| 主权项 |
1. A synthetic resin-made thrust sliding bearing including: a synthetic resin-made upper casing having an upper annular flat plate-shaped portion; a synthetic resin-made lower casing having a lower annular flat plate-shaped portion which is superposed on said upper casing so as to be rotatable about an axis of said upper casing and opposes said upper annular flat plate-shaped portion, a first and a second annular projection disposed on said lower annular flat plate-shaped portion concentrically therewith, and a lower annular recess surrounded by said first and said second annular projection; a synthetic resin-made thrust sliding bearing piece constituted by a disk which is disposed in the lower annular recess, is brought into sliding contact with an upper surface of said lower annular flat plate-shaped portion defining a bottom surface of the lower annular recess and a lower surface of said upper annular flat plate-shaped portion, and has a circular hole in a central portion thereof; and a lubricating grease interposed at sliding interfaces between, on the one hand, the lower surface of said upper annular flat plate-shaped portion and the upper surface of said lower annular flat plate-shaped portion defining the bottom surface of the lower annular recess and, on the other hand, an upper surface and a lower surface of said thrust sliding bearing piece which are respectively brought into sliding contact with said lower surface and said upper surface, said upper casing being combined with said lower casing by causing an outer peripheral edge thereof to be resiliently fitted to an outer peripheral edge of said lower casing, said synthetic resin-made thrust sliding bearing characterized in that said thrust sliding bearing piece is formed of a polyethylene resin whose density is 0.925 to 0.970 g/cm3 and whose melt flow rate (190° C., 2160 g) defined by ISO 1133 is 0.1 to 20 g/10 min. |
