Koyo B-68 drawn cup needle roller bearing, 9.525 x 14.288 x 12.7 mm

These Koyo B series drawn cup needle roller bearings have a full complement of needle rollers in a drawn steel cup with open ends, in inch series sizes. 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 original drawn cup design combines maximum load-carrying capability with the advantages of the drawn outer ring. The inward-turned lips of the cup mechanically retain the full complement of needle rollers, which gives positive radial retention even when the shaft is removed repeatedly during servicing.

The range has 69 inch series sizes with needle roller complement bore diameters from 6.35 to 69.85 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

• Full complement of needle rollers: maximum radial load-carrying capability for the size
• 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 3.55 to 68.8 kN and basic static load rating C0 3.68 to 191 kN
• Matching IR and IRA 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. For the same bore, the BH series has a larger outside diameter, and both are inch series designs with the dimensions listed in millimetres here.

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.

Fitting and use

The suggested mounting dimensions in the variant specification give correct running clearance for most applications, and the shaft surface should be 58 HRC or equivalent. For housings of low rigidity, reduce the housing bore as shown in the Koyo catalogue, by amounts from 0.010 mm for bores up to 9.5 mm to 0.036 mm for bores over 76.2 mm. Where the outer ring rotates relative to the load, reduce both the housing bore and the inner raceway diameter by 0.013 mm.

Press the bearing into the housing with an installation tool used with a standard press. The tool must be coaxial with the housing bore, and the stamped end of the bearing (the end with the identification markings) goes against the angled shoulder of the tool. Do not hammer the bearing into place, even with a mandrel, and do not 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 an inner ring from the Koyo IR or IRA series, which is designed as a loose transition fit on the shaft and should be clamped against a shoulder.

Related products

Also available from Koyo: the Koyo BH drawn cup bearing range, the Koyo HK drawn cup bearing range and the Koyo HK.2RS sealed drawn cup bearing range.