Tool first: run the 2:1 inline speed reducer checker for immediate fit feedback. Then use the report layers to verify evidence, understand boundaries, and lock your next engineering action.
Input torque, speed, duty, and backlash target to screen whether a 2:1 inline branch is ready for RFQ.
No result yet.
Run the checker to see topology recommendation, 2:1 boundary alignment, and next action.
SEW RX2016 tables show discrete points around 2:1 (for example 1.92, 2.04, 2.13), not a universal exact 2.000 option in every size. Screening should treat 2:1 as a tolerance target and verify exact ratio per frame.
SEW RX corridors include 1.30 to 8.65, while NORD single-stage references include ranges such as 1.41 to 8.09 and catalog extremes down to 1.07 and up to 13.10. 2:1 is common, but model-level selection still depends on torque and size table boundaries.
Neugart guidance describes single-stage planetary ranges around 3:1 to 10:1 and two-stage multiplication to 9:1 to 100:1, with decreasing efficiency as stages increase. Strict 2:1 requests remain a mismatch warning for many planetary-first assumptions.
ISO 6336-1 defines spur/helical tooth-capacity method boundaries, and ISO/TR 14179 thermal rating baselines are tied to explicit ambient and sump assumptions. Any quick checker output outside these assumptions must be treated as review status.
ISO 281 usage notes (JTEKT summary) state L10 is 90% reliability, while 99% reliability maps to a1 = 0.25. If the project requires higher reliability, life and bearing margins derate quickly and may force a larger frame.
NORD angled-gear guidance notes that worm ratios can run high and may self-lock, but higher ratios can lose efficiency due to stronger sliding. This is a useful counterexample when buyers optimize only for compactness or headline ratio.
These anchors support first-pass decisions before RFQ. Any item with incomplete public parity is explicitly marked and should not be treated as guaranteed equivalence.
| Metric | Published Context | Why It Matters | Source Family |
|---|---|---|---|
| Speed-torque inverse relation | NORD DS1013 states speed and torque are inversely proportional in reducer application context. | Validates why a 2:1 request halves speed and raises torque before loss factors. | NORD DS1013 catalog |
| SEW discrete near-2 ratio evidence | RX57/RX67/RX77 tables include near-2 discrete points such as 1.92, 2.04, and 2.13. | Shows that exact 2.000 is not guaranteed on every model even when 2:1 intent is valid. | SEW gear units catalog 2016 (RX tables) |
| SEW RX corridor upper/lower bounds | RX catalog coverage includes 1.30 to 8.65 in the cited tables. | Confirms 2:1 stays inside mainstream single-stage inline range. | SEW gear units catalog 2016 |
| NORD single-stage catalog extremes | DS1013 lists one-stage ratios from 1.07:1 (lowest standard) to 13.10:1 (highest standard). | Explains why corridor compatibility must still be checked at model/size level. | NORD DS1013 catalog |
| NORD published one-stage expansion signal | NORD public release cites 1.41 to 8.09 single-stage range with expanded torque/speed envelope. | Supports 2:1 commercial availability while preserving the need for size filtering. | NORD single-stage news release |
| Planetary stage practical range signal | Neugart guidance: single-stage about 3:1 to 10:1; two-stage about 9:1 to 100:1. | Flags topology mismatch risk when 2:1 is forced into planetary single-stage assumptions. | Neugart multi-stage guidance |
| ISO 6336-1 applicability | Defines load-capacity principles for spur/helical involute gears with explicit scope and exclusions | Prevents over-trusting outputs outside the documented method boundary. | ISO 6336-1:2019 scope abstract |
| ISO/TR 14179-1 thermal baseline | Thermal rating reference baseline is 25 degC ambient and 95 degC oil sump; modifiers apply for other conditions. | Turns ambient and lubrication assumptions into explicit decision gates rather than hidden defaults. | ISO/TR 14179-1 scope notes |
| Duty class boundary language | NEMA vs IEC guide lists IEC duty types S1-S10 and notes IEC does not recognize service factor as NEMA does. | Starts/hour and duty hours should map to a named duty type in RFQ, not only scalar inputs. | NEMA Motor Standards vs IEC Motor Standards |
| Reliability derating anchor | ISO 281 usage summary: L10 corresponds to 90% reliability; reliability factor a1 is 0.25 at 99%. | High-reliability projects can require larger bearing/life margins than nominal torque alone suggests. | JTEKT/Koyo ISO 281 explanation |
| Single-stage bevel efficiency comparator | NORD reference: 96-98% per bevel stage in stated context | Useful as comparator signal only, not a direct inline-helical guarantee for every supplier. | NORD bevel gear unit application article |
| Inline orientation context | SEW gear-unit overview distinguishes inline (parallel shaft direction) from right-angle branches | Avoids architecture confusion when users jump between inline and right-angle pages. | SEW gear unit overview |
This round focuses on information gain, not wording refresh. Each row maps a concrete content gap to a verifiable evidence addition and a decision-level consequence.
