R 408.11903 Definitions; B, C.

Rule 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.