From the very bottom to the very top.

Ronny Fischer and his colleague have just loaded the last barrel of drilling fluid onto the trailer, the early mowing shift is almost over for today. The freshly treated "bouillon" is needed at one of the roughly 1,000 drilled filter wells. "The wells are drilled for dewatering, because it is essential that the deposit be kept free of water. There are 7,000 litres in the barrel on the trailer, which now has to be taken from the central liquid treatment plant (ZSA) to Reichwalde, Feldriegel 30 – not a problem today; over the last few days, with black ice, this was no easy undertaking. Without the tyre pressure control system, we would probably have been stuck all the time."

"Once I actually had to unhitch at the back — I could turn the trailer on my own, the ground was that slippery." As "foreman for drilling equipment and stabilisation," his official job title, Ronny Fischer supplies the "drillers" with all the equipment they need – core barrels, drill rods and occasionally a heavy press capable of exerting up to 20 tonnes when nothing else will do and a drill rod has become hopelessly stuck. In addition, the contaminated drilling fluid has to be extracted from the pits. "That's why our 5023 not only has the loading crane but also a rear PTO shaft that drives the appropriate vacuum pump on site. With the full barrels we then head back to the central liquid treatment plant (ZSA). A cycle, really," he explains, as he taps the column-mounted shifter and the 231-hp diesel runs in the next-higher gear. According to Frank Schroeckh, responsible at Vattenfall Europe Mining AG for process management and optimisation, the fleet comprises more than 80 Unimogs. The four mining sites are between 18 and 68 km apart. "The majority of our Unimogs come from the high-mobility model series. We use them wherever normal vehicles would get stuck."

Take the Welzow-Süd open-cast mine in Brandenburg, which mainly supplies the Schwarze Pumpe power station with coal. Four Unimog 5023 are used here as conveyor-belt inspection vehicles. Because two pre-stripping plants operate in parallel there, the overburden runs over two conveyor systems that must be inspected and maintained around the clock. Driver Jens Reiber monitors one of the 13-kilometre-long belts and covers between 40 and 100 kilometres per shift. Twice per shift the belt must undergo a detailed visual inspection. To clear blockages – in the worst case to extinguish overheated rollers – he carries all sorts of tools on board: spades, shovels, but also crowbars and tow ropes. "The fire extinguisher with its pressure cartridge is in the red box on the flatbed. Fortunately, it is rarely needed." The return conveyor belt is supported by so-called garlands, lower roller assemblies. They wear out quickly. Jens Reiber notes suspicious components and replaces them en bloc on the following repair day. "On average, about 100 items need to be replaced on each repair day." All four "baBs", conveyor-belt inspection vehicles designed for minimal operator interaction, run, unlike their counterparts in Nochten, on 24-inch 445/70 Michelin XM 47 tyres with an agricultural tread. They also do without tyre pressure control.

"Two vehicles are constantly on the move, the other two are on call. The braking system wears out quickly in operation, so we use sealed brakes with polyurethane sealing lips. Downtimes still vary, but the Unimog are optimally equipped for this service. With a wading depth of up to 1.2 m, no water hole is too deep," explains Schroeckh, who knows this area west of the Spree near Spremberg like the back of his hand. Driver Jens Reiber, who is over 1.80 m tall, also appreciates other features of his yellow diesel work vehicle. "It's not just the off-road capability and the simple, ergonomic operation. Unlike its predecessors, larger people can also drive comfortably. The U 5023 is also comfortable and well sprung."