| Gap in prior draft | Added evidence (dated) | Decision consequence |
|---|---|---|
| Exact 2:1 availability was implied too generally. | Added SEW discrete-ratio evidence near 2:1 and NORD size-range boundaries (snapshot 2026-05-26). | 2:1 is now treated as a tolerance-band intent that must be confirmed per selected frame. |
| Thermal boundary had weak standards anchoring. | Added ISO/TR 14179-1 baseline assumptions (25 degC ambient, 95 degC sump; modifier factors required outside baseline). | Hot or atypical duty now escalates to review/no-go unless thermal evidence is provided. |
| Duty/start inputs lacked named operating-class mapping. | Added NEMA-vs-IEC duty-class signal (S1-S10 and service-factor treatment difference). | RFQ preparation now requires duty type and sequence context, not just starts/hour. |
| Reliability interpretation was under-specified. | Added ISO 281 reliability anchor through JTEKT summary (L10 = 90%; a1 = 0.25 at 99%). | High-reliability targets now explicitly trigger bearing-life derating checks. |
| Alternative topology downside lacked a hard counterexample. | Added NORD worm-branch evidence on ratio, self-locking potential, and efficiency tradeoff at higher ratios. | Comparison now includes a concrete "not-use" condition, not only strengths. |
| Scenario | Good Fit Signal | Not-Fit Warning | Decision Note |
|---|---|---|---|
| Conveyor or transfer line asks for strict 2:1 speed trim | Yes, this page and tool are primary fit. | No major mismatch if duty inputs are complete. | Use helical-first shortlist, then confirm thermal and shaft-load margins before release. |
| Project demands <5 arcmin backlash with compact frame | Use as initial branch check only. | Do not lock supplier only from quick result. | Escalate to precision class verification and stiffness tests. |
| Requirement is actually 3:1 to 10:1 and multi-stage likely | Partial fit, but not ideal for final architecture. | Avoid forcing a 2:1-centric decision model. | Switch to broader ratio workflows after confirming intent drift. |
| User insists on planetary single-stage at 2:1 | Use only to expose mismatch risk. | No-go as direct fit in this quick model. | Validate if ratio can move to >=3:1 or change topology to helical. |
| Ambient above 55 degC and frequent start-stop | Use for risk surfacing, not final release. | Avoid direct procurement commitment from calculator output. | Run full thermal and bearing-life review with lubricant selection. |
| Buyer compares quotes without unified duty template | Use report checklist first. | Avoid raw price ranking without normalized assumptions. | Issue one RFQ template to all candidates before comparison. |
| Boundary Topic | Published / Defined Condition | Decision Impact | Source |
|---|---|---|---|
| Ratio scope for this page | Quick checker calibrated around 2:1 with an execution corridor of 1.2 to 3.5 and strict decision band around 1.9 to 2.1. | Out-of-band values are marked boundary/review to prevent misuse of 2:1 logic. | Page method design (based on query intent and catalog windows) |
| Single-stage inline helical reference corridor | SEW RX references include 1.30 to 8.65 and NORD one-stage references include ranges such as 1.41 to 8.09 with catalog extremes beyond that. | 2:1 remains in mainstream single-stage inline territory. | SEW and NORD public references |
| Planetary single-stage applicability | Neugart guidance highlights technically sensible ranges around 3:1 to 10:1. | 2:1 planetary single-stage requests are flagged as branch-mismatch risk. | Neugart epicyclic and multi-stage guidance |
| Duty and starts boundary | Tool boundary uses duty <=24 h/day and starts <=240/h, while IEC duty-type language (S1-S10) should be used for formal RFQ context. | High cycle counts or non-continuous regimes require explicit duty-type mapping before final ranking. | Tool guardrail + NEMA/IEC duty guidance |
| Temperature boundary | Tool envelope uses ambient -20 to 80 degC for first-pass interpretation; ISO/TR 14179 thermal baseline is stated at 25 degC ambient and 95 degC oil sump. | Boundary or off-baseline temperatures require thermal correction, not direct catalog transfer. | Tool guardrail + ISO/TR 14179-1 baseline |
| Bearing-life reliability boundary | ISO 281 interpretation uses L10 as 90% reliability and applies reliability factor a1 for higher confidence targets. | Procurement decisions based only on nominal torque can understate life risk in high-reliability programs. | JTEKT/Koyo ISO 281 explanation |
The tool couples boundary gating, topology branching, duty-adjusted rating checkpoints, and explicit decision states.
