His Lordship`s Horse

Woddle, run my bath would you and please fend off any more of those infernal complaints about that creature, if it`s not the staff it`s the villagers.  He`ll be sold and that`s that, they must understand, there`s little else I can do.

Yes, Your Lordship, I`ll see to it straight away.

What, the bath or the villagers?

Both, Your Lordship.  We all know Your Lordship cannot be held responsible if the animal has to go. If it cannot run well enough and earn its keep, then it has no use.  I`ll speak to the staff about it myself, I`m sure they will see what has to be done. After all, they should be grateful to Your Lordship for all he does, not just for them but for the village as a whole.

Thank you, Woddle.

Your Lordship.


                                          ++++++++++++

What did `e say? I suppose `e`s still adamant the poor thing will be sold.  What`s it to be then Mr Woddle, French meat and German glue?  It`s been with us a long time has that one, those of us that`s been 'ere a year or two remember `im as a foal.

Oh, the old bugger won`t budge, you know him as well as I do.  That poor horse has given his best but now it seems that`s no good.  Bred to win, they said, and just because he`s not winning he`s out.  Fodder, just like the rest of us.

Now young David`s back from university, `e`s doing something about it.  Loves that horse, `e does, loves `im. One of us that boy, despite the rest of 'em; you can tell by the way 'e drinks `is tea, uses a mug, `e does.  And `e takes the bus everywhere.

That`s because he`s disqualified.

From using a cup?

From driving.

Well he could get driven about, like them.

Not since they had to sell the Rolls, he can`t.  Even the Mini had to go. That`s why an old horse doesn`t stand a chance.

Got up a collection, that`s what `e`s done. Nearly everyone from the village has put in, there`s enough to give the old fella another go.  Proper training that`s what they says `e needs.

The old fool will never allow it, not if he`s already made up his mind.

                              +++++++++++++++

A large scotch, please Woddle.

Yes Your Lordship.  Is the temperature of the bath acceptable?

It`s fine, thank you Woddle.

The cook tells me Master David has got some money together, from the villagers, that could give the horse a reprieve.

Has he by George.  In fact, most of the arranging done in The George, no doubt. Well, if that`s what the boy wants, and he`s got the money to do it.

Yes, Your Lordship.

You don`t sound too sure, Woddle.

I can`t help feeling that in his Lordship`s father`s day neither the villagers nor the staff would have been allowed any involvement in the matter. Your people have been the prominent family around here for centuries and I wonder whether this will give ideas to them that should know their place, if Your Lordship knows what I mean.

                                   +++++++++++++++++++

There`s a few that knows horses says e`s got a good chance, maybe even Ascot next year.

Really, I had no idea the horse was that good.

Oh yes, Mr Woddle, `e`s a thoroughbred, sure enough.  Plenty of people been sniffing round since they heard 'e might be up for sale, proper racing people.

Not from the Glue factory, then?

Well, you know what peoples like, scare mongering, they say things like that to get everyone going.  No, `e`s a gooden.  No one realized it `till young David started putting the word out and people got interested.

                                    +++++++++++++++++++++

Your Scotch, Your Lordship.

Thank you, Woddle.

They say the animal has potential, Your Lordship, there`s even talk of Ascot if he`s trained properly.

Ascot.  They did say his parentage was good, I just didn`t bother to find out.  Maybe he is better than we thought.  Enough money to keep him and train him properly, you said.

Apparently so, Your Lordship.  And plenty of prize money to come if they are right.

Yes,  but of course it`ll have to go to the villagers.

It`s Your Lordship`s horse. The villagers will expect a little something, but they will never understand its true earning potential.  A valuable animal like that could help enormously with the finances and this house needs money. Think of it, Your Lordship, fewer taxis, more staff, more wealth, more ... of everything.

Quite right, Woddle, we must keep it, tell the villagers the creature is safe with us.

                                       ++++++++++++++++++++

Looks like he`ll retain it after all.  Mark you, if it doesn`t start winning it`ll be gone in a shot. And don`t think the villagers will see any of the money, or us, for that matter.

Thank you Mr Woddle, for all you`ve done. I know you would `ave `ad a word with `im, `e listens to you.

