limestone, cement and later also fireproof products. The current Josefstollen pit was opened up in the mid-1960s, and it is from here that all TKDZ raw materials have come since 1965 following the end of overground mining. Since 2007 the company has relied on three articulated dumpers made by construction machinery specialist Bell for this work. Last year it was decided to replace the oldest Bell B30D, which had already clocked up 12,000 operating hours.
The company opted for a two-axle special-purpose vehicle – the Bell B30E 4x4 – which has been in service since early 2016. The necessary power for underground use is delivered by an MTU Series 6R 1000 engine rated at 246kW. It is based on the Mercedes-Benz OM 936 engine and was developed specifically for off-highway applications in the agricultural, construction and industrial sectors. Working all year round on an alternating single shift, each machine clocks up as many as 1500 operating hours a year.