The self-propelled modular transporter (SPMT) widening adaptor for high and wide loads from heavy lifting and transport specialist Mammoet will go into service for the first time in September in the US.

Launched in April at the Bauma 2016 trade fair, in Germany, the SPMT widening adaptor allows for increased track width of a split SPMT – thereby widening the loading platform without the need to add more SPMT trailer units to safely execute the transport of large loads, such as transporting cargo from mines to port.

In heavy transport, high and wide loads with a high centre of gravity – such as large pipe rack modules – are typically transported on multiple rows of SPMTs. Connecting more SPMT trailer units side by side creates a wider loading platform, ensuring stability of the load during its transport and enhancing safety. However, in many cases, this increased load capacity, as a result of the additional trailer units, is not required.

Identifying room for improvement, Mammoet designed the widening adaptor, which allows for variable spacing of split SPMT trailers and power pack units (PPUs). This allows for more cost-effective transport of specific loads and reduces the carbon footprint of loads that would otherwise need more SPMTs and PPUs.

Heavy transport vehicles manufacturer Scheuerle was contracted by Mammoet to engineer and fabricate the SPMT widening adaptor. Scheuerle developed a new variation of the SPMT that is divided down the middle along its entire length. Double sets of articulated arms are attached to the inner walls of the two SPMT halves and runners that slide over a central tube down the middle of the SPMT. The central tube keeps the articulated arms aligned as they move to either increase or decrease the track width.

The split SPMT with widening adaptor has a minimum width of 3 m and a maximum width of 6.4 m; therefore, one row of split SPMTs can replace two rows of conventional SPMTs. By removing the widening mechanism and placing it on top of the two reconnected SPMT halves, the width is reduced to 2.43 m, making it possible to fit the split SPMT into a standard flat-rack shipping container for efficient shipping.

Although the company’s growth in the South African and other African mining sectors has slowed, owing to the downturn in commodities prices, Mammoet SA marketing manager Ryan Amos says the company sees great potential for further expansion in Africa.

“We are focusing on informing the local mining industry about our service offering, highlighting that our tailor-made solutions are driven by the goal to prevent downtime of . . . operations and, thus, save costs. We are hoping that, in time, these markets will be open to trying a new approach to transporting heavy loads – one that has been proven to be successful in several projects worldwide.”

Reduced Travel Time
Mammoet’s approach to managing heavy-haulage was demonstrated in 2013 when the company loaded a 3 500 t dragline onto SPMTs and transported it about 35 km through the New Mexican desert to the El Segundo mine, in the US, for coal miner Peabody Energy.

Though the dragline was designed to ‘walk’ at a maximum speed of about 160 m/h, it would have taken the machine longer than a month to reach its destination at this speed. Delivering the dragline in just 12 days, Mammoet reduced travel time by as much as 60% while eliminating the need for expensive power generators.

Never before has a machine of this weight been transported over such a long distance, highlights Mammoet, adding that the road to the mine had a width restriction, owing to an archaeological excavation site along the way. This meant that Mammoet had to use a longer SPMT train than was desirable. Several 7% inclines presented more difficulties and, while the transport was scheduled outside of New Mexico’s rainy season, heavy rain and snow made the journey additionally hazardous.

Mammoet mobilised 150 SPMT lines in a five-train-wide and 30-train-long configuration. Owing to the width restrictions on the road, the SPMT train could not be made wide enough to provide an optimally stable platform for the heavy load. To pre-empt possible deflection issues, the company installed load spreaders on each trailer to ensure that the dragline’s weight was spread evenly over the SPMTs.

To overcome the steep incline, extra pulling power was enabled by placing scrapers in front of the transport vehicle. When rain and snow weakened the surface of the road, Mammoet reinforced the road with steel plates to provide a surface strong enough to carry the 4 400 t load safely to its destination.

Transporting the dragline in this way reduced travel time by 18 days, enabling Peabody Energy to start using the dragline much sooner than originally expected. The chosen approach also eliminated the need for expensive power generators and 24/7 road and power line construction support for at least a month, as well as the widening of the road to about 36 m from 18 m. Transporting the dragline across the desert, thus, saved Peabody triple the time and double the money, Mammoet concludes.