"Design a comprehensive, IoT-based predictive maintenance system for industrial equipment, focusing on advanced technical details. Outline the system architecture, including hardware components (e.g., IoT sensors, gateways), software components (e.g., data ingestion, processing), and cloud infrastructure. Explain the role of data analytics and machine learning algorithms in predicting equipment failures and optimizing maintenance schedules. Provide technical examples of successful implementations, highlighting key challenges and lessons learned. Ensure the explanation is tailored to an audience with a strong technical background in IoT development and data analytics."