A preload bearing is provided for mounting into an orifice in a shock-inducing platform. The bearing includes a cylindrical housing insertable into the orifice of the platform with a housing axis oriented vertically in relation to the platform, the housing having a closed bottom end and an open top end; a scraper that attaches to the bottom end of the housing for receiving compressive load from underneath; a crown roller disposed to extend radially from the housing; a shaft coaxial with the crown roller disposed within the housing along a roller axis perpendicular to the housing axis; and a cap that covers the open top end of the housing.