Run an immediately usable two-stage sizing screen, then move through evidence-backed boundaries, trade-offs, and RFQ actions in one page. This URL is intentionally tool-first and decision-focused.
Deterministic pre-RFQ checker with explicit boundary logic and uncertainty disclosure.
You already have motor speed, target output speed, and target torque and need a fast two-stage feasibility screen.
Your procurement team must separate "quotable" from "production-ready" with auditable evidence fields.
Your project is in pre-RFQ stage and needs to eliminate clearly out-of-bound options first.
You need to place a final purchase order immediately and do not plan additional thermal/noise/life validation.
Your target ratio is far above 300:1 or duty conditions are clearly outside this page boundary.
Your use case is safety-critical and requires regulation-grade validation, not screening-grade guidance.
| Market | Trigger | Requirement | Sourcing impact | Source |
|---|---|---|---|---|
EU market placement (motor/drive package included) EU Commission page verified 2026-05-04 | Applies when in-scope electric motors or variable speed drives are part of the supplied system. | Regulation (EU) 2019/1781 applies from 2021-07-01; IE3 is required for many 0.75–1000 kW 3-phase motors, IE4 is mandatory for 75–200 kW categories from 2023-07, and in-scope VSDs must meet IE2. | A mechanically suitable gearbox quote can still fail procurement if bundled motor/drive efficiency classes are non-compliant. | S11 |
U.S. plant operation (occupational noise) OSHA page verified 2026-05-04 | Applies when gearbox-motor assemblies can affect workplace noise exposure levels. | OSHA Table G-16 uses time-weighted limits (90 dBA/8 h, 95 dBA/4 h, 100 dBA/2 h), and the hearing-conservation action level is 85 dBA (8-hour TWA). | Noise data should be part of supplier acceptance because remediation costs can exceed small unit-price savings. | S7 |
| Subject | Known boundary | Decision implication | Source |
|---|---|---|---|
| ISO 6336 method validity envelope | Validated formula envelope includes pressure angle 15°–25°, helix angle ≤30°, and transverse contact ratio 1.0–2.5. | If your geometry sits outside this envelope, request supplier method extension or test evidence before freezing design. | S1 |
| ISO 281 bearing-life interpretation | Basic rating life is linked to 90% reliability (L10 concept), not a direct warranty life commitment. | Require reliability percentile, duty cycle, and lubrication assumptions in RFQ life claims. | S10 |
| Catalog ratio versus architecture | A public family shows standard ratios up to i=289.74 but double gear units up to i=27,001. | Do not treat total ratio alone as a fair comparison proxy; capture stage count and architecture in quote templates. | S5 |
Public vendor data for industrial parallel-axis families shows two-/three-stage products commonly cover wide ratio windows (for example i up to 289.74 in one family), but extreme reductions may require compound or alternate architectures.
Boundary: This is a product-family reference, not a universal market maximum for all wholesale suppliers or all spur-only designs.
Sources: S5
A current industrial benchmark reports roughly 98% (1-stage), 97% (2-stage), and 96% (3-stage), so stage count changes OPEX and thermal load, not only ratio availability.
Boundary: These values are directional benchmarks from one manufacturer context; final RFQ decisions need model-level test definitions.
Sources: S4
ISO 6336 and AGMA 2101 are rating frameworks for pitting/bending capacity and factor handling; they do not by themselves validate assembled drivetrain behavior in your exact duty profile.
Boundary: Thermal, NVH, lubrication, and system integration still require supplier test data and acceptance criteria.
Sources: S1, S3
Supplier “precision” statements should be tied to flank tolerance class terminology and backlash measurement method, not just marketing labels.
Boundary: Cross-supplier comparisons are weak if class definitions, temperature state, and load state are missing.
Sources: S2, S5
Current EIA references show U.S. industrial electricity at 8.95 cents/kWh (2026-02 monthly) versus 8.62 cents/kWh (2025 annual average), so the same loss power maps to materially different annual cost outcomes.
Boundary: Energy price is location- and contract-dependent; this checker is a screening estimate, not a financial guarantee.
Sources: S8, S9
EU market rules for motors and drives have dated thresholds: Regulation (EU) 2019/1781 applies from 2021-07-01, with IE4 mandatory for selected 75–200 kW motor categories from 2023-07 and IE2 requirements for in-scope drives.
Boundary: This compliance gate is region- and product-scope-dependent; apply only when your shipment includes in-scope motor/drive content for the EU market.
Sources: S11
OSHA Table G-16 pairs noise with allowed duration (90 dBA/8 h, 95 dBA/4 h, 100 dBA/2 h), and hearing-conservation actions start at 85 dBA (8-hour TWA).
Boundary: This is a U.S. occupational benchmark and does not replace local jurisdiction rules or machine-specific noise certification.
Sources: S7
One public family lists standard R-series ratios up to 289.74 while double gear units can reach 27,001, so high catalog ratio claims may involve additional reduction stages.
Boundary: Do not compare quote prices by total ratio alone; require stage count, architecture, and efficiency chain to be declared.
Sources: S5
1. Total ratio i = motor rpm / output rpm.
2. Stage split estimate uses √i for quick two-stage distribution.
3. Output power uses P(kW)=T(Nm)×n(rpm)/9550.
4. Total efficiency estimate multiplies per-stage efficiency assumptions.
5. Annual loss cost = loss power × duty × 365 × electricity price.
This method intentionally avoids fake precision: where public evidence is weak, outputs are labeled as screening-only and escalated to verification tasks.
| Question | Known from sources | What you still must verify |
|---|---|---|
| Strength calculation method | ISO 6336 / AGMA 2101 are core rating frameworks, with ISO 6336 formula validation published inside defined geometry envelopes. | If geometry is outside published validity ranges, request explicit method extension or empirical test closure. |
| Two-stage ratio and structure availability | Public product families show broad two-/three-stage windows. | Your target ratio, footprint, and gearbox envelope compatibility. |
| Efficiency | Public benchmark example: about 98/97/96 by stage count; EIA industrial price references currently range from 8.24 to 8.95 c/kWh by data window. | Supplier-specific wholesale test method and load-point curve plus price-sensitivity check before final total cost ranking. |
| Life and reliability | ISO 281 defines 90% reliability basic rating life basis. | Bearing selection details, lubricant contamination, duty transients. |
| Regional market compliance | EU motor/VSD rules apply by scope and date (2019/1781 in force from 2021-07-01; IE4 applies to selected 75–200 kW categories from 2023-07). | Verify bundled motor/drive compliance before commercial award, not after mechanical shortlist. |
| Topic | Status | Impact | Minimum action |
|---|---|---|---|
| Cross-brand two-stage spur efficiency distribution (same test method) | Pending confirmation (no unified public database) | Cross-brand catalog efficiency comparisons can mislead selection when test conditions are inconsistent. | Require test duty point, efficiency map points, oil temperature, load range, and measurement uncertainty in RFQ data. |
| Public failure/return-rate benchmarks by stage count in each industry | No reliable public dataset | Public averages are not sufficient to predict your project-level failure probability. | Request supplier failure-mode history, 8D cases, in-warranty return definitions, and sample size details. |
| Public supplier lead-time samples by region and specification | Pending confirmation (insufficient public samples) | Procurement schedule risk is hard to quantify accurately from public data alone. | Bind latest acceptable delivery dates in RFQ terms and lock lead-time commitments separately for sample, pilot, and mass-production phases. |
| Option | Useful ratio window | Efficiency reference | Strongest use case | Main risk | Evidence status |
|---|---|---|---|---|---|
| Two-stage spur/helical parallel-axis | Typical medium-to-high reduction demand; public family examples can reach i≈289.74 (series-specific). | About 97% (stage benchmark example) | Balanced target across efficiency, structural complexity, and cost. | Cross-supplier parameters become non-comparable when duty boundaries are undefined. | Public product-family evidence exists, but same-method cross-brand datasets remain limited. |
