How Volvo revolutionised the articulated dump truck

THE portfolio of Swedish company Volvo is both extensive and impressive, ranging from domestic cars and SUVs to commercial trucks and buses.

Volvo ‘Penta’ provides power units for marine and land applications, while Volvo Autonomous Solutions is at the forefront of material handing automation.

Volvo is also the parent company to a host of companies, however it is Volvo Construction Equipment that concerns this piece – in particular the Volvo dump truck.

Volvo were the pioneers of the articulated dump truck (ADT) in 1966 with the release of the 631 in 1966.

Previously, dumpers had been built around agricultural tractor units, which relied on the non-driven, small wheels of the front axle to steer.

The 631 was a twin axle dumper, with engine and cab at the front and dumper at the back, joined by hydraulic articulated steering.

With drive to both axles, this made the dumper highly manoeuvrable with excellent traction, even in the most challenging terrain.

The 631 was joined by the three-axle 831 in 1968 and the rest as they say, is history.

Manufactured in Volvo’s dedicated ADT factory in Braas, Sweden, the Volvo BM 861 was released in 1979.

Powered by a Volvo 5.5liter turbocharged engine, the 861 produces 170hp.

The torque converter transmission has four gears in both forward and reverse, operated by a large lever under the steering wheel at the left.

The 861 is available in 4wd or 6wd format (from 1983) with differential locks for each driven axle, and is equipped with air over hydraulic brakes.

Apart from the articulated steering, another key design feature is the twin A-frame bogey axles which can move independently of each other. The rotating cylinder at the pivot of the machine keeps the front tractor unit upright in the event of the dumper body capsising.

Various dumper bodies were available for 861, the standard body capable of holding 18tons.

Twin six-stage ramps are capable of tipping the load to a 70-degree angle for fast ejection in 18s.

This is thanks to the Vickers hydraulic pump with a 130/min capacity, driven directly from the engine on the right--hand side.

Worthy note is the optional exhaust gas ducts which fed the exhaust through the floor of the tipper body, heating the floor to prevent earth sticking.

The Volvo BM 861 was replaced by the ‘A’ range of dumpers with the A20 taking its place. Today, the A range is a market leader in ADT’s and is currently in its seventh generation, with the A25G the smallest model.

Many 861 dumper bodies were also reinvented as tractor dumper trailers by engineering a drawbar at the pivot point.

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