Breaking the mould in the haulers sector

The construction equipment sector is a fast-moving place, and nowhere is this more true than in the haulers sector. Articulated dump trucks (ADTs), rigid dump trucks (RDTs) and scrapers are sold all over the world across the quarrying, road building, mining and general construction industries, and manufacturers are working hard to make their equipment stand out in this competitive market.

The big news from the sector came in December last year, when Volvo announced a deal to acquire the RDT and ADT manufacturing business of its rival Terex for US$ 160 million – a transaction that fundamentally altered the competitive landscape for this industry.

Meanwhile, manufacturer Bell also surprised the market by showcasing its largest ever ADT, the 60 ton (54 tonne) capacity B60 concept model, at the inaugural Bauma Africa exhibition in Johannesburg, South Africa, last autumn.

Only one other manufacturer in the world has claimed to develop a 60 tonne true ADT, and that is XCMG, which unveiled its own prototype, the DAE60, at the end of 2012.

By entering the 60 tonne weight range, these machines are competing with the lower end of the RDT market, but six-wheel drive should give these models a distinct off-road advantage over their rigid counter-parts.

Fresh design

But unlike XCMG’s prototype, which to all intents and purposes looked just like a 50 tonne capacity model but a little larger, Bell departed from the traditional ADT design when developing the B60.

The B60 combines the traditional ADT concept – all-wheel drive, articulation steering and an oscillation joint – but with a single rear axle. This opens up opportunities for the ADT specialist in a domain that was previously only contested by rigid haulers.

Chief engineer Wynand van der Walt said, “We have adopted the two-axle concept of an RDT, with the difference that the front axle is also driven and the front and rear chassis are independent. This makes the truck a complete 4x4, unlike the conventional rigid trucks, which are 4x2 with limited suspension and poor ability to negotiate unmaintained areas along the route or at the load and tip areas.”

The front end of the B60 is the same as the B50D model, but the engine’s power output has been increased from 380 kW to 420 kW in the B60 and it features a 7-speed Allison transmission rather than the 6-speed transmission of the B50D.

The most visible differences are at the back end. The back axle is a dedicated 70 ton (63 tonne) truck and haulage axle from Kessler. To achieve the 60 ton (54 tonne) capacity, the body is also much wider than an ADT and more resembles a conventional rigid-type bin.

The rear chassis and suspension are also distinctly different from an ADT concept. A cradle supports the rear axle with struts being used to create active shock absorption for a controlled ride.

Bell aims to test the concept B60 further afield in Southern Africa, and also plans to build more units this year for testing on various customer sites. The production launch is timetabled for 2015.

Emissions laws

Meanwhile, another big talking point for the ADT market has been the introduction of strict new off-highway diesel exhaust emissions laws in Europe and North America.

The EU Stage IV and EPA Tier 4 Final legislation came into force on 1 January this year, cutting the amount of nitrous oxide (NOx) and particulate matter (PM) released in diesel exhaust even further than was required under the previous phase of legislation.

In fact, these emissions will be reduced to ambient atmosphere levels, which is why come even claim they would clean the air around them, particularly if working in cities. But in order to achieve this, a range of new aftertreatment components must be added engine systems to bring them up to scratch.

OEMs have been busy redesigning their machines to accommodate these changes. Indeed, Volvo will this year launch a new, Stage IV/Tier 4 Final-compliant ADT range – the G-Series. The range consists of the 24 tonne capacity A25G; 28 tonne capacity A30G; 33.5 tonne capacity A35G and A35G FS; and the 39 tonne capacity A40G and A40G FS models.

All models boast Volvo CE’s new turbocharged six-cylinder engines, with gross power ranging from 235 kW to 350 kW. Other on-board technology includes a retarder to control downhill hauling speeds using wheel brakes and the engine brake, together with automatic traction control (ATC) and differential locks as standard.

The ATC system automatically switches between drive combinations of 6x6 and 6x4 to ensure lower fuel consumption or provide maximum traction when needed. If necessary, all differentials can be 100% locked, causing all wheels to rotate at the same speed for maximised traction in slippery conditions.

With the A35G FS and A40G FS, full hydraulic suspension on all wheels is said to increase productivity and make for a more comfortable ride, while the A35G, A35G FS, A40G and A40G FS models can be equipped with Volvo’s on-board weighing system. This technology allows for precise machine productivity monitoring, and can help to optimise payload and minimise wear, tire damage and high fuel consumption.

The machines also come fitted as standard with CareTrack, Volvo CE’s telematics system. Accessed remotely, CareTrack provides machine information such as fuel consumption and service reminders that allow improved planning and operation.

Technology

Caterpillar has also developed new Tier 4 Final/Stage IV-compliant ADTs, and on-board technology is a key feature of this new range as well. The C-Series consists of the 23.6 tonne payload 725C, and 28 tonne payload 730C and 730C EJ ejector body.

The range boasts automatic traction control together with the Cat 6F/1R power-shift transmission, which electronically modulates clutch engagement pressures for smooth, positive shifts.

The transmission now also incorporates Caterpillar Advanced Productivity Electronic Control Strategy – a system that aims to improve acceleration, maintain torque-converter lock-up and ground speed during critical shifts, and increase rimpull.

The 725C’s Cat C9.3 Acert engine is rated at 234 kW, while the Cat C13 Acert in the larger models is rated at 274 kW, and all three models are available in US EPA Tier 2/EU Stage II equivalent, and Tier 3/Stage IIIA equivalent, as well as the Tier 4 Final/Stage IV.

Cat said that compared with previous models, the 725C had a +4% gain in gross power and a +20% boost in gross torque. It said the 730C and 730C EJ models had nearly +16% more gross power and more than a +30% gross torque improvement.

It is clear that a lot of changes are taking place when it comes to the design of new ADTs, which is interesting considering it is a relatively small sector - the global market is in somewhere in the region of 4,000 trucks per year.

If you compare this to the hundreds of thousands of crawler excavators or wheeled loaders that sell in the same regions each year, ADTs start to look like a niche market. Nevertheless, manufacturers are in fierce competition to meet and indeed exceed the requirements of their buyers. Now that the strict Tier 4 Final/Stage IV emissions laws are in place, it will be interesting to see where technology in the sector moves to next.