Patent ID: 7513497

Claim:
An image forming apparatus comprising: a main body for performing an image forming operation; a sheet feeding cassette detachably mounted in the main body, the sheet feeding cassette including: a pair of cursors spaced apart a predetermined distance and facing each other for regulating a position of a recording sheet stored in the sheet feeding cassette; a rack provided on each of the pair of cursors; a pinion provided between the racks and having an outer peripheral surface and being formed with teeth arranged in a circle for engagement with each of the racks, the pinion including an annular flange that is coaxial with the circularly arranged teeth and has a diameter larger than the circularly arranged teeth; and a boss for supporting the pinion rotatably, the pair of cursors being movable in conjunction with each other by the way of the racks and the pinion; and a rib provided adjacently to the annular flange of the pinion at a predetermined space from an outer peripheral surface of the annular flange in an insertion direction of the sheet feeding cassette, the rib including a circular receiving portion disposed to contact the outer peripheral surface of the annular flange in the insertion direction of the sheet feeding cassette to keen the pinion from moving in a radial direction, a pinion receiving surface of the circular receiving portion having a curvature radius that is substantially the same as a curvature radius of the outer peripheral surface of the annular flange.