Setting down lifted objects in precise locations is a crane operator's chief responsibility, requiring great concentration over long periods of time. The work may tax the mind and not the body, but crane operators get just as tired as construction workers who use their muscles.
而如何將起重物放在精準的位置，是吊手最大的責任，因此必須長時間集中精神，雖然只是「勞心」，但一天下來疲倦的程度不比勞力的工人輕微。