 miles on the clock yet still good enough to do a regular days work. In these enlightend times it is all about economy and expense, and I should well imagine that in the 1950's it was much the same. These vehicles cost money so you need to get as much out of it as possible, as cheaply as possible for as long as possible. I stand by my estimate of 90 hp at the fly wheel, open to correction by some one who has worked on one.

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Offline peterchall

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Re: Landing-Craft accident, Railway Street, Chatham - 1953
« Reply #369 on: May 11, 2013, 22:53:20 »
The RR Meteor was a 27 litre , 600 bhp unsupercharged version of the Merlin aero engine. I simply assumed the output of our engine, at 7.7 litres, to be proportional:
600/27 x 7.7 = 171 bhp, and I see no reason for that to be wrong. Why do you suggest 90 bhp? At 11.7 bhp/litre that would be way below the norm for even the side-valve engines of the day – even the Ford 8 managed 22.5 bhp/litre.

The Meteor was a 12-cylinder vee engine, so had 2.25 litres per cylinder; thus a 4-cylinder adaption of that would be a V4 of 9 litres capacity with an output of 200 bhp.

There was a 7.7 litre RR car engine of 1927 with an output of 97 bhp. Could our engine be a later version of that?

Actually that is only of general interest, of course, because there would still have been little engine braking and my scenario would still be much the same .

And you seem to rule out prior damage further up the hill, so a high speed at the Alex is necessary for it to topple.
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Offline Sentinel S4

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Re: Landing-Craft accident, Railway Street, Chatham - 1953
« Reply #368 on: May 11, 2013, 22:02:30 »
Nice one Peterchall. I cannot fault much of what you have written. However I think that you have over-estimated the HP of the unit by about 80 horses. I would be very suprised if it could put out more than about 90 horses, hence the low gearing.

I have doubts as the the ropes being shocked into parting. As a matter of course the driver or his mate would have checked the ropes before leaving their over night stop. If any were slack they would have been re-tied, I haul wooden products and will stop a couple of times en-route to make sure that nothing has come loose. Loose ropes and straps fret and will wear through finally parting. However I think that the side swipe on the bus cut the ropes.

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Offline peterchall

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Re: Landing-Craft accident, Railway Street, Chatham - 1953
« Reply #367 on: May 11, 2013, 21:39:06 »
PS to above: The engine plays a minor part in the event. I should have put the 'Start Here' further back at "Thus we have total drag for the whole lot of: "
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Offline peterchall

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Re: Landing-Craft accident, Railway Street, Chatham - 1953
« Reply #366 on: May 11, 2013, 21:31:04 »
Scenario is that the LC started to topple just after passing the Alex. I posted this a few posts ago:
Suppose the LC actually toppled and hit the road 150 feet before the viaduct – it would require only 45% retardation (less than an MOT pass) to stop it under the viaduct, in 4.5 seconds. Would the drag of the LC along the road on its bottom corner, plus the brushing contact with the bus, provide that?

I think it probably would, so by the time it hit the bus it was already going quite slowly. There is very little road showing in the original photo, and it's difficult to tell its state. And wouldn't the worst damage be farther back?

If the speed at the Alex was slower, what caused it to topple? The rear wheels of the trailer hitting the kerb farther up due to trailer swing, hard enough to cause a big enough 'shock' to break its securing ropes, perhaps? But it was a straight road - why should trailer swing occur?
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Offline mikeb

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Re: Landing-Craft accident, Railway Street, Chatham - 1953
« Reply #365 on: May 11, 2013, 20:28:39 »
Quote
go directly to Start Here
I did.

 So, worst case scenario then, brakes fail, rig is held back by engine alone and accelerates down the hill andat the Alex  the LC is doing 44/48 mph. The LC gets dislodged somehow and hits the bus. That point of contact would have been a pavement width just out of shot in the original photo. This means that the 45 tons of LC and tractor has gone from 48/44 mph to 0 mph in roughly its own length. Such a deceleration would have put the driver through the windscreen. It didn't appear to have hit anything else, and as far as we know it didn't tear up the road. So, I return to my previous thought, the brakes must have been working otherwise, what actually stopped it? The brakes must have been having some effect as PC's figures show that the engine alone could not have stopped it. The closing speed at the Alex must have been considerably lower surely.