I suspect Master David will be pleased.

Wouldn`t be surprised if `e wasn`t down The George right now, workin` `ard on `is strategies.  I`ll phone and give `em the good news.

                                ++++++++++++++++++++++

Your bottle of water, Your Lordship.

Bottle of water? I can`t remember asking you to bring me a bottle of water, Woddle.

Oh yes, Your Lordship, as I was leaving His Lordship`s bathroom after bringing up the scotch, I distinctly heard His Lordship say, “whataboutawaterbottlewoddle”.

Trajectory

It seems strangely old now.  Not because of the fading, wrinkling paint but because it just looks all wrong.  The tyres are like something you would fit to a cart and the mechanism that tilts the barrel is too simple, too brassy yellow, too mechanical and outdated.  The whole thing is tired, feeble and irrelevant.  In its day it was considered a formidable weapon; new and interesting. Capable of launching a four-pound shell over a couple of miles, it could make itself known. Have this, it said, it`s something special. It was once proud, now it`s just there, and strangely old.

I haven`t seen the rest of the crew for years, not since just after the war ended when we got together for a few pints before being demobilized. I suspect they`re all dead now.  I`m in my late eighties and that`s unusual for our generation – the wartime smokers and drinkers, half starved but still managing to chase around, staying out all night if the chance arose.  We dispersed to different parts, the three of us, the other two going up North and me back to London.  Charlie had plans for his father`s building firm and Johnny was set on emigrating to Canada, to farm and raise a family in the Big Country, as he put it. We all talked a lot about what we would do after the war; it was what kept us going, our plans.

It`s partly the memory of those days that takes me on these outings.  But it`s also an opportunity to get out from behind those dreary old curtains, hemmed in by four walls with only my stale old photographs and the occasional visit by the Home Help for company.  The rest of them that goes along are alright and we have a bit of a natter, you know.  And the coaches these days are very comfortable, not like they used to be, and there`s every convenience – mind you, at our age you need them.  At one time I`d take off without a second thought, travel all over, as far and as fast as possible, slowing down only for my wife and kids, their wellbeing, their comfort the only things holding us back. But now, even though there`s only me, I stay put more.  It`s an effort to just get up in the mornings, sometimes.

+++++++++++

The gun, we were told back then, was a considerable feat of engineering.  We would learn how to load it, aim it and fire it.  I was in charge you see, I had the stripes, and it was my job to work out what angle to raise the barrel to.  Well, that`s not quite true, we were often given that information but I had to understand a little of the theory, that was part of my job.  The shell would reach its maximum velocity, or as we said, speed, as it left the barrel. Muzzle velocity they called it.  From then on it would slow and fall towards the earth.  The trick was to know at what angle you launch the shell for the distance you wanted it to travel.  It was called, by those blokes from HQ who taught us, a trajectory problem.

+++++++++++

The trip was out to an old airfield, now disused, where old tanks and guns from our time had been collected over the years and now formed part of a display.  A historic theme park, they said.  I sat next to a lady I hadn`t met before, although she was a regular, apparently, having lost her husband several years ago.  Marjorie, that was her name, born and raised in Derbyshire, had three children, five grandchildren and a long career in teaching behind her.  A bright young thing she must have been, and I bet she was once pretty, you could tell, and there was something in the way she spoke of her life that made you think she hadn`t stood still for long.  Her and the late `Mr Marjorie` had been keen travellers, they`d lived abroad teaching English and ran something like a small holding in one of the countries they`d lived; the only way, she said, to ensure a regular supply of food.  I watched the loose skin on her throat as she spoke and her wrinkled hands, as they made constant adjustments to her knitted cardigan, trying to imagine a young woman conquering the classrooms of Africa, or Asia, or wherever it was.  To be honest, it wasn`t easy.

+++++++++++

The path of a shell, I remember from the classroom sessions all those years ago, in terms of trajectory (we`d yet to consider actual direction) could be divided into two coordinates: the vertical and the horizontal.  Horizontally, it was being slowed by air resistance but we would ignore this because as it was airborne for such a short period of time there shouldn`t be a significant effect. So, as far as the horizontal was concerned the speed was constant.  Vertically, it was a different story: gravity was forever trying to bring it down to earth.  This meant that the distance the shell would travel was given by its horizontal speed and the time it took before it hit the ground.  But, of course, it didn`t fall straight away, unless the gun was fired with the gun barrel horizontal.  First it would climb.

