61804 bearing: complete specifications & equivalents
The 61804 is a ISO 15 radial bearing sized 20 x 32 x 7 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Bore diameter d | 20 mm |
| Outer diameter D | 32 mm |
| Width B | 7 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN / C3 available |
| Tolerance class | P0 |
| Cage | steel, stamped ribbon (J-type) |
| Basic dynamic load rating C | 4.03 kN |
| Basic static load rating C0 | 2.32 kN |
| Fatigue load limit Pu | 0.104 kN |
| Reference speed (thermal) | 45000 rpm |
| Limiting speed (mechanical) | 28000 rpm |
| Operating temperature | -40 to +150 °C |
| Mass | 18 g |
| Manufacturer designation | SKF 61804 |
| Standard | ISO 15 |
| Catalog version | SKF PUB BU/P1 17000/1 EN (Oct 2018) |
| Last verified | 2026-09-24 |
Source: catalog reference (SKF PUB BU/P1 17000/1 EN (Oct 2018)) · extracted 2026-09-24
Parameters extracted from the official SKF Rolling Bearings catalogue (SKF PUB BU/P1 17000/1 EN (Oct 2018)); SKF® and SKF Explorer® are trademarks of AB SKF, used here for identification only — mpnbase is not an authorized SKF distributor. Boundary dimensions are ISO 15 interchangeable; current production values may differ, verify at skf.com.
Dimensions in inches & 61800-series range
| Bore d | 0.787 in |
|---|---|
| Outer diameter D | 1.26 in |
| Width B | 0.276 in |
| ISO bore code | 04 |
| Radial section height (D−d)/2 | 6 mm |
| Smallest bore in 61800-series | 10 mm |
| Largest outer diameter in 61800-series | 420 mm |
| Width range across 61800-series | 5–38 mm |
| Bore position in 61800-series (smallest first) | 5 of 39 |
| Bore above smallest 61800-series size | 10 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 61804-ZZ | GENERIC-ISO | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 20×32×7 mm envelope per ISO 15; seal variant differs (OPEN vs ZZ) — confirm sealing suits the duty. |
Interchange levels: full standard interchange · partial verify parameters · verify manual confirmation required. Links resolve to the equivalent model's specification page where available.
How the 61804 model number is decoded
In the 61800-series (ISO 15 diameter series 8) the last two digits encode the bore: 61804 carries bore code 04 = 20 mm. Outside diameter 32 mm and width 7 mm come from the ISO 15 boundary-dimensions general plan. With no seal suffix the bearing is open: no shields or seals are fitted and lubrication is supplied by the application. For normal-load mounting with a rotating inner ring on a 20 mm shaft, typical catalogue practice is a k5 shaft seat with an H7 housing bore — verify against the actual load direction and magnitude. In the SKF catalogue this open execution carries the bare designation; protected variants are ordered separately as -2Z and -2RSH.
Typical equipment & failure modes
Common applications
- space-constrained gearboxes
- clutch and transmission assemblies
- robotics and automation joints
- lay shafts and idler shafts
Known failure patterns
- contamination wear from dust and dirt ingress through the open arrangement
- lubricant starvation when no regreasing interval is maintained
- rolling-contact fatigue spalling after the rated L10 life is exceeded
- brinelling from static overload or hammering during mounting
Selection pitfalls — read before you substitute
- At a 20 mm bore, a shaft-seat burr or an overtight setscrew can score the thin inner ring of 61804; check shaft finish and runout (target Ra ≤ 1.6 µm) before pressing it home.
- The 618xx thin section at 20 mm bore has only a 6.0 mm radial section height: it saves space but is highly sensitive to misalignment, shaft deflection and shock loads — verify shaft stiffness before choosing it over a 6204.
- The open 61804 has no lubricant retention: grease escapes and contaminants migrate straight into the 20×32×7 mm raceway, so specify a sealed arrangement for dusty or washdown duty.
- Open bearings tolerate the highest speeds in the 61800-series but need a defined regreasing interval; run-to-failure lubrication is the dominant cause of early failure in open 61804 units.
- Deep-groove ball bearings tolerate only minutes of misalignment; if the 32 mm housing cannot be aligned, switch to a self-aligning type rather than shimming 61804.
- The open 61804 needs external sealing and application-supplied lubrication; in the SKF catalogue the protected variants are separate order numbers 61804-2Z (shields) and 61804-2RSH (contact seals), not suffix-free 61804.
- The 4.03/2.32 kN ratings here are SKF Explorer-class figures from catalogue PUB BU/P1 17000/1 EN (Oct 2018); SKF can revise internal geometry and ratings without changing the designation, so treat the catalogue version and date as part of the specification and re-verify for critical drives.
Frequently asked questions
What are the dimensions of a 61804 bearing?
A 61804 deep-groove ball bearing has a 20 mm bore, 32 mm outer diameter and 7 mm width (0.787 × 1.26 × 0.276 in), per ISO 15 boundary dimensions. It is an open bearing with no seals or shields. Geometry-based estimated mass is about 18 g for a steel-cage unit; catalogue masses vary slightly with seal and cage design.
How does the 61804 bore code work?
The last two digits of 61804 are bore code 04, giving 04 × 5 = 20 mm bore. The 32 mm outside diameter and 7 mm width follow the ISO 15 diameter series, not the bore code alone.
What does no suffix on 61804 mean?
A bare 61804 designation means open: no shields or seals, normal CN radial clearance and P0 normal tolerance unless further suffixes are ordered. The application must supply and retain the lubrication.
How does the 61800 compare with other series at the same 20 mm bore?
618 is an extra-thin section: 32×7 mm, only 6.0 mm radial section at 20 mm bore, far smaller than a 6204, for space-limited layouts at the cost of load rating and misalignment tolerance.
What is the SKF designation and catalogue data for 61804?
In the SKF Rolling Bearings catalogue this size is listed as 61804 — the open (unsealed) execution, 20×32×7 mm per ISO 15. Quoted values: C 4.03 kN, C0 2.32 kN, Pu 0.104 kN, limiting speed 28000 r/min, mass 18 g. Brand suffixes (2Z, 2RSH) differ from the industry-neutral spelling 61804.
Reviewed & verified by the MPN Base engineering desk against source catalog SKF PUB BU/P1 17000/1 EN (Oct 2018) on 2026-09-24. Read our editorial & correction policy.