Emergency engineering 10 August 2010

They're machines that deal with life and death situations. As a result, both the engineering and detail of fit for purpose construction are key to emergency vehicles. Keith Read reports

Whether you're a hardened truck man with 'HGV' running through your veins like the 'Brighton' in Brighton rock, or a small boy in short trousers, the sight and sound of a fire engine answering a shout is evocative of heroes. But what about that big red machines with two-tone sirens and blue-flashing lights? What's it like under the panels and paintwork, compared to the fire engines of just a couple of decades ago, let alone those from our boyhoods?

The simple answer is that the latest machines on the fire station floor are as different to machines even from the 1980s as chalk is to cheese. Brian Wiggins, sales director of Worcester-based AMDAC-Carmichael Limited – more familiarly known by its former name of Carmichael – is one that has seen big changes in the design, particularly of aircraft fire and rescue vehicles to meet changing requirements of operators. And he sees more to come in the future.

"One of the most significant trends we are currently seeing from customers is a demand for reduced emissions," he comments. "Although these vehicles are largely exempt from many of the [Road Vehicles] Construction and Use and Emissions Regulations, customers are increasingly conscious of the need to reduce unnecessary environmental damage."

And it's not just engine tailpipe emissions that have come under the microscope. Some extinguishing materials, such as BCF (bromochlorodiflouromethane) – which is ozone-depleting and all but outlawed these days – have been replaced. Even the foam used to fight real fires is of a concern. As a result, less-toxic substitutes are frequently used, especially for training purposes.

Looking at Carmichael's Cobra 2 family of aircraft fire and rescue vehicles – which serve both civil and military applications – emissions reduction is clearly all about cleaner, more efficient propulsion engines, which are also used to drive PTOs (power take offs) linked to pumps and other on-board equipment. Here, the desired move is the step up from Euro 3 standards to Euro 5 – and the same is true for its conventional fire engines, which are mainly for export.

For Carmichael, that is posing a challenge, since Caterpillar, which supplies the company with its C18 propulsion unit, has not yet confirmed a Euro 5 version of what is essentially an off-road-vehicle engine. "We are currently looking at a number of possible alternatives," comments Wiggins, but explains that there is a dilemma here.

Carmichael has found the C18 to be a highly efficient and dependable engine, with an exemplary service record, since discovering it several years ago and pioneering its use in aircraft fire and rescue vehicles. And Wiggins makes the point that making its fire-fighting vehicles cleaner is not as simple as just switching to another existing Euro 5-certified engine that happens to have the right power output and performance.

"We're still talking to various suppliers, but we're log-jammed in a position where a Euro 5 engine presents a serious problem in that, to avoid exceeding set pollution levels, these engines will go to reduced power or shutdown if dirty exhaust is detected," he explains. "In our view, that is nonsensical in an emergency service vehicle. Issues, such as automatic reduction of power output by the engine ECU, fly in the face of one of the key requirements of any emergency vehicle – 100% maximum power available all of the time. Fortunately, we're not obliged to provide a certified engine. So if the industry is moving towards cleaner engines, we believe that Euro 5 compliant will be adequate."

What does he mean by Euro 5 compliant? Essentially, an engine that does not pose a potential threat of automatic shutdown, yet broadly meets the emissions standards customers are demanding. What Carmichael is now seeking is an engine manufacturer that can provide such an engine – and the proof that its meets the emission standards. thereby avoiding having to do its own costly chemical analysis. "It's a question of finding the right one," he says.

He also adds that some newer, cleaner engines are known to experience problems with red diesel, the fuel that many airport operators use for fire and rescue fleets. "I am sure that things like this can be overcome," says our Carmichael man, who also believes that current exemptions from Construction & Use Regulations may yet be eroded, except where they conflict with the fundamental operation of the vehicle in its role.

That aside, with Cobra 2 water-carrying capacity now up to 14,000 litres and more onboard equipment adding to its overall weight, chassis construction has also had to come under the microscope. "The carrying capacity of the chassis has had to be increased so we have been looking at our supplier base and determining where we can get this componentry from, because we're an assembler of proprietary items," explains Wiggins.

This, in turn, means that axles and suspensions are having to be re-verified for their suitability and matched to individual vehicles' operational demands by Carmichael's CAD teams. Incidentally, in common with other manufacturers, Carmichael is also seeing ESP (electronic stability programme), traction control and similar safety systems increasingly appearing in emergency vehicle specifications – again, in part, to help handle the requirements of increasingly demanding vehicles.

