Thrust ball bearing · 512 series
51204 bearing
20 × 40 × 14 mm
The 51204 is a thrust ball bearing with a 20 mm bore, 40 mm outside diameter and 14 mm height. Light series with greater height and capacity than 511.
- Bore d
- 20 mm 0.7874 in
- Outside diameter D
- 40 mm 1.5748 in
- Height H
- 14 mm 0.5512 in
- Dimension series
- 12
- Load directions
- Axial in one direction only
Designation explained
What 51204 means
Standard bearing numbers encode the type, the dimension series and the bore. Anything after the base number — seals, clearance, cage — is a suffix.
| Part | Meaning |
|---|---|
5 | Thrust ball bearing, single direction |
12 | Dimension series 12 (thrust) |
04 | 04 → 20 mm bore (04 × 5) |
Variants
Common 51204 variants
Suffixes change the bearing without changing its boundary dimensions. The exact letters differ between manufacturers — always order by the full designation from the maker you choose.
| Suffix | Example | Meaning |
|---|---|---|
(no suffix) | 51204 | Standard single-direction design: shaft washer, housing washer, ball and cage assembly |
M / TN | 51204-M | Cage material: brass (M) or polyamide (TN) — varies by size and maker |
Same bore
Other 20 mm bore bearings
Every standard bearing in this reference with a 20 mm bore, from light to heavy sections.
| Designation | Type | D | B / H |
|---|---|---|---|
| 6004 | Deep groove ball bearing | 42 mm | 12 mm |
| 6204 | Deep groove ball bearing | 47 mm | 14 mm |
| 6304 | Deep groove ball bearing | 52 mm | 15 mm |
| 6404 | Deep groove ball bearing | 72 mm | 19 mm |
| 61804 | Deep groove ball bearing | 32 mm | 7 mm |
| 61904 | Deep groove ball bearing | 37 mm | 9 mm |
| 16004 | Deep groove ball bearing | 42 mm | 8 mm |
| 1204 | Self-aligning ball bearing | 47 mm | 14 mm |
| 1304 | Self-aligning ball bearing | 52 mm | 15 mm |
| 2204 | Self-aligning ball bearing | 47 mm | 18 mm |
| 2304 | Self-aligning ball bearing | 52 mm | 21 mm |
| 7204 | Angular contact ball bearing | 47 mm | 14 mm |
| 7304 | Angular contact ball bearing | 52 mm | 15 mm |
| NU204 | Cylindrical roller bearing | 47 mm | 14 mm |
| NU304 | Cylindrical roller bearing | 52 mm | 15 mm |
| NU2204 | Cylindrical roller bearing | 47 mm | 18 mm |
| NU2304 | Cylindrical roller bearing | 52 mm | 21 mm |
| 30204 | Tapered roller bearing | 47 mm | 15.25 mm |
| 30304 | Tapered roller bearing | 52 mm | 16.25 mm |
| 32004X | Tapered roller bearing | 42 mm | 15 mm |
| 32204 | Tapered roller bearing | 47 mm | 19.25 mm |
| 32304 | Tapered roller bearing | 52 mm | 22.25 mm |
| 51104 | Thrust ball bearing | 35 mm | 10 mm |
| UCP204 | Pillow block bearing unit | — | — |
Where to buy
Find 51204 at sellers
Search results on independent sellers. We are not affiliated with them, do not earn from these links and do not see their prices or stock. Results mix brands and variants — check the full designation before you order.
About these dimensions. Boundary dimensions follow ISO 104 (thrust bearings — boundary dimensions), dimension series 12, and are the same for every manufacturer of a standard 51204. Chamfers, load ratings, speed limits and weight depend on the manufacturer and design and are not shown — use the maker's datasheet for engineering decisions. Last checked 9 October 2026. Spotted an error? Tell us.
Learn more
What size is a 51204 bearing?
A 51204 is a thrust ball bearing with a 20 mm bore, 40 mm outside diameter and 14 mm height (20 × 40 × 14 mm). These boundary dimensions follow the ISO dimension plan, so they are the same across manufacturers.
Where are the load ratings and speed limits?
They depend on the manufacturer and internal design, so we do not list a single value. Check the datasheet for the exact full designation you intend to use.
Need 51204 data for a whole catalog?
We can help with that.
Normalized specifications, variants and supplier listings for every bearing you sell, with the source behind each value.