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Marching orders for truck engineers Money is no object, or so you might think, when it comes to designing frontline military vehicles. It ain’t necessarily so, as John Dickson- Simpson discovered at this year’s Defence Vehicle Dynamics show.

uch of the headline news, in British circles at least, from the big Unimog running gear gets everywhere: including this mine-proof MacNeillie Defence Vehicle Dynamics (DVD) display of military vehicles at personnel carrier. Mthe end of June was related to the start of delivery to the British Army of 6,928 cargo carriers and 288 recovery trucks built by MAN of Germany. Yet for engineers the main intrigue of this year’s DVD show at Bedfordshire’s Millbrook proving ground lies in the American products that dominate military activity around the world, not least in Iraq and Afghanistan, where greater technical co-operation between allies surely would be strategically beneficial. But the Americans can hardly be accused of being possessive about their vehicle technology. Witness Lockheed Martin, and Stewart & Stevenson. They have acquired, respectively, Britain’s Supacat, ’s and Pinzgauer of Austria and Britain. The main reason why American military vehicles attract the admiration of engineers is that they seem to reflect a desire to devise the best products for the job, not the cheapest. Take the six-wheel-drive Mowag Duro truck chassis, from the General Dynamics stable, for example. It has a DeDion rear axle with high The fence in defence: Force chassis-mounted final-drive units, Protection’s Mastiff six-wheeler with an coil springs giving large deflection, outrigged fence to deflect explosions and transverse location by a Watts and diffuse blasts. linkage that eliminates any sideways displacement. The DeDion cross- tube doubles as an effective anti-roll bar. Another Mowag chassis with axles located by mid-anchored long tubes forms the base of two examples of special bodywork displayed by Penman of Dumfries. One is for defusing explosives and the other is a chain-flailer for clearing landmines. The Lockheed Martin military truck chassis adopts the design of Supacat of Honiton, Devon, with a stiff spaceframe chassis and independent air suspension. The air springs are arranged transversely, reacting against a lever connected to double-wishbone independent

General Dynamics Mowag: equipped by Penman of Dumfries for bomb disposal.

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Marching orders for truck engineers

Tatra 8x8: swing-axle independent air suspension on a single-spine tubular chassis.

suspension. A further development by Lockheed Martin is this suspension in bolt-on modules so that a four- wheel-drive chassis can be converted into six-wheel-drive or even an eight- wheeler. Prototype diesel-electric hybrid vehicles from Lockheed Martin are on trial with the US Army. An open-top, low-slung, four- wheel-drive, fast-response combat vehicle grossing 6.5 tonnes and derived from the Supacat is being made by Devonport Management of Plymouth. Its B-series Cummins engine drives through an Allison automatic gearbox (much in evidence on other trucks at the DVD show). Operations in Iraq and Afghanistan are sharpening the focus on ability to survive mines and roadside bombs. Mowag’s coil-sprung DeDion drive-axle: transverse location by central Watts Ingenious blastproof designs are one result, and development is being linkage. refined apace, witness monocoque welded hulls with vee-section bellies. One of the latest is a modular range of armoured carriers spanning 9.5 to 14 tonnes from S MacNeillie and Son of Walsall, West Midlands. Running gear is derived from the Mercedes-Benz coil-sprung Unimog, including the OM904 four-cylinder engine (with remote hydraulically- powered cooling) allied to electro-pneumatic transmission with eight forward and six reverse ratios. Thanks to a low floor, the air-conditioned interior has enough headroom to afford unhindered movement of seven tall troops in full battle kit. Other blast-absorbent vehicles are on the way from International, JCB, BAE, Mercedes-Benz and Oshkosh (in conjunction with Protected Vehicles Inc of Charleston, South Carolina). Another military specialist from Charleston, Force Protection, is supplying the British army with an ingeniously protected six-wheeled personnel carrier called the Mastiff. The tough chassis is straightforward – bonneted and leaf sprung – but the blast shielding is an unusual assembly of grid fencing outrigged from the truck to diffuse and deflect explosions yet affording outward vision for the crew. Drive to all three axles is taken through an Allison gearbox from a Caterpillar engine. The

MAN eight-wheeler recovery-truck: rear axles on Sisu of Finland: 8x8 with low-mounted cab. Hemscheidt hydraulic struts for power-levelling the chassis.

