61903-FAG bearing: complete specifications & equivalents

Specification table

Source: catalog reference (HR 1 Rolling Bearings (Jan 2020)) · extracted 2026-09-25

Parameters extracted from the official FAG Rolling Bearings catalogue (HR 1 Rolling Bearings (Jan 2020)); FAG® is a trademark of Schaeffler Technologies AG & Co. KG, used here for identification only — mpnbase is not an authorized FAG/Schaeffler distributor. Boundary dimensions are ISO 15 interchangeable; current production values may differ, verify at schaeffler.com.

Cross references & equivalents

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 61903-FAG model number is decoded

61903 is supplied open, without shields or seals, so the arrangement around it must supply and retain the lubricant. Within the thin 619xx section (diameter series 9 of ISO 15), multiplying bore code 17 by five gives the 17 mm bore; the 30 mm outside diameter and 7 mm width follow the same boundary-dimension plan. For a rotating inner ring on a 17 mm shaft under normal load, catalogue practice seats it on a j5 shaft fit with an H7 housing bore — confirm against the actual load direction and magnitude before committing. In the Schaeffler HR 1 catalogue this open execution carries the bare designation; protected variants are ordered separately with suffixes 2Z (steel shields), 2RZ (non-contact rubber seals) and 2RSR (lip-contact rubber seals).

Typical equipment & failure modes

Selection pitfalls — read before you substitute

• Large bores like the 17 mm of 61903-FAG demand clean, burr-free seats; one raised burr under a ring this size cocks the bearing and concentrates load at the raceway edge, cutting life drastically.
• The 619xx thin section (6.5 mm section height at 17 mm bore) trades load capacity for compactness; stiff, accurately aligned seats are essential or edge loading will spall the raceway early.
• Storage matters for open bearings: 61903-FAG leaves the factory with rust preventive only, so clean it and apply the service grease at assembly even if the rings look oily from the wrapper.
• Open bearings tolerate the highest speeds in the 61900-series but need a defined regreasing interval; run-to-failure lubrication is the dominant cause of early failure in open 61903 units.
• Never mix components between two 61903-FAG units: rings, cage and balls are factory-matched and are not field-interchangeable, even between identical designations.
• The housing bore for the 30 mm OD should be round within IT7; an oval bore pinches the outer ring of 61903-FAG and shows up later as two-point loaded raceway wear.
• The open 61903 has no integral sealing; in the Schaeffler HR 1 catalogue the protected variants carry suffixes 2Z (two steel shields), 2RZ (two non-contact rubber seals) and 2RSR (two lip-contact rubber seals). Do not confuse FAG's 2RZ with a contact seal — the RZ lip does not touch the inner ring, which is why its speed capability stays close to the open bearing.
• The 34500 r/min mechanical limiting speed puts 61903 at the top of the HR 1 deep-groove speed range (thermal reference speed 17800 r/min); at these speeds cage design and grease shear dominate — run open with oil-mist or air-over-oil lubrication and verify the thermal reference speed for the actual load before committing.
• At 17 mm bore the 61903 sits in Schaeffler's small-bore range; HR 1 ships these sizes with a pressed steel or plastic cage and P0 tolerance as standard — for instrument or spindle accuracy order the P6/P5 variant explicitly, since P0 runout figures will not hold.
• At 4.59 kN dynamic load rating (C) and 2.56 kN static (C0), 61903 is a light-load FAG bearing: L10 life above a few kN of equivalent load is short, so size up to a 62-series on the same bore if the duty sees shock or frequent starts.
• At only 14 g, 61903 is a lightweight FAG bearing that can be handled by hand; still press it onto the shaft with a sleeve against the inner ring — never through the balls or outer ring.
• The 17×30×7 mm envelope of 61903 gives a D/d ratio of 1.76 and 6.5 mm radial section height — a standard FAG medium section balancing load capacity and speed; the standard cage is adequate up to the listed speeds and C3 clearance is the common hot-shaft choice.
• The 4.59/2.56 kN load ratings, mass 14 g here are Schaeffler HR 1 Rolling Bearings (Jan 2020) catalogue figures for 61903-FAG on the 17×30×7 mm ISO 15 envelope; internal geometry and ratings legitimately differ between brands, so re-verify before substituting another manufacturer's 61903 in a rated drive. Where FAG has since released an X-life version of this size, its expanded C/C0 ratings supersede the HR 1 print values quoted here.
• Schaeffler has moved many HR 1 sizes to the X-life generation with higher C/C0 ratings; the designation is unchanged, so a current eKatalog listing for 61903 may quote higher values than the HR 1 print figures on this page — the envelope is identical either way.
• FAG standard tolerance for this size is P0 (PN); P6/P5 precision executions exist for spindle-adjacent duty but carry different order numbers in the Schaeffler system — they are not a selectable sorting of standard stock.