Hot Vulcanised lagging application involves the chemical cross-linking of five reactive layers during the autoclave curing process. To achieve the desired 100% rubber tear adhesion all five layers must crosslink at the same time. Occasionally conditions can be created in the autoclave that prevent this happening, and result in non-uniform adhesion around the pulley circumference. This bulletin explains how these conditions occur and what needs to be done to eliminate this problem.
Spare pulleys are held so that in the event that an operational pulley requires replacement this can be done quickly and efficiently at the timing dictated by the mine maintenance personnel. The reason for changing a pulley broadly falls into two categories: