This single canonical page answers both brushless gearbox and 2 to 1 gearbox brushless intent. Use the tool first for immediate guidance, then validate with method, evidence, boundaries, risk controls, and procurement actions.
Review cycle: every 6 months, or within 72 hours after material standards/regulatory updates.
Use this as an engineering assumption. Final efficiency must be verified with supplier load-point test data.
Boundary notice: this page is a fast-screen tool for 0.15-22 kW, ratio up to 180:1, and duty up to 24 h/day. Outside this envelope the checker stays directional only.
Fit means execute RFQ. Conditional means validate first. Not-fit means re-architecture.
Formula summary: required ratio = motor speed / output speed; motor torque = (9550 × kW) / rpm; output torque estimate = motor torque × ratio × efficiency; required rated torque = target torque × service factor.
| Type | Preferred ratio/stage | Conditional max | Thermal conditional loss |
|---|---|---|---|
| planetary | 2.0:1 to 10.0:1 | 120:1 | 0.22 kW |
| spur-inline | 1.8:1 to 6.0:1 | 80:1 | 0.18 kW |
| harmonic | 30.0:1 to 120.0:1 | 180:1 | 0.35 kW |
| worm | 10.0:1 to 60.0:1 | 120:1 | 0.30 kW |
| ID | Source | Use in page | Confidence |
|---|---|---|---|
| S1 | NIST Guide to the SI, Chapter 4: derived units (J = N·m, W = J/s) NIST · Published Current web edition · Verified 2026-05-05 Open source | Unit consistency for torque/power formulas and RFQ unit normalization. | High |
| S2 | IEC 60034-1 Rotating electrical machines - Rating and performance IEC · Published 2026-03-13 · Verified 2026-05-05 Open source | Duty-cycle interpretation and motor rating boundary language. | High |
| S3 | Consolidated Regulation (EU) 2019/1781 - Ecodesign for motors and variable speed drives EUR-Lex · Published Consolidated text 2023-01-24 · Verified 2026-05-05 Open source | Scope/exclusion boundaries and required load-point disclosures (full/75%/50%). | High |
| S4 | 10 CFR 431.12 Definitions (U.S. electric motor classes) eCFR / U.S. DOE · Published Current text · Verified 2026-05-05 Open source | U.S. class-definition boundaries to avoid wrong compliance assumptions. | High |
| S5 | 29 CFR 1910.95 Occupational noise exposure OSHA · Published Current text · Verified 2026-05-05 Open source | Table G-16 PEL reference, 85 dBA action level program trigger, 140 dB peak statement. | High |
| S6 | OSHA Standard Interpretation: 140 dB impact/impulse policy under 1910.95 OSHA · Published 2025-07-30 · Verified 2026-05-05 Open source | Clarifies integration of 80-130 dB impulsive noise and enforcement interpretation. | High |
| S7 | Directive 2003/10/EC Article 3 worker noise thresholds (EU exposure limits) EUR-Lex · Published Consolidated version 2019-07-26 · Verified 2026-05-05 Open source | EU lower/upper/action limit framework: 80/85/87 dB(A) and peak pressure limits. | High |
| S8 | CDC/NIOSH: Understand Noise Exposure (REL 85 dBA, 3 dB exchange guidance) CDC / NIOSH · Published Current page · Verified 2026-05-05 Open source | Risk escalation explanation for long-shift and high-variance noise environments. | High |
| S9 | NIOSH Criteria for a Recommended Standard: Occupational Noise Exposure (98-126) CDC / NIOSH · Published 1998-06 · Verified 2026-05-05 Open source | Historical evidence basis and long-term hearing-risk framing for conservative decisions. | Medium |
| S10 | ANSI/AGMA 6034-C21 Enclosed Cylindrical Wormgear Speed Reducers and Gearmotors AGMA · Published 2021-04-09 · Verified 2026-05-05 Open source | Thermal/service-factor method context for wormgear risk framing (paid standard). | Medium |
| Topic | Audit gap | Evidence increment | Boundary / limitation | Minimum action | Trace |
|---|---|---|---|---|---|
| Occupational noise thresholds (US) | Previous copy mentioned noise risk but lacked hard trigger numbers and impulsive-noise handling logic. | OSHA 1910.95 Table G-16 uses 90 dBA at 8 h as the PEL framework; hearing conservation program triggers at 85 dBA TWA; impact/impulse should not exceed 140 dB peak. | These are worker-exposure controls, not direct product pass/fail design specs. Limitation: Plant layout, shift pattern, and PPE attenuation still change real exposure outcome. | Require station-level dosimetry and hearing-conservation check as a procurement gate for high-noise zones. | S5, S6 Updated 2026-05-05 |
