Blow-outs and the art of tyre replacement
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iE DIFFERENCE between a car id a commercial vehicle tyre is A one of size alone. When the r tyre punctures, the motorist ies his spare wheel and takes e punctured one to his local re dealer.
But when a 32-ton artic has a re blow-out, a scissor jack is A quite the thing to do the job. So the sale of a commercial :hide tyre should ideally be acked up by a mobile .eakdown service. And since rries have a habit of travelling I over the country, the tyre .eakdown service should also Ter nationwide coverage.
Associated Tyre Specialists 1/4TS) provides such a service. ke its main competitors it is a lbsidiary of a tyre manufacirer — Michelin. (Dunlop has ational Tyre Service, Goodyear as Tyreservices, Avon has lotorway Tyres, Pirelli has Cenal Tyre Company). Despite this s-up, it is by no means an inmtuous relationship; ATS will apply any make of tyre, not just lichelin.
There are 420 depots in the TS network, the vast majority f which run at least one tyre reakdown van. In the few areas f the country that are not well overed (such as parts of ScotInd) ATS may occasionally subontract a breakdown call to nother member of the National yre Distributors Association. ATS supplies and fits tyres for )mmercial vehicles, cars, agrialtural tractors, industrial plant id earthmovers — the whole Inge.
When a haulier buys some fres from ATS he gets a copy of ie ATS breakdown book listing le company's tyre depots. This oak also acts as a credit guarntee showing that the haulier as paid for the tyres and so is reditworthy if he has a tyre reakdown.
If one of the haulier's lorries as a blow-out, the driver hones the nearest ATS depot, uoting the breakdown book's umber, and ATS will provide oadside assistance. During the light the depots have a telephone-answering machine that lives the home number of the yre fitter on night duty.
The bill for the tyre or tube supplied and the assistance will be forwarded by the assisting ATS depot to the ATS depot that supplies the haulier's tyres, which in turn will invoice the haulier.
ATS charges the NTDA rates for call-outs; £11.50 per man hour plus an £8 turn-out fee during the day, or £17 per man hour plus a £1 5.5 0 turn-out fee outside normal hours.
At first sight this may seem a little steep. Is a tyre breakdown service really worth that much? To get a better insight, I spent an entire day with a tyre fitter based at one of the two ATS depots in Newbury, Berkshire.
One of the 33 depots in the ATS (Southern) regional company, it covers an area of approximately a 10 mile radius. Although Newbury in the Royal County of Berkshire does not sound like a mecca for heavy lorries there are two important routes crossing the territory. Running east-west four miles to the north of Newbury is the M4, and running right through the town is the A34 that links Southampton with the Midlands.
Dave Mellett has been a tyre fitter with ATS for 13 years. His working day is scheduled to start at 8.30am and I arranged to meet him at the Newbury depot at that time. But when I arrived at the appointed time Davehad already been at work for an hour and a half. A low loader artic — fortunately unladen — had one of its susies come off while travelling at speed. All the trailer brakes had immediately locked on, ruining every tyre. An expensive way to stop. This had happened at 6.30am and the driver needed to be on his way as soon as possible. So Dave Mellett and two other fitters had been called in early to see to it and the lowloader was just leaving as I arrived.
Our first call of the day was not a breakdown but one of the depot's regular customers who had phoned in for a routine tyre change. It was easier for an ATS tyre breakdown van to go to the customer's depot, therefore the job sheet was passed to Dave so he could load the correct tyres on his van.
There are three breakdown vans at this particular depot, all petrol-engined Transits with custom-built pick-up style bodywork. Complete with their equipment they cost around £8,000 each and ATS keeps them for three to four years or 60,000 miles. Each van is equFpped with a 6kW (8bhp) donkey engine (usually a Briggs and Stratton) to power an Ingersoll-Rand compressor which gives the air pressure to power the air wrench and pump up the tyres.
I was told that the vans are not radio-controlled for the simple reason that there is little point. If a fitter has to be re-directed to another job while out on a call he still has to return to depot to pick up the necessary tyres.
Dave and I arrived at the customer's depot about three miles outside Newbury at 8.50am. The "patient" was a Bedford TK1260 sludge tanker which needed four new tyres on its back-axle. The company's own fitters had already jacked it up over the pit.
Dave immediately got to work taking off the nearside rear wheels and stripping off the old tyres. These would be returned to Michelin for remoulding. Although it was just a routine tyre change, Dave had also brought a spare inner tube in case the existing ones were not worth reusing.
He also inspected and cleaned the flap that protects the tube from the heat build up in the rim. During re-assembly he lubricated the tyre beading with potash soap to help prevent it sticking to the wheel — the odds were that he would be the one to change it next time the tyres were replaced.