| Three-stage spur/helical | Higher total reduction ratios, typically for low-speed high-torque output. | About 96% (stage benchmark example) | When two-stage paths cannot satisfy ratio and thermal limits simultaneously. | Additional stages increase efficiency and thermal burden. | Public stage-level benchmarks exist, but model-level confirmation is still required. |
| Worm-dominant architecture | High single-stage reduction potential (series dependent). | Public values vary significantly; model-tested data is required. | Space-constrained layouts with explicit self-locking behavior requirements. | Heat loss and lubrication window can become primary project risks. | Public evidence is fragmented and cross-brand comparability is weak. |
| Planetary hybrid path | Common in high-ratio and high power-density applications. | Depends on stage count and architecture; supplier curves are required. | When package size constraints and torque density have higher priority. | Higher procurement cost and tighter tolerance-control demand. | Product documentation is available, but unified cross-brand test comparisons are still limited. |
| Common claim | Counterexample / limitation | Decision impact | Minimum executable action | Source |
|---|---|---|---|---|
| “Two-stage can always absorb high ratio requests.” | Public catalogs show two-/three-stage windows up to about 289.74 in one family, while much higher ratios can require double units or alternate architectures. | Pure ratio comparison can mask architecture changes and distort cost/efficiency expectations. | Force suppliers to declare stage count, architecture path, and tested efficiency chain at quoted operating points. | S5 |
| “One measured dBA number is enough for compliance.” | OSHA limits are tied to both level and duration; 95 dBA is limited to 4 hours and 100 dBA to 2 hours. | Ignoring duration can turn a “passing” lab value into a field non-compliance risk. | Request noise data by duty cycle and define acceptance at real operating duration, not only nameplate conditions. | S7 |
| “A fit result guarantees lowest operating cost.” | EIA industrial electricity references vary (8.24, 8.62, 8.95 c/kWh), changing annual loss cost even with identical loss power. | OPEX ranking can shift during procurement cycles when energy assumptions move. | Use multi-price sensitivity in RFQ evaluation and lock the financial assumption date. | S8, S9 |
Boundary misuse risk
High/HighTreating screening output as final procurement approval without thermal, noise, and life validation.
Mitigation: Limit this page to pre-RFQ filtering and enforce a mandatory validation matrix before award.
Cost mismatch risk
High/MediumComparing only unit purchase price while ignoring energy-loss cost and maintenance windows.
Mitigation: Calculate loss-cost baseline with current electricity price and run annual sensitivity bands.
Scenario mismatch risk
Medium/MediumApplying light-duty parameters to high-shock duty can leave service factor below safe range.
Mitigation: Declare shock class, duty cycle, and service-factor source explicitly in RFQ terms.
Evidence-definition risk
High/MediumEfficiency, backlash, and life metrics from different temperature/load/test definitions can distort comparisons.
Mitigation: Require test method and boundary conditions for every core metric; treat missing definitions as non-comparable.
Keep this page as the canonical screening entry, then move to RFQ actions and adjacent architecture pages for full feasibility closure.
Assumptions: Service factor 1.35, 2-stage efficiency 97%, 16 h/day, industrial electricity price 8.95 c/kWh.
Process: Total ratio i=25, split approximately evenly into two stages at about 5:1 each.
Result: Produces actionable supplier-screening inputs, but thermal balance and backlash tests are still required.
Assumptions: Attempting to cover an ultra-high reduction ratio with two stages at comparable power.
Process: The checker enters boundary state and recommends three-stage or mixed-architecture review.
Result: Prevents out-of-bound results from being misused as direct order decisions.
Assumptions: Nominal torque rating is identical, but test definitions are undisclosed.
Process: The risk layer flags the offers as non-comparable and outputs a minimum evidence request list.
Result: Shifts evaluation from quote-price debate to evidence completeness and controllable risk.
