Roadholding and Handling




Cornering power describles the relationship between a tyre's slip angle and the cornering force it is developing

  


There is a finite amount of friction available to a tyre, illustrated by the 'Friction Circle'

 

   




When weight is transferred across an 'axle', a net loss of cornering force results

  



Anti-roll bars reduce body roll ...

 



... but stiffen the suspension as the body rolls - transferring weight across the 'axle'

 

Footprints

It’s years since I’ve read Daniel Defoe’s, Robinson Crusoe, the story of a shipwrecked beard; although I do remember, as a child in the 1960s, watching a TV series based on it.  Or should I say, I remember listening to the theme tune.  When it started it was like nothing you had ever heard before; a sort of wailing that seemed to build in the first second or two, as if someone had forgotten to plug in the record player. Like when you hear a car skidding - a screech that at first you think, ‘What’s that’, and then in a moment it’s full on and you recognize it for what it is.

It was like Crusoe himself: I mean, there was definitely something  lacking at first. When he arrives on the island, Crusoe walks along the beach until he sees footprints, and then thinks someone else is there too.  Surely he must have known he was smack-bang back where he started and the prints were his.  I couldn’t understand how he let himself think he wasn’t alone.  What about the sun? Didn’t he see that because its position appeared to change in respect of his direction of travel he was actually walking around an island? 

And then, by way of explaining his idiotic behaviour as some natural desire not to be alone, Friday arrives. To me, Friday was simply another inexplicable anomaly. Crusoe was so pleased when he finally got a companion.  Why?  All I wanted for him was that he would build machines to pass his day, to ease his life, to give him fulfilment, to make the most of his freedom – not spend his time fussing around with another person.  

There's a rhythm to the story of life and we all have an individual beat to go along with our own lyrics; a rhyme that resonates for us and us alone. Mine has always been the wonder of making things; and my music is engineering. All those years ago I would walk around our family garden thinking of all the things to construct and discover, imagining that I was alone on a desert island - while my mother implored me to put my socks and shoes back on.

I wondered what would have happened if, as a castaway on the island, I had a car, or better still, a truck. I could run lights for my cave off its alternator; attach drive belts and pulleys to its wheels; move great objects with it; haul with it; escape in it; hide in it.  I could even drive round the island to make sure I was alone.  Today, I look back with longing at the simplicity of those childhood dreams and invention. Now I know that things are more complex and if I had a truck, and I drove it round the island, I’d be considering the tyres and what was going on with their footprint.  My mind is too cluttered and my imagination too conditioned for the romance of adventure.  Knowledge has marooned me in a suit and tie.

I would be thinking, not of natives, cannibals and cutlasses but of forces, slip angles and hysteresis. Tyres, I would say, are viscoelastic and exhibit behaviour that`s not quite plastic.  Cornering power, inflation pressure and vertical load, are all connected with tyres, grip and the type of road. And I’d think that if the beach were a road, it would generate not only mechanical grip but adhesive grip as well.  Like when sellotape is stuck onto a smooth surface - a desk, for example.  I’d probably imagine molecules in the tyre and road being attracted to one another and how the tread pattern would be trying to disperse water and make sure nothing got between the two surfaces. I wouldn’t be able to get friction out of my mind.

Mechanical grip would also be there; right there at the front.  I would be seeing in my mind’s eye the tyre slipping on the road as  it rotated onto its footprint.  Every time, its direction of travel being different from the direction it was pointing.  I’d see how the tyre’s carcass and tread deformed and then recovered at the footprint, as the truck cornered.  I’d know that this recovery rate was different to the deformation rate and that’s how the tyre clings on, mechanically.  Materials, they’d be there as well, swirling around my brain: what’s best for tread and what for carcass. High hysteresis; more grip but more heat.  Cross-ply construction, more internal friction but stronger; radial ply, less heat and lasts longer.

