Keywords: A-frame derrick.gif en A-frame derrick means a derrick in which the boom is hinged from a cross member between the bottom ends of two upright members spread apart at the lower ends and joined at the top; the boom point secured to the junction of the side members and the side members are braced or guyed from this junction point date https //www osha gov/pls/oshaweb/owadisp show_document p_id 9832 p_table STANDARDS Occupational Safety Health Administration U S Department of Labor PD-USGov Uploaded with UploadWizard Derrick cranes |