In order to improve a seizure resistance as well as restricting of a dispersion
of a rotation torque, surface roughness of a large diameter side end face (4A)
of a tapered roller (4) is defined as a value satisfying both the following
conditional expressions (1) and (2).
where, Ra(r) is an arithmetic average of roughness in a radial direction on
the large diameter side end face of the tapered roller, and Ra(c) is an arithmetic
average of roughness in a peripheral direction on the large diameter side end face
of the tapered roller.