| Occupational noise thresholds (EU) | EU thresholds were not mapped, making cross-region compliance planning ambiguous. | Directive 2003/10/EC Article 3 sets lower/upper/action structure at 80/85/87 dB(A), with peak pressure thresholds at 112/140/200 Pa. | Directive applies to worker protection obligations, not to motor efficiency labeling. Limitation: Member-state enforcement and implementation details can be stricter than the minimum directive text. | Keep an EU site checklist in RFQ review: daily exposure, peak pressure, and hearing-protection assumptions. | S7 Updated 2026-05-05 |
| EU ecodesign scope boundary for brushless + gearbox products | Earlier text risked over-generalizing IE-class assumptions to all brushless integrated products. | Regulation (EU) 2019/1781 Article 2 targets specific induction-motor/VSD classes and explicitly excludes certain fully integrated products whose motor performance cannot be tested independently. | Clause scope is product-topology dependent: integrated designs may fall outside direct requirement sections. Limitation: Scope judgments still need product-level declarations and testability details from suppliers. | Ask suppliers for clause-level applicability statement and exemption rationale before accepting efficiency claims. | S3 Updated 2026-05-05 |
| Load-point evidence for efficiency claims | Efficiency discussion lacked required load-point evidence and test-context detail. | EU 2019/1781 Annex I requires rated efficiency disclosure at full/75%/50% load for in-scope motors plus additional loss information at defined operating points. | Applies to in-scope motors/VSDs; integrated assemblies may require a different test route. Limitation: Public data are often incomplete for packaged gearbox-motor offers. | Reject quote comparisons without explicit load-point values, test method, and ambient assumptions. | S3 Updated 2026-05-05 |
| US DOE class-definition boundary | US compliance statements were previously too broad for brushless gearbox combinations. | 10 CFR 431.12 definitions emphasize motor class distinctions (for example induction topology, duty, frame/use definitions), which do not map 1:1 to every brushless gearmotor bundle. | Legal class definitions organize compliance scope; they do not replace application-specific thermal/backlash validation. Limitation: The section is definitional; additional subpart requirements must still be checked per product class. | Require vendor declaration of exact applicable class and referenced test standard before bid acceptance. | S4 Updated 2026-05-05 |
| Formula dimensional consistency | Tool formula section lacked explicit SI basis for torque/power dimensions. | NIST SI guide defines joule as N·m and watt as J/s, supporting dimensional checks for torque and power conversion. | Dimensional consistency verifies calculation structure, not real-world drivetrain efficiency. Limitation: Correct units do not guarantee correct assumptions. | Freeze RFQ unit schema (kW, rpm, N·m, dBA) and reject mixed-unit submissions. | S1 Updated 2026-05-05 |
| Cross-vendor thermal/backlash benchmark availability | Previous copy implied comparability despite missing harmonized public datasets. | As of 2026-05-05, no reliable public harmonized dataset was found that normalizes thermal derating and hot-load backlash across major gearbox vendors. | This is an evidence-availability statement, not proof that vendors are equivalent or non-equivalent. Limitation: Private test benches may exist but are not publicly reproducible. | Mark this dimension as pending confirmation and require same-protocol witness test data per candidate. | Pending verification / no reliable open dataset Updated 2026-05-05 |
| Topic | Known | Unknown / gap | Minimum action |
|---|---|---|---|
| Unit conversion / basic formulas | Known via NIST and deterministic math | N/A | Keep consistent units in RFQ package |
| Regulatory scope labels | Known clause framework exists | Product-specific scope mapping often missing | Collect clause-level declaration from supplier |
| Cross-vendor thermal derating curves | Partial vendor-specific documents | No harmonized public dataset | Require normalized heat-run evidence |
| Backlash under hot load | Catalog nominal values | Unified measurement protocol absent | Request hot-state, load-direction-specific data |
If your decision depends mainly on medium-confidence areas, treat the current result as conditional even when the tool says fit.