On the other side of the coin, reducing weight to compensate for larger water tanks and additional heavy on-board equipment is another continuous process, although opportunities are increasingly limited. One area under consideration, though, is the crew cab. "We have a cab frame at the moment that's made in high-grade stainless steel and it's a very heavy box-section designed to meet ECE 29 crash impact standards," explains Wiggins.

"That's one area where we're looking to design some weight out, while still maintaining the safety standards." Lightweight Formula 1 cockpit-style composite materials are one idea. "We haven't suggested we're going to stay with stainless steel," he says. "So long as it meets safety standards, we don't really mind what it's made out of."

And, for the time when emergency vehicles finally come to the end of their life, recycling versus reusing is presenting manufacturers such as Carmichael with different concerns. "A percentage of the bodywork is GRP [glass reinforced plastic]," explains Wiggins. "But what we can see happening, as legislation tightens, is 'reuseable' will become unacceptable. Body panels will have to be capable of being melted down and recycled. So we see a move away from GRP to polyurethane or polycarbonates.

The space race
Meanwhile, for the design and development teams at Browns Coachworks – another long-established fire and rescue vehicles specialist – membership of the Magic Circle, rather than the IRTE, might be useful, according to Ian Mawhinney, director and general manager. Almost without exception, every new order for an emergency vehicle brings the same request from fire authorities: give us more space storage.

"In a lot of cases, we're being asked to provide more space within the envelope of the vehicle for the equipment that the fire authorities want to carry," he says. Not only that; almost every vehicle is bespoke, with no two brigades specifying the same combination of lockers, racks, shelving or even water tanks and pumps.

"We have seen an increased use of foam and the pumps have become more complex and much more highly automated," explains Mawhinney. And he adds: "One of the biggest change we've seen over the past three or four years has been the increased use of CAFS [compressed-air foam systems], although there's not a clear consensus among the brigades as to whether it is so wonderful."

However, the switch by many to CAFS means Browns now has to install pump units that incorporate different technology. "These tend to come as integrated units from pump manufactures such as Godiva in Warwick," he says. What about the consequent requirement for more foam tanks, more plumbing and more controls? Mawhinney says that is an issue, but adds that the key assemblies do come as part of the pump systems.

More importantly, he points to a noticeable trend towards getting away from pure fire-fighting appliances to what a lot of the brigades are now calling 'rescue-pumps'. These retain their extensive fire-fighting capabilities – and the specifications that underpin them – but also include other equipment on board for dealing with the 50% or more of emergency services shouts that are not fire-related – road traffic accidents, for example.

And another change: while cab safety remains a clear priority, Mawhinney explains that, with the vast majority of brigades now using factory-built cabs –themselves designed and tested to comply with European regulations – some of the demand for coach-built cab specials has diminished. And with it has gone the need for coachmakers to undertake specialist design and development work.

It's good to talk
However, the need for coachbuilders and equipment suppliers to talk to chassis-cab manufacturers has never been greater. Mawhiney: "Every new order is a new project. Our customers say: 'Here's our last vehicle. We now want to add x, y and z: can you find a way of stowing that for us, either by clever stowage of the existing equipment or using every nook and cranny on the vehicle?' That's another ongoing challenge that means we have to communicate."

And the same applies to the relatively new breed of smaller, lighter weight fire appliances being developed for restricted access areas. These require creative thinking but also a lot of co-operation between different parties. The machine set to replace Cornwall Fire Brigade's existing 'micro fire engine' (based at Looe, and one of the first in the country) provides an excellent example. That vehicle, a Kawasaki Mule fire engine, was specified to negotiate the narrow streets of fishing villages such as Polperro and, after almost 20 years' sterling service, is about to be replaced by an even more flexible and powerful machine.
Jon Norris (who left school to become a motor mechanic and has since used his emergency services and engineering skills to start FireTech Special Vehicles in Dorset, specialising in such vehicles) says the new unit will have 4WD, instead of 2WD. It will carry a similar two-man crew but a wider range of equipment, including a portable pump, two breathing apparatus sets, extinguishers, suction and delivery hoses, a hose reel branch and a 3m ladder. It will also be faster than the current 20mph machine and, like all emergency vehicles, carry blues-and-twos.

