Gear Ratio / RPM-Speed Calculator implementation

Binding contract

This record describes what an executable surface must bind and validate. It does not claim that a public calculator, package, or production route is deployed.

Record owner

Guth Instruments

Lifecycle

verified-clean

Evidence ID

t4-139

Effect

Computation or source lookup only

Input and validation requirements

A zero gear ratio creates an undefined division, and an unspecified tire-diameter unit can change the calculated speed by a factor of 12.

Required corrections

No binding erratum is attached to this unique-name record. Implementers must still preserve the declared units, domain, and failure behavior.

Inspectable interface fixture

The sample below is evidence for interface and validation tests, not a production implementation.

{
  "inputs": {
    "mode": "speed_at_rpm",
    "rpm": 3000,
    "gear_ratio": 3.5,
    "final_drive": 3.73,
    "tire_diameter_in": 26
  },
  "expected_outputs": {
    "speed_mph": 17.7748
  },
  "working": "Convert diameter: 26 in ÷ 12 = 2.1666667 ft. Circumference = π × 2.1666667 = 6.8067841 ft. Speed = (3000 × 6.8067841 × 60) ÷ (3.5 × 3.73 × 5280) = 1,225,221.1349 ÷ 68,930.4 = 17.7748 mph."
}

Other records

Sources and evidence

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

• VERIFIED_LEDGER.json
• evidence-tranche4/tranche4-results.json