Keep Workers Safe From Moving Parts In Overhead Lifting Systems With Coupling And Line Shaft Guards
Couplings that connect different parts of components and machinery and power-driven, rotating line shafts for power transmission can be hazardous to personnel working on or in proximity to overhead handling equipment if they make contact with these moving parts. That’s why these mechanical components should be shielded with guards that serve as barriers to prevent access to these dangerous areas during normal operation of the lifting equipment.
In overhead cranes, hoists, and monorails four guarding types are used most often:
- Fixed guards are permanently attached to the equipment and cannot be moved.
- Removable guards can be disconnected and removed to help with maintenance or inspection tasks.
- Interlocked guards are connected to the power source of the equipment, shutting it off automatically if they are opened or moved.
- Self-adjusting guards move in relation to the item being guarded and the operator of the equipment.
Both the Occupational Safety and Health Administration (OSHA) and the American Society of Mechanical Engineers (ASME) have published requirements for the use of guarding devices for couplings and line shafts. They include:
OSHA 1910.179(e)(6)(i): Exposed moving parts such as gears, set screws, projecting keys, chains, chain sprockets, and reciprocating components which might constitute a hazard under normal operating conditions shall be guarded.
OSHA 1910.179(e)(6)(ii): Guards shall be securely fastened.
OSHA 1910.179(e)(6)(iii): Each guard shall be capable of supporting without permanent distortion the weight of a 200-pound person unless the guard is located where it is impossible for a person to step on it.
ASME B30.2-2016 and ASME B30.17-2017: Both crane standards contain requirements for guarding similar to the OSHA 1910.179 regulation, but add requirements for maintenance personnel to ensure all guards have been replaced if they are lost or damaged before returning the crane or hoist to service.
In addition to the OSHA and ASME standards, there are several best practices for the installation and use of guards for couplings and line shafts on overhead lifting equipment. They include:
- Fixed guards should be installed and securely fastened to shield all moving crane, hoist, or monorail parts that might constitute a hazard under normal operating conditions. Those hazards should be identified by a qualified person during normal operating conditions (rather than during maintenance and inspection procedures).
- Guarding should be substantially constructed and securely fastened to ensure its effectiveness.
- Guarding should be made of material that cannot be easily and accidentally deformed by personnel or contact with a load.
- Line shafts and couplings in the walking path of overhead cranes with cab-based controls should be guarded.
- Guard attachments should be inspected regularly to verify that they are secure and that they do not show signs of significant deterioration or corrosion.
- Guards should be visually identified or marked to properly identify the guarded hazard.
- Guards that are removed for inspection or service should be reinstalled prior to operation of the crane or hoist.
- Crane inspectors should document that guards have been installed on all moving parts which might constitute a hazard under normal operating conditions and that the guards are properly secured and marked to identify the guarded hazard.
- If the guards have been removed for maintenance or any other reason, the overhead lifting equipment must not be powered and operated until they have been reinstalled.
Looking for more best practices for the safe operation and use of overhead lifting equipment? The Overhead Lifting Best Practices Guide is offered as a free download from the members of the Overhead Alliance: the Crane Manufacturers Association of America (CMAA), Hoist Manufacturers Institute (HMI) and the Monorail Manufacturers Association (MMA). The document was developed by the group’s Service and Safety Committee in collaboration with OSHA through the Crane, Hoist and Monorail (CHM) Alliance. Through this partnership, the organizations provide information, guidance and access to training resources that help protect the health and safety of worker using hoists, cranes, and monorails.