Norris' company focuses on the US-made Polaris Ranger ATV, which carries a four-man crew, and can reach 45mph. That machine has a 50-gallon water tank as well as a similar range of equipment to the Kawasaki Mule. "It has the ability to enter areas with restricted access that would prevent a conventional fire engine attending, and it can carry more than the Mule," he explains. "However, if brigades want even more carrying capacity, then we base a range of designs based on Land Rovers, both 4x4 and 4x6. Six years ago, we launched our Challenger range, based on the Land Rover 110 and 130 chassis, with the option of a crew cab."

Revolution or evolution
None of the above should leave you with the impression that the technology for fire and rescue vehicles and their equipment is revolutionary. Station tutor Mark Gilbert, from the Fire Services College at Moreton in Marsh, Gloucestershire, says developments are part of a process of evolution. "If you take something like an aerial platform, we always want bigger, higher and further reach. But I believe the biggest development over the past 10 to 20 years has been that of our hydraulic cutting equipment," he says.

"With structures such as boron tubes in modern motor vehicles, the manufacturers of cutting equipment have had to develop robust, heavier-duty tools. At the same time, we've had to work with other services – such as crane and recovery firms – when we're dealing with road-traffic accidents involving HGVs."

Gilbert, who instructs fire fighters from around the world, also says that, at the other end of the scale, fire-fighters themselves often identify small hand tools able to tackle some of the difficult jobs when undertaking rescue from road-traffic accidents. He gives the example of cutting away plastic trim components, and says that tools to handle such everyday items are increasingly being incorporated into the vehicles' range of equipment – hence the mushrooming storage requirements.

Transformed transmission
Allison Transmission used Interschutz (held every five years in Hannover, Germany, for the fire and rescue community) to launch its M6620 transmission, designed for airfield crash trucks. The new gearbox builds on the record for performance and reliability of its existing M6610.

Manlio Alvaro, Allison's European marketing manager, confirms that vehicle manufacturers worldwide – including Daimler, Renault, Iveco, DAF, Scania, MAN and Volvo – offer Allison automatics for a variety of fire and emergency applications. This new box has software and hardware upgrades aimed at improving durability, while also resulting in lower operating costs and simplified maintenance," he says.

In addition, Allison has taken the opportunity to make transmission tuning a reality – to mach different operator's specific requirements. The claim is that this development will enable drivers to get optimum acceleration even in off-road conditions such as when traversing an airfield to reach a stricken aircraft. "For ultra high performance applications, Allison can increase the shift points to keep the engine at peak torque, and so maximise acceleration," explains Alvaro.

Colour bind
Red is the colour usually associated with fire and rescue vehicles. But that's not always been the case. 45 years ago, when Coventry ran its own fire service, fire chief Albert Leese discovered that, at night, his bright red fire engines appeared black under sodium street lighting. After working with the then Transport & Road Research Laboratory (now TRL), he painted all his machines lime-green-yellow – a colour now known as Coventry Fire Brigade Yellow.

In 1974 the vast West Midlands authority took over Coventry's fire service, and its machines were repainted red. However, the added conspicuity that Coventry Fire Brigade Yellow offers is not lost on airport fire services.

Former assistant divisional officer Alan Gilbert, now a consultant to Birmingham airport fire service, says yellow – and white – are easier to see than red. Some airports, such as Newcastle, prefer white fire appliances, but add their corporate colour – purple in Newcastle's case. Carmichael, which makes many of the fire engines seen at airports, says demand from its customers for yellow paintwork runs at 50-50, with red.

Pumping up the pressure
Andy Roe is director of sales for pump systems manufacturer Godiva (part of the IDEX Fire Suppression Group) agrees. "We can offer CAFS [compressed-air foam systems] equipment in a number of different configurations, ranging from the Mini-CAFS – a self-contained retro-fit unit for the compartment of an existing vehicle – to our Prima vehicle pump, with an integrated SmartCAFS module," he says. "We can also offer a range of engineered packages that emergency service vehicle builders can integrate into their designs, according to customer requirements."

All Godiva compressed air foam systems feature so called 'smart switch' technology that allows for pre-programmed foam positions and discreet control of wet-to-dry foam composition. "We incorporate FoamLogix electronic foam proportioning for accurate and reliable foam injection into the water stream. This system can be operated by one crew member from a single control panel," explains Roe.

"An appliance equipped with CAFS equipment contains a high-volume air compressor (1,400 to 5,800 litres per minute) integrated with a foam-proportioning system and the normal centrifugal fire pump," he adds. "Typically, a Class A CAFS foam application will consume 20% of the water used in a conventional water attack. So a fire truck equipped with CAFS has a much greater fire fighting capability. For specific applications this has led to the development of smaller, lighter appliances."

Keith Read

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