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Mechanical design · concept selection

Bearing Selector

Compare five rolling-bearing families at one shaft bore. Screen catalog L10 life, static safety, allowable speed, and the arrangement limits that simple rating calculations tend to hide.

NTN catalog No. 2203/E · 1,136 bearings · 1.5–200 mm bore
Scope, method, and limitations

This is a bore-first concept selector. Enter reactions at one bearing—not total shaft load—and compare sourced NTN series at that bore. Ratings and speed limits are manufacturer-specific.

The result is not a final arrangement design. It does not calculate shaft reactions, opposed-pair induced thrust, preload, fits, internal clearance, lubrication life, contamination, temperature, or modified life. Always confirm a selected part in the current manufacturer catalog.

Duty point

Display units
Use the resolved radial reaction at one bearing.
Expert options
Requirements, lubrication, and families
Acceptance targets
Arrangement and preload
Variable duty
Leave blank for the constant duty point above.
Use for known reactions at B, C, and later positions.
Families to compare

Screening result
Top candidate
—
—
L10 life
—
90% reliability basis
Static safety
—
C₀ / P₀
Speed margin
—
allowable / operating
C / PReady when the calculation engine finishes loading.

Defaults are usable immediately. Calculate to compare all five bearing families.

DesignationFamilyEnvelope mmC kNC₀ kNP kNL10 hs₀Speed marginStatus

Life by candidate

Compares calculated basic L10 life at the entered constant duty. The vertical axis is logarithmic so candidates separated by orders of magnitude remain visible; equal vertical spacing does not mean equal hours. The dashed line is the required-life target.

Calculate to see how many applicable candidates meet the target.

Proportional load sensitivity

Scales radial and axial load together while holding speed, load ratio, catalog factors, and lubrication basis fixed. The entered duty is 1.0×. This is a sensitivity study—not a variable-duty or independent radial/axial sweep.

The steeper roller-bearing curves reflect the 10/3 life exponent; ball-bearing curves use an exponent of 3.

Bearing cross-section

Arrangement concept

Rings / shaftApplied loadContact or locating direction
Diagrams are functional schematics, not manufacturing drawings. Envelope proportions use catalog bore and OD; internal raceway and rolling-element geometry are illustrative.
Technology triage, not sizing: highlighted options have transparent screening triggers at this duty. They require different physics, specialist data, and often a dedicated system design.
Known-reaction system screen: each position is selected independently. The tool identifies the limiting position but does not solve shaft equilibrium or stiffness-based load sharing.
PositionStatusBore mmFr kNFa kNrpmCandidateL10 h

Screening boundary: The input loads must already be reactions at one bearing. Angular-contact and tapered bearings normally require an opposed-pair equilibrium calculation, while the NU cylindrical series cannot carry axial load.

Calculation method

Equation (1) · Equivalent dynamic radial load

\[P = X F_r + Y F_a\]
  • P: equivalent dynamic radial load
  • Fr: applied radial bearing reaction
  • Fa: applied axial bearing reaction
  • X, Y: NTN family and load-ratio factors

Equation (2) · Basic rating life

\[L_{10h}=\frac{10^6}{60n}\left(\frac{C}{P}\right)^p\]
  • L10h: basic rating life in hours at 90% reliability
  • C: manufacturer basic dynamic rating
  • n: rotational speed in rpm
  • p: 3 for ball bearings; 10/3 for roller bearings

Equation (3) · Equivalent static load

\[P_0=\max(X_0F_r+Y_0F_a, F_r)\]
  • P0: equivalent static radial load
  • X0, Y0: NTN static-load factors

Equation (4) · Static safety factor

\[s_0=\frac{C_0}{P_0}\]
  • s0: basic static safety factor
  • C0: manufacturer basic static rating

What the recommendation means

Only candidates passing the requested life and static targets, the selected catalog speed limit, and NTN's stated basic-life formula range can qualify. The recommendation then favors family suitability for the axial/radial ratio before comparing envelope size. It is a starting family and part—not an automatic design approval.

Lubrication concepts

Grease is oil held in a thickener. Selection requires the base-oil type and viscosity, thickener compatibility, NLGI consistency, additives, operating temperature, speed factor, load, water/contamination exposure, fill quantity, and replenishment interval. A stiffer NLGI grade is not automatically a higher-viscosity oil, and mixing incompatible thickeners can destroy consistency.

Oil can support higher speed and remove heat, but delivery matters: bath and splash systems are simple but can churn; circulation adds filtration and cooling; jet delivery targets high-speed contacts; air-oil supplies small metered quantities with carrier air. Check operating-temperature viscosity, level, drains, orientation, seals, filtration, start-up supply, and failure behavior.

Sealed-for-life means a specific bearing, grease, fill, seal, temperature, and duty combination—not infinite life. Solid/special lubricants need explicit product ratings. Selecting no lubricant excludes the standard rows in this catalog and elevates plain, gas, foil, or magnetic alternatives.

Preload, clearance, and pairs

Operating clearance is the installed internal clearance after fits, temperature, centrifugal effects, and elastic deformation. Preload is negative operating clearance or an intentional axial force used to increase stiffness, positioning accuracy, and resistance to rolling-element skidding. Too much preload raises torque and temperature and can sharply reduce life.

Fixed-position preload is established by ring/spacer geometry and is sensitive to tolerance and thermal growth. Constant-pressure preload uses a spring and is less thermally sensitive but generally less stiff. Back-to-back pairs provide a wide effective spread and moment stiffness; face-to-face pairs accommodate more misalignment; tandem pairs share thrust in only one direction. This tool does not convert preload force into internal contact loads without candidate-specific stiffness data.

Multi-bearing systems

A shaft system needs an explicit axial locating strategy and a thermal-expansion path. One common arrangement uses a locating bearing and an NU/N-style floating position. Fixed-fixed arrangements can create unintended thrust as shaft and housing temperatures diverge. Loads in statically indeterminate three-or-more-bearing systems depend on shaft, housing, and bearing stiffness and require a coupled model.

The variable-duty input evaluates repeated known reactions; it does not solve shaft reactions. Use shaft free-body analysis first, then verify fits, shoulders, deflection/misalignment, minimum load, seals, mounting, and maintenance.

Official references