Bearing Equivalent Dynamic Load 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-7

Evidence ID

t7-061

Ledger rows

1

No ledger note is attached.

Review findings

The arithmetic formula is standard, but the instrument specification is underspecified for a reliable lookup-table implementation. It must identify the bearing manufacturer or table convention, bearing type and geometry, the e-ratio selection rule, valid input ranges, and pure-axial-load behavior. The honest label should state that the result is an equivalent dynamic load only, not bearing life or bearing-selection approval.

Formula and scope findings

• P = XFr + YFa is the standard equivalent dynamic bearing-load equation only after the bearing type, contact angle, load ratio Fa/Fr, and applicable factor table have been selected.
• The specification does not define how X and Y are selected from bearing type/e-ratio tables. X and Y are not universal constants; they vary by bearing construction, contact angle, row arrangement, and manufacturer table.
• The specification omits the usual branch condition comparing Fa/Fr with e. For example, a commonly tabulated single-row deep-groove ball-bearing convention uses X=1, Y=0 when Fa/Fr <= e, and different factors when Fa/Fr > e.
• The specification does not state constraints that Fr and Fa must be nonnegative loads expressed in compatible units.
• The specification does not define handling for pure axial loading Fr=0, for which Fa/Fr is undefined and the applicable bearing calculation may require a separate manufacturer rule.

Unit assumptions

• Fr and Fa must use the same force unit; P has that same force unit.
• The test vectors use newtons unless explicitly marked kN.
• X and Y are dimensionless.
• The e values and X/Y factors are dimensionless and apply only to the stated bearing-table convention.
• The table fragments use a widely tabulated ISO 281-based bearing-factor convention for single-row deep-groove ball bearings; the exact bearing manufacturer's catalog must take precedence for a production calculator.

Boundary hardening

BREAK_CLAIMED · SELF_FLAGGED

The calculator cannot determine the formula branch without the missing bearing type/e-ratio factor tables, and an extreme but representable input combination overflows a typical floating-point implementation. Signed axial input also produces a physically invalid negative result unless the magnitude convention is enforced.

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": {
    "bearing_type": "single-row deep-groove ball bearing, 15-degree contact-angle table",
    "Fr": 1000,
    "Fa": 0,
    "Fr_unit": "N",
    "Fa_unit": "N",
    "e": 0.22,
    "X": 1,
    "Y": 0
  },
  "expected_outputs": {
    "P": 1000,
    "P_unit": "N"
  },
  "reference_data": {
    "bearing_table": "single-row deep-groove ball bearing, 15-degree contact-angle factor table",
    "condition": "Fa/Fr <= e",
    "e": 0.22,
    "X": 1,
    "Y": 0,
    "source_convention": "widely tabulated standard value, ISO 281-based bearing-factor convention"
  },
  "working": "Fa/Fr = 0/1000 = 0. Since 0 <= e = 0.22, use X = 1 and Y = 0. P = XFr + YFa = (1)(1000 N) + (0)(0 N) = 1000 N."
}

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-tranche7/tranche7-results.json
• BOUNDARY_HAZARD_CATALOG.json