sentences:  The South African Iron and Steel Industrial Corporation (ISCOR) installed a trolley power assist line
  for diesel electric trucks at its Shishen mine in March 1982.Afterwards the company also installed a trolley power assist system at its Grootegeluk coal mine in Lephalale, South Africa.ISCOR (now known as Mittal Steel South Africa) is the largest user of trolley power assist trolleytruck systems in the world.