PNA20-42 bearing: complete specifications & equivalents
The PNA20-42 is a DIN 616 radial bearing sized 20 x 42 x 20 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 20 mm |
| Outer diameter D | 42 mm |
| Width B | 20 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | none |
| Basic dynamic load rating C | 19 kN |
| Basic static load rating C0 | 32.5 kN |
| Fatigue load limit Pu | 4 kN |
| Reference speed (thermal) | 16000 rpm |
| Limiting speed (mechanical) | 18000 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 140 g |
| Manufacturer designation | PNA 20/42 |
| Standard | DIN 616 |
| Catalog version | SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.6 alignment needle roller bearings, with an inner ring |
| Last verified | 2026-09-26 |
Source: catalog reference (SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.6 alignment needle roller bearings, with an inner ring) · extracted 2026-09-26
Parameters extracted from the official SKF Rolling Bearings catalogue (SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.6 alignment needle roller bearings, with an inner ring); 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 & PNA-series range
| Bore d | 0.787 in |
|---|---|
| Outer diameter D | 1.654 in |
| Width B | 0.787 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 11 mm |
| Smallest bore in PNA-series | 12 mm |
| Largest outer diameter in PNA-series | 62 mm |
| Width range across PNA-series | 12–20 mm |
| Bore position in PNA-series (smallest first) | 4 of 9 |
| Bore above smallest PNA-series size | 8 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| NKIS20 | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 20×42×20 mm envelope, but catalogue C/C0 differ between the executions (19/32.5 vs 28.6/39 kN) — boundary dimensions match, not a load-rating equivalent. |
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 PNA20-42 model number is decoded
The self-aligning needle roller bearings with inner ring execution PNA 20/42 pairs a flanged needle roller ring (20 mm inner-ring 42 mm OD, 20 mm wide) with a sphered seat: the outer ring swivels a few degrees to follow frame deflection. Reading the designation: PNA marks the self-aligning execution (inner-ring inner ring), the numbers giving 20 mm inner-ring bore and 20 mm width; the sphered outside diameter 42 mm follows the series plan. The alignment range is meant for static seat errors, not continuous swivelling under load — dynamic pivoting races the sphered surface and requires grease with extreme-pressure additives. Selection arithmetic: C 19 kN against C0 32.5 kN gives a C0/C ratio of 1.71, and the 4 kN fatigue load limit Pu sets the floor for the adjusted-life calculation at contaminated lubrication. Mounting: seat the convex outer ring surface in its sphered counterpart dry first, confirm the 20 mm inner-ring raceway rotates freely through the full alignment range, then lubricate and assemble for service.
Typical equipment & failure modes
Common applications
- steering knuckles and kingpin supports with seat angle errors
- pivot bearings where housing bores cannot be kept coaxial
- linkage eyes and clevis mounts on frames that flex
- agricultural machinery joints exposed to frame distortion
Known failure patterns
- needle edge loading and raceway denting when the shaft deflects beyond the compensation range
- polymer cage deformation when the local temperature exceeds the 120 °C sustained limit
- grease starvation at the roller ends when relubrication intervals are stretched in dirty duty
- corrosion pitting from condensation in intermittently operated machinery
Selection pitfalls — read before you substitute
- On a 20 mm seat the housing bore quality dominates life: a bore 0.02 mm out of round pinches the 42 mm ring or cup into a lobed shape, and the rollers then trace the housing's geometry error, not the design load.
- Contamination, not fatigue, kills most small needle bearings: with raceways this narrow, one hard particle dents a full-width line — seal the housing even when the bearing execution itself is open.
- Do not interchange envelope-identical needle families blindly: PNA 20/42 shares its 20×42×20 mm outline with inner-ring and sealed siblings whose ratings differ — the family letters are part of the specification, not decoration.
- The 19/32.5 kN ratings and 140 g mass are SKF catalogue values transcribed from ch. 7.6 of PUB BU/P1 17000 (PDF table page 652); combined-type axial ratings appear in the text above because the structured record carries radial values only.
Frequently asked questions
What mounting mistakes ruin a PNA 20/42?
Press on the ring faces only with a fitting sleeve, keep everything square to the 20 mm seat, and never transmit force through the rolling elements. Follow the catalogue's seat tolerances — the narrow needle contact forgives neither tilt nor burrs.
Is the PNA 20/42 sealed?
No — this execution is open and depends on the housing sealing arrangement; grease it at assembly and keep the relubrication interval short in dirty duty.
Which dimensions does the PNA 20/42 have?
A PNA 20/42 measures 20 mm bore/Fw × 42 mm outside diameter × 20 mm width (0.787 × 1.654 × 0.787 in). From SKF catalogue PUB BU/P1 17000: radial dynamic rating C 19 kN, static C0 32.5 kN, fatigue limit Pu 4 kN, limiting speed 18,000 r/min, reference speed 16,000 r/min, mass about 140 g.
What does PNA 20/42 mean in SKF part numbering?
PNA marks the self-aligning needle roller family (inner-ring with machined rings): figures give the 20 mm seat and 20 mm width; the convex outer-ring outside surface aligns within roughly ±2° in its sphered seat.
Reviewed & verified by the MPN Base engineering desk against source catalog SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.6 alignment needle roller bearings, with an inner ring on 2026-09-26. Read our editorial & correction policy.