While inflating the new tyres (9.00x20 Michelin XL) to 90/95psi Dave used a portable tyre cage. He had earlier shown me a gruesome picture of what can happen if a tyre explodes and a cage is not used. The picture showed a clear impression of a tyre fitter — on the ceiling.
I noticed that Dave inflated the tyre and only then removed the air line, with great dexterity so that he did not lose too much air, and inserted the valve core. He explained that it is quicker to inflate the tyre without the valve core and if he notices a bulge appear in the sidewall during inflation he can quickly pull off the air line and the air will escape immediately.
Before replacing the wheels on the TK, Dave chipped-off some of the flaking corrosion on the faces of the inner and outer rims ho that they bedded together cleanly and squarely. He said that failure to do this can loosen the wheels; the flakes drop off later on and so the wheels are no longer tight.
Careful to replace the outer wheel so that the valve was diametrically opposite the inner one (so that both were accessible), Dave then referred to his ATS manual to check the torque setting for the TK's wheel nuts (339Nm-407Nm/250-3001bft). He used his Yutani air wrench to quickly replace the wheel nuts, torqueing them up to the correct setting with a torque wrench.
All four tyres on the back-axle were done by 10am, 70 minutes after we had arrived. Dave said he would normally have taken about 45 minutes but he had spent a little longer explaining each step to me.
We were back in the depot by 10.15am and able to grab a quick cup of tea before the next job was passed through to Dave. Another local customer in Hermitage, about five miles away, had just phoned in. His shovel loader had a puncture in its front offside tyre and could we send someone to repair it?
. Taking a suitably sized inner tube with us we went up to the customer's premises, a timber merchants and saw mill, to tackle the puncture in what turned out to be an ageing AllisChambers shovel loader.
After jacking up the vehicle and putting blocks underneath, Dave let the remaining air out of the punctured tyre and tried to remove the cover with the wheel still on the vehicle.
But the tyre had been on that wheel for years and was not coming off in a hurry; the locking ring, flange, cover and rim were seemingly welded to one another. So Dave started up the compressor engine in his Transit (he has a Honda donkey engine which ATS fitted as an experiment and which is proving very satisfactory) and used the air wrench to remove the wheel nuts so that he could work on the wheel on the ground.
He eventually persuaded the locking ring and the flange to separate and inspected the inner tube in the 14.00x24 Firestone tyre. Although the tube had already been patched half a dozen times the owner considered there was still some life left in it, so Dave added a seventh patch. He had no difficulty spotting the puncture; there was a starshaped mark on the tube that corresponded with a similar mark on the inside of the cover. This is caused by the tyre hitting something hard and angular and is called a "star fracture shock mark" in the ATS manual.
While re-assembling the wheel Dave once again used the potash soap so that it would not stick so badly the next time. Having inflated the tyre to 35-40psi the job was finished by 11.50am. Had it not been for the sticking rim it would have taken little over half this time.
In the depot again at 12noon I was looking forward to lunch but it was not to be. It was a fairly warm day and as the temperature goes up so does the incidence of lorry tyre blow-outs. A call had just come in from the police switchboard which connects the emergency telephones on the M4.
An artic had suffered a blowout on the nearside inner of its trailer — a 10.00x20 radial was needed. We found the vehicle easily enough on the east-bound carriageway of the M4 by the Newbury exit. It was a Daf 2300 pulling a huge bulk step-frame single-axle semi-trailer laden with wood chips. Dave took one look at the trailer tyres and his heart sank. "These are crossply, not radial," he groaned. There was nothing for it but to run back to the motorway phone about a quarter of a mile away and ask for a 10.00x20 cross-ply to be brought out. (Maybe twoway radio could be useful?) While Dave was away at the phone the driver made himself useful by loosening the wheel nuts and borrowing Dave's bottle jack to jack up the trailer.
On removing the nearside trailer wheels we saw that the tread rubber of the punctured cover had wrapped itself around the hub and was well and truly jammed. "It did go with a hell of a bang," said the driver by way of explanation. Dave managed to get a knife to the tread rubber and cut it away from the hub.
By then the second ATS van from Newbury had arrived with an Avon Routemaster cross-ply. This was put on in double quick time and the wheels replaced. Dave did not know the torq setting for the wheel nuts on it unusual trailer and so the dri‘, helpfully suggested that th should be tight! Dave used t judgment and the air wren( finishing it by hand with a b and socket.
The Oaf was back on the mo again by 1.15pm and we ft lowed it eastward along the A so that we could leave ti motorway at the next exit. Al fitters give the drivers a tag a vising them to check tt tightness of the wheelnuts aft not more than 50 miles but Da■
doubted whether many drive bother — this driver W E heading for Rainham in Essi and was already two hours b hind schedule.
