Ball bearings

84.82 - Ball or roller bearings. 8482.10 - Ball bearings - Tapered roller bearings, including cone and tapered roller assemblies 8482.30 - Spherical roller bearings 8482.40 - Needle roller bearings 8482.50 - Other cylindrical roller bearings 8482.80 - Other, including combined balllroller bearings 8482.20 - Parts : 8482.91 8482.99 - - Balls, needles and rollers - - Other This heading covers all ball, roller or needle roller e bearings. The are used in lace of smooth metal bearin s and enable fr-iction to be consi erably reduced. T ey are genera ly fitted between the bearing ousing and the shaft or axle, and may be designed to give radial sup oa (radial bearings) or to resist thrust (thrust bearings). Certain beanngs may be designed for 0th radial and thrust support. "dP H P % Normally, bearings consist of two concentric rin s (races) enclosing the balls or rollers, and a cage which keeps them in place and ensures that tfleir spacing remains constant. The bearings classified in this heading include : (A) Ball bearings, with single or double rows of balls. This group also includes slide mechanisms with bearing balls, for example : (1) Those consisting of a steel outer ring rigidly locked with a brass inner rin which has i: six slots arranged lengthwise and in the shape of elongated ellipses enc osing small steel balls. (2) The restricted-travel type, of steel, comprising a grooved cylinder, a ball cage and a housing. (3) The fiee-travelling type, of steel, com rising a segment, a casing enclosing the bearing balls, and a guide rail with a groove o triangular section. P (B) Roller bearings, with single or double rows of rollers of any shape (cylindrical, conical, barrel-shaped, etc.). (C) Needle roller bearings. These differ from ordinary roller bearings in that they are bearings with cylindrical rollers of a uniform diameter not exceeding 5 rnm and having a length which is at least three times the diameter. The ends of the rollers may be rounded (see Subheadin Note 2 to the Chapter). These rollers are fitted between the two rings of the bearing an in most cases no cage is used. % Owing to the high pressure to which they are exposed, bearings are normall of steel (especially chromium steel), though some for particular uses are of bronze, copper or p astics. PARTS The heading also covers parts of ball, roller or needle roller bearings, e.g. : (I) Polished steel balls whether for bearings of this heading or not), the maximum and minimum diameters o which do not differ from the nominal diameter by more than 1 % or b more than 0.05 mm whichever is less; balls not conforming to this definition are c assified in heading 73.26 (see Chapter Note 6). (2) Bearing balls of copper, bronze, plastics, etc. (3) Needles or rollers for bearings, of any shape. (4) Rings, cages, fixing sleeves, etc. * * * The heading does not cover machinery parts incorporating ball, roller or needle roller bearings; these are classified in their own appropriate headings, e.g. : (a) Bearing housings and bearing brackets (heading 84.83). @) Bicycle hubs (heading 87.14). -