Patent ID: 8764296

Claim:
A thrust bearing disposed to oppose a thrust collar installed at a rotary shaft, comprising: a groove section formed at a bearing surface disposed to oppose the thrust collar; a first groove group constituted by a plurality of first spiral grooves formed at an inner circumferential side of the bearing surface; a second groove group formed at an outer circumferential side of the bearing surface more than the first groove group and constituted by a plurality of second spiral grooves wound in the same direction as the first spiral grooves, and the groove section having the first groove group and the second group; and an annular land section formed at a portion where a fluid is drawn located either at an inner circumferential side of the first groove group or an outer circumferential side of the second groove group, wherein at least part of the first spiral grooves of the first groove group and part of the second spiral grooves of the second groove group are in communication with each other via part of a partial communication section, and the number of the second spiral grooves of the second groove group is equal to or more than the number of the first spiral grooves of the first groove group.