Offline peterchall

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Re: Landing-Craft accident, Railway Street, Chatham - 1953
« Reply #364 on: May 11, 2013, 18:36:10 »
It’s falling into place.
I’ve set out the maths in detail for anyone who wants to follow my reasoning – and shoot holes in it if they wish. For those not interested in that, go directly to Start Here

Engine Braking
Vacuum in petrol engine cylinders during ‘engine braking’ = 11-12 lb/sq.in.
Brake Mean Effective Pressure (bmep) – the ‘push’ on the pistons to produce the power – in those days was about 95 lb/sq.in.
Hence braking effect was about 12% of the power.
Our engine gave about 171 bhp, 12% of which = 21 hp
21 hp = 21 x 550 = 11550 ft.lb of work /second
Assume that gearing was such that the maximum power was reached at 12 mph = 17.6 ft/second.
Retarding force from engine = 11550/17.6 = 656 lb.

Applied to a 1.1 ton car (2500 lb) that would cause a retardation of 656/2500 = 26% = speed loss of 5.7 mph/second, quite a drag, equal to at least ‘normal’ braking.
Applied to a 45 ton (100,800lb) rig it is 656/100,800 = 0.65%  retardation = speed loss of 0.14 mph/second, hardly noticeable, which is why I suggested earlier that it didn’t really matter whether the driver missed a gear or not, and wondered if he would even try to change gear.

Note: The 171 bhp assumed for our engine is based on the RR Meteor tank engine from which it was derived,  and equates to 22 bhp/litre capacity. With 4 big cylinders that compares well with the average of about 25 bhp/litre of the smaller, and hence more efficient, cylinders of the car engines of the day

Transmission and Tyre Drag
As stated before, a vehicle will roll easily on my drive of about 1 in 20 (5%), so at a guess I would put the actual drag at about 3%.
That is for a car with a 5-speed gearbox, thus having 6 pairs of gearwheels in mesh (5 in the gearbox and 1 in the final drive) and 9 ball or roller bearings in the drive chain = 15 ‘resistance points’.
Our tractor had, we think, a 6-speed gear box + final drive + chain drive, making 9 pairs of gears and 11 bearings = 20 ‘ resistance points’ (I don’t think the drag of the chain drive would have much been different to that of 2 gearwheels) hence a drag of 4% for the tractor seems reasonable. 4% of 12 tons = 1075lb
Most sources suggest about 1% for the drag of a pneumatic tyre, so I’ve assumed that for the trailer. 1% of 32 tons = 717lb

Thus we have total drag for the whole lot of:
Engine braking = 656 lb
Rolling resistance of tractor = 1075 lb
Rolling resistance of trailer = 717 lb
TOTAL = 2448 lb

Force acting down a 1/16 gradient = 45 tons/16 = 6300 lb

Thus resultant force down slope = 6300 – 2448 = 3852 lb
That acting on the 45 ton unit would give an acceleration of 3.8%, or a gain of 0.84 mph/second

Start Here
From 12 mph at the top of the hill the speed of the unit at the Alex pub would be 44 mph
Without engine braking the speed would be 48 mph

In either case it would be enough to turn the unit over, and fit the report of brake failure

There are variations of course, apart from those inherent in the assumptions. If the brake failure had occurred farther down the hill the final speed would be lower, but the trailer might have hit a kerb, as previously suggested, and dislodged the LC, enabling it to turn over over at a lower speed.

Whatever the case, does it seem logical, and is the driver vindicated?  :)

If so, the question now is – why the brake failure?
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Offline peterchall

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Re: Landing-Craft accident, Railway Street, Chatham - 1953
« Reply #363 on: May 10, 2013, 17:00:32 »
I feel sure that just hitting the bus would not have stopped it almost within its own length, and tipped the LC over. Unfortunately the photo of the bus is not very good, but I think a broadside-on blow big enough to do that would have damaged it beyond repair. However Smiler, do you remember what kind of gearbox a CD45 had? How many speeds and whether it had a range change/auxiliary box?

SentinelS4, re intermittent brake failure, I have given some thought to that but can’t think of anything. The only case I can remember (2nd hand) was an internal blockage of a flexible pipe in a hydraulic system preventing one brake from working. There was no leak, so nothing showed up on external examination, and the brake assembly itself was OK – but it wasn’t an intermittent fault.

