Source: https://guthlabs.ai/docs/instruments/bearing-l10-life-calculator/

instrument / verified-clean

# Bearing L10 Life Calculator

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

Status: **VERIFIED_CLEAN**Lifecycle: **verified-clean**

## Inspectable records

[01**Overview**Purpose and lifecycle](<https://guthlabs.ai/docs/instruments/bearing-l10-life-calculator/>)[02**Mechanism**Method and assumptions](<https://guthlabs.ai/docs/instruments/bearing-l10-life-calculator/mechanism/>)[03**Implementation**Binding and validation](<https://guthlabs.ai/docs/instruments/bearing-l10-life-calculator/implementation/>)[04**Qualification**Evidence and errata](<https://guthlabs.ai/docs/instruments/bearing-l10-life-calculator/qualification/>)

## 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`