Koyo BK1210 drawn cup needle roller bearing, 12 x 16 x 10 mm

These Koyo BK drawn cup needle roller bearings have caged needle rollers in a drawn steel cup that is closed at one end, for shaft-end mounting. Drawn cup needle roller bearings support radial loads and reduce friction between rotating components, with a drawn steel outer cup that serves as the raceway for the needle rollers. The small cross-section gives high load-carrying capability in minimum space, and the bearing is installed with a press fit in the housing.

Drawn cup bearings suit compact, economical designs where it is not practical to harden and grind the housing bore, or where the housing material has low rigidity, such as cast iron, aluminium or plastics. The one-piece steel cage is designed to provide rigidity and minimise wear, and it separates the roller guiding and roller retention functions. The open end of a BK bearing is typically not sealed.

The range has 13 metric sizes with needle roller complement bore diameters from 12 to 40 mm. Koyo bearings are made by JTEKT Corporation.

Where this product is used

• Transmissions and transfer cases
• Engines and valve trains
• Steering and braking systems
• Axle supports
• Outboard engines
• Power tools
• Copiers, fax machines and paper-moving equipment
• Appliances

Features

• Caged needle rollers in a one-piece steel cage: high speed capability and maximum lubricant retention
• Closed at one end for shaft-end mounting
• Drawn steel cup raceway pressed into the housing: compact cross-section and economical mounting without a hardened, ground housing bore
• Basic dynamic load rating C 5.24 to 38.4 kN and basic static load rating C0 6.55 to 79.2 kN
• Grease lubrication speed rating 5,200 to 18,000 min-1
• Matching JR series inner rings are available in the Koyo range where the shaft cannot be hardened and ground

Key specifications

Available sizes

Selecting the right option

Choose the size from the shaft (the needle roller complement bore diameter Fw), the housing bore (outside diameter D) and the width C. Use the open-end HK series where the shaft passes through the bearing.

Drawn cup needle roller bearings accommodate radial loads only. The maximum dynamic radial load P should be less than Cr/3, where Cr is the basic dynamic load rating, and the static load safety factor f0 (C0 divided by the maximum applied static load P0) should be greater than 3.

Sizes with two needle roller and cage assemblies carry a lubricating hole in the outer ring; the variant specification identifies them.

Fitting and use

For a one-piece heavy-section steel or cast iron housing, the catalogue recommends a shaft tolerance of h5 (or h6) and a housing bore tolerance of N6 (or N7). For housings of low rigidity, use R6 (or R7) for the housing bore. Where the outer ring rotates relative to the load, use f5 (or f6) for the shaft and R6 (or R7) for the housing bore, and for oscillating motion use j5 (or j6) for the shaft. The shaft surface should be 58 HRC or equivalent.

Install a closed-end bearing with a press tool that has a pilot, with the stamped end of the bearing (the end with the identification markings) against the angled shoulder of the tool, and a positive stop. The bearing should sit inset in the housing by at least 0.20 mm. Do not hammer the bearing into place or press it tightly against a shoulder.

Do not inspect an unmounted drawn cup bearing by measuring its outside diameter, because the thin cup can go out of round during heat treatment and becomes round and correctly sized when pressed into a true housing or ring gage. Remove a bearing by pushing it through a straight housing, and do not reuse it after extraction.

Where the shaft cannot meet the raceway hardness, case depth and surface finish requirements, use a Koyo JR series inner ring with a loose transition fit on the shaft (g5), clamped against a shoulder.

Related products

Also available from Koyo: the Koyo HK drawn cup bearing range, the Koyo HK RS sealed drawn cup bearing range and the Koyo B drawn cup bearing range.