The problem with a thread of this length is that we forget what has already been stated (including what has been stated by ourselves), hence the repetition. I don’t want to boast (not much anyway :)), but I think I was the first to suggest the driver might have missed a gear, in Reply#206 of 27 February, when I wrote:
“Is it reasonable that (a) he tried to change down as he approached (the corner by Southill Barracks), missed the gear, took the turn in neutral and was unable to regain control, or (b) was in a gear appropriate for the flattish road before the turn and didn’t realise how steep the hill was, and tried to change down on the hill?” I think this is the 2nd time I’ve referred to that!

I have also suggested that a swinging trailer might have clouted the kerb hard enough to dislodge the LC so that it tipped over at the bottom at quite a low speed. I can’t find that post quickly, but I’m sure I asked if that was reasonable, but got no answer. Since then I’ve concluded that, at the low speed involved, the answer would have been ‘no’.

Then S4 asks ‘Why on Earth would he (the driver) stop at the top of the hill?’ What if the brakes had got hot on that run down from Horsted? He would have felt the extra pedal travel and that, plus his experience, would surely suggest that a stop might be prudent. All the evidence, mentioned several times, suggests a legal speed limit of 12 mph and I see no reason why he wouldn’t obey that. The hill is straight with a constant gradient and not very long so, with everything gathered up, what was there to lose? Even with an icy road the braking force was so marginal that I can’t see how things could have gone so far as to get out of control.

So I’ve taken that driver to heart and am still looking for reasons why it would not have been his fault :). One reason would be the reported one of complete brake failure and the engine braking and transmission drag being insufficient to prevent the vehicle completely running away.

I’ve already stated why I think the engine braking in bottom gear in this case would be little different from that of a car in top gear, and stated that, if I were choosing the final drive ratio for this tractor, I would choose one giving about 25 mph at maximum power. One picture is as good as a thousand words, so let’s have a look at that:

For simplicity we have a 2-speed gearbox. The driving power in high-gear is shown by the full black line and the power needed to drive the unladen vehicle along a level road is shown by the full red line. The maximum speed is at ‘M’ (28 mph) if it were a petrol engine; with a diesel engine the governor would cut-in a ‘D’, limiting the speed to about 22 mph. That is the primary difference between a petrol and diesel engine for the construction of a scenario – once the vehicle speed got beyond that the engine couldn’t be revved fast enough to find a ‘lost’ gear. If I have given the impression that a petrol engine would not give better braking than a diesel it was unintentional – I have not changed my mind.

‘R’ is the ‘red-line’ (recommended maximum) speed for the engine, unattainable in high-gear on a level road. However, if we come to a down gradient the power required will become less, and with our foot hard on the throttle the speed will rise although the power falls until, somewhere between 37 and 40 mph, something is likely to go ‘BANG’! The maximum acceleration, or 'pulling', is where the gap between the red and black lines is the greatest - at about 15 to 20 mph

If we now meet a steep uphill, or someone hooks a landing craft on to us, the power needed is shown by the dotted red line and we need to engage low-gear, and the driving power in that is shown by the dotted black line. The maximum speed is now ‘m’ (15 mph), and the red-line speed ‘r’ (14 mph) is now attainable, so we need to watch our right foot! If it were a diesel it would cut-off at ‘d’ (10 mph).

If we engage low-gear on a level road the speed could go as high as about 18 mph, just on the point of going bang. This 2-speed box is, of course, a great simplification, so have sympathy for the poor mutt who has to work all that out for a 16-speed transmission :)

This post is getting a bit long, so I’ll just answer S4’s question: Plain phosphor-bronze bushes are not suitable for high rotary speeds unless pressure lubricated, which would be an unnecessary complication in a gearbox, when ball or roller bearings are available.

Back later with some other thoughts.
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Offline smiler

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Re: Landing-Craft accident, Railway Street, Chatham - 1953
« Reply #362 on: May 10, 2013, 09:19:01 »
I've followed this thread right through from the very beginning as I worked on a number of these Scammells in the 60s. I must say at times it`s been very interesting and other times very repetitive. After all of it I tend to agree with Mike B #357 that it was probably an accident where the bus had not left enough room and the load could not stop in time to prevent hitting it.