When I cornered around the island, I would know that weight was being transferred across the truck and that its cornering power was being compromised.  Grip is increased as vertical load is increased, but the loss on the unloaded side is greater than the increase on the loaded side. All that scenery; those palms and white sands wouldn’t register, as I pondered the question of inflation pressure. Higher pressure, less slip; lower pressure, greater grip.  A tyre possesses a finite amount of friction - use it all for cornering and there’s none left for traction.  Lift-off oversteer, yaw rate gain; nothing will ever be quite the same. 

Sitting at my desk and thinking of those uncomplicated days in our garden, I know there`s no going back and that in the rhythm of my life the music is now softer and almost every word has changed. Footprints in the sand soon disappear. 

          

The Perfect Form

The outer casing must be loose fitting and flexible enough to allow for plenty of movement, and be reasonably tough. The materials used should provide warmth and be very dark in colour, so that mud and dirt will not show. The coating will need to be soft to the touch and such that it can be brushed out to allow the removal of accumulated dust. The frame will be broad and strong, providing sufficient room inside for the apparatus that will power this formidable creature. The body needs to be set on strong, powerful supports that are themselves positioned on large pads so that a high level of stability is achieved. A broad head must be built with eyes that are dark in appearance, so as to complement the coat, but be bright in every other way. The nose will be sensitive to all scents and smells, no matter how faint, and the mouth strong, its bite firm.

The head should be filled with a large brain capable of clear thought and appreciation. Additional powers will be built-in that are beyond the scope of this description but can be summarized as ‘psychic’. The brain must have the facility to switch off peripheral thought and apply all its energy to a set task, usually determined by the brain itself (for example, chasing a pheasant in preference to walking to heel). This attribute will manifest itself in considerable bravery which, when alloyed to an immense sense of loyalty, can only be considered as being beyond price. The propensity for loyalty combined with the independence afforded by self belief will result in an interesting attitude towards affection. Basically, attention will be gratefully received and returned, but at arm’s length. Lap is a word associated with drinking not sleeping.

The physical appearance should be such that any reasonably sighted person would describe it as being beautiful, and such that it would bring a smile to the most ardent dog hater’s lips. This is achieved by every aspect of the form being in perfect proportion and of ideal size. Faultlessness in looks is reflected in physical performance, and unprecedented power will be on tap at a moment’s notice.

If you manage to put such a thing together or you have a Black Labrador that you recognize from this description, then you are surely blessed.

Vera: Black Labrador bitch. Born Dec 1996, Modbury, Devon. Died May 2012, Exmouth, Devon.

This 1978

 In 1978, we did it like this:

 


We tied knots in ropes, like this;

  



Our hands were grimy and rough, like this;



We hauled sheets up on to the load and roped them, like this;

With a fly-sheet on top, like this;



Not roped, so water was thrown off, like this;







And on cold mornings we coaxed those bloody Gardners into life, like this.

  

2010: A Good Year

Every thing has an opposite. There is matter and anti-matter, day and night, hot and cold, fact and…

January

The year starts with a call for ‘sensible control’ with regard to lorry drivers' pay. Although, according to The Times, it should be remembered that attractive remuneration packages are the only way to attract the very best skills, there is mounting concern in some quarters about these six figure sums. High wages, the paper argues, could lead to an unrealistic opinion of self worth that encourages arrogance – for example, if similar payouts were made to bankers, it says, all sorts of problems could arise.

February

In the House of Commons, Prime Minister’s Question Time erupts and the Speaker has to warn both opposition party leaders as to their conduct. The Liberal-Democrat Prime Minister, Lembit Opik, had commented on the proposed Labour and Conservative Party accord, the so called Torred Alliance, saying a government formed from such a liaison would probably see the country at war, violent crime on the increase and the price of essentials, such as diesel, ‘go through the roof’. The Labour leader, Mr Balls, had to be physically restrained as he denied any cooperation with the Tories and Lord Blair for the Conservatives, shouting to make himself heard above jeering MP’s, said that whatever government he lead, no matter what it was called, would be ‘true-blue, through-and-through’.

