Buyers should prioritize the engine model (typically Volvo D6E), ensuring it meets local emission standards (Tier 3/Stage IIIA or higher). Verify the operating weight (approx. 21-22 tons) and bucket capacity (0.75-1.5 m³) to match project needs. Crucially, inspect the hydraulic system pressure and flow rates, as these determine the machine's breakout force and cycle times. For used units, check the recorded working hours and the condition of the undercarriage (track links, rollers, and idlers), which accounts for a significant portion of maintenance costs.