Patent ID: 7909515

Claim:
A double row ball bearing comprising: an outer ring having a larger-diameter raceway surface and a smaller-diameter raceway; an inner ring comprising a larger-diameter raceway surface and a smaller-diameter raceway surface corresponding respectively to said larger-diameter and smaller-diameter raceway surfaces of said outer ring; a row of larger diameter-side balls disposed between said larger-diameter raceway surface of said outer ring and said larger-diameter raceway surface of said inner ring; a row of smaller diameter-side balls which are disposed between said smaller-diameter raceway surface of said outer ring and said smaller-diameter raceway surface of said inner ring and comprise a pitch circle diameter smaller than a pitch circle diameter of said larger diameter-side balls; a larger-diameter cage holding said row of larger diameter-side balls; and a smaller-diameter cage holding said row of smaller diameter-side balls, wherein a difference between a revolution period of said larger diameter-side balls and a revolution period of said smaller diameter-side balls is smaller than a difference between the revolution period of the larger diameter-side balls and the revolution period of the smaller diameter-side balls which would be obtained if the larger diameter-side ball and the smaller-diameter side ball are equal in diameter and contact angle to each other, and wherein the revolution period of said larger diameter-side balls is substantially equal to the revolution period of said smaller diameter-side balls.