Swing reduction gear assembly

A swing reduction gear assembly for a swing device having an upper structure mounted for swinging movement by way of a swing bearing on a lower structure on which an inner race of said swing bearing is mounted, comprising:

• an internal gear wheel formed on said inner race of said swing bearing in a tank for oil for the lubricating of said swing reduction gear assembly;
• a swing reduction gear drive having a casing,
• an output shaft of said swing reduction gear drive being integrated at a lower end thereof with a pinion meshing with said internal gear,
• a lower bearing for supporting said output shaft for rotation on said casing,
• a sealing collar fitted on an outer periphery of said output shaft and located at an upper face side of said pinion,
• a retainer mounted on said casing at a lower side of said lower bearing,
• an oil seal fitted at an inner periphery of said retainer and held in engagement with an outer periphery of said sealing collar, said oil seal having a lower face side lip portion formed thereon, and
• a disk-shaped plate mounted to an outer periphery of said sealing collar such that said lower face side lip portion of said oil seal is normally held in contact with an upper face of said disk-shaped plate,
• wherein said sealing collar has an oil passage formed at an inner periphery of a lower end thereof, said oil passage communicating with meshing teeth of said pinion and said internal gear wheel to such an extent that part of the oil which is squeezed out from between the meshing teeth of said pinion and said internal gear wheel is passed therethrough to reach adjacent non-meshing ones of said teeth.