When massive, open-pit mines like the Minera Escondida — in Spain's Atacama Desert — need to pull millions of tons of minerals out of the ground each year, they rely on fleets of huge, "Ultra-Class" haul trucks. The ETF Haul Train, however, pulls four times the minerals of these stone-toting behemoths with just one driver.
Haul trucks are not like the typical dump trucks that you see in urban construction sites. They are specially designed for the rigors of high-production mining, with multiple axles and reinforced frames. This class of truck is capable of moving loads anywhere from 50 to 400t (compared to 35-100t for a standard quarry truck), the largest of which is known as the "Ultra Class". The vast storage capacity that makes these vehicles so valuable also makes them difficult to manoeuvre, requiring specially trained drivers to operate, and wide roads to drive on.
So rather than just make a bigger mining truck, European Truck Factory of Germany built a smarter one. ETF mining trucks can tote anywhere from 170-400t individually, depending on the model, spreading the weight out over as many as seven axles with four tires per axle. A "Central Tyre Inflation System" actively monitors and adjusts the pressure within each wheel as the ground surface changes — lowering the pressure for travelling over soft ground and re-inflating as the ground firms. If a tire goes flat, which would immediately sideline most haul trucks out of fear for axle damage, the ETF mining truck will automatically raise that axle and alert the driver but still be able to finish his run. What's more, these trucks are both all-wheel-drive and all-wheel-steering, which greatly reduces the necessary turning radius.
The ETF's most impressive feature, however, is that multiple trucks can be linked together into a single, unified Haul Train operated by a single driver. Each truck in the train is connected via a steel arm not only physically links them but also carries control data — throttle, brake, and steering input — from the lead truck so that no matter how many are connected, they operate in unison. This allows a single driver to haul as much as 1520 US tons of material — per trip. The Earth will be hollowed out in no time. [Wikipedia - ETF Trucks 1, 2]