March

Overcrowding at some Truck Stops, particularly at motorway service areas, becomes too much for some drivers, who demand action on the matter. The problem is not the amount of truck drivers using these facilities but other people attracted by the luxurious surroundings and high quality food. Some truckers go as far as to suggest that the price of a two-course gourmet meal from the heavily subsidised menus should rise to at least one pound. This, they say, would help to keep out some of the riff-raff. It was stressed, however, that tea and coffee should remain free of charge.

April

The Millennium Cannon, one of the great attractions of the South Coast, is running out of ammunition and may have to close unless a substitute is found, official sources warn. Since its opening in the year 2000, the enormous gun, a tribute to British engineering, has fired over 5000 Citroen 2CV’s back across the English Channel to France. Now the vehicle is in short supply. However, it is hoped the attraction will be adapted to take the Renault Espace. In other news, the Renault Magnum is made an honorary British Lorry, a title bestowed only once before when the Volvo F10 became a Scammell.

May

The Congestion Charge is hailed a great success. The charge, levied on train operators that fail to provide services that are suitable and efficient enough to attract commuters off the road, has lead to significant improvements to the rail network. The resulting reduction in the number of cars travelling into some major city centres has brought about the removal of bus lanes. In London, the Mayor, Jeremy Clarkson, welcomed the general fall in traffic and announced that in order to assist commerce all bus lanes in the capital would now be for the sole use of lorries – and Aston Martins.

June

The very last MAN rolls off the production line and the demise of the Munich based company is mourned by the German people. Although, in the end, these trucks were simply badged ERF’s, the nation’s pride suffers. This is partly due to feelings running high over the resent shut-downs of both BMW and Mercedes Benz. The EC canvasses member states on how best to deal with these closures, but rejects a suggestion that the factories should be flattened and a victory parade held.

July

Once again celebrations are taking place throughout England as the nation’s victorious World Cup football team prepare to fly home after their 5-0 defeat of Italy in the final. Some pundits have speculated that this year festivities might be less enthusiastic as complacency sets in. However, we should never forget, says Sir Bobby Charlton, chairman of the FA and England Manager for the past forty years, that although his team has won every final since 1966, Scotland have been a close second on several occasions, so we should take nothing for granted. At Wimbledon, Murray beats Federer to take the men’s title, again.

August

The Truck Show season is well under way and excitement mounts as it is reported that a foreign built truck could be on show at Santa-Pod this year. Thousands of British enthusiasts flock to the site in the hope of getting a rare glimpse of a Scania.

September

A diplomatic row breaks out after it is announced that the parent company, Foden, will be closing a number of its subsidiaries in the US. Although the engine maker Cummins will survive, a Foden spokesperson says that, as most American drivers prefer Foden vehicles over indigenous makes, there is little else it can do. Foden’s closest rival in the US, Bedford, declines to comment.

October

Cross-channel ferry operators report brisk business as many trucks cross the channel to the UK just to fill up with diesel. Although all foreign registered vehicles are forced to buy road tax when they enter the country, the UK’s fuel prices are still the lowest in Europe – and low enough to make the trip worthwhile.

November

The Man Booker literary prize has been won by the European Union for its work, EU Regulation 561/2006. The judges complemented its style, “... a complexity that bordered, in places, on the incomprehensible. An essential quality in any Booker winner”, they said. The judges also liked the plot, enjoying the fact that, in the end, so many questions were left unanswered. This aspect, they commented, was the work's main attraction. The fact that some parts would be interpreted in different ways by different people was, “simply divine ... a delicious mix of contradiction and the absurd”. They loved the fact that a British lorry driver, for example, could see the regulations in a different way, than say, a German traffic policeman.

December

The season of good will is not a happy time for all and at this time year our thoughts should be with those who are suffering. A rare form of metal fatigue, probably the result of being exposed to quiet, open stretches of countryside, is attacking speed cameras. Very few are expected to survive the winter. Scientists are still unable to find a cure but believe the problem is similar to the one that wiped out traffic light cameras in 2009.