Offline Sentinel S4

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Re: Landing-Craft accident, Railway Street, Chatham - 1953
« Reply #361 on: May 10, 2013, 06:14:39 »
An AEC Matador would be plenty strong enough to pull the complete rig at a walking pace to the Dock Yard if required.

What if the accident was caused by one of those 'now they work/now they don't' 'brake problems'. You must have encountered them in your years as a fitter, Peterchall. Someone comes in with a fault on their vehicle but no fitter can find it, however as soon as they drive off the forecourt the problem returns...... Generally it is the loose nut behind the steering wheel that is the problem..... :) :) :) :) :)

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Offline peterchall

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Re: Landing-Craft accident, Railway Street, Chatham - 1953
« Reply #360 on: May 09, 2013, 23:29:53 »
I’m sure the LC was going too fast when it got to the bottom of the hill, although why that was is the subject of the argument/discussion. I can’t see how it could have hit the bus end-on, or it would have ended up with its stern squashing the bus against the fire station wall, with the LC across the New Cut. I think it fell off and was being dragged along the road on its bottom corner, or even its side, so that its rising bow was sticking out to the left, and it was that which ‘scraped’ across the bus like a hook. We don’t know if it actually finished up where Merc's original photo shows it or if it had been moved there. The recovery process seems well under way

The rate of deceleration, even from 40 mph, wouldn’t have been that much if it fell off soon after passing the Alex – I think I mentioned a possible figure in a recent post. The question is whether the friction between the craft and the road could have been enough – perhaps, with that final encounter with the bus, it would have been.

Regarding brake failure as an excuse and not a fact, perhaps police investigation in those days wasn’t as thorough as now, but I’m sure that the driver would have been rumbled, if not by the police, by the workshop where the tractor would have been taken.

I know the tractor is apparently still hooked-up in Newmanfan’s photo, but we don’t know how soon after the accident that was taken. Is there any significance in the mention in the newspaper report that an AEC Matador ‘assisted' in the recovery – did it actually take over and do the towing for the short journey that was left?
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Offline Sentinel S4

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Re: Landing-Craft accident, Railway Street, Chatham - 1953
« Reply #359 on: May 09, 2013, 22:23:22 »
First rule: Cover your backside.

Second rule: Make it plausible.

Third rule: Make the speed reasonable.

Fourth rule: Try to work out a sequence of events for the Police Note Book.

I believe that the drive allowed the rig to get away from him. It is easily done, both of us have had it happen. He had an unbraked trailer on a draw bar going down a fair hill early on a cold, damp Feb morning. I believe that it just got away from him. As you say "Sorry Guv, the brakes went". Oh yes, "and the trailer had a snake on, really there was nothing I could do". Brake fail is the oldest excuse in the book when something like this happens, today though it does not carry much weight with the Law as they can down load every thing onto their computer and see exactly what the driver was doing for days prior to the accident.

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Offline mikeb

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Re: Landing-Craft accident, Railway Street, Chatham - 1953
« Reply #358 on: May 09, 2013, 22:11:23 »
Quote
I have just re-read what I said about the striking of the bus. That would account for the load breaking free as this blow would have wiped the ropes off of the LC.

S4, you have pre-empted something that has been going through my mind and has been puzzling me, as mentioned before. The photo shows substantial damage to the front off side of the bus. The report states that the bus was spun around and there was damage to the SIDE of the bus when it came into contact with the LC. We know the bus was re-built and instead of retiring her along with her sisters, M&D got another five years use out of it. The bus was in New Cut, standing at 90 degrees to Railway Street. The LC must have hit the bus at quite a speed to do this damage and turn it in such a way. The bus would come in at approx 8 / 10 tons, depending on how many passengers were on board. Perhaps Peter can give us an estimate at the closing speed of the LC to do this? And yet the LC et al has come to halt almost within its own length and a straight line from the corner of New Cut. What stopped it if not its own brakes / engine? The only thing it hit, it seems was the bus. It doesn't seem to have actually hit the viaduct.

What if there wasn't a brake or transmission failure at all? Is it possible the LC simply came down the hill under control, but too fast? On reaching the bottom our driver saw there was a right hand bend, perhaps the road was wet, realised he was going to hit the bus which was on the stop line of New Cut, braked hard but the trailer didn't follow the tractor exactly, the LC hit the bus a mighty bang and that plus the drivers action brought it to a halt. The drivers first excuse for miss judging the bend "sorry Guv, me brakes went".

