Cab development and production remain high-cost elements in any new or upgraded truck model programme. As with passenger car and van platforms, tooling and other related costs require the maximisation of component sharing, notably of metal stampings, across a truck maker’s weight range.
External cab width, measured across the doors, not including mudwings, has become a focus of attention in such rationalisation efforts. Nearly all top-of-the-range forward-control (or ‘cab over’) European heavy truck cabs are now a full 2.5m wide, above vertical valanced front wheel arches. Crew access has to be via three, four or even five vertical ‘ladder’ steps, which is fine for long-haul but much less acceptable for multi-drop operations, where easier driver access is demanded and price and payload are also more critical.
Mercedes-Benz has just unveiled its new Antos range of ‘cruiserweight’ trucks, marking the latest episode in the German manufacturer’s hitherto seemingly convoluted cab design strategy
Scania is notable in producing only full-width cabs, albeit in three different heights. Because it builds nothing lighter than 18 tonnes gvw, it can ‘get away’ without a narrower cab. Those customers who buy the company’s 18 tonne four-wheelers for distribution work often do so for their own rationalisation reasons; typically they are also running heavier Scanias.
Mercedes-Benz has just unveiled its new Antos range of ‘cruiserweight’ trucks in the 16 to 26 tonne gvw category. Their introduction marks the latest episode in the German manufacturer’s hitherto seemingly convoluted cab design strategy. Its current Axor range, which Antos will replace, was developed in double-quick time about ten years ago when the company’s flagship (full-width-cabbed) V6 and V8-engined Actros models were seen to be too heavy and expensive in some markets, against Swedish competition particularly.
Axor was an unashamed compromise design. It made use of Mercedes’ much smaller and narrower, as well as, crucially, lighter and cheaper, cab from its 6 to 15 tonne Atego range.
Axor was an unashamed compromise design. It made use of Mercedes’ much smaller and narrower, as well as, crucially, lighter and cheaper, cab from its six to 15 tonne Atego range. However, it had to be mounted some 300mm higher on the Axor chassis to accommodate the 12 litre (Brazilian made) diesel engine. It meant the 2.3m-wide Atego cab had, for the full-width Axor chassis, to be equipped with incongruously large black plastic mouldings which served as necessarily protruding mudwings while also filling in the vertical space between the front wheels and the lower extremities of the steel cab shell.
With the new Antos, such awkward solutions to the cab width challenge are avoided. It has been helped by the adoption of the same new in-line-six engine family, sharing common outer dimensions, for Antos and its heavier Actros stablemate. Mercedes has followed the ‘two width’ rationalised design route adopted a decade or more ago by its Italian rival Iveco and more recently by MAN. The 2.3m-wide Antos cab, providing easier crew access, shares the sidewalls and doors – made up from what are acknowledged to be the costliest stampings in a cab – with that of the 2.5m-wide Actros. But Antos’s narrower floor plan, front and rear panels and roof, as well as its wrap-around fascia, sleeper bunk and trim are necessarily different. Though starting from a ‘clean CAD screen’ there were opportunities for some commonisation there as well.
The opinions expressed here are those of the author and do not necessarily reflect the positions of Automotive World Ltd.
Alan Bunting has a background in engineering, and has been writing on commercial vehicle and powertrain related topics since the 1960s. He has been an Automotive World contributor since 1996.
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