Three critical areas of focus appear to be uppermost in the minds of fire and emergency people when they’re shopping for new fire units. Firstly the onboard equipment needs to be up to minimum standards at least, and have the capacity for reach and storage that may outclass the emergency. Cabin profile and safety is another critical area, to ensure crews can not only fit in with their safety gear, but can be protected against the inevitable unexpected turn of events. The chassis is a third area and in this, the agility of an F&E unit in any circumstances is crucial to delivering solutions where they are needed at the earliest possible opportunity.
Examples of metropolitan fire tenders that have been called to an event where access is off-highway highlight the advantage of all-wheel drive and sometimes all-terrain ability. A grass fire that threatens to escalate needs instant action, but to a fully laden 4×2, a sand track is as daunting as a rock-strewn hillclimb.
The financial boundaries of tenders for these units reflect ever-present budget pressures across all jurisdictions, but increasingly dangerous conditions call for more flexibility in selection. An immobile fire truck waiting for a rural brigade off-highway unit that can make it to the scene escalates the likelihood of property loss and sometimes threats to public safety.
Most truck manufacturers offer all-wheel drive versions of their 4×2 or 6×4 platforms, but some specialise in all-wheel drive only.
Tatra Trucks is one of the latter. It steers clear of 4×2 and instead focuses its engineering and development into a modular all-wheel drive system that is unique in any company.
The all-wheel drive system deserves a closer look, and is based on independent swing-axles that distribute traction evenly across all surfaces.
Full articulation is available to each wheel, independent of its opposite number, maximising tyre tread contact with the ground.
Electronic axle and inter-axle diff locks are driver controlled, and all axles are supported on Tatra’s tubular backbone chassis, which is built in modules, allowing drive and steer axle extensions as the application demands.
As a result, fire and emergency as well as military users around the globe recognise Tatra Trucks’ reputation of taking high gross weights across terrain that can often bring ‘optional’ all-wheel drive trucks to a halt.
As an example, and on demonstration in Australia at present, Tatra’s T817 6×6 fire tender weighs in at nearly 12-tonnes. The truck has a 26-tonne GVM and is rated to pull an additional 38-tonnes on-highway and 20-tonnes off. Tatra’s own air-cooled 13-litre V8 diesel engine is known globally for its durability, and Tatra claims the absence of cooling fluids and plumbing systems is a major attraction in locations where ambient temperatures are extreme, and support could be hours or even days away.
The 325kW and 2,100Nm of torque drives through a six-speed Allison 4500 heavy-duty transmission. Tatra’s own 2.30TRK auxilliary gearbox splits the drive for low speed traction.
The steering rear axle helps deliver an 18-metre turning circle – a critical advantage when a crew is engaged in a dangerous scene in tight circumstances. The front end has disengageable drive, axle differentials and hub reduction, while the rear end adds an inter-axle differential as well. Load-sharing airbag suspension helps maximise traction.
Swing axles are to cars what seat belts would be to motorcyclists – all peachy until things go pear-shaped. But in the low speed environment these trucks tend to operate in, getting three, four or five drive wheels on each side of the truck pulling their weight individually means swing axles can be an important advantage.
The independent half-axle system is simple but effective. Each axle is cushioned by a coil spring enclosed in an air bellows, which is mounted on the top of the axle – out of harm’s way – and secured to the centrally mounted tubular chassis. In a bogie axle arrangement, the application may demand ultra heavy-duty use, and so the axles can also be linked with a multi-leaf steel spring. The air supply to the bellows is controlled by the load and axle position, maintaining spring frequency no matter the load on the individual wheel.
As a result, when the truck moves across broken terrain, a wheel that drops into a pothole has no effect on the wheel on the opposite side of the truck. The chassis is insulated against twisting moments and the load and crew are protected. Additionally, all wheels are in complete contact with the surface and traction is maximised.
The system is no less effective on the flat where the surface is soft sand or gravel. Even distribution of torque through the Allison auto box to each of the 14.00R20 tyres gives crews the best chance of getting to the rockface of the incident without compromise.
The certified ROPS/FOPS compliant cab is not designed to win a beauty pageant, but the aluminium frame and heavy-duty aluminium plates provide high levels of protection to crews, including a flat roof that’s tough enough to stand on.
The demo truck has a 9,000-litre water capacity with two 100-litre foam concentrate tanks. The low-pressure pump provides a rated flow of 3,000-lp/m at 1.0 MPa, while the high-pressure unit delivers 400lpm at 4.0MPa. A DN 25 60-metre hose connects to a gun type branchpipe rated at 200lpm.
The superstructure is glass fibre reinforced polyester and is fabricated in the Czech Republic
Front nozzles are fitted for mobile fire suppression, a ringfeeder tow hitch, electric recovery winch, light mast, 28v 50-85A generator and four-section 12.5-metre etension ladder are all standard fit.
Tatras are distributed throughout Australia and New Zealand by a Western Australian company, Offroad Trucks Australia, which works closely with major mining, construction and emergency services operations.
Based in Maddington, near Perth, Offroad Trucks has a branch in the Queensland town of Mackay, providing parts, service and technical support to its major customers close to their base of operations. The company also has dealers in NSW and SA and over 25 authorised service outlets throughout Australia.
Spare parts for engine, driveline, suspension and bodywork for all Tatra trucks sold in Australia are all on-site at local Tatra warehouses.
Technical support is kept current by rotating Tatra service personnel to the factory annually for training by design and development engineers. The factory people bring lengthy experience in off-road operations in some of the most hostile environments in the world.
Relatively low volume, a high level of customisation, and engineering designed for life threatening events that demand absolute reliability means F&E vehicles are more likely to be assessed on capability as much or even more so than price.
The heavy-duty nature of the Tatra platform means it’s package will rarely win a tender competition on price alone, but in any comparison, the critical features and specs of Tatra’s 817 6×6 fire tender make a compelling case.
For more information, go to www.offroadtrucks.com.au