IT'S BEEN calculated that if a rapid intervention firefighting vehicle
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doesn't reach a burning aeroplane within three minutes there's little point in it going at all — the plane will be burnt out ! Not exactly a pleasant thought when you're sitting strapped into your seat on board expecting to be blasted into the air.
It may not be much consolation, but Chubb Fire Security Limited has introduced an RlV — which sets new standards. Based around the Scammell Nubian 2 chassis, the Protector 2 probably represents the state of the art as far as RIVs are concerned.
They must conform to an unbelievably stringent set of requirements as well as having an on-off road capability — after all aeroplanes don't choose where they are going to crash !
When Chubb offered us a fully equipped Protector 2 for test we tried to devise a way of realising all its potential. We carried out our usual specific tests first to determine acceleration, speeds in gear and braking; but next we took it over some of the roughest terrain we could find and finally put it through its fire-fighting paces.
The Nubian 2 chassis is available in either 4 x 4 or 6 x 6 format. Our test vehicle used the 6 x 6 chassis, fitted with the optional Cummins VTA903 V8 power plant. This develops a maximum gross power of 373kW (500bhp) and is the largest output available. (The VTA903 is both charged-cooled and turbocharged, while the VT903 standard engine is simply turbocharged.) The Nubian 2 chassis represents a complete change in Scammell design as far as Nubians are concerned. Previous models were front engined, but for the Nubian 2 the mighty Cummins is mounted at the rear.
Not only does this allow a lower cab profile, it also improves weight distribution and almost any engine size can be accommodated. Transmission for the Nubian is by means of an Allison HT750DRD fully automatic five-speed gearbox and torque converter which drives the wheels via a Kirkstall AG B7000 two-speed auxiliary transfer box. Both the selection of front-wheel drive and range change are by means of air cylinders.
When the 1.96 to 1 ratio of the box is selected, front-wheel drive too is automatically engaged. Kirkstall axles are used all round and all three have crossdiff locks.
All the components — especially the Cummins engines and Allison transmissions — were chosen because of their acceptance worldwide. This is important for a vehicle that could be operating in locations as diverse as Abu Dhabi and Alaska. Cummins has a network of service agents throughout the world, and the Allison transmission is a familiar unit and easy to maintain.
Because of the high .cost of RIV's, speedy maintenance is essential — an airport can't afford to keep a spare I And, depending on the category status of the airport, a certain number are required anyway.
Although Scammell will supply an untrimmed version of the Motor Panels MKIV steel cab, Chubb builds its own. It is made from a welded steel frame which is panelled with aluminium alloy. The roof, however, is made of grp.
To protect the crew, the steel framework has a number of box sections in a roll cage configuration and the cab meets EEC crash regulations. Chubb has fitted safety glass for the windshield and side windows, and it has centre steering with passenger seats on either side.
All instruments relating to the automotive side of the vehicle (speedometer, tachomer, air gauges and ancillaries) are on a panel directly in front of the driver. There are Leyland "G" cabtype stalks around the small steering wheel to control indicators, horn flash and headlamp dip/flash and wash/wipe.
The rest of the automotiveassociated controls, with the exception of the gear selector and park brake lever, are arranged on an angled panel to the left of the driver. These include the starter switch, tractive control, auxiliary gearbox selector, and a host of lighting and other switches.
On the driver's right side is a similar panel housing, housing the firefighting controls with gauges for pump pressure and an auxiliary air-pressure gauge.
A combination control operates the water tank valve, foam liquid tank valve, and monitor lock all in one go. This is said to make it easier and quicker to bring the firefighting systems into operation.
Other controls include the pto engagement lever, and a myriad of lights indicate the tank content level. On the driver's immediate right there is the automatic selector, park brake lever and controls for the rightand left-hand side lines.
At first, the array of instrumentation and controls look as similar in number and complexity to those on an aircraft itself ! But it has all been carefully planned and designed and is very logically laid out. Indeed Chubb tells me that the RIV's at New York's airports are one-man operated ! He not only drives the vehicle but operates the firefighting monitor (the foam gun on the cab top). Perhaps London Transport and other municipal transport operations should take note ?
Getting into the Protector's driving seat — through the nearside door — is easy enough and checker plate style rubber flooring not only stops slipping but also insulates the cab. There is further protection from the acoustic insulation and double skinning in the rear bulkhead, roof and side panels.
It's almost eerie to start up the massive Cummins engine when one is so far away from it. A slight shudder is all you feel as it bursts into life, and the noise from such a giant unit is very low — Chubb says it's around 81 to 82dBa in the cab.
Having started up it's just a question of selecting the auto transmissions, releasing the park brake, and putting your foot on the throttle. The big machine pulls away without any apparent effort and soon has you rocketing along. I wasn't too keen on the close proximity of the throttle and brake pedals, or the fact that they are the same size and both on the right of the column. I would have preferred a larger brake pedal, perhaps with two pendant arms — one on each side of the steering column. But the set-up didn't present any real problems although it might for a fireman wearing big boots !
As with most automatic transmissions, first on the Allison had to be manually selected. The rest of the gear selection follows standard Allison practice with 2, 2-3, 2-4, and 2-5 positions.
For some reason Chubb — or perhaps Scammell— has mounted the lever quadrant with the lower gear positions nearest the rear of the cab and neutral and reverse furthest away. Strangely, the numerals are upside-down in this arrange ment. Although this presents n( problem, it seems unnecessary.
