Rear strut and front strut of a blue luffing construction crane against a blue sky and clouds with forest in background

front strut rear strut main chords luffing construction crane tower tower crane pendant working jib jib cable jib hoisting unit expanding tackle strut pole crane construction building trolley highrise low angle sky clouds drone 4k aerial city leaning cable suspended machinery outdoors outdoorsnature powerful high blue day modern industry development engineer lifting structure site tall boom contractor load hook chain