DEAR
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SIR
HEAT EXPANDING BRAKE DRUMS • I am prompted to write to you with reference to the news article Vehicle Inspectorate Report (CM 10-16 December) which highlighted the level of brake defects in annual tests.
In the report, V I director Ron Oliver suggests that one of the reasons why brake-related defects continue to be the highest cause for test failure is that many operators fail to give sufficient time for new brake linings to bed themselves in properly. A valid point! am sure, but perhaps your Workshop writer could take up this point further and ask the question: "Bed themselves into what?"
I believe most workshop operatives would accept that the brake drum is the last component to be considered for replacement when braking effort is down. Many may also be surprised to read that a representative of the UK leading brake drum manufacturer is promoting the merits of brake drum skimming. One has to recognise that a brake drum is very much a precision manufactured component. To work to its maximum efficiency it needs its brake path to have 100% contact with the brake shoe under braking. Yet so often, relined brake shoes are put back into worn, heatcracked brake drums.
When brakes are applied kinetic energy of the vehicle is turned into heat. It is calculated that a 32-tonne truck, travelling at 60mph (961an/h) will have some 8,630, 000ftlbs (11,700, 000Nm) of energy to convert into heat, this heat is dissipated through the drums. A 161/2in (42cm) diameter brake drum will expand by 10% of its cool size when heated to 500°C.
If heat cracks are present in the brake path of the drum when inspected on service, consideration needs to be taken that as the drum expands under heat, so will the cracks open up at the same 10% ratio. When this happens the character of the drum changes and it becomes an effective cutting tool with many hundreds of cutting edges to greatly increase the wear rate of any brake lining material.
This means, apart from the safety aspect, having brake drums skimmed can make much • I have been an international driver for 11 years and have to say that your "Italian Blues" report (CM 17-21 December) was a load of rubbish.
Day One. I always know what weight I am carrying by checking the papers and CMR, documents. I have always stopped at passport control and shown my passport at the window. You can have a queue to get your papers stamped at any odd time of day — there is no system to beat.
How can you muscle your way through the lines of trucks if they are all waiting for the same ferry? You are directed to a specific lane and wait until you are called on.
Your driver has been to France a good few times so why was he surprised that the gates were locked until 22.00hrs? That rule has been in force for over 14 years and the French drivers are under the same restrictions. When you drive on the Continent and work within the laws of that country, you have nothing to worry about.
Day Two was fairly good but I would be a bit worried about the Ministry men wanting to look at the tachograph charts as you started driving at 10.30am, yet it was mid-evening when you arrived at Modane and just before midnight when you drove through the Frejus Tunnel.
Day Three. On your way at 07.00hrs, tired and grubby and only able to wash in cold water once since leaving home. Rubbish. There are hundreds of cafs and services on route to stop at for a wash and brush up with hot water.
Day Four. I always find out that if you smile and laugh a lot most people get less grumpy. I see you didn't complain about being loaded at 9 o'clock at night, and getting your Custom papers.
Day Five: I also see there was no real praise for the fast transit of Italian and French Customs at Mont Blanc and Cluses. Your reporters always moan about the delays but say nothing about the fast and good times.
Day Six. You have to pay for the use of roads by tax on fuel and tolls on motorways — foreign drivers have to when they come to his country (sic). I never sat about waiting for clearance at Dover.
My comment. The majority of drivers from the UK are a great bunch of men. They work long hours and they respect the laws of the countries they visit, the same as you expect foreign drivers to respect the laws here. When I am in a queue for Customs or anything, no one pushes in front and I am not abusive. Only a minority of drivers you meet cannot be bothered to get a wash, do not respect people in cafés and never try to speak the tongue of the country they're in.
I drove on the Continent for 11 years with a tanker carrying hazardous chemicals which have more restrictions than most general goods. I had a great time and would love to go back to it (I was made redundant three years ago when the company ceased trading). I still drive tankers but only in the UK.
I know you will not print any of this or try to correct your report but! hope you do as there are hundreds of drivers laughing at your driver. If I was still driving over there (I hope to some day, possibly with my own unit), I could take your reporter with me and show him how to get on with the continentals, customs and police.
Stewart Munson Gravesend Kent fl We stand by our report and the events depicted happened in the order we describe them. The article contained no factual inaccuracies whatsoever — Ed.
FROM OLD CARS TO MIIJTARY TANKS IN Hiked the comment on driver training (CM 10-25 November). My job is teaching HGV Class I with a Leyland Crusader (15 years old but nice and warm!). Although our students take the same test as back in the UK, we do driver training with loads on the back (but empty for the test). As our students go on to drive Scammell Commanders with up to 60 tonnes of tank on the back, the advantage of progressing from old cars and the like via light armoured vehicles goes without saying.
Cpl R J Fry BFPO 16, West Germany IN I have found it! The deliberate mistake on your Newcastle upon Tyne map, —1)4, Sandford Road should in fact be Sandyford Road.
A Robinson Transport Manager SLD Pumps Newcastle upon Tyne SOtT about that — Ed.