GB/T 301 51200 Series Thrust Ball Bearings Specification

Specification summary of GB/T 301 (thrust ball bearings, boundary dimensions) as it applies to 51200 series thrust ball bearings: what the document fixes, where its scope ends, the ISO, DIN and GB/T equivalents, and the dimensions supplied to it.

GB/T 301 — Scope

GB/T 301 is the Chinese national standard for the boundary dimensions of thrust ball bearings — the shaft washer bore, the housing washer outside diameter and the assembled height that fixes the shoulder spacing.

What GB/T 301 Does Not Fix

It fixes the envelope and not the rating, and it does not address the radial load these bearings must never be asked to carry: a thrust bearing has no radial capacity and has to be located radially by something else.

This division of labour is the thing to carry away from any bearing standard. A boundary dimension standard makes bearings interchangeable; it does not make them equivalent. Two bearings of the same designation from different makers mount in the same seat and are not required to have the same load rating, the same internal design, the same cage or the same speed limit.

Dimensions Supplied to GB/T 301

Catalog Products Governed by GB/T 301

GB/T 301 governs more than this one series. In this catalog it applies to:

• 51100 Series Thrust Ball Bearings
• 51200 Series Thrust Ball Bearings
• 51300 Series Thrust Ball Bearings
• 51400 Series Thrust Ball Bearings
• 52200 Series Double Direction Thrust Ball Bearings
• 52400 Series Double Direction Thrust Ball Bearings

When to Cite GB/T 301

GB/T 301 is the Chinese national standard and is what a Chinese manufacturer works to, so citing it removes any ambiguity on an order placed in China. It restates the same dimensions as its ISO parent, so quoting both — the GB/T number and the ISO number — is the practice that survives a supply change.