This document discusses preventive maintenance and root cause analysis of a sealed quench furnace used in an axle heat treatment line. The furnace was experiencing frequent breakdowns related to the heating and quenching units, including damage to the loading track, failures of the quench oil pump coupling and air cylinder seals, and delays in reaching the required temperature. Root cause analysis using why-why analysis and fishbone diagrams identified issues like a lack of rigid track support, improper burner design, pump misalignment, and components being too close to high heat. Countermeasures were implemented such as adding rigid track supports, modifying the burner design, changing couplings, and increasing cylinder height. After implementation, availability increased from 96.07