Next the ABS black box was disconnected and the 5km/h
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runs were repeated. The theory is that you press the brake and then let it off again as the wheels lock up. Looking in the mirrors you can see the rear wheels pick up speed before reapplying the brakes. The wheels take up to two seconds to speed up on a low-friction surface, during which time the back end is kicking further out of line. When you are heading towards a line of cones (let alone a pedestrian or crashed car) this can seem endless.
As the rear wheels lock up, forgetting to depress the clutch will result in a spin.
The next run had the truck straddling the wet tarmac and the foil to create split braking conditions. With the ABS functioning this is not a problem; without it you have to be very quick in letting the brake back off.
When the brakes are applied, the front wheel on the road will grab, directing both back wheels towards the foil. If both rear wheels get on to the foil before the brakes are off, all is lost, The rear wheels are at an angle to the direction of travel, so it takes longer for them to speed up again. In reality, if both back wheels got on to the foil, the vehicle would spin.
Drivers from NYNAS Linkman were on the course. They found it a valuable and, in some parts, frightening experience. All commented on the violent shaking of the cab. "I thought it was going to tip over," was a typical comment.
The course has grown out of anti-rollover training initially set up by BP following 67 petrol tankers turning over across Europe in 1989. It contracted AOMTC (roughly the Austrian equivalent to the RAC) to set up the course. Within two years BP had recorded a 70% drop in rollovers and a 50% fall in road traffic accidents.
For the past two years the course has been run by IRST but with a continuing subsidy from BP and vehicle support from MAN. 1RST's equipment is mobile and it operates throughout Europe, generally spending about six weeks in the UK carrying out training at test tracks and other suitable areas.
The rollover section of the course again started with a theory session looking at how and why rollovers happen.
There are two main causes of rollovers, says Baddeley: roundabouts and accident avoidance. Both are made more likely by bad loading of the tanks. To provide rollover training, BP refurbished a six-compartment tanker and fitted retractable outriggers.
It was driven round in 30m circles on dry asphalt at increasing speeds until the outrigger touched the ground. With compartments five and six 90% full (10 tonnes at the back) the vehicle could lap at 49kmrh. When the load was moved up to compartments one and two, the outrigger landed at 36kin/h.
With compartments part laden the load slops the opposite way to that the vehicle is turning. So going round a roundabout as the truck turns left, the load slops right. Steering to the right to go round the roundabout the load slops to the left—but even further up the side than before. Exiting the roundabout the swinging load gets further impetus. On straightening the steering the load takes over, sloshing up the nearside of the tank, and taking the truck over on to its side.
Back on the test track drivers made figureof-eight runs to discover when the outriggers hit the ground. You don't get any indication at all that it is going to go oven" was the comment from all the drivels on the course. But after a quarter of an hour on the track most could predict accurately when they had gone too far. At the end of the day all the drivers felt that they had benefited from the experience. Many were chastened that they had been so unprepared for so long. Certainly there is no shortage of companies prepared to pay £289 (ex-VAT) to put their drivers through the oneday course.
by Colin Sowman
IRST (phone 01727 844678) will be running a series of advanced courses for LGV drivers around the UK as follows:
7-11 May Scotland
14-18 May Teeside 21 May-1 June Manchester 4-7 June Bristol 10-14 June Essex