Patent ID: 7832301

Claim:
A swing mechanism for a construction machine, said swing mechanism being provided with: a swing frame, an inner race having an internal gear on an inner circumferential portion thereof and mounted on a side of an undercarriage, an outer race rotatably arranged surrounding said inner race and provided with said swing frame mounted thereon, a pinion inserted through a pinion insertion hole formed in said swing frame and maintained in meshing engagement with said internal gear, a pinion drive device for rotationally driving said pinion, and a pin fit-in hole arranged in said swing frame such that a knock pin fixed on said outer race is fitted in said pin fit-in hole to position said swing frame, wherein a pin fit-in hole portion through which said pin fit-in hole is formed extends so as to bulge radially inwardly and is arranged on said swing frame at a location in a vicinity of a place of meshing engagement between said pinion and said internal gear such that said pin fit-in hole portion extends toward said pinion insertion hole, and said pin fit-in hole is located on a line that extends through a center of rotation of said outer race and a center of rotation of said pinion.