+++++++++++

I told Marjorie a bit about my life, and although she was probably at least 15 years younger than me she recognized the heart of it, the fundamental nature of those earlier years: getting on with things, mending, making stuff work and not wasting time complaining. I left the army and trained as a mechanic before chucking that in and going on the road with my own lorry. I had a mate who managed a local factory and I got a lot of work from them.  Soon, through the network of their customers, ones I was already delivering to, I got more work.  I put in the hours but didn`t mind.  I was my own boss and when our children came along, we, my wife and I, borrowed money to build the business and secure their futures.  It was risky, if we failed it would have meant years of debt and poverty, but we didn`t and soon there was a small fleet of lorries, our own yard and our own house.  I worked all hours, driving, managing, fixing, I did whatever was needed.  Crisis came and went; good times and bad.  We even did some continental work, when it was rare and far more of an adventure than it is now. I once spent weeks stuck in Greece because of some dispute or other, virtually living under the trailer.  I was even arrested in Germany and spent a few days in a police cell before being released, a few quid lighter and all over some stupid traffic law of theirs.  But I took it in my stride, shrugged it off, moved on.  It didn`t seem five minutes before my own son came of age and came on board.  He became the driving force, carrying on when things seemed to be changing so fast and I could no longer keep up.  He still runs the business but it`s nothing like it was; I wouldn`t recognize it now, it`s not even in the same yard.  They have all the modern technology, all the computers and things.  He uses words I don`t understand.  Telematics, I thought, was a kids program on the telly but apparently it`s all to do with being able to see what the lorry`s doing without involving the driver. It beats me, I can tell you.

+++++++++++

The instructor drew a large arc in chalk across the board, representing the path of the shell, and then vertical and horizontal arrows that originated at the point the arc started. It looked something like this; although, as you can see, I`ve used a bit of colour.

He wasn`t, we were mightily relieved to find out, going to go into the maths but this was not, he said, a big issue as it was all essentially intuitive.  Launched at an angle to the horizontal the round would have part its velocity travelling in the horizontal, as already explained, and part in the vertical.  The proportion of which dictated by the angle itself: the steeper the launch angle the greater the vertical element of its velocity. Gravity is a constant force, so the acceleration pulling the round down will be constant. From the muzzle velocity we could establish the vertical speed and then calculate the time it would take for the round to reach its maximum height and fall to earth, all the while, we were told not to forget, it would be describing an arc.  Even as the round climbed, its vertical acceleration would be negative (as would its horizontal one if we were not ignoring air resistance) slowing it, dragging on it until it finally started coming down.  While it was doing all this the shell was being carried along by its horizontal speed until, of course, its time ran out and it hit the ground.

+++++++++++

We walked around the exhibits, for want of a better word, had a cup of tea and a sandwich in the cafeteria (too much noise: people can`t eat these days without constant chatter and background music) and then headed home.  In the coach a film was playing on the television screen at the front.  I could hardly see it let alone hear what was being said, but because it was on I couldn`t hear Marjorie properly either, so I closed my eyes. I was tired after travelling so far. Slowly, I sank further into the seat.

    

Jubilee Cerebralation

I wonder if Her Majesty the Queen sat on the throne as the morning of her Diamond Jubilee approached and pondered the mental capacity of her governments, both past and present; I know I did.  She of all people will have realized that just because someone has had a privileged upbringing it doesn`t naturally follow that they are clever.  With all due respect, she only has to look to her own progeny to see that although public school and university can fill a head with facts, it`s the capacity of the brain to manage, interpret and apply them that`s important – that rare ability to assess and come to the right conclusions, and then make sound decisions.  I suppose we must be grateful that her lot can`t do any real damage. But the same can`t be said for some non-royals, where the superiority engendered by public school combined with knowledge and limited cerebral capacity can be such a dangerous cocktail. And if she was thinking along those lines, she will have had little choice but to be reminded of all those Prime Ministers that have kneeled before her.

