Patent ID: 6439072
Filing Date: 2002-08-27
Classification: F16H,Y10T

Abstract:
A ball screw comprising:a screw shaft including a first ball screw groove formed in an outer peripheral surface thereof and formed into a spiral shape, said outer peripheral surface being smoothly grounded; a ball nut including a second ball screw groove formed in an inner peripheral surface thereof and opposing said first ball screw groove; a plurality of balls rollingably fitted between the first and second ball screw grooves for allowing the ball nut to move with respect to the screw shaft; a dowel provided at a portion of said first and second ball screw grooves of said ball nut so as to guide a ball to move over a thread of said screw shaft and to circulate along said first and second ball screw grooves, thereby to form a circulation path; and a cylindrical retainer separately disposed between said screw shaft and said ball nut in a radial direction of said screw shaft, and provided with a plurality of elongated holes extending in an axial direction thereof at its peripheral surface for separating said balls from one another in a circumferential direction thereof and for rollingably holding said balls therein, wherein a distance defined between said screw shaft and said retainer is smaller than a distance defined between said dowel and said retainer in said radial direction.