| Option | Typical ratio | Efficiency band | Precision | Best fit scenario | Main risk | Evidence boundary | Counterexample / limit | Sources |
|---|---|---|---|---|---|---|---|---|
| Planetary (single/dual stage) | 2:1 to 100:1 | 90-96% (screening only) | Medium to high | 2:1 to 20:1 compact torque multiplication | Backlash and heat rise differ by lubrication and preload method | Ratio/efficiency bands are engineering-screen defaults, not harmonized cross-vendor legal limits. | A 2:1 setup can still fail when enclosure heat-soak pushes temperature above motor/grease limits. | S10 + Public dataset gap audit (2026-05-05) |
| Spur-inline multi-stage | 1.8:1 to 80:1 | 92-97% (screening only) | Medium | Cost-sensitive inline layouts with moderate ratio | Noise and shaft support limitations under shock load | Cross-vendor hot-state backlash data are not publicly harmonized; catalog values are not directly comparable. | Low-cost spur option can pass room-temperature test but drift under long duty and repeated starts. | S5, S8 + Public dataset gap audit (2026-05-05) |
| Harmonic drive | 30:1 to 160:1 | 60-85% (screening only) | Very high | High positioning precision, low backlash priority | Heat and duty-cycle derating under continuous load | No reliable open benchmark normalizes thermal derating across vendors at identical duty and ambient. | Precision benefit does not help if continuous-duty thermal limit forces torque derating below target. | Public dataset gap audit (2026-05-05) |
| Worm gearbox | 10:1 to 120:1 | 45-85% (screening only) | Low to medium | High ratio with simple layout and potential self-lock tendency | Thermal saturation and efficiency penalty at high duty | Thermal-capacity design guidance exists, but standard access is paid and execution remains vendor-specific. | Lower upfront price can be offset by energy loss and cooling retrofit under 16-24 h duty. | S10 |
| Audience | Use this page | Do not use alone |
|---|---|---|
| Application engineer | Early architecture screening | Final release without supplier test evidence |
| Procurement | RFQ requirement definition | Vendor ranking from brochure values only |
| Operations / maintenance | Risk checkpoints for duty and noise | Lifetime prediction without field duty data |
| Decision node | Option A | Option B | Tradeoff | Hidden risk | Trigger | Recommendation | Sources |
|---|---|---|---|---|---|---|---|
| 2:1 remains the target ratio | Keep 2:1 and optimize controls | Increase ratio or stage count | Option A keeps efficiency and simplicity; Option B raises torque margin but can increase thermal/load complexity. | Treating a control-loop issue as purely mechanical can lock in unnecessary hardware cost. | If controller-only baseline meets acceleration and overshoot targets, postpone gearbox redesign. | Run controller baseline first, then move to hardware only if torque shortfall persists. | S1 + Pending control-loop dataset |
| Accept vendor efficiency claim | Single-point catalog efficiency | Load-point evidence package (full/75%/50%) | Option A is faster but high uncertainty; Option B delays procurement but improves lifecycle-cost predictability. | Single-point values can understate heat-loss risk at partial load and long duty. | Thermal estimate gap >20% between model and bench should force evidence escalation. | Treat missing load-point evidence as conditional at best. | S3 |
| Noise handling in high-duty cells | Comfort-only acoustic check | Compliance-grade dosimetry workflow | Option A is lightweight but may miss legal triggers; Option B adds process overhead but reduces enforcement risk. | Impulsive peaks can push exposure risk rapidly even when average noise looks acceptable. | Any measured impulsive events near high peak levels or 85 dBA TWA should start formal program checks. | Integrate acoustics into RFQ scoring, not post-install troubleshooting. | S5, S6, S7, S8 |