Possible?

Offline Sentinel S4

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Re: Landing-Craft accident, Railway Street, Chatham - 1953
« Reply #357 on: May 09, 2013, 17:20:25 »
Most if not all lorries of any given era form 1940 on can easily out pace a car from a standing start when empty. I have done so many times with units from the early 1960's to the present (Vintage units before anyone says anything). Even a 100 horse unit can out pull a car from a standing start, up to about 20 or 30 mph. The last time I did this was in an admitedly modern unit with a trailer on and really upset a Porsche owner. These vehicles are geared much lower than cars. In bottom (1 st) you might get as much as 10 mph, in crawler you will be redlining at 6 mph. You have stated that with six gears then the maximum speed would be in the region of 35 mph. They were and are geared to pull.

Drag: If this was a chain drive as we think the there would be drag from the gearing between the wheel sprockets and diff sprockets (a huge reduction gearing right there). There would be drag from the diff gearing the the drag from the gear box. I am open to correction but were these not built with plain phosphor bronze bushes and not roller and ball bearings? There in itself is a lot of drag. You only need one of those to have a few thou extra wear and gear swapping is going to be a bit harder.

Engine Braking: HGV drivers are taught that the engine is your first brake. The foot brake comes second with assistance from the engine and gear box. Third you have the parking brake. If all else fails the you look for a piece of scenery that will slow or stop you without killing yourself (someone has to answer the inevitable questions and fill out the reams of paper when the dust settles).

Curve: I know it is extreme but ride down that hill on a double decked bus, or just go for a ride along a familiar road, and the corners seem much tighter and narrower. My other thought was to have suggested that you open the sun roof of a car and sit there but that is not safe so please don't try  :) :). The view changes when your bum is above what you are used to. In a car you generally sit below pedestrian eye line so you perception is some what different to when walking. However when your bum is above the roofline and well above pedestrian eyeline  the what seems a gentle curve becomes a tight corner. I think it is down to perspective.

You and the older driver convinced me that petrol would be a better braking option and now you are saying that this is not the case. If this was the big four pot 7.7 lump then why not? I know they did not have the best compression in the World but as you state it is down to the butterfly valve shutting of the air that did the work, same as it is a butterfly valve in an exhaust retarder doing the work from the opposite side.

Why on this Earth would he stop at the top of the hill? There would be no need to. He could see that it is a good metaled road and not some dirt track. He would have noticed there are bus stops so he would know large vehicles use it. He might have even tried to slow to allow a bus going the other way pass. As for ten seconds to find another gear, ten seconds is an eternity when you have fluffed a change (did it myself today, 2nd low to 8th high I nearly stalled. I meant to go from 2nd to 4th but caught the range change selector with my little finger. Oops  :). I do so love the Wandsworth one way system).

What if he came around the top corner at 12 -15 mph. He then decides that the hill is getting steeper so he automatically goes for a down change to 'gather it up'. Because of the wear in one of the bearings (plain) she is reluctant to engage and spits it back. He then ends up with a box full of neutrals (been there done that). By now the 45 tons is enjoying a 20 mph blast of freedom and this is rising. He jumps onto the brake pedal that hard it breaks the front push rod but leaves the rear in situe so he only has rear brakes on the unit. These are overcome by the 45 tons that is now really having fun at 30 - 35 mph when a bus heaves into view. In an effort to avoid ripping the front of the bus off he grabs a handfull of lock and manages to leave most of the bus intact but in doing this he compromises the load which decides to make a bid for freedom. However the bridge gets in the way and it all come to a shuddering halt..............

I think the reason there are so many views to this thread is our little battle of wills and words.  :)

S4.

I have just re-read what I said about the striking of the bus. That would account for the load breaking free as this blow would have wiped the ropes off of the LC. There is something we missed Old Friend.  :) :) :) :)
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Offline peterchall

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Re: Landing-Craft accident, Railway Street, Chatham - 1953
« Reply #356 on: May 09, 2013, 11:28:59 »
Again you are not really taking any notice of what I am saying
I’m not sure who it is who is not taking any notice of what is being said. Many posts ago you identified a point near the junction of Maidstone Road and The Ridgeway where the driver ‘lost it’, suggesting that he then had problems all the way down to the top of the final hill. You say that those men wrote the Rule Book on HGV driving – does that not mean checking that all is well before descending a steep hill, including stopping if necessary? After stopping, the only gear change possible is UP! I asked whether it was less likely that he would miss an up-change than a more difficult down-change, and if it was reasonable to spend 10 seconds trying to find a gear? Reply awaited.

