Bearing L10 Life Calculator

Inspectable records

Ledger state

The current ledger marks this instrument verified clean within the source-bound verification corpus.

Area

Mechanical, Civil & Structural Engineering — Statics/Dynamics, Strength of Materials, Machine Design, Civil, HVAC, Vibration

Tranche

tranche-5

Evidence ID

t5-020

Ledger rows

1

No ledger note is attached.

Review findings

L10 is the basic rating life at which 90% of an adequately large group of identical bearings are expected to survive under the stated operating conditions; it is not a guarantee for an individual bearing. The honest label should explicitly say basic rating life, nominal 90% reliability, and constant-load/constant-speed assumptions. Adjusted rating life requires applicable a1, a2, a3 or modern ISO 281 life-modification factors and additional lubricant, contamination, reliability, and material data.

Formula and scope findings

• The notation is ambiguous: L10 is stated as revolutions, but L10h=L10×10^6/(60N) treats L10 as millions of revolutions. If L10 is actual revolutions, the correct hours formula is L10h=L10/(60N). If L10 is expressed in million revolutions as L10m=(C/P)^p, then L10h=L10m×10^6/(60N).
• The implementation must not apply the 10^6 factor twice; doing so would overstate life by 1,000,000.
• The output name is specified as L10h, while the formula uses Lh; use one consistent label.

Unit assumptions

• C and P must use the same force units, such as both N or both kN; only their ratio is used.
• N is rotational speed in revolutions per minute (rpm).
• p=3 applies to ball bearings and p=10/3 applies to roller bearings.
• The corrected hours calculation uses L10 as actual revolutions: L10h=L10/(60N).
• P is the dynamic equivalent bearing load, not merely an arbitrary radial or axial load.
• C is the manufacturer-specified basic dynamic load rating for the selected bearing.

Boundary hardening

BREAK_CLAIMED · SELF_FLAGGED

The stated L10h formula multiplies L10 by 10^6 even though L10 is already specified in revolutions, producing a result one million times too large; the calculator also needs validation for P=0 and a defined convention or rejection for negative speed.

Errata and corrections

No applied erratum is attached to this unique-name record.

Inspectable example

4 review vectors are recorded. One source-bound sample is shown below.

{
  "inputs": {
    "C": 10000,
    "P": 2000,
    "force_unit": "N",
    "bearing_type": "ball",
    "N": 1200,
    "speed_unit": "rpm"
  },
  "expected_outputs": {
    "L10_revolutions": 125000000,
    "L10h_hours": 1736.1111111111
  },
  "working": "p=3. C/P=10000/2000=5. (C/P)^p=5^3=125. L10=125×10^6=125,000,000 revolutions. L10h=125,000,000/(60×1200)=125,000,000/72,000=1,736.1111111111 hours."
}

Related workflows

No source-defined multi-instrument workflow membership is recorded.

Sources and evidence

These pointers bind the page to evidence. They do not grant authority or collapse verification into deployment.

• VERIFIED_LEDGER.json · VERIFIED_CLEAN
• evidence-tranche5/tranche5-results.json
• BOUNDARY_HAZARD_CATALOG.json