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ISO 9001:2000 Certified Quality Management System

Bearing Technical Data

PACAMOR KUBAR BEARINGS has technical expertise available to assist with design engineering for custom products. Available options include, but are not limited to, custom rings, retainers, balls, shields, seals, lubricants, and packaging. Whether our bearing is included in the Original Equipment Manufacturer's design or is installed in a high quality overhaul, the PACAMOR KUBAR BEARINGS name is one you can trust.

The following pages contain specific technical data and calculations to aid you in bearing selection and/or bearing design.

Abec Tolerances

PACAMOR KUBAR BEARINGS are manufactured to standard grades of precision with established tolerances for size and geometric accuracy. These standards are known as ABEC classes as set by the Annular Bearing Engineers Committee of the American Bearing Manufacturer's Association (ABMA)...


Operational conditions such as temperature, loads, speed, torque, and environment will determine the appropriate lube for the application. Oils are used where low bearing friction torque is a primary consideration. Grease may provide longer operating life and resist lubricant loss due to centrifugal force at higher speeds. PACAMOR KUBAR BEARINGS Engineers are available for design consultation and recommendations...

Life & Load Calculations

The following formulas permit the calculation of the fatigue life of bearings subjected to radial loads or combined radial and axial loads. Some of the formulas include approximations. Contact PACAMOR KUBAR BEARINGS Engineering Department if the calculated life is borderline in comparison to the desired life or if the loading conditions differ from those presented...

Shaft & Housing Fits

Line to Line to slightly loose shaft and housing fits are desirable for most applications. Interference fits may be necessary to prevent one bearing ring from turning relative to its mating part under heavy loads or when cycle vibration is present. An interference fit causes a 50-80% loss in radial play. The contact angle of a radial bearing under axial load is related to the radial play remaining in the bearing after installation...

Radial Play

Radial play is the radial internal looseness between the balls and races. It is the measured value of the total movement of one ring with respect to the other in a plane perpendicular to the bearing axis. Radial play is not related to the ABEC class or quality of the bearing. Factors that require control of radial play are speeds, loads, thermal conditions, mounting fits, along with axial motion and deflection rates...

Recommended Shoulder Dimensions

Minimum and maximum shoulder dimensions for optimum shaft and housing fits of miniature and instrument ball bearings.

Bearing Installation Guide

At no time can any installation forces be transmitted from one bearing ring to the other through the balls. Incorrect installation can cause brinneling of the bearing balls, which can result in bearing vibration, noise, and reduced life When installing a bearing on a tight shaft, force is be applied to the inner ring ONLY. When installing a bearing in a tight housing, force is be applied to the outer ring ONLY. Force may be applied only to the ring that is being mounted...

Bearing Handling Practices

Bearing handling is as important as bearing design and cleanliness. Improper handling can contaminate or damage the bearing assembly. Proper handling and installation helps to maximize bearing performance and bearing life.

Bore and OD Codes

Miniature and Instrument ball bearings inner and outer diameters can be further calibrated to very specific size ranges by denoting their applicable dimensional codes.

Design Data

Specific internal data on miniature and instrument ball bearings including ball complement and size, land diameters, and retainer styles.


Description of PACAMOR KUBAR BEARINGS part numbering system and methodology for identifying a PKB part number.

Bearing Cross Reference

This ball bearing cross reference is a guide for interchanging ball bearing part numbers among ball bearing manufacturers. This bearing cross reference is offered as a guide only, as manufacturers change ball bearing nomenclature occasionally. Therefore, the guide is offered to assist in the bearing cross reference process but not as a final and complete ball bearing interchange...

For further assistance with bearing selection and design, please feel free to contact our engineering team or look at our online catalog.