This Specification has been developed by the Crane Manufacturers Association of America, Inc. (CMAA), an organization
of leading electric overhead traveling crane manufacturers in the United States, for the purpose of promoting
standardization and providing a basis for equipment selection. The use of this Specification should not limit the ingenuity
of the individual manufacturer but should provide guidelines for technical procedure.
In addition to Specifications, the publication contains information which could be helpful to the purchasers and users of
cranes and to the engineering and architectural professions. While much of this information must be of a general nature,
it may be checked with individual manufacturers, and comparisons may be made, leading to the selection of the proper
equipment.
These Specifications consist of nine Sections, as follows:
74–1 General Specifications
74–2 Crane Classification
74–3 Structural Design
74–4 Mechanical Design
74–5 Electrical Equipment
74–6 Inquiry Data Sheet and Speeds
74–7 Appendix
74–8 Glossary
74–9 Index
Users of these Specifications must rely on their own engineers/designers or a manufacturer representative to specify or
design applications or uses. These Specifications are offered as information and guidelines which a user may or may not
choose to adopt, modify or reject. If a user refers to, or otherwise employs, all or any part of these Specifications, the user is agreeing to the following terms of indemnity, warranty disclaimer, and disclaimer of liability.
The use of these Specifications is permissive and advisory only and not mandatory. Voluntary use is within the control and
discretion of the user and is not intended to, and does not in any way limit the ingenuity, responsibility or prerogative of individual manufacturers to design or produce electric overhead traveling cranes which do not comply with these
Specifications. CMAA has no legal authority to require or enforce compliance with these Specifications. These advisory
Specifications provide technical guidelines for the user to specify an application. Following these Specifications does not
assure compliance with applicable federal, state, and local laws or regulations and codes. These Specifications are not
binding on any person and do not have the effect of law.
CMAA and MHI do not approve, rate, or endorse these Specifications. They do not take any position regarding any patent
rights or copyrights which could be asserted with regard to these Specifications and do not undertake to ensure anyone
using these Specifications against liability for infringement of any applicable Letters Patent, copyright liability, nor assume any such liability. Users of these Specifications are expressly advised that determination of the validity of any such copyrights, patent rights, and the risk of infringement of such rights is entirely their own responsibility.
Caution must be exercised when relying upon other specifications and codes developed by other bodies and incorporated by
reference herein since such material may be modified or amended from time to time subsequent to the printing of this
edition. CMAA bears no responsibility for such material other than to refer to it and incorporate it by reference at the time of the initial publication of this edition.
SUMMARY OF CHANGES SINCE THE 2015 REVISION OF SPECIFICATION #74
Article 1.4.1.1.1, 1.4.1.2.1 ................................Runway rail cleanliness
Table 1.4.1-1 ....................................................Modification of runway rail straightness and elevation
Article 1.4.2 ......................................................Anchorage / Restraints Devices
Article 1.5.4, 5.11 .............................................Runway/bridge conductors combined in one article
Article 1.7 .........................................................Revision of section
Article 1.7.3 ......................................................FEA design statement
Article 3.3.2.5.3 ................................................Addition of in service wind load to collision load case
Article 3.4.4.3 ...................................................Corrected error in formula
Article 3.4.7 ......................................................Addition of load case for fatigue
Article 3.5.1 ......................................................Girder proportions
Article 3.5.5 ......................................................Deflection and camber
Article 3.6.4 ......................................................End truck deflection
Article 3.10 .......................................................Restraint Devices
Article 5.2.1.3.1 ................................................Motor design for inverter applications
Article 5.5.6 ......................................................Dynamic braking resistors in conductive dust
Article 5.4.7.5 ...................................................Practices inside enclosures (new)
Article 5.4.7.6 ...................................................Practices outside enclosures (new)
Article 5.4.7.7 ...................................................Suppression devices (new)
Article 5.5.5 & 5.13.2........................................Removed duplication and changed text
Article 5.5.6 ......................................................Resistors in conductive dust (new)
Article 5.6.10 ....................................................Modified text (addition of intentional reset)
Figures 5.7.3c, 5.8.1, 5.15.6 ............................Added recommended layouts for cab, pendant and radio
Article 5.9.3.4 ...................................................Added text for operation with molten metal
Article 5.11.8 ....................................................Conductor Bar Isolation Sections
Article 5.13.12 ..................................................Regenerative power considerations
Article 5.13.13 ..................................................Application of IEEE 519 for cranes
Article 5.15 .......................................................Wireless data (new)
Article 5.18 .......................................................Magnet controls (new)
Article 5.19 .......................................................Rail clamps (new)
Appendix ..........................................................Added appendix for non-mandatory crane design information
Glossary ...........................................................Anchorage
Glossary ...........................................................Common mode failure
Glossary ...........................................................Conductive dust
Glossary ...........................................................Critical load drop
Glossary ...........................................................EMC
Glossary ...........................................................EMI
Glossary ...........................................................Hazardous locations
Glossary ...........................................................Intentional reset
Glossary ...........................................................Magnet
Glossary ...........................................................Magnet controller
Glossary ...........................................................Plain Reversing Control changed for Reversing Control
Glossary ...........................................................Regenerative power system
Glossary ...........................................................Restraint
Glossary ...........................................................RFI
Glossary ...........................................................Modified Undervoltage Protection definition
