Crane Boom Angle Indicator
A crane boom angle indicator is a regulated safety device that measures and displays the angle of the crane boom relative to the horizontal, in degrees, to the operator at the control station. Required by OSHA and WorkSafeBC when rated capacity depends on boom angle, it enables safe lift planning by comparing angle to load charts, preventing overload and tipping.
On a shop floor or industrial site, the boom angle indicator is used during routine lift planning and execution. Operators read the current boom angle to determine maximum allowable load from load charts, which are organized by boom length and angle. Capacity decreases sharply at lower angles, so the indicator is critical for avoiding overload, tipping, or boom failure. It integrates with Load Moment Indicators (LMI) and boom hoist limit devices for real-time alarms and automatic cut-outs. Daily pre-use checks verify indicator legibility and calibration, while supervisors use readings in Safe Work Procedures and lift plans to specify minimum angles and maximum radii for heavy lifts.
When exactly does WorkSafeBC require a boom angle indicator?
Under OHSR s.14.7, a boom angle device is required whenever the rated capacity of a crane or hoist is affected by boom angle and the boom is movable in the vertical plane. The indicator must be readable by the operator at the control station.
How does the boom angle indicator relate to load radius, and can radius substitute for angle?
Many regulations allow either boom angle or boom radius indication. WorkSafeBC s.14.7 requires a means to indicate boom extension or load radius if capacity is affected by those. Radius indicators must be accurate within 97–110% of true radius. Angle indicators are more common due to simplicity and robustness.
What are the minimum performance/accuracy expectations for boom angle indicators?
California Title 8 requires indicated radius or equivalent to be within no greater than 110% and no less than 97% of actual radius. The indicator must clearly show angles in degrees at all times, provide visual warning before unsafe angles, and be mounted for operator visibility and control. Routine verification and calibration are critical.