Didn`t they realize, Her Majesty will have asked herself, just as I did,  that economic weakness continuing over decades must have a root cause. And if they couldn't get their heads round that simple fact, how in the name of the future king are they going to deal with the number of other important problems the country has to face.

The Queen was no doubt thinking, as I still do, that countries that do really well, all round, are those maximising their resources.  Australia mines precious metal, sheikdoms in the Middle East drill for oil - and Germany retains a skilled manufacturing base. When Prime Minister Blair was planning to solve this country’s problems by sending 50% of all school leavers to university, Germany was sending 67% of theirs into apprenticeships.  While we allowed Foden and ERF to be sold abroad, losing control of the future of hundreds of jobs, BMW were deciding on how British workers would fit into the German economy. (The same deliberation TATA now has to make on behalf of India.) By not being totally reliant on one particular area of business, the Germans have maintained and spread their assets, and survived the better for it.

Our eggs, The Queen will have lamented, as I have on so many occasions, all seem to be in one basket, our resourse of established industries supported by a skilled workforce ignored. In her reign she will have seen British companies using British made machinery build large parts of the world that we know today.  She will have seen roads filled with British vehicles of all descriptions and she will have seen a significant part of the workforce occupied in manufacture.  Now, only 15% of business in the UK is in manufacturing; we are almost totally reliant on the service and financial sectors. The result of successive governments following the free market principle of natural selection is that we have had to spend billions of pounds of public money bailing out banks in order to save our constrained economy. This last ditch measure is the result of years of poor thinking and mismanagement - similar measures taken years ago with the manufacturing sector would have saved this country at least some of the pain it`s going through at the moment. While millions in the UK remain in poor employment and vast numbers of young people exist without the hope of a future let alone training, the banks, because they`re all we`ve got left, attempt to increase their reserves.  And as we pay for benefits and bail-outs, the rising economies in the East hunger for the produce of manufacturing: the machines and merchandise needed to build a modern infrastructure.    

We are not pleased, I hear Her Majesty say, speaking for the two of us, and demand better governance by truly clever and capable people. We demand a policy on business, not just a short term strategy.  We demand a larger manufacturing sector with appropriate skills training.  We demand long term, full employment. 

I waved my Union Flag on the Sunday of the Queen's Jubilee parade, watching a procession of the country`s elite escorted by German built police cars and motorcycles. But I didn`t wave it for them, not any of them.  Well, except one.  

Horse

It wasn`t my first truck, and it certainly wasn`t one I would have naturally chosen – it just sort of came along. I had been running an ERF up until then but things between us were getting a bit tense to say the least. Basically the old girl was under powered - not a crime in itself, especially when refuelling, but annoying in the long term - and she had let me down on more than a couple of occasions, which was, I forced myself to admit, unforgivable.  I have always accepted the diesel ingrained in my skin (a situation dating back long before barrier cream and then latex gloves became compulsory), in fact, at one time, I wore those black, ingrained fingernails with a certain amount of pride.  However, that particular ERF tested my apathy towards dermatitis to the limit.  We had spent a lot of time together: all those sunny days and open roads; misty mornings and muddy lorry parks.  I loved the feel of her.  I loved sensing her engine power as the revs climbed and fell every time we accelerated away from traffic lights or when we climbed a hill.  I loved the touch of the non-syncronised gearbox, the way each ratio fell into place at end of that long lever - and the satisfaction of getting gearchanges right.  There`s nothing like driving a loaded artic, especially one you feel connected to in such a way.  Every vibration, every change in road surface and engine note, sent a sensation of raw oneness between me and my machine.  What she felt, I felt and it was great to have such attachment and control.  And every night I would check her over, making sure nothing needed tending to before the following day – bedding her down, I used to call it. Over the years, and like this, we`d wound our way North and South, East and West.  Then, as if it had crept up on me without warning, I came to realize she`d become tired and was no longer up to the job.  

So there it was that remarkable new truck.  Air assisted throttle, gear change, clutch – everything.  Synchromesh gearbox with 16 ratios, power assisted steering and, unusually for that time, a big and comfortable sleeper cab.  I had never seen anything like it, and had certainly never even considered one before.  It was my first Volvo, bought after a chance encounter, and it became the first of many.  The trucks were quite simply the right tool for job.  Driving became less tiring, less painful and, I suppose, less challenging.  It was easier and in a world of increasing legislation and traffic, it helped.

