Richards Bay Minerals (RBM) supplies approximately 25% of the worlds pigment and welding rod markets, 25% of the demand for iron for ductile iron castings, and a quarter of the world market for zircon, used in the production of ceramic tile and sanitary ware. Western Star trucks and Unitrans are there as RBM business partners in supplying these world markets.

Unitrans have acquired 10 Western Star purpose-built specification truck tractors to haul their road-trains. Operating at 15O tons gross combination mass (GCM) and a total length between 40 and 45m depending on type of trailers, the road trains are employed on mine roads that the public use. These impressive vehicles haul 3 trailers each carrying 35-ton per trailer with a total payload of around 105 tons. Combined with an un-laden combination tare mass of 42 tons, 150 tons GCM is easily attained.

The whole rig runs at a permissible 9 tons per axle and is no more than 2.6m wide or 4.3m high in terms of the Regulations. Lights, glass, braking-systems and reflective markings all comply with SABS specifications. Every trailer has a top tarpaulin that can be raised for loading and ensures that no product blows out of the trailers and onto any following vehicles. The Western Stars are also equipped with daytime running lights that automatically illuminate as soon as the park brake is released to comply with mining safety regulations where vehicles must travel with headlights illuminated at all times.

Since 1984, and for more than 20 years, Unitrans has hauled Heavy Mineral Concentrate (HMC) for RBM. The formidable task is to deliver 3,6 million tons of HMC annually to RBM’s Mineral Separation Plant (MSP), and DaimlerChrysler has been there as Unitrans consistent partner and supplier of truck tractors for side-tipping, trailer road-trains. “The challenge,” explains Fil Morkel, MD of Unitrans Freight, “Is a balancing act where road transport must be consistent at all times of the day and night in delivering HMC at the rate of 600 tons per hour to receiving hoppers at the plant. While transport costs are a small proportion of total mining costs, reliable transport is absolutely critical to RBM’s production output.”

Special technical features of the new Western Star haulers include:

- A 565 horsepower Cummins ISX engine developing 2500Nm is employed. Engine torque is electronically stepped, so that the engine develops 2000Nm in the 1st six gears, then 2300Nm in the next six followed by 2500Nm in the top six, to prevent wheel-spin when pulling away with empty trailers.

- An Eaton Fuller, 18-speed Autoshift transmission with 3050Nm capacity is fitted to make the prime mover easier to drive and also prevent possible driver abuse though inappropriate gear selection. Autoshift changes gear very quickly – when the combination is travelling very slowly gears can change without stopping. Autoshift also allows very quick, aggressive downshifts to use the engine brake to its greatest effect. The Cummins engine brake provides the same kW in retardation as for maximum forward power.

- 32 brake boosters are actuated when a driver applies the brake pedal. A big 1000 litres/min naturally aspirated compressor is fitted to cope with the very large air demand that 3 trailers and 16 axles create.

- Automatic lubrication systems are fitted to protect chassis components in dirty working environment. A Cummins Centinel system automatically replaces old engine oil with new lubricant as the vehicle moves because fuel consumption is in excess of 1 litre per km and oil change intervals would otherwise be very short.

- Almost all visible shiny items on the truck are made from either polished stainless steel or aluminium rather than chromed steel for long-term corrosion resistance.

The road trains operate with 4 drivers per rig, 24-hours around the clock, in 3 eight-hour shifts. Western Star major component suppliers Cummins and Eaton together with Western Star national distributors, Liebherr Africa (Pty) Ltd ensure high uptime in this world-class operation.