Screening confidence increases from kinematics to catalog windows to standards-scope alignment.
| Step | Logic | Output |
|---|---|---|
| 1. Input sanity gate | Validate positive numeric inputs, duty/time constraints, ratio corridor, and ambient envelope before any branch selection. | Valid input pack or explicit boundary/error with recovery path. |
| 2. Topology branching | Auto mode prioritizes inline helical for <3:1 intent and warns if forced planetary contradicts single-stage corridor. | Recommended topology with mismatch flags where applicable. |
| 3. Kinematic conversion | Use speed/ratio relation for output speed and torque conversion with efficiency assumption layer. | Estimated output speed and torque checkpoints. |
| 4. Duty-adjusted rating checkpoint | Compose service factor from load profile, operating time, starts/hour, ambient shift, and assumption mode. | Required rated torque checkpoint for shortlist screening. |
| 5. Decision state and CTA | Map result into go/review/no-go plus boundary note, explanation bullets, and engineering handoff action. | Actionable next step instead of raw numeric output. |
If the tool returns review or no-go, package inputs and checkpoints into one standardized RFQ before supplier ranking.
Unknown values remain explicit. The table favors decision relevance over decorative completeness.
| Option | Strength | Tradeoff | Data Confidence | Typical Fit |
|---|---|---|---|---|
| Inline helical (single-stage focus) | 2:1 compatibility is straightforward in public ratio windows; compact and procurement-friendly. | Backlash/precision limits can require premium classes and tighter validation. | Public ratio windows are available; cross-brand lifecycle parity is partially unknown. | Default branch for strict 2:1 inline projects. |
| Inline planetary (single-stage) | High torque density and lower backlash potential in precision classes. | Single-stage range signals often start around 3:1, creating mismatch for strict 2:1. | Practical stage-range references are public; 2:1 direct fit evidence is limited. | Use when ratio intent can shift upward or stages can be re-allocated. |
| Right-angle bevel/hypoid branch | Strong comparator for high efficiency and 1:1 to 1:10 stage references. | Shaft orientation changes and packaging assumptions differ from inline goals. | Efficiency and ratio references are public for comparator use. | Not primary for inline-only constraints; useful as alternative architecture check. |
| Worm-oriented branch | Can provide large reduction in compact envelope for some duty classes. | At higher worm ratios, strong sliding can reduce efficiency; self-locking behavior can also alter control strategy. | NORD guidance explicitly flags lower efficiency tendency at higher worm ratios. | Usually not first choice for strict 2:1 inline efficiency-driven selection. |
Risks are grouped by misuse, cost distortion, topology mismatch, and release controls so each one has an executable mitigation.
