KoyoDouble-Row Spherical Roller Bearing – 1:12 Tapered Bore, 140 mm ID, 250 mm OD, 68 mm Width, Open, W33 Lubrication Groove, C3 Internal Clearance

Product Description

What this part is

Koyo 22228RRKW33C3 double-row spherical roller bearing. Series: 222, dimension series 22. Bore: 140 mm, tapered 1:12. Outside diameter: 250 mm. Width: 68 mm. Open on both faces.

Decoding the designation

222 — Koyo dimension series 22 spherical roller bearing. 28 — bore code, 28 x 5 = 140 mm. RR — Koyo internal design: convex asymmetrical rollers in two rows, an inner ring with a centre guide rib and retaining ribs on both sides, and a copper-alloy prong-type machined cage. K — Bore Form: 1:12 tapered. W33 — the outer ring carries a lubrication groove and three radial lubrication holes. C3 — Internal Clearance: greater than standard. Searchable forms: 22228 RR K W33 C3, 22228RRK W33 C3, 22228RRKW33.

What these specs mean in practice

A double-row spherical roller bearing carries very high radial load and takes thrust in both directions, and its spherical outer raceway lets the inner ring and rollers swivel to absorb shaft deflection and housing misalignment. The RR internal design runs faster than Koyo’s symmetrical-roller RH, RHR and RHA designs: the asymmetrical roller profile reduces sliding friction and roller skew, and the machined brass cage suits sustained high temperature. C3 clearance leaves room for thermal growth and for the radial preload that mounting on a tapered seat introduces. Lubrication: oil or grease, fed through the W33 groove and holes without removing the bearing.

Bore form and adapter sleeve

The 1:12 tapered bore mounts on an adapter sleeve. The matching sleeve for a 22228K is a Koyo H3128, which has a 125 mm cylindrical shaft seat, and it is secured with a KM 28 locknut and an MB 28 lock washer. Driving the bearing up the taper sets the running clearance, so the fit is adjustable on a plain shaft with no shoulder or step.

Fitting notes

Bore: 140 mm at the large end of the 1:12 taper. Shaft seat under the H3128 sleeve: 125 mm. Item weight 36.80 lb. The three outer-ring holes accept the housing feed port; align one hole with the port when setting the outer ring.

Cross-references

140 x 250 x 68 mm tapered-bore C3 sphericals with the W33 lubrication feature: SKF 22228 CCK/C3W33, FAG 22228-E1-K-C3, Timken 22228EKJW33C3, NTN 22228EMKD1C3 and NSK 22228EAKE4C3; internal design and cage differ by maker. Koyo 22228RHRKW33C3 is the same envelope in the symmetrical-roller pressed-steel-cage design, a related size. Koyo 22228RRW33C3 is the straight-bore version of this bearing.