For over a year, an Allison-equipped Mercedes Zetros 1833 water transporter has run in esco’s Bernburg salt mine, where a rock salt deposit yields about 600 tons of salt per hour.
A total of 146 production and specialty mining vehicles are used in the mine, but the Zetros 1833 4x4 presented an interesting challenge. The water transporter would not fit through the 2.9 x 2.5 meter mine shaft and was therefore split into two and lowered 380 meters on a hook. Once in the warm, dusty labyrinth of dark tunnels, the vehicle was welded back together, the cut-off points strengthened with a batten in the esco-owned workshop. Then the 6,000 liter, stainless steel water tank with rear spray bar was mounted, and within a month, the Zetros began operating. Equipped with an Allison 3000SP fully-automatic transmission, the truck replaced an IFA W50 4x4 built in the 1980s which had been used for over 30 years. Expectations were even higher for the newcomer.
“We searched for an off-the-shelf vehicle to reduce costs. The vehicle had to feature a robust chassis, all-wheel drive and a fully-automatic transmission to cope with the difficult driving surfaces. A payload of at least seven tons was necessary: a six-ton tank capacity and an additional ton to account for the bodywork.
The Mercedes Zetros with an Allison transmission was a good choice,” explains Volker Grzeschuchna, Head of Mechanical and Electrical Engineering Underground at esco - european salt company. “We are entirely satisfied with the vehicle; it provides heightened driving comfort.”
While water is necessary for the drilling process, spraying roads is one of the vehicle’s primary tasks since humidity in the Bernburg salt mine is quite low – only 25 to 30%. This reduces rusting, but also improves driver visibility which can become difficult due to the combination of dry air and routine mining activities. Tractor shovels regularly drive blasted salt pieces to roll crushers. From the roll crushers, the salt is transported to a grinding mill to be sieved, producing salt for everything from the road to the table. This process can fill the tunnels with salt dust clouds as thick as smoke.
The Allison-equipped Zetros has a maximum speed of 50 km/h, but generally waters the roads at approximately 10 km/h, using its rear spray bar and covering about 400 km per month. Additionally, it refills water containers within the entire 7.5 x 3.5 km mining area, allowing removal of salt dust from vehicles and workers. Only used as required depending on dust exposure and container water levels – some days 10 hours, other days not at all – the vehicle operates in a three-shift-system.
Allison defies difficult terrain
Salt soil is hard and rough, challenging vehicles and operators with gradients of up to 20%. While the vehicle winds into narrow galleries and through pitch-black tunnels, absolute alertness is essential. Robust underground mining vehicles with flawless drivability and easy handling are required. “There are off-road driving conditions underground. The Allison fully-automatic transmission is paying off, especially on inclines and slopes. It allows optimal vehicle control, even at low speeds,” says Grzeschuchna.
According to Thomas Weilbeer, esco’s Giant-Equipment Instructor, driver training is very simple. The Allison transmission is appreciated by the miners without exception. Each of esco’s 15 trained operators can fully concentrate on driving, while the transmission handles changing gears, automatically selecting optimal shift points.
Allison transmissions are designed to deliver superior performance, durability and minimal maintenance, reducing downtime and operating costs. The 326 HP Mercedes OM 926 LA engine with Allison 3000 Series fully-automatic transmission delivers excellent startability and acceleration. The torque converter multiplies engine torque at vehicle launch. Allison’s Continuous Power Technology with advanced electronic controls allows continuous power transfer during shifting for efficient operation and reduced driveline damage. The integral output retarder further enhances vehicle control over rough surfaces and reduces service-brake heat and wear.
Will the Zetros see daylight again? “No. At least not in one piece,” saya Grzeschuchna. “In 30 years at the earliest, it will be disassembled into individual parts and transported for scrapping.”
