Patent ID: 8807838

Claim:
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; and a synthetic resin-made thrust 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 of the synthetic resin-made thrust bearing piece, said upper casing being combined with said lower casing by causing an outer peripheral edge of the upper casing to be resiliently fitted to an outer peripheral edge of said lower casing, said synthetic resin-made thrust sliding bearing further including a silicone grease that is interposed at sliding interfaces between, on the one hand, the upper surface of said lower annular flat plate-shaped portion defining the bottom surface of the lower annular recess and the lower surface of said upper annular flat plate-shaped portion and, on the other hand, an upper surface and a lower surface of said thrust bearing piece which are respectively brought into sliding contact therewith, said silicone grease including a methylphenyl silicone oil as a base oil and 12(OH)StLi as a thickener so as to set a worked penetration of said silicone grease to not less than 258 and not more than 279, said methylphenyl silicone oil having a coefficient of kinematic viscosity at 25° C. which is not less than 3,000 cSt and not more than 11,000 cSt.