Preventive maintenance is time-bound and scheduled maintenance of all equipment, like oiling the gears, shaft-alignment etc. Predictive maintenance is carried out after monitoring equipment and finding something unusual. eg: if a bearing is overheating, there might be a lubrication problem. For this, LLF (look, listen, feel) round is carried out once in a while of the plant. Break-down maintenance is carried out after an equipment has failed. Eg: replacing a shaft after it has broken.