1. Continuous torque and efficiency curves with declared test method.
2. Thermal boundaries (oil temperature, housing temperature, duty definition).
3. Backlash/tolerance class with measurement condition and acceptance method.
4. Bearing-life evidence and lubrication assumptions tied to duty cycle.
1. Separate lead time commitments for sample, pilot, and production lots.
2. Warranty and failure-mode reporting scope with data cut definition.
3. Non-conformance workflow and response SLA (8D or equivalent).
4. Change-control obligation for material, process, or tolerance updates.
Core conclusions are linked to traceable sources. If evidence is weak or unavailable, the page explicitly labels it as "pending confirmation/no reliable public dataset" instead of inventing certainty. Review cadence: every 6 months or earlier when standards or data are updated.
ISO 6336-1 validates the calculation basis inside specific geometry ranges (pressure angle 15°–25°, helix angle ≤30°, transverse contact ratio 1.0–2.5) and does not guarantee assembled drive-system behavior by itself.
https://www.iso.org/standard/63819.htmlDefines tolerance class structure and allowable flank deviation values for cylindrical involute gears.
https://www.iso.org/standard/45309.htmlLists ANSI/AGMA 2101-E25 (published 2025-07-31) and records ANSI/AGMA 2001-D04 as replaced by 2101-E25.
https://www.agma.org/wp-content/uploads/2026/03/MPMA_Publications_Catalog.pdfShows stage-dependent gearing efficiency benchmark: 98% (1-stage), 97% (2-stage), 96% (3-stage).
https://download.sew-eurodrive.com/download/html/33346739/en-EN/891277287548168610059.htmlLists R-series ratio i=3.21–289.74, reduced-backlash i=3.5–281, and double gear units up to i=27,001, highlighting that extreme catalog ratios can involve compound architecture.
https://www.sew-eurodrive.com.co/products/gear_units/standard_gear_units/helical_gear_units_r/helical_gear_units_r.htmlGives horsepower conversion used in sizing checks: 1 hp = 745.6999 W.
https://www.nist.gov/pml/special-publication-811/nist-guide-si-appendix-b-conversion-factors/nist-guide-si-appendix-b8Provides enforceable thresholds for screening: Table G-16 includes 90 dBA/8 h, 95 dBA/4 h, 100 dBA/2 h, and the hearing-conservation action level is 85 dBA (8-hour TWA).
https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.95Reports U.S. industrial electricity price at 8.95 cents/kWh for February 2026 (release date 2026-04-23).
https://www.eia.gov/electricity/monthly/epm_table_grapher.php?t=epmt_5_6_aShows U.S. industrial average electricity price at 8.62 cents/kWh (2025 annual value) and 8.95 cents/kWh (February 2026 monthly value).
https://www.eia.gov/electricity/monthly/epm_table_grapher.php?t=table_5_03Defines basic rating life at 90% reliability and scope boundaries, relevant for supplier bearing-life evidence requests in wholesale RFQ reviews.
https://www.iso.org/standard/38102.htmlStates scope (0.12–1000 kW), entry into application on 2021-07-01, IE4 requirement for 75–200 kW motors from 2023-07, VSD IE2 requirement, and projected annual savings of 106 TWh by 2030.
https://energy-efficient-products.ec.europa.eu/product-list/electric-motors_enC1. Two-stage windows are broad but not unlimited.
C2. Every added stage usually costs efficiency.
C3. Strength calculations are necessary but insufficient.
C4. Tolerance and backlash claims need explicit test language.
C5. Energy-price assumptions materially change total-cost ranking.
C6. Regulatory fit can invalidate a mechanically valid shortlist.
C7. Noise risk is time-weighted, not a single-number check.
C8. Catalog ratio headlines can hide architecture complexity.
Keep this result as screening evidence, then launch RFQ validation with thermal, backlash, lifecycle, and delivery commitments.
This page is an engineering screening aid, not legal/compliance advice and not a substitute for wholesale validation. For safety-critical or regulated deployments, escalate to certified design review and machine-level risk assessment.
