3218-A bearing: complete specifications & equivalents
The 3218-A is a ISO 15 radial bearing sized 90 x 160 x 52.4 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 90 mm |
| Outer diameter D | 160 mm |
| Width B | 52.4 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel, stamped ribbon (J-type) |
| Basic dynamic load rating C | 130 kN |
| Basic static load rating C0 | 120 kN |
| Fatigue load limit Pu | 4.55 kN |
| Reference speed (thermal) | 4300 rpm |
| Limiting speed (mechanical) | 3600 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 4150 g |
| Manufacturer designation | 3218 A |
| Standard | ISO 15 |
| Catalog version | SKF PUB BU/P1 17000/1 EN (Oct 2018) |
| Last verified | 2026-09-27 |
Source: catalog reference (SKF PUB BU/P1 17000/1 EN (Oct 2018)) · extracted 2026-09-27
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 & 3200-series range
| Bore d | 3.543 in |
|---|---|
| Outer diameter D | 6.299 in |
| Width B | 2.063 in |
| ISO bore code | 18 |
| Radial section height (D−d)/2 | 35 mm |
| Smallest bore in 3200-series | 10 mm |
| Largest outer diameter in 3200-series | 200 mm |
| Width range across 3200-series | 14–69.8 mm |
| Bore position in 3200-series (smallest first) | 19 of 22 |
| Bore above smallest 3200-series size | 80 mm |
Cross references & equivalents
No verified interchange data yet. Send an inquiry and our team will confirm equivalents manually.
How the 3218-A model number is decoded
3218 A is SKF's 90 mm-bore double-row angular-contact ball bearing of the 3200 series — two ball rows back-to-back for two-direction axial location in one unit, 90×160×52.4 mm. A on a double-row bearing means no filling slots, so both rows carry their full ball complement in both directions. with no cage suffix the double-row A execution uses the standard stamped steel ball-centred cage. Envelope 90×160×52.4 mm (3.543×6.299×2.063 in), 35.0 mm radial section height, C 130 kN, C0 120 kN, Pu 4.55 kN.reference speed 4,300 r/min (thermal) and limiting speed 3,600 r/min (mechanical), catalogue mass 4150 g. Speed planning distinguishes the two published ceilings mechanically: the cage and balls tolerate 3,600 r/min while thermal balance under catalogue load sets the 4,300 r/min reference; at dm ≈ 125.0 mm the corresponding dn is approximately 450k mm·r/min. Envelope economics: the 52.4 mm width over a 35.0 mm section yields 1.50 mm of ring width per section millimetre, and the bearing weighs 4150 g for 130 kN of dynamic capacity — about 32 g per rated kN. Speed-ratio note for this exact unit: the reference speed is 4,300 r/min against a 3,600 r/min limiting speed, i.e. a reference-to-limit ratio of 1.19.
Typical equipment & failure modes
Common applications
- process pump and agitator drives
- crane and winch gearboxes
- paper-machine dryer-section gearing
Known failure patterns
- false brinelling on the loaded row while the shaft stands idle under vibration
- snap-ring groove or two-piece-ring damage when the D execution is pressed home through the wrong ring
- stamped steel cage noise and pocket wear in marginal-lubrication starts, where a brass-cage execution would survive
- mounting score marks when the bearing is cocked over a burr or keyway
- hard-particle indentation of the asymmetric raceway in unfiltered oil
Selection pitfalls — read before you substitute
- A capped 3218-2Z/-2RS1 execution of this envelope exists for sealed-for-life duty; an open double-row bearing needs application sealing and a defined lubricant supply.
- A capped 3218-2Z/-2RS1 execution of this envelope exists for sealed-for-life duty; an open double-row bearing needs application sealing and a defined lubricant supply.
- A capped 3218-2Z/-2RS1 execution of this envelope exists for sealed-for-life duty; an open double-row bearing needs application sealing and a defined lubricant supply.
- The double-row 3218 takes thrust in both directions by itself — that is the reason to choose it over two single-row bearings: one housing bore, one fit, built-in set geometry.
- Catalogue ratings are SKF PUB BU/P1 17000 figures for 3218 A as the double a steel execution; the other order numbers of the 3218 size are different products and may carry different ratings — always quote the full designation when purchasing.
Frequently asked questions
What are the dimensions and catalogue data of 3218-A?
3218 A measures 90 mm bore × 160 mm OD × 52.4 mm width (3.543 × 6.299 × 2.063 in), mass about 4150 g. SKF 17000 ratings: C 130 kN, C0 120 kN, Pu 4.55 kN, reference speed 4,300 r/min (thermal) and limiting speed 3,600 r/min (mechanical).
What does the A suffix mean?
A on a double-row bearing means no filling slots, so both rows carry their full ball complement in both directions. with no cage suffix the double-row A execution uses the standard stamped steel ball-centred cage.
What does the D mean in A?
D marks a two-piece inner ring, used on the heavy 33-series executions to simplify mounting; the rest of the suffix identifies the cage (MA brass outer-ring-centred, M brass ball-centred, J1 stamped steel, TN9 PA66) and snap-ring/clearance options (NR, CB).
Does the 3218 double-row bearing need pairing?
No — both ball rows are built into one bearing, so bidirectional location does not require a second unit. Controlled axial clearance is part of the design rather than a field adjustment.
Reviewed & verified by the MPN Base engineering desk against source catalog SKF PUB BU/P1 17000/1 EN (Oct 2018) on 2026-09-27. Read our editorial & correction policy.