Source: https://guthlabs.ai/docs/instruments/clutch-brake-torque-capacity-calculator/

instrument / verified-with-binding-errata

# Clutch/Brake Torque Capacity Calculator

The current ledger marks this instrument verified with errata that must be applied at binding time.

Status: **VERIFIED_WITH_ERRATA**Lifecycle: **verified-with-binding-errata**

## Inspectable records

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

## Ledger state

The current ledger marks this instrument verified with errata that must be applied at binding time.

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

**Tranche**: tranche-5

**Evidence ID**: t5-084

**Ledger rows**: 1

No ledger note is attached.

## Review findings

The arithmetic and both stated formulas are standard under their respective assumptions. Verdict is NEEDS_REVIEW because the wear-model selection and the exact meaning of n are not fully specified. The third vector exposes a unit-conversion trap; its corrected result is 56.25 N·m, not 506.25 N·m.

### Formula and scope findings

- The formulas are standard and correct only when n means the number of active friction surfaces and F means the total axial clamping force acting on the friction pack.

- The specification provides both uniform-wear and uniform-pressure formulas but does not define an input or rule for selecting which wear model to use; the computed result is therefore ambiguous.

- The common alternative convention counts friction pairs rather than friction surfaces, so the definition of n must be explicit in the interface and documentation.

### Unit assumptions

- μ is dimensionless.

- F is in newtons.

- ro and ri are radii, not diameters, and must use the same length unit.

- The resulting torque T is in force-length units; with F in newtons and radii in metres, T is in N·m.

- For the uniform-wear model, r_eff=(ro+ri)/2 assumes ri<ro and a physically valid annular friction surface.

- For the uniform-pressure model, r_eff=(2/3)(ro³-ri³)/(ro²-ri²) assumes ri<ro and consistent length units.

## Boundary hardening

**BREAK_CLAIMED** · SELF_FLAGGED

The uniform-pressure formula becomes undefined when ro=ri because its denominator ro^2-ri^2 is zero. The instrument should reject that geometry rather than return a numeric torque. Additional hazards are the physically invalid n=0 boundary, the unspecified branch-selection criterion, and the sign convention for axial force and torque.

## Errata and corrections

### Tranche errata

**T_Nm** · vector 3

506.25

56.25

output contradicts her own working, which computes (and self-corrects to) 56.25

## Inspectable example

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

````
{
  "inputs": {
    "mu": 0.3,
    "F_N": 4000,
    "ro_m": 0.15,
    "ri_m": 0.08,
    "n_friction_surfaces": 2,
    "wear_model": "uniform_wear"
  },
  "expected_outputs": {
    "T_Nm": 276
  },
  "working": "r_eff=(ro+ri)/2=(0.15+0.08)/2=0.23/2=0.115 m. T=n·μ·F·r_eff=2·0.3·4000·0.115=0.6·4000·0.115=2400·0.115=276 N·m."
}
````

## 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_WITH_ERRATA`

- `evidence-tranche5/tranche5-results.json`

- `BOUNDARY_HAZARD_CATALOG.json`