Section R. 408.11903 - Definitions; B, CRule 1903.
(1) "Boom" means a structural member hinged at the lower end to a fixed location and used for supporting hoisting tackle.(2) "Boom angle" means the acute angle between the longitudinal center line of the boom and the horizontal.(3) "Boom stop" means a device used to limit the angle of the boom at the highest position.(4) "Crawler crane" means a rotating superstructure with a power plant, operating machinery, and boom mounted on a base equipped with crawler treads for travel, and used for hoisting and swinging loads.Mich. Admin. Code R. 408.11903