PARTNER INSIGHT


design criteria for both top-running and under- running configurations.


 Mechanical and component changes: New details define end-truck geometry, bearing stress limits and trolley hoist load distribution. The revisions also tie component sizing more closely to material strength and fatigue data for modern steels.


 Electrical and control system enhancements: References to the latest wiring practices and control technologies include recommendations for variable- frequency drives (VFDs), anti-sway systems and programmable logic controller (PLC)- based motion control.


 Safety and inspection clarifications: Expanded commentary provides inspection intervals, maintenance record guidance and enhanced labelling and guarding requirements. These updates strengthen alignment with OSHA regulations and modern risk management practices.


 Glossary updated: To improve clarity across engineering, manufacturing and inspection activities, the revision added a new definition: Diaphragm. A plate or partition between opposite parts of a member, serving a definite purpose in the structural design of the member


Specification 74 ensures that overhead lifting equipment is safe and reliable.


and can be either full depth or short depth. Full depth diaphragms may stop short of tension flange except at the ends of structural box members. Short depth diaphragms are typically located in the compression stress zone of the web and are used for web buckling stability or to support bridge/trolley rail, or both.


Ongoing support Additional commentary helps users interpret


design formulas, apply duty classes and assess expected service life. These notes give engineers more flexibility while maintaining standardisation and safety. In total, the updates to the specifications


reflect CMAA’s ongoing effort to modernise its specifications to support evolving technologies. The revisions account for the latest developments in digital controls, performance monitoring and life cycle design principles. 


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