| Risk | Trigger | Impact | Mitigation |
|---|---|---|---|
| Formula-transfer risk | Applying ratio math without duty class, reliability target, or thermal assumptions. | Undersized shortlist and later redesign cycles. | Enforce service-factor, duty-type, reliability, and thermal checks before using any go outcome. |
| Topology mismatch risk | Forcing planetary single-stage on strict 2:1 requirement. | Unstable commercial comparison and avoidable RFQ churn. | Use auto branching and explicitly mark 2:1 planetary mismatch as review/no-go. |
| Cost-ranking distortion | Comparing quotes with inconsistent duty templates. | Choosing low headline price with hidden performance penalty. | Issue one normalized RFQ template with shared assumptions and acceptance criteria. |
| Thermal underestimation | Ignoring ambient and lubricant effects in continuous operation. | Higher losses, oil degradation, and shortened life. | Trigger thermal review when ambient and starts/hour approach boundary states. |
| Release-gate risk | Treating quick-check result as final sign-off. | Field failure or late project delay. | Require engineering sign-off on gear rating, bearings, seals, and integration loads. |
If open evidence is incomplete, this page keeps the gap visible and provides a minimum next step.
| Topic | Current Status | Why Uncertain | Minimum Next Step |
|---|---|---|---|
| Cross-brand normalized price at strict 2:1 and same duty profile | To be confirmed / limited open evidence (checked 2026-05-26) | Public catalog and marketing pages typically omit transaction-normalized pricing under one shared duty template. | Collect at least 3 RFQs with identical duty, backlash, thermal, and compliance assumptions. |
| Cross-brand lifecycle comparison under one cycle profile | To be confirmed / limited open evidence (checked 2026-05-26) | Life claims are often published with different test assumptions and application contexts. | Request life-rating assumptions, safety factors, and derating logic from each supplier. |
| Exact efficiency parity at partial load around 2:1 across suppliers | Partially known / not fully normalized (checked 2026-05-26) | Public references provide directional efficiency and ratio statements, but not one shared partial-load protocol across brands. | Run one shared efficiency test protocol during technical bid clarification. |
| Scenario | Premise | Process | Outcome |
|---|---|---|---|
| High-cycle conveyor retrofit with strict 2:1 intent | Input 1450 rpm, 80 Nm, moderate load, 16 h/day, starts 20/h, backlash target 12 arcmin. | Tool remains in helical-inline corridor, computes rated torque checkpoint, and returns go with engineering handoff. | Team proceeds to shortlist and avoids ratio/topology drift before RFQ release. |
| Integrator forces planetary branch at 2:1 | Commercial request asks for planetary label while ratio remains strict 2:1. | Tool flags branch mismatch using stage-range evidence and sets review/no-go state. | Project avoids false-equivalent comparison and resets to feasible topology discussion. |
| Hot environment plus high start frequency | Ambient near 55 degC and starts near upper boundary for frequent duty. | Service-factor uplift pushes result to review, requiring thermal and lubricant validation. | Risk is surfaced early and budget is redirected to reliability checks before commitment. |
What does 2:1 mean for speed and torque in this page?
At first order, output speed is input speed divided by two. Output torque increases inversely with speed and is then reduced by efficiency effects.
Why does the tool still show review for a valid 2:1 input?
Because torque envelope, backlash target, duty, starts, or ambient can trigger risk even when the ratio itself is valid.
Is this a complete replacement for detailed gear design?
No. It is a gate-0 screening tool designed to prevent early architecture mistakes, not a final release calculation.
Can I use this page for 5:1 or 10:1 selection?
Only as directional context. The page is calibrated around strict 2:1 intent and will boundary-flag larger ratio drift.
Does "2:1" always mean an exact 2.000 catalog ratio?
Not always. Catalogs often provide discrete points around 2:1 (for example 1.92 or 2.04), so exact ratio should be confirmed at the model-size level.
Why does auto mode prefer inline helical for 2:1?
Public single-stage windows for inline helical explicitly include 2:1, while planetary single-stage references often start around 3:1.
Can a 2:1 project still use planetary?
It can, but usually through a different stage strategy or architecture. This page flags direct single-stage mismatch risk.
How should I interpret backlash values here?
As screening classes, not guarantees. Final backlash depends on grade, preload, assembly, and test protocol alignment.
Why include lubrication mode in quick screening?
