| A | Infrequent or standby service with long idle periods. | Occasional lifting; generally not used as part of a continuous production process. | Usually light and highly variable loading. | Often planned around ISO 4301 groups U0–U2 with Q1–Q2, subject to the actual load spectrum. | Maintenance areas, utility facilities, assembly areas, and equipment rooms. | Do not select this class solely because the maximum load is low; verify the expected annual cycles and longest periods of inactivity. |
| B | Light service with intermittent handling. | Approximately 2–5 lifting cycles per hour, normally with short operating periods. | Light loading with occasional lifts near rated capacity. | Commonly considered within ISO 4301 U1–U3 and Q1–Q2 planning ranges. | Light warehouses, service bays, repair shops, and occasional material handling. | Check that starts, stops, travel distance, and load distribution do not exceed the assumed intermittent duty. |
| C | Moderate service for general industrial use. | Approximately 5–10 lifting cycles per hour with regular daily use. | Moderate loading; rated-capacity lifts occur periodically rather than continuously. | Often evaluated within ISO 4301 U2–U4 and Q2–Q3 planning ranges. | Machine shops, fabrication facilities, general manufacturing, and process support. | A common general-purpose choice, but confirm the required total working cycles and average load spectrum. |
| D | Heavy service with repetitive production handling. | Approximately 10–20 lifting cycles per hour and regular operation across the workday. | Moderate-to-heavy loading with frequent use of a substantial portion of rated capacity. | Often evaluated within ISO 4301 U3–U5 and Q2–Q3 planning ranges. | Production lines, steel fabrication, foundry support, and high-use manufacturing areas. | Consider higher hoist, motor, brake, wheel, and structural fatigue requirements when production is repetitive. |
| E | Severe service with high production demand. | More than approximately 20 lifting cycles per hour, often over multiple shifts. | Heavy and frequent loading; a significant share of lifts may approach rated capacity. | Often evaluated within ISO 4301 U5–U7 and Q3–Q4 planning ranges. | Continuous production, heavy fabrication, material stockyards, and demanding process operations. | Use measured or carefully estimated cycle counts, duty-cycle duration, speeds, accelerations, and load history. |
| F | Continuous severe service requiring maximum reliability and durability. | Very high utilization, often dedicated to a specific production process and operating for extended periods. | Very heavy or highly concentrated loading with frequent near-capacity lifts. | Frequently associated with ISO 4301 U6–U9 and Q3–Q4 planning ranges, subject to engineering verification. | Specialized process cranes, high-throughput production, heavy-duty transfer operations, and continuous-duty facilities. | Require a project-specific fatigue, thermal, mechanical, electrical, and maintenance assessment rather than a generic class selection. |