Half the bearings that cross our trade counter arrive with a question attached: what is it? Here is how we answer it, and how you can answer it yourself before you ring anyone.
Start with the markings
Most bearings carry their identity on the face of a ring. A typical marking like 6204 2RS C3 tells you nearly everything:
- 6204 is the designation. The 6 means a deep groove ball bearing, the 2 is the dimension series, and the last two digits give the bore: multiply by five, so 04 means a 20mm bore.
- 2RS means rubber seals on both sides. ZZ would mean metal shields. Nothing after the number usually means an open bearing.
- C3 is internal clearance, slightly looser than standard. Worth matching: a C3 bearing in a motor is there for a reason.
The maker’s name matters less than the number. A 6204 is a 6204 whether the ring says SKF, NSK or FAG, which is why we can usually offer you a choice of brands and prices on the same bearing.
No markings? Measure it
Years of heat, rust and spinning shut this door often. When the markings are gone, three measurements open it again:
- Bore (the hole), measured across the inner ring
- Outside diameter, across the outer ring
- Width, across the face
Use callipers, and measure in millimetres first. A 20 x 47 x 14 measurement identifies a 6204 on its own, because standard bearings live in standard families. If your numbers land between sizes, measure again in inches: older British machines are full of imperial bearings, and a reading like 0.75 x 1.875 that looks odd in metric is telling you something.
The awkward ones
Taper roller bearings come in two parts, cup and cone, each with its own number. Measure both, or bring both. Housed units hide the insert inside a casting, so quote the number cast into the housing as well as any you find on the bearing. And anything from a machine built before the 1980s may follow older numbering entirely. We keep the reference books for exactly this.
When the bearing is not the real problem
A bearing that failed young usually had help: a worn shaft seat, a damaged housing, misalignment, or the wrong clearance for the job. If the new bearing spins loose on the shaft, fitting another one is not a repair. That is a job for our machine shop, which can build the seat back up and grind it true, so the replacement lasts the way the original did.
Or just let us do it
Identification is free. Bring the worn bearing to the trade counter in Kingswinford, or send a photo of the markings and your three measurements to sales@pegasus.gb.net. We will name it, quote it across brands, and have it with you in under 24 hours nationwide: same day around the Black Country on our own vans. Ring 0121 544 7788.