Because lubrication choice affects efficiency and thermal behavior enough to change go/review outcomes near boundaries.
What should I send suppliers after using this tool?
Share ratio, torque profile, speed, starts/hour, duty, ambient, backlash target, mounting envelope, and acceptance criteria in one template.
How many RFQs should I collect for reliable comparison?
A practical minimum is three quotes under one normalized duty and tolerance template.
What is the fastest way to reduce rework risk?
Resolve topology fit and duty assumptions before discussing commercial options and lead times.
When should I escalate from quick tool to engineering review?
Escalate on any review/no-go result, ratio drift, thermal boundary, or precision requirement tighter than baseline classes.
Source-backed fields include checkpoint dates. Heuristic sections are explicitly labeled in boundary and uncertainty tables.
| Source | Checkpoint Date | Data Used | Link |
|---|---|---|---|
| SEW gear units catalog (R/RX, edition 2016) | Snapshot checked: 2026-05-26 | RX57/RX67/RX77 discrete ratios around 2:1 (for example 1.92, 2.04, 2.13) and broader 1.30 to 8.65 coverage. | https://download.sew-eurodrive.com/download/pdf/17103975_G08.pdf |
| NORD NORDBLOC.1 single-stage helical catalog (DS1013, 12/2019) | Snapshot checked: 2026-05-26 | Lists one-stage ratio extremes (1.07 to 13.10), ratio/torque context, and speed-torque inverse note. | https://www-westus-01.nord.com/media/documents/bw/ds1013__6014502_1219_screen.pdf |
| NORD single-stage news release (2019-08-05) | Snapshot checked: 2026-05-26 | Public range signal for one-stage variants (1.41 to 8.09) with expansion context. | https://www.nord.com/us/company/current-events/news-archives/articles/news_134336.jsp |
| Neugart multi-stage gearbox wiki | Snapshot checked: 2026-05-26 | Single-stage planetary range around 3 to 10 and two-stage range around 9 to 100; notes efficiency reduction with added stages. | https://www.neugart.com/en-us/wiki/multi-stage-gearbox |
| ISO 6336-1:2019 | Snapshot checked: 2026-05-26 | Scope and exclusions for spur/helical load-capacity method applicability. | https://www.iso.org/standard/63819.html |
| ISO/TR 14179-1:2001 | Snapshot checked: 2026-05-26 | Thermal rating baseline assumptions include 25 degC ambient and 95 degC oil sump, with correction factors for other conditions. | https://www.iso.org/cms/%20render/live/en/sites/isoorg/contents/data/standard/03/46/34636.html?browse=tc |
| NEMA Motor Standards vs IEC Motor Standards | Snapshot checked: 2026-05-26 | Shows IEC duty types S1-S10 and notes that IEC does not recognize service factor as NEMA does. | https://www.nema.org/docs/default-source/motor-and-generator-guides-and-resources-library/8-nema-motor-standards-vs-iec-motor-standards-v2.pdf?sfvrsn=bd2a240_2 |
| JTEKT/Koyo bearing life explanation (ISO 281 context) | Snapshot checked: 2026-05-26 | Defines L10 as 90% reliability life and provides reliability factor a1 values including 0.25 at 99% reliability. | https://koyo.jtekt.co.jp/en/support/bearing-knowledge/5-2000.html |
| NORD bevel gear unit technical article | Snapshot checked: 2026-05-26 | Bevel stage comparator reference including 1:1 to 1:10 and 96-98% efficiency context. | https://www.nord.com/us/company/current-events/blog/bevel-gear-units.jsp |
| NORD angled gear units (bevel vs worm) article | Snapshot checked: 2026-05-26 | Describes worm-ratio and self-locking context and notes lower efficiency tendency at higher worm ratios. | https://www.nord.com/en/nord-group/current-events/blog/angled-gear-units-bevel-gear-or-worm.jsp |
| SEW gear unit overview | Snapshot checked: 2026-05-26 | Inline/parallel-shaft vs right-angle branch positioning in product architecture. | https://www.seweurodrive.com/products/gear-units/gear-units.html |
Continue with adjacent pages after finishing the 2:1 inline screening workflow.
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