What "Extreme Duty" Means: Duty Classification Standards Compared
How CMAA 70 and 74, ISO 4301-1, FEM 1.001, ASME BTH-1, hoist and motor duty ratings define severe service, what OSHA adopts, and how controls enforce it.
ASME BTH-1 Design Categories and Service Classes: Rated Load Cycles
How ASME BTH-1 assigns a design category and service class to below-the-hook lifting devices, converts use into load cycles, and sets fatigue and drive design.
Load Spectrum and Design Life: Converting Duty Cycle to Hours and Cycles
How a duty cycle becomes working cycles, a load spectrum factor, and a duty class, why the cube law governs it, and how bearings, gears, and monitoring use it.
Fatigue vs. Static Strength: Why Heavy Machines Crack at Low Stress
Why heavy machine frames crack below yield: S-N curves, weld-toe notches, stress range, cycle counts in continuous duty, documented failures, and monitoring.
Designing for 24/7 Operation in Abrasive, Hot, and Wet Environments
How round-the-clock duty in abrasive, hot, and wet service changes bearing life, grease, seals, steel strength, sensors, and condition monitoring design.