After that I`d almost completely given up on British machinery.  Although I ran a Ford van there was little else British built to choose from, both on four wheels or two. Triumph and Norton motorcycles were all but dead with only a few diehards buying what was left coming from the factories.  By the mid eighties I was riding a BMW, a flying brick; unbreakable, solid reliability that carried me for miles.  The bike was equipped with factory built luggage, a smooth, four cylinder engine, and controls so brightly coloured they looked like something out of a sweet jar. But it worked. It was easy to use and I loaded it, rode it, serviced it occasionally and hardly ever checked anything, apart from the tyres (on any motorcycle, you`re a fool if you don`t).  Shaft driven and bullet proof, it offered soulless reliability.

In 1987 I took it to Spain, crossing on the ferry from Plymouth to Santander, and then rode back across France to Cherbourg. Through the Pyrenees the BMW performed faultlessly.  Nothing phased it.  Rain one day covered the whole lot, me included, with a pasty yellow mulch thrown up from the road.  I jet washed the BMW off at a B&B that night and never gave it a second thought, or a dose of WD40.  In the intense heat of the lower levels, I suffered; the motorcycle didn`t. For me, that motorcycle and my Volvo truck heralded a new age of disconnected technology – they did their thing, I did mine.

In the Pyrenees I stopped one night in a small village I came across nestling in the rock and scrub of the mountains.  Cottages, shops and bars ran down each side of the road and I could see huts jotted about in the hills above.  A small stream ran along one side of the road.  I booked into a B&B and went into an adjoining restaurant for a meal.  No one spoke English and to my shame I spoke little Spanish, so everything was done with the universal sign language of hunger and thirst.  The food was apparently locally sourced, so it was meat and no vegetables - and a beer. When I had finished and I went to the counter to pay, a hairy individual, probably of similar age to myself, and not dissimilar in appearance, turned to me and in the recognizable accent of an Englishman said, “Is that your machine out there?”  And it was those few words that started a bar crawl.

He had gone out there in the 60s, when free love and flower power were `in` and the cool thing to do was to `drop-out` in sunnier climes like San Francisco – and Spain.  Post Second World War Britain was captivated by the memory of war, which became associated by the next generation with the establishment, restriction, discipline and duty.  Traditional values were rejected and a contrasting ideology emerged of colour, love and personal freedom; a revolt was almost inevitable. We walked from bar to bar as he told me how he lived in a hut in the hills with no electricity or running water.  Everywhere we went he was greeted like the old eccentric he probably was, and at each bar we drank a thick red wine, because, he said, it was cheap.

In one place the elderly matriarch of an owner took a special, and on first appearance, disapproving interest in him.  When I asked about what she was saying, he told me it was just fuss about his drinking and concern that he should look after himself better.  She had known him since he first arrived, all those years before, in that small village, the place he`d not moved from since. His lifestyle obviously hadn`t changed despite his age, although the ideology, I felt, was long forgotten: drink, odd jobs and his little shack on the hill seemed to be a cruel destiny for one who must have had such a clear dream.  The rest of the village had moved on with the world.  The villagers dressed fashionably, casually; they travelled outside the area to work. I looked closely and saw that almost every one of those road side cottages had a satellite dish on the roof. When I left him to return to my accommodation, my new friend staggered off alone; the rats in the sewers couldn`t have looked more dishevelled – or less miserable.

My current motorcycle was not one I had thought I wanted.  I`d been looking for something a bit different, and then found it.  Touring motorcycles had become cumbersome, over stacked with delicate looking fairings and luggage. I wanted something capable of racking up the miles but also one that could cope with the rough and unexpected tracks of Spain and beyond.  And one I could ride on those days I wasn't out working the Volvo.  I looked, inevitably, at BMW GS adventure motorcycles but they were bulky and dated.  Then I came across a Triumph dealership and went in to browse.  I walked out with a receipt for a Triumph Explorer.