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technology was developed in South Africa. Another South African vehicle is the four-wheel-drive RG31, already made under licence by General Dynamics and soon also by BAE Land Systems. This is said to be able to cope with roadside bombs, and a soldier can fire the gun while staying protected inside the vehicle. Similar protection is provided by the Textron four-wheel-drive M1117 armoured vehicle, of which 1,900 are said to be in combat. It not only repels rocket-propelled grenades but can survive under-hull mine blasts. Already established, too, is the Bushmaster personnel carrier, originally from Australia and now marketed by Oshkosh and Thales. This fast and mobile crew carrier is a development of AD1, by Bendigo of Australia and Timoney Technology. The 330hp Caterpillar engine gives this four- wheel-drive machine a top speed of over 66mph, with a 600-mile range. All-round independent double-wishbone suspension is by ArvinMeritor. Despite all this exotic development, the abundant vehicles for dart-about military duties are four-wheel-drive Land Rovers and six-wheel-drive Pinzgauers. The latest versions of both were at the DVD show. A controversial Land Rover called the Snatch has been developed by Ricardo and NP

Pinzgauer 6x6: in active service in Afghanistan.

Bolt-on goody: short tipper with its own air suspension converts a Lockheed Martin four-wheeler into a six-wheeler.

Aerospace of Coventry, which does Mowag/Penman axles: located by the re-armouring and lifts gross long tubular arms from mid-chassis weight to four tonnes. cross-trunnion. The Pinzgauer, made in Guildford, Surrey, in the latest form for the Ministry of Defence is called the Vector, enhanced by Armour Holdings of Gloucester. It grosses 6.5 tonnes and has exceptional cross-country mobility that benefits from the centre-trunnion two-spring rear bogie. A turbocharged 2.5-litre Volkswagen diesel provides the power. Protection against machine- gunning and rocket-propelled grenades, as well as mine blasts, is a feature of the crew carriers shown at DVD by US manufacturers International, Oshkosh and Textron. Evidently, the weight of armour needed to provide protection against guerrilla activity is causing concern. But technology is coming to the rescue with composites that resist blasts, shrapnel and gunfire as effectively as steel but at a third of the weight. All sorts of laminates of Kevlar, polyethylene, glass-fibre and

Lockheed Martin Supacat: low-profile six-wheel tipper with independent air suspension all round.

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London Low ceramic (which shatters bullets) Tubular space-frame Supacat were shown at DVD by NP chassis: low centre of gravity and Aerospace, Permali Gloucester and high torsional stiffness. Emission Scanfiber of Sindal, Denmark. Need to carry ever heavier equipment and armour has brought attention to eight- and even ten-wheeled rigids to keep wheel loads down enough to maintain mobility over soft ground. The latest designs from Finland’s Sisu are impressive. By dropping the cab ahead of the front Zone wheels a low profile is obtained, keeping overall cab height down to 2.6 metres. This compares with the MAN eight-wheeler’s cab height of 3.3 metres. Vision from the Sisu cab is seriously obstructed, however, by small windows and thick pillars, highlighting a vexing conundrum for Concerned? military vehicle designers: how to reach a tolerable compromise between vulnerability and ability to see out. The Sisu has a 445hp Caterpillar C13 12.5-litre engine driving Don’t be! through an Allison automatic gearbox and Steyr two-speed transfer box for permanent all-wheel-drive. Like most military multi-wheelers, the Sisu has articulating two-spring We have a range of retrofit suspension for the rear bogie, but there is no load equalisation between solutions that will enable the two front axles. Such parsimony seems crude for off-road work. It contrasts with the front suspension arrangement of Foden military eight- you to comply wheelers, production of which has ended, with two trunnion-rocking springs to share front-end load, and radius rods locating the axles. Similar suspension is fitted to some Leyland military eight-wheelers. • Cost effective First prize for brave innovation in rigid multi-wheelers must go to the • Quick and easy to install Czech Republic’s Tatra, with every wheel independently sprung from a stem-to-stern tubular spine, into which are integrated the Twin Disc • Simple to maintain automatic gearbox, final-drive units and propeller shafting. Power comes from a Cummins 10.8-litre or Caterpillar 12.5-litre engine. Axle units can be added to the tubular spine as required, so there can be anything from For more information and technical two to six axles. Loads are equalised between the axles of bogies by air details visit our website suspension. www.kleenairsystems.co.uk All costly no doubt, but offering Double-wishbone suspension with the remarkable off-road performance 500mm of travel: reacts against for which some armies are prepared transverse air springs on Lockheed to pay. K Martin trucks. Or contact Alan Barnard by phone on 07810 482242 or email [email protected]

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