Specifying specialist vehicles? Tap into VT's experience 03 February 2010

If you're wondering what to specify for a specialist vehicle, and how to go about it, it's worth talking to the man who heads up automotive engineering at the massive VT Group (formerly Vosper Thornycroft).

Steve Cobbold looks after the organisation's responsibilities for British Airways' ground support vehicles, while also supporting the New Dimension (National resilience Fire & Rescue equipment) contract and VT's operational marine contracts.

He refers, for example, to current extensions of lean airside operations at Heathrow Terminal 5, which mean that aircraft support vehicles are pulled from zones, rather than simply being assigned to individual aircraft, as was traditionally the case. "So there are fewer vehicles and there is more pressure to keep as many of them available and working as possible," he explains. "And that, in turn, means extending service intervals as far as possible, generally optimising maintenance intervention and going for reliability as the number one criterion, when we specify vehicles and vehicle components."

Cobbold's bailiwick covers some 5,500 BA vehicles, of which around 3,000 are powered. On the New Dimension side, that includes specialist fire fighting equipment, based on MAN chassis, while on the air support side, it's a mix of cargo delivery tractors, aircraft cargo loaders, secure vehicles for high value cargo, electric baggage tugs and trailers, airport buses and vans.

And we're talking about a 'cradle to grave' service, with BA identifying the operational requirements and VT developing the specification, going to market with tender documents, engaging with suppliers for trials, project managing and providing whole life maintenance. So he has a wealth of experience.

"Gearing up for T5 involved helping BA to acquire around 1,000 vehicles," he explains, adding that some of the kit – such as Renault vans – is straightforward stuff, but for electric baggage trucks and cargo tractors it's a different ball game. "For T1 and T4, BA used a standard electric tug with a single motor and a traction battery, but T5 is much more challenging. It has three terminals, which are separate buildings with their own apron areas and taxi ways, and the only way equipment can move from one to another is through tunnels – and that means gradients, which are a significant challenge for electric tugs pulling a few tonnes of baggage."

Cobbold worked with Millbrook and encouraged tug suppliers to provide prototypes for testing. "We worked with Millbrook to identify the topography of T5 so they could devise programs to simulate loads during a working day. Then we used their rolling dynamometer rig to run the tests. It's not ground breaking, I know, but without going to those lengths we couldn't have guaranteed the in-service reliability of that is paramount to both our operations. The the Linde variants we eventually specified weren't even on the design table before we started this."

It was a similar story with the cargo delivery tractors, except the requirement was to replace standard Mulag and Douglas towing tractors, only designed to pull a few tonnes of cargo 0.7km along the flat. "For T5 that distance could be 5.5km and, again, there was the inevitable consequence of those gradients. Also, we wanted the units to travel much faster and to tow greater weights. In this case, we decided to look at RORO dock handling type units and settled on the Terberg tractor, built in Utrecht. That's actually used for carrying trailers on a fifth wheel coupling, whereas we needed a straight towbar for aircraft pallet trailers. So we replaced the fifth wheel with 3.5 tonnes of concrete block in steel ballast to get the traction."

What about optimising maintenance? Cobbold says technicians have been running a number of programmes, one of which is oil testing, aimed at minimising the times equipment is hauled off to the workshops, and instead keeping it out on the airport ramps. "That makes a big difference for a lean operation like this. For example, we acquired 85 of the Terberg tractors, whereas in the past we might have run with an additional five vehicles to provide the maintenance float. Extending the oil change intervals helps, but you can only do that by monitoring the oil."

Interestingly, Cobbold says that almost all vehicles that go anywhere near aircraft must have auto transmissions, and that the preference is for Allison (partly an accident of history, but also to minimise driver training and parts inventories), although some vehicles run with ZF and Voith gearboxes. "There are two reasons: one is we don't employ professional HGV drivers for these positions and the second is that many of these vehicles have to approach aircraft directly, or interface with equipment that is itself in touch with the aircraft. So two-pedal operation and being able to inch forward and back is the only safe way."

On that point Cobbold also warns transport engineers to think carefully when specifying auto boxes. "A few years ago, we needed some 18 tonne chassis cabs with powered roller bed floors to handle palletised cargo. Normally, we would have specified Allison transmissions as per the existing 50-strong fleet. But time was a problem and the chassis supplier had chassis in stock with his own automated manual gearbox. The problem was that, while it was great on the road, when you select reverse, the vehicle didn't move until the driver blipped the throttle. When you're reversing to touch an aircraft that's just not an option."

That said, he says all the auto gearboxes on his fleet have proved extremely reliable. "We have vehicles that are 15 years old, where the transmissions have never been out. Many have auxiliary drives and power take offs and, although the mileages are relatively low, they are on intensive operations, running around 1—2,000 operating hours per year for the baggage carriers and up to 3,000 for the Terbergs."
What about emissions? Clearly, European regulations don't apply to off-road operations, but Cobbold explains that BA went for Euro 5 specification engines for its airport buses. "They only clock 20,000—30,000 miles per year, but they stand idling at air side for a long time, so it is a high engine run time." And there are BA's green credentials to consider. "In many cases now we go for Deutz engines, because we believe they're ahead of the game on emissions: we've used them on the transfer transporters and cargo loaders. But we also use Mercedes Eur 5 engines and the Terbergs came with Cummins B series."

Author
Brian Tinham

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