Articulating Boom : An aerial device consisting of two or more folding boom sections whose extension and retraction modes are accomplished by adjusting the angle of the knuckle joints
NFPA 1911 Standard for the Inspection, Maintenance, Testing, and Retirement of In-Service Automotive Fire Apparatus, 2007 ed. https://www.iafc.org/files/1EVM/evms_NFPA1911_1071 andEVT.pdf, (Std: Insp, Maint, Tst and Retirement of In-Srvc Automotive Fr Aptus - Amer) {415 NFC}