Patent ID: 7556469

Claim:
A swing frame structure for construction machinery, said swing frame structure being arrangeable in a swing upperstructure and having a center frame composed of side plates and a reinforcement plate joined to each other, wherein: said swing frame structure is provided with mating portions for bringing said side plates and said reinforcement plate into engagement with each other such that said side plates and said reinforcement plate are positioned relative to each other, and further wherein said mating portions comprise lug and hole joints, respectively, and said lug and hole joints comprise holes formed through said side plates and lugs formed on said reinforcement plate such that said lugs can be inserted into said holes, respectively; and wherein said side plates are each provided with a lifting hole for enabling to lift said construction machinery, a hole for a boom foot pin and a hole for a boom cylinder pin, and said holes in each of said side plates are each formed at a position below a line connecting a center of the corresponding hole for said boom foot pin with a center of the corresponding lift hole but above a line connecting a center of the corresponding hole for said boom cylinder pin and said center of the corresponding lift hole.