Patent ID: 7455574

Claim:
A locking system for a spindle when a power tool is powered off, the locking system being disposed in a body and combined with the spindle, said locking system comprising: a cam having a shaft hole, into which the spindle is inserted; an annular space formed between an inner wall surface of the body and an outer wall surface of the cam; a plurality of restricting portions formed on the outer wall surface of the cam, each of the restricting portions comprising a middle surface and two inclined surfaces each having a first end connected to the middle surface, and a second end away from the middle surface, wherein: a first gap between the first end and the inner wall surface of the body is smaller than a second gap between the second end and the inner wall surface of the body; a plurality of projections are respectively formed between the two restricting portions, and a third gap between an outer surface of each of the projections and the inner wall surface of the body is smaller than the second gap; a plurality of elastic components are disposed within the middle surface of each of the restricting portions along a radial direction of the cam, and each of the elastic components comprises a spring and a steel ball facing an inner surface of the body; a driving disk is disposed at one end of the body and in contact with the cam, the driving disk has a first surface and a second surface, a shaft passage is formed between the first surface and the second surface, the spindle is inserted into the shaft passage, a plurality of stopping blocks is protrudingly formed on the first surface and inserted into the annular space, each of the stopping blocks has a middle portion formed with a flange and has two flat surfaces respectively connected to two sides of the flange, and a corresponding one of the steel balls is in direct contact with a lateral surface of the flange and one of the flat surfaces simultaneously; and a plurality of roller pairs are disposed in the annular space and between the two stopping blocks, and a diameter of each of the rollers is greater than the first gap.