| Use IE/compliance labels in bids | Reuse label without clause mapping | Clause-level applicability + exemption statement | Option A shortens paperwork but can create contractual/compliance exposure; Option B is slower but auditable. | Integrated motor-gearbox topologies can be out-of-scope for sections teams assume are mandatory. | If supplier cannot map claim to specific article/definition, mark as unresolved. | Require article-level traceability before final supplier ranking. | S3, S4 |
| Risk | Probability | Impact | Signal | Mitigation | Sources | Updated |
|---|---|---|---|---|---|---|
| Ratio is copied from speed target but ignores load torque spikes | High | High | Tool result toggles between fit and not-fit after small torque change | Use shock level and service factor, then request transient torque logs before PO. | S1, S10 | 2026-05-05 |
| Assuming catalog efficiency at all load points | High | Medium | Thermal loss in bench test exceeds estimate by >20% | Ask supplier for full/75%/50% load points with test method and ambient condition. | S3 | 2026-05-05 |
| Compliance claims reused without checking integration scope | Medium | High | Supplier cannot map claim to exact clause in EU/US definitions | Collect clause-level scope statements (EU 2019/1781 Article 2, 10 CFR 431.12). | S3, S4 | 2026-05-05 |
| Noise treated as comfort only, not safety/compliance | Medium | Medium | Measured dBA near workstation crosses action-level threshold | Add acoustic line item to RFQ and validate against OSHA 1910.95 limits. | S5, S6, S7, S8 | 2026-05-05 |
| 2:1 request is actually a control-loop problem, not gearbox problem | Medium | Medium | Speed target can be met by controller tuning without torque shortfall | Run controller-only baseline before locking gearbox hardware change. | Pending: no reliable public cross-vendor control-loop dataset | 2026-05-05 |
Premise: 1.5 kW BLDC, 3000 rpm input, requested 1500 rpm output, moderate shock, 16 h/day.
Process: Run tool with planetary single stage baseline. Validate ratio, thermal loss, and required rated torque margin.
Outcome: Usually Fit or Conditional depending on torque margin and candidate torque class.
Recommendation: Keep planetary/spur options open and request hot-state backlash data before purchase.
Premise: Same motor family but precision requirement increased after motion-control review.
Process: Switch gearbox type to harmonic, re-run result and thermal loss; compare with planetary multi-stage.
Outcome: Precision improves while thermal headroom can tighten significantly.
Recommendation: Treat efficiency and thermal tests as gating metrics, not optional checks.
Premise: High duty cycle and continuous operation, procurement favored lower upfront cost.
Process: Run worm profile with same torque targets and observe service-factor and loss changes.
Outcome: Conditional/Not-fit risk often appears under continuous duty due to thermal burden.
Recommendation: Add lifecycle cost model (energy + downtime + maintenance) before final selection.
Premise: Inputs exceed quick-screen envelope while team still expects deterministic recommendation.
Process: Tool returns boundary state with directional numbers and explicit escalation step.
Outcome: No direct architecture approval is provided in boundary state.
Recommendation: Move to full engineering model, supplier dyno data, and duty-cycle validation.
Alias intent and URL policy
Method and boundary
Risk and procurement execution
Ready to move from screening to execution? Send your real duty-cycle profile, temperature limits, and target backlash class.
Submit RFQ Package Re-run checker with updated data