When sourcing a heavy-lift crane, you must prioritize the Maximum Lifting Capacity (500t) and the Main Boom Length, which typically ranges from 80m to 100m. Ensure the crane features a high-strength U-shaped or oviform boom to minimize weight while maximizing structural rigidity. Additionally, verify the Engine Power (kW) and Torque to ensure the chassis can handle the gross vehicle weight during transit, and check for multi-axle steering systems (usually 7-9 axles) to guarantee maneuverability on construction sites.