Patent ID: 8613558

Claim:
A constant preload device of a ball bearing, the preload device comprising: an elastic member having a hollow shape with openings at both sides in an elastic direction; and two holders which are inserted into the openings at the both sides of the elastic member, respectively, wherein each of the holders includes: a flange part configured to contact an end portion of the opening, into which the holder is inserted, to regulate an extension of the elastic member in the elastic direction thereof; and a claw part configured to engage with the other holder such that the holders are slidable with respect to each other between a first position and a second position along the elastic direction, wherein in the first position the claw parts of the respective holders contact each other to regulate separation therebetween in the elastic direction such that the elastic member is held between the holders to have a first length which is shorter than a free length of the elastic member, and in the second position the claw parts of the respective holders are separated by a distance in the elastic direction such that the elastic member is held between the holders to have a second length which is shorter than the first length, and wherein when the preload device applies preload to the ball bearing, the ball bearing is contacted to the preload device only at an outer ring of the ball bearing.