51200 Series Thrust Ball Bearings

The medium thrust series: at the same bore it is both larger across and taller than the 51100 — a 51204 is 40 × 14 mm against 35 × 10 for the 51104 — so it carries a heavier axial load in the same three-part, one-direction construction. One row is deliberately absent: there is no 51219 tabulated here, because the only table that lists one gives a height that breaks the series' own ladder and no second source confirms it.

The 51200 is the medium of the two thrust series, and it is the same kind of step as the 6300 is over the 6200: nothing about the shaft changes. A 20 mm shaft takes a 51204 of 40 mm outside diameter and 14 mm height, where the light 51104 of the same bore is 35 × 10. At the large end the pair is 150 × 38 mm against 135 × 25. Since a thrust bearing's capacity comes from the rolling-element circle and the number of balls that fit on it, a larger washer is directly more axial load — and correspondingly more height in the assembly.

One row of this series is deliberately missing, and it is worth saying why rather than leaving a reader to wonder. There is no 51219 tabulated here. The only table consulted that lists one gives a 95 mm bore bearing a height of 40 mm, which breaks the series' own ladder — the 51218 is 35 mm high and the 51220 is 38 mm — and no second source could be found that confirms it. A single-source row that also contradicts the series' monotonic progression is not something this library will print, so the series runs 51200 to 51218 and then 51220. An absence that is stated is better than a number that cannot be checked.

The rest of the series is complete over the bore ladder: 51200 at a 10 mm bore, 26 mm outside diameter and 11 mm high, up to 51220 at 100 mm bore, 150 mm outside diameter and 38 mm high. Bore codes follow the rule used everywhere else in this library, exceptions and all — 00, 01, 02 and 03 are 10, 12, 15 and 17 mm, and from 04 upwards the code is multiplied by five.

Every designation in the table below links to its own page with the ISO 104 dimensions, the bore-code arithmetic, the same-bore comparison against every series of all three types, and the section explaining why no radial clearance group applies to this type.

This series runs from a 10 mm to a 100 mm bore. The sub-library as a whole reaches 200 mm, and the widest single bearing in it is a 6340, 420 mm across, in the 6300 series. This one stops short of it.

d = bore diameter, D = outside diameter, H = bearing height. All of them are ISO 104 standard values and are the same for every manufacturer. H is the height of the assembled stack, not the thickness of one washer: a thrust ball bearing is a shaft washer, a ball and cage set and a housing washer, and ISO 104 fixes only the envelope the three of them occupy together. The last column is derived: radial section = (D − d) / 2, the wall thickness you are working with when you size the housing. No load rating and no limiting speed appears here — see the bearings index for why.

Outside diameter × overall size in millimetres, for the 5 smallest bores in this database. The full charts, one per type, are on the bearings index. Reading a row is what a machine designer does when the shaft is already fixed: the bore does not change, the housing bore does. Across the type boundary the last number changes meaning — it is a width above and a height below — so compare within a type, then decide whether the job wants a ball bearing, a tapered roller or a thrust bearing at all.