A little education needed for my next riposte
I’m not sure where that education should be directed. First let me explain that because a tractor has to pull 5 times the weight that a car engine does, it does not mean that the gear ratios are multiplied by 5 – that would mean that it could accelerate at the same rate as the car and have 1/5th the maximum speed! I can explain how gear ratios are chosen, if you wish.

The figures you quote are for cars under power – we are concerned with their engines being used as brakes, a totally different concept.

A 6-speed gearbox, whether designed to handle the 90 bhp of a car or the 450 bhp of an HGV, has the same number of rotating parts, all carried in ball or roller bearings, and the HGV unit won’t be all that much harder to turn – definitely nothing like 5 times as much.

The drag is enormous, why do you think that we STILL down change when slowing?
All I can think of is to take advantage of engine braking and thus save brake wear. It has nothing to do with gearbox drag, because all the same parts are rotating, whatever gear is engaged, so drag is unaffected.

It’s fairly easy to get an idea of the resistance provided by a vehicle’s transmission. Find a variety of bits of sloping ground and release the brakes in neutral – the gradient of the bit on which it just starts to roll equals the transmission drag. For instance, my drive has a gradient of about 1 in 20, and a vehicle will roll freely on that, so I know that its rolling resistance is less than 1/20 = 5% of the vehicle’s weight. So perhaps my assumption of up to 2% for rolling resistance should have been more like 4%. But even that is only 8% of the retardation necessary from the brakes to pass the MOT, and about 5% of that of an emergency stop. But I suppose every little helps and relieves the load on the brakes, making fade less likely.

However, a modern artic with gearboxes totalling 16 gears has 16 pairs of gearwheels in mesh, compared with 5 pairs in the average car, so the gearbox drag might be about 3 times that of a car – that is 3 times not very much, but with an unladen artic it will probably feel about 3 times as much as with a laden one. But (and this is another repetition of what has been stated before :)) it is irrelevant because this thread is NOT about a 2013 HGV.

You have got to get out of the car mindset
I’m in the car mindset because your research shows that the tractor had a 7.7 litre petrol engine and a car is the only valid comparison we have, there being, so far as I know, no petrol engined HGVs today. Also it might help our non-technical readers who drive cars to follow things better - judging from the read count, it is a popular thread.

I mentioned ‘hooning around’ an airfield in a AEC Matador to illustrate that in those days, if you could drive a car you could drive an HGV, and that wouldn’t apply today - it was not in any way intended as a claim that I could have driven the unit in this thread. You have yourself quoted many cases showing how difficult today’s HGVs are to drive. So, as I have stated before (the need for repetition again :)), to compare today’s HGVs with any vehicles of the 1950s is not valid. Can I suggest that you need to get out of the modern HGV mindset :)

The camber is a little off and that curve is much tighter than it looks.
I’m not sure how one can tell how a curve is much tighter than it looks, but can say that, measured as accurately as I can from GE, the top curve is about 95 feet radius and the bottom one about 160 feet and is the basis for my assumptions on what might have happened to our LC on those curves. I know you have doubts about theory, but I used the same (very simple) formula used by traffic and railway engineers in determining the elevation to be given to a bend in a road or railway.

However, if the CG of your artic is on the centre-line and 8 ft above the road, you could take the top bend at 26 mph and the bottom one at 34 mph. Allowing a bit for adverse camber, a bit for the ‘this seems too fast’ factor, and a bit for ‘peterchall's assumption error’, I reckon 15 and 20 mph on those bends would be about right. But, again, this thread is not about today’s artics!

I am sorry Peterchall but your assumptions are wrong.
I have no doubt that some are, and I have no objection to being told that, especially if accompanied by a reasoned explanation. It would also be nice to get a message of agreement now and again, especially if I have asked “is that so?” etc :)

Anyway, back to the theme of the thread: It now looks to me as if brake fade was unlikely.

Where to next? Brake failure, as in the original report?
It's no use getting old if you don't get artful

 

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