Back in the depot for a we earned lunch, depot managi Tony Palmer told us that it hz been fairly quiet while we we out; there had just been a fe cars come in for new tyres batteries.
Our lunch break was term nated after 30 minutes by a loc farmer phoning up for a new s( of tyres on his tractor. I-I wanted remoulds, 14.00x34 the rear and 7.50x16 for 01 front. Dave was able to fin these in the store — there ar massive stocks and if a partict lar size is not available it will b fetched from a nearby ATS pot.
Because it is in a good farmin area the Newbury ATS depc does a lot of agricultural tyr work, and in terms of turnovE agricultural tyres are numbE two after lorry tyres and befor car tyres.
Incidentally, ATC says thz coaches generally have a ver good tyre breakdown recorc This is partially due to the fat that coach drivers and owner tend to pay more attention t tyre maintenance and pressure; and also because coaches ar substantially lighter than artics.
We arrived at the farm abou three miles away at 2.50pm t find the David Brown 1210 trac tor waiting for us in the yard.
Because it was a straightfor ward job Dave did not need ti take the wheels off to change th tyres and so got straight on witl jacking up the rear offside. H,
said there was no particula order in which to tackle th, wheels but he preferred to ge the hardest ones out of the wa, first.
Because tractor tyres an necessarily more flexible thal commercial vehicle tyres (th( rear ones on this tractor shoutt be inflated to just 14psi) they an held on the rim merely by th beading; there is no flange an locking ring. As Dave worked quickly round le tractor, replacing the worn lut Goodyear originals with the amoulds, I noticed his economy f action. After years of practice e has got the job down to a fine irt and everything he did ninimised the amount of effort equired and made the job aster. "When I started out as a 're fitter I used to feel extausted after each job and take minutes to recover in the van! lut I don't seem to notice it low," commented Dave.
The tractor tyre change went ery smoothly and Dave cornleted it in just under the hour, Iresenting the bill to the armer's wife. Including "free fiting" it came to about £390, even ising remoulds.
When we returned to the delot at 4pm things were buzzing. he driver of a low-loader had Phoned in to report a blow out in an inner rear tyre of the railer. He had managed to get if the 1+.14 near Hungerford lbout 12 miles away but the tyre lad caught fire and was moking badly.
The problem was that the low aader had an unusual tyre size 12.00x20 — and the Newbury lepot did not have one in stock, ilthought it managed to locate ine at the ATS depot in Anlover. So Dave took an inner ube and flap out to the Ireakdown while a van was sent o the Andover depot to collect a yre and then go on to the oreakdown. When Dave and I arrived at the low loader we found that it was a heavy haulage outfit with two German-built enormous computers and pulled by a Mercedes unit. The driver said it grossed 86 tonnes and that the load was worth EW4m. It had arrived in Dover that morning off the ferry where the current driver had taken it over and was bound for Worcester that evening. The acrid smell of burning rubber still hung in the air around the low loader.
While waiting for the tyre to come from Andover Dave jacked up the trailer and removed the rearmost outer offside wheel to get at the punctured cover. When he looked at its remains it was hardly surprising that it had blown out. It was a cross-ply with the Government's familiar old War Department stamp on the sidewall! The rest of the tyres were modern radials.
The driver explained that a Dutch driver who had brought the outfit over from Germany had fitted the rogue cross-ply only that morning in Dover after a puncture when coming off the ferry.
At this point Dave noticed that the other offside inner cover was also flat and needed replacing as well. He went off to borrow the phone at a nearby garage to see if a second 12.00x20 tyre and tube could be found.
The first one arrived at 5.10pm and was quickly fitted, and we stood around waiting for the second one to arrive from Andover. Dave checked the other trailer tyre pressures and found they were all too high; most were round 135psi instead of 110psi.
After being delayed a tittle in the evening traffic the third ATS van arrived at 6.40pm with the second tyre, and 10 minutes later the job was finished with the low loader on its way to Worcester.
Dave and I were back in the Newbury depot at 7.05pm — a 12-hour day for him with just a short break for lunch and 10 minutes for a cup of tea in the morning.
Was that an average day I asked Dave? "Not every job is as awkward as the shovel loader was and we don't often get the mix-up between radials and cross-plies," he replied. But the day was not exceptionally bad by his standards — most are a little more straightforward and some are worse.
At least the weather had been kind to us; my idea of hell would be to repeat the exercise on a cold, wet and windy November day.
While acknowledging that not all tyre fitters are as experienced or conscientious as Dave Mellen, from what I saw a commercial tyre fitter working on callouts has to be worth more than he commands at present.