Patent ID: 6925900
Filing Date: 2005-08-09
Classification: F16H,Y10T

Abstract:
1. A ball screw, comprising: a shaft including a spiral-shaped shaft groove having a semicircular-shaped section; a nut including a spiral-shaped nut ball groove corresponding to the shaft groove and having a semicircular-shaped section; balls rotatably fitted between the nut ball groove and the shaft groove so as to be held by and between the two grooves; and, a circulation member defining a ball circulation passage for allowing the balls to circulate endlessly therealong, wherein a width of a portion of the nut ball groove is formed larger than that of the remaining portions of the nut ball groove with the depth of the larger-width portion of the nut ball groove remaining the same as that of the remaining portions of the nut ball groove; and wherein a length of the larger-width portion along the spiral-shaped nut ball groove ranges from a length equivalent to that of two balls to a length corresponding to a half winding of the balls along the spiral-shaped nut ball groove.