I love the way she pulls instantly, something to do with the ride-by-wire technology, as well as the torque developed by her 3-cylinder, 1215cc engine. Switchable ABS, traction control and cruise control make her a joy to ride, while giving me a certain amount of control – and a feeling of security.  Virtually maintenance free shaft drive, a higher performing generator for those electronics, and off road capability; she`s a beauty. I wash her and get the polish and WD40 out, not always because I have to but because I want to. It beds her down for the night.   

Building a Scania R500 - Part 6. Tyres

I`m building a Scania R500 - from a 1:24 scale kit produced by ITALERI. 

I`ll be looking at aspects of truck construction as I go along, hopefully highlighting some basic truck technology.  It`s easy to think that modern vehicles bear no resemblance to those of the past, but that`s not true.  Suspension and steering; engine, transmission and final drive; and tyres are all there to maximise the laws of physics, and have retained the same configuration since diesel replaced steam.  Cost and natural performance limits have meant that the chassis abandoned long ago in car design is still used in truck manufacture.   Yes, your truck is computer controlled and a modern marvel;  but so is the modern cruise liner - which is still a Titanic underneath.

Building a Scania V8 R500 Part 6 - Wheels and Tyres

Tyres are probably the most important component of any vehicle.  As strange as it may seem, like all that electronic wizardry, tyres are complicated bits of engineering. They also comprise a number of different materials.  All the digital technology and hardware that`s now a part of any truck, works on small patches of rubber in contact with the ground. 

Tyres will have a number of different rubber (elastomer) compounds and, maybe, rayon or nylon used for the ply, as well as steel cords. With tyres, the critical points are:

• Most modern trucks use tubeless, radial tyres fitted to one piece wheels
• Two or three piece wheels are usually used with stiff, cross-ply tyres for ease of fitting. (These wheels are found on military trucks used in the field or those operated in remote areas where tyre fitting has to be done by the vehicle's crew.) Wheels split in this way need inner tubes
• correct pressure is very important - heat destroys tyres, and it has to be created.  In short, low pressure shortens a tyre`s life and uses fuel
• correct fitting and balance ensures correct service life. 
• cross-ply construction is not shown on a side wall.  Radials are marked R or radial (bias-belted, B or bias) 
• Inflate a newly fitted tyre in a cage or a van - tyre fragmentation at 140psi can kill
• bits of tyre on the hard shoulder of a motorway are not necessarily from remoulds, they will probably be from a poorly maintained tyre that`s got too hot 
• Aspect ratio or profile is used to alter a tyres performance.  There are disadvantages to low profile tyres but the advantages are many.  These include: load bearing, handling and weight.

Wheels fitted to most modern trucks are one piece construction and dished between the rims (wells).  The dish shape ensures that tyres can be fitted, i.e. one bead is dropped into the well, allowing the tyre`s other bead to be brought across the wheel rim.  In the past, with very stiff cross-ply tyres, two or three piece wheels had to be used.  Some special applications still use split rims or two piece wheels for ease of fitting.  However, these are usually on vehicles used out of the range of a professional tyre fitter.

Radial ply tyres are found on all road vehicles these days - even motorcycles and trucks, where cross-ply tyres or bis-belted tyres were once used.  Radial ply is at 90 degrees to the bead (straight across inside the tyre`s rubber) and runs cooler than cross-ply construction.  Heat uses more energy, so creates higher rolling resistance, and destroys tyres.  Radials last longer and use less fuel.  They are not as tough as cross-ply tyres, so are not always used on heavy duty/rough terrain applications.  Radials handle most dynamic forces better. 

Side wall markings include size information in metric and imperial.  This radial (R) tyre has 22.5 inch wheel. Lower aspect ratios have many advantages including better handling but they also reduce the suspension effect of the tyre.  With trucks they are sometimes used simply to lower the overall height of the vehicle. Other side wall markings may include European load index numbers and speed index letters.  US weights are also shown on some tyres.  A DOT stream of numbers relates construction and ends with a number that indicates the tyre`s age. E.g.  2012 means the tyre was made in the 20th week of 2012.

Aspect ratio (profile) is a very important part of a tyre`s characteristics.  Care should be taken to match tyre sizes properly as increased stress can be induced in incorrectly paired units.  When radials replaced cross ply tyres, the advantages were similar to those now offered by lowering profile.

