FAG6306Open Heavy-Series Deep Groove Ball Bearings 30 x 72 x 19 mm, Normal Clearance, 2 Pcs

Product Description

What this part is

Two single-row deep groove ball bearings in the 63 heavy dimension series — 30 mm bore, 72 mm outside diameter, 19 mm wide, open on both sides. Deep groove ball bearings carry radial load plus axial load in either direction. The 6306 is one of the most widely fitted industrial bearing sizes there is: electric motors, small and medium gearboxes, pumps, fan and blower shafts, agricultural drives and conveyor idlers.

Decoding the designation

6 – single-row deep groove ball bearing3 – dimension series 63, the heavy section and width06 – bore code, 06 x 5 = 30 mm boreNo closure suffix – open both sides; a 2Z would be steel shields, a 2RS1 contact rubber sealsNo clearance suffix – normal (CN) radial internal clearance

What these specs mean in practice

On a 30 mm shaft the heavy 63 section gives 72 mm outside diameter and 19 mm width, against 62 x 16 for a medium 6206 and 55 x 13 for a light 6006. Same bore, meaningfully more capacity and life — which is why the 6306 is the default when a 30 mm shaft has real load on it. The cost is a larger housing bore and a lower speed ceiling than the lighter series.

Being open, these arrive without service grease. Each needs lubricating on assembly and sealing by the housing, and an open bearing is not a substitute for a 6306-2Z or 6306-2RS1, which arrive pre-greased and closed against contamination. In exchange, an open bearing relubricates freely and runs happily in splash or circulating oil, which is why gearboxes specify it.

Clearance is normal (CN). If the machine had a 6306/C3, fit a C3 — a normal-clearance bearing on a hot shaft or a tight interference fit loses its clearance to thermal growth and runs hot.

Published specifications

Bore: 30 mmOutside diameter: 72 mmWidth: 19 mmDimension series: 63 (heavy)Rows: 1Closure: open, both sidesInternal clearance: normal (CN)Material: through-hardened bearing steel

Quantity and configuration

Sold as one lot of 2 Pcs — two individual open bearings, not a matched or preloaded pair. No shields, no seals, no snap rings. Convenient for a two-bearing shaft where both ends are replaced together.

Fitting notes

Press or heat-mount on the inner ring only; never drive mounting force through the balls. For a rotating inner ring under normal load, j5 to k5 on the shaft with an H7 housing bore is the usual pairing. Fill roughly a third of the free internal space with grease or rely on housing oil, and provide housing sealing — the bearings have none of their own.

Interchange guidance

Genuine interchanges are same-envelope 30 x 72 x 19 mm 6306 bearings: FAG 6306, NSK 6306, NTN 6306, Koyo 6306, Nachi 6306 and Timken 306K. A 6206 or 6006 shares the bore only and is a smaller, lower-capacity bearing — a related size, never a substitute. A 6306-2Z, 6306-2RS1 or 6306/C3 changes closure or clearance.