The acceleration of the full, laden Protector really was quick 50mph being reached in jus over thirty seconds. But mon impressive was the manner ii which the vehicle reached thes speeds with scarcely a murmu being heard in the cab. If 2-5 i selected, the Chubb change up or down in the range ti second to fifth. But selection of the intermediate gears holds it at the upper ratio. That is to say, 2-4 limits the vehicle to fourth gear, although of course it will change up to third or down into second. With a top speed of 120km/h (74mph) the Protector is quite a mover when flat out. It never 'elt unsafe or unstable, in spite Df 91 00 litres of water sloshing around behind me.
Steering it was effortless and he brakes were well up to heir task.
Car-like is a term increasingly ipplied to modern commercial (ehicles, especially long-haul )nes, but it was never more ippropriate than with the Mubb.
Excellent forward vision hrough the large deep windcreen, and good side-mirrors nade it as easy as a big car to ontrol. My only complaint, if can be called such, was that le monitor rattled incessantly n its catch, but Chubb enineers tell me they have modied this release catch so that it ion't be a problem in future. When Scammell designed its ew range of Nubians it de cided to make them conform to C&U Regulations. The brakes are to EEC standards, and although firefighting vehicles are exempt anyway it conforms to width and axle load requirements too.
If the performance as far as acceleration and speed was impressive the Chubb's gradeability was even more so. It pulled away without any qualms on a one-in-three slope, but incredibly it did this in high range ! I suspect if adhesion could be maintained, the Protector would climb up the side of a house in low ratio. The park brake, which has spring chambers, held the vehicle easily on the one-in-three in both directions.
After our specific tests, we took the Protector round the rough road terrain we use for tipper evaluation and then onto our mud plugging area. Apart from the rattle from the monitor catch, the Chubb was a pleasure to drive. It handled all the rough road we could find at speed.
Cornering through the tight bends was effortless and the vehicle always felt secure. The really muddy and wet sections, where water lay in puddles two feet deep presented no problems either. The low ratio was never really needed as the Chubb just kept on going.
One complaint here concerned the mirrors and side windows. Both dirtied up quickly and the mirror brackets didn't have enough torque to retain the heads — they kept swinging round toward the cab sides. I think, though, that this is a simple matter of adjustment.
Across the wooded sections of the test area, the Chubb dealt with bushes and small trees as if they didn't exist — it has a strong bumper/front protection arrangement which looks capable of dealing with almost anything.
Also, the angled front and rear ends give excellent ground clearance for good approach and departure angles. The single centrally mounted wiper dealt readily with thrown-up mud and water, aided by the washers.
But for firefighting, when foam is driven back onto the screen, a special deluge device is fitted above the screen. This simply has jets pointing down to the screen and water is pumped at fairly high pressure through them.
After the muddy section testing we came to wash the vehicle off. The air hose we were using from an ordinary tap couldn't remove the dirt, so the Chubb people started the engine and used the two side hoses. Opening all the side compartments we found that mud had got into them too but they are designed to be hosed out.
The power of the side hoses — which are somewhat like massive sub-machine guns to look at and hold — was extraordinary. Such was the recoil, that it took an effort to stop oneself being knocked over.
Of course a firefighting appliance is only as good as its equipment, so to test this aspect of the Chubb we took it to an Aircraft establishment, where eight 204-litre (45 gal) drums of aviation fuel were used to simulate a fire. So effective was the foam monitor (discharging 4,500 litre/min (990 gal/min) that the fire was almost put out before our photographer could get his pictures !
The monitor, as stated before, can be operated by the driver if desired, but of course duplicate controls are fitted to their own control panel.
Access to the monitor platform is via a hatchway on the vehicle's nearside through the cab. Hydraulics controlled the angle and sweep of the monitor on our test vehicle although the standard equipment is manually operated. But should the hydraulics fail, the former can be manually operated.
A two-piece flap on the end of the monitor allows a variation in the spread of foam, so for a widespread fire a semi-closed position is best while for a more contained one the flaps are opened up.
Certainly, the foam making capability of the Chubb was very impressive. It is generated by a special Chubb-designed, round-the-pump proportioning method which introduces the foam concentrate into the water system.
Of course the main pump is the thing that gives the foam its pressure and the Godiva pump on the Chubb is mounted amidships. It is shaft-driven from the pto and this in turn is engaged by a Scammell multiplate pto clutch.
To cut out any likely operational constraints, the pto can be engaged at any engine speed, whether or not the Protector is moving. The pto has been designed so that uninterrupted transmission of power to the pump is maintained at all times regardless of the transmission ratio selected. To prevent the vehicle being damaged by debris or escaping fuel, a deluge device is fitted below the front bumper and rest of the protector to emit foam.
For small engine fires or fuel spillages a special heavy gas (BCF) hose is an option on the Chubb. Apparently jet engines can be virtually destroyed by foam — a costly way to put an end to a minor fire.
With all this sophisticated and complicated equipment, Chubb has still kept maintenance in mind. As has been mentioned, few airports can afford to keep spare vehicles, so downtime must be kept to an absolute minimum.
With this in mind the Chubb is built to a modular format with three main sections the cab, the water tank, and the engine/transmission. Plates can be removed inside the cab to gain access to components, while the tank can be removed in an hour to get at the pump and so on.
As far as the engine is concerned two doors at the rear give access to the back of the unit and two more on top reach the turbocharger and ancillaries. Detachable panels make for easy engine removal.
There's no doubt the Chubb is an extremely well-designed and conceived machine. Its modular build is both sensible and practical and the use of grp for the the water tank gives strength, low weight and good space utilisation.
At the same time Chubb has given the Protector 2 a streamlined and modern appearance, which is in keeping with the glamorous image of air travel.
Let's hope its services aren't needed but it's good to know how effective it can be. Because of the vast range of auxiliary equipment and features which can be added there is no basic price for the Protector 2. However, depending on specification, prices vary from E150,000 to E200,000.