Aspect ratio is a simple calculation

Next:  Part 7 -  Brakes

Stopping

I read a magazine article this week where a journalist attacked the stopping distances quoted in the Highway Code.  Modern braking systems and tyre compounds, he claimed, have shortened the distances in which we can bring our vehicles to a halt.  The whole thing, he seemed to be suggesting, was so out of date it was next to useless.

Yes, I thought, braking distances for some vehicles may have shortened, but the overall picture is not quite that simple.  The Highway Code may be old in detail but the general message still holds true.  Here`s why.

The Highway Code uses a short reaction time (0.7 seconds). 

The distance a vehicle will travel while the driver reacts lengthens as reaction time increases.  Most drivers take a little longer, in fact on a motorway reaction times can reach 1.5 to 2 seconds. 1 second is considered a reasonable representation, but by no means average.  Coefficients of friction between the tyres and the road have increased with modern compounds and construction.  The Highway Code uses 0.65, which is no longer typical for most cars - they can now exceed 0.8. Many trucks and buses, however, still have tyres that only achieve about 0.65. 

A speed of 30mph is used for the calculations above. The deceleration rate and reaction time calculated is the same for all speeds quoted in the Highway Code.  The figures for s, reaction distance of 9 metres and braking distance of 14 metres, are taken from the code.



The Highway Code stopping distances compared with those representing greater tyre friction coefficients and increased reaction times.  

The end result is similar stopping distances.  It should be noted that impacts that occur at the same point along these distances will vary in speed between the two sets of graphs (e.g. at 50mph, the Highway Code figures show the vehicle braking before 20m has been covered. With a longer reaction time, the driver doesn`t start braking until after 20m).  The dotted line on the Highway Code graph illustrates the squared relationship between energy (work) and speed. The braking distance (red) at 60mph is about 4 times that of 30mph, despite the speed being only doubled. 



Building a Scania V8 R500 - Part 5. Drive

I`m building a Scania R500 - from a 1:24 scale kit produced by ITALERI.

I`ll be looking at aspects of truck construction as I go along, hopefully highlighting some basic truck technology.  It`s easy to think that modern vehicles bear no resemblance to those of the past, but that`s not true.  Suspension and steering; engine, transmission and final drive; and tyres are all there to maximise the laws of physics, and have retained the same configuration since diesel replaced steam.  Cost and natural performance limits have meant that the chassis abandoned long ago in car design is still used in truck manufacture.   Yes, your truck is computer controlled and a modern marvel;  but so is the modern cruise liner - which is still a Titanic underneath.

Building a Scania V8 R500 Part 5 - Driveline

All vehicles use diesel (DERV - diesel engine road vehicle) power.  Modern engines utilize extremely high, common rail fuel systems, where injectors are opened electronically - as opposed to the older, lower pressure systems that used fuel pressure created by the injection pump to open injectors.  Exhaust gas driven turbos, used to increase are mass in the combustion chambers, are common.

All gearboxes are conventional, synchronized, manual types but many have automated clutches.  Manual boxes are often 4-speed with additional input and out put ratios (range-change and splitters).

After the gearbox, the driveline comprises: universal (Hooke`s) joints; splined joints; differential; half-shafts:

Prop-shaft has a universal joint (UJ) at each end.  And a splined joint somewhere along its length

Looking at the UJ at the back of the gearbox.

The centre of the UJ, the centre cross.  The joint is based on this small component.  UJs are needed to allow for change in direction of the prop-shaft.  A UJ is not, however, a constant velocity joint. 

The prop-shaft angle will change as suspension deflects, so its effective length will change in addition to its angle.  A splined joint allows for this extension.

The `diff`is the housing that contains the final drive crown wheel and pinion gear as well as a differential.  Differentials are necessary because the rear, driven wheels will not always run at the same speed (when the vehicle is cornering). Bevel gears rotate in the spider attached to the crown wheel.  Half shafts are splined into the spider.  If one half-shaft slows compared to the other, torque is transferred to the other shaft, via the bevel gears.

Next  Part 6 - wheels and tyres