The TTHD design has an identical pair of hardened and ground steel rings with tapered raceways. Because both rings have the same bore and outside diameter, housings should be designed to clear the outside diameter of rotating rings and shafts stepped to clear the bore of stationary rings. Controlled-contour tapered rollers are used and equally spaced by a cage. All components are separable. Most TTHD bearings are supplied with case-carburized components, which are well-suited for applications where extremely high thrust loads and heavy shock may be encountered. For very low-speed applications with unusually high loading, TTHD bearings can be supplied with a full-complement of rollers. Extensively used in numerous applications, including oil well swivels, top drives, pulp refiners, extruders and gearboxes. Applications for full-complement bearings should be reviewed by your Timken® engineer to help ensure selection of the proper bearing. Timken® Tapered Roller Thrust Bearing, Machine Race Type TTHD, 4 in Bore Dia, 8-1/2 in Outside Dia, 1-13/16 in Width, Steel Bearing