Swing bearing

A swing bearing comprising:

• an annular outer ring having a first raceway groove formed on an inner circumferential surface thereof;
• an annular inner ring having a second raceway groove formed on an outer circumferential surface thereof in such a manner as to face the first raceway groove of the outer ring, and disposed concentrically with the outer ring and rotatably in relation to the outer ring;
• and a plurality of rolling elements disposed in a load-carrying race formed between the first raceway groove of the outer ring and the second raceway groove of the inner ring;
• wherein the outer ring is composed of a pair of split rings which are obtained by splitting the outer ring at an axially midpoint of the first raceway groove and are fixed together;
• the inner ring is composed of a pair of split rings which are obtained by splitting the inner ring at an axially midpoint of the second raceway groove and are fixed together;
• and
• each of the split rings of the outer ring and the split rings of the inner ring is formed of a plate member having a predetermined thickness.