Introduction: 10 RFQ inputs and 4 weighted dimensions help OEM buyers shorten 2 quotation cycles and avoid costly interface errors.
Why an Incomplete RFQ Costs More Than a Slow One
An RFQ that arrives quickly but omits torque, speed, shaft load, or mounting orientation rarely produces a usable quotation. The supplier must ask follow-up questions, the buyer must revisit the machine design, and the apparent time saving is transferred to engineering and procurement. SLTM's KC series helical-bevel geared motor shows why a technical inquiry should describe the complete interface, not only a model preference.
A complete RFQ also improves comparison. When every supplier receives the same duty data and document requirements, differences in frame size, ratio, motor selection, and commercial scope become visible. Without that common basis, a low price may simply reflect a lighter assumption or an excluded accessory.
The Hidden Cost of Missing Data
Missing data creates technical and commercial risk. An undefined service factor can lead to a frame that is too small for shock. An unspecified shaft load can invalidate bearing life. An ambiguous mounting drawing can change the housing, reaction points, and seal orientation. These issues usually appear after drawings are approved, when schedule pressure makes every change expensive.
The risk is not limited to the gearbox. A late motor-voltage change may alter the starter, cable, enclosure, and spare strategy. A missed washdown requirement may change coating and sealing across the whole machine. A clear RFQ prevents those interface decisions from being made by assumption.
What a Complete Inquiry Changes
A complete inquiry lets the supplier return a model with a visible basis: torque, ratio, motor power, mounting, documents, and commercial boundaries. It also gives the buyer a checklist for reviewing the answer. The goal is not a longer document. The goal is fewer unresolved variables at the point of order.
The Ten Technical Inputs at a Glance
The ten inputs below cover the mechanical, electrical, environmental, and documentary interfaces that commonly determine whether an OEM gearmotor can be installed and accepted without rework.
- Duty profile and load torque at the output shaft.
- Required output speed and acceptable operating range.
- Service factor, shock level, and starts per hour.
- Motor power, voltage, frequency, and control method.
- Shaft, flange, mounting, and envelope drawings.
- Ambient temperature, dust, moisture, and washdown conditions.
- Annual operating hours and load spectrum.
- Certification, traceability, and inspection requirements.
- Test records and agreed acceptance criteria.
- Lead time, spare parts, warranty, and delivery constraints.
| Input | What to provide | Why the supplier needs it | Risk if missing |
|---|---|---|---|
| Duty profile and torque | Continuous, peak, and starting torque at the output shaft | Defines thermal and mechanical load | Wrong frame or coupling |
| Output speed | Normal rpm plus operating range | Fixes motor speed and ratio | Process speed mismatch |
| Service factor | Factor, shock level, and starts per hour | Adds the agreed severity allowance | Undersized gearbox |
| Motor and control | Power, voltage, frequency, enclosure, and starting method | Matches electrical and control interfaces | Starter and protection errors |
| Shaft and mounting | Dimensioned shaft, flange, orientation, and envelope drawing | Confirms fit, reaction points, and service access | Rework at installation |
| Environment | Temperature, dust, moisture, chemicals, and washdown | Guides sealing, coating, and lubrication | Premature leakage or corrosion |
| Duty cycle | Annual hours, load spectrum, reversing, and idle time | Supports thermal-life assessment | Poor lifecycle estimate |
| Documentation | Certificates, traceability, standards, and inspection scope | Defines evidence for market and project acceptance | Rejected shipment or audit gap |
| Acceptance tests | Tests, limits, instruments, records, and witness points | Makes release criteria verifiable | Ambiguous acceptance dispute |
| Commercial constraints | Lead time, spares, warranty, packaging, and delivery basis | Aligns technical scope with project schedule | Incomparable quotations or delay |
Inputs One to Three: Torque, Speed, and Service Factor
Duty Profile and Load Torque
The RFQ should distinguish continuous torque, peak torque, and starting torque at the driven shaft. Each value needs a duration and the condition that produces it. Jam torque, breakaway torque, and the torque limit of any mechanical protection should be included because they influence frame and coupling choice.
The source of the load estimate matters. A calculated conveyor pull, a torque trace, a motor-current record, and a machine-builder assumption have different confidence levels. Stating the source helps the supplier test whether the proposed frame has enough thermal and mechanical margin.
Output Speed and Ratio
Output speed should be expressed in rpm at the driven shaft, with the acceptable adjustment range and the normal set point. If a variable-frequency drive will be used, the RFQ should state the intended motor-speed range and any minimum-speed requirement because lubrication and cooling can change at low speed.
The supplier can then check the ratio against the selected motor and gearbox frame. A ratio that is arithmetically possible may still fall outside a model table or require a different number of stages. That trade-off should appear in the proposal.
Service Factor and Starts per Hour
Service factor, shock character, and starts per hour should be stated together. A high-inertia machine that starts twice per hour may be less demanding than a lightly loaded machine that reverses every minute. The worst normal hour is more useful than an average value that hides peak thermal load.
The RFQ should also identify the starting method, acceleration time, and any controlled-ramp function. A direct-online start, soft starter, and variable-frequency drive create different electrical and mechanical conditions even when the steady-state load is identical.
Worked Example of a Shock-Load Adjustment
For illustration, assume a machine requires 2,000 Nm continuous output torque and the agreed service factor is 1.4. The adjusted selection torque is 2,800 Nm. A candidate frame below that value is excluded, even if its motor-power range appears compatible. The next frame must then pass shaft-load and thermal checks.
This example is intentionally simple. Its value is the visible record: base torque, factor, adjusted torque, and frame evidence. If the peak or starting requirement is higher than the adjusted continuous value, the governing number must be replaced before the frame is confirmed.
Inputs Four to Six: Motor, Mounting, and Environment
Motor Power, Voltage, and Control Method
Motor data should include voltage, frequency, phase, enclosure, insulation, duty, and starting method. The destination market may require a specific efficiency class, marking, or documentation package. The control method should be named because the gearmotor proposal may need a different brake, encoder, terminal box, or thermal protection.
Motor power must be checked against the gearbox duty, not chosen independently. A motor large enough to accelerate the load may overload the gear unit during a jam unless torque protection is defined.
Shaft, Flange, and Mounting Drawings
Attach a drawing that shows shaft diameter, length, key, shoulder position, flange pattern, pilot diameter, hole threads, mounting orientation, and available envelope. Mark the driven member, belt or chain direction, and the point where external load acts on the output shaft.
A dimensioned drawing reduces ambiguity more effectively than a written description such as foot mounted or vertical. It also lets the supplier check whether the motor can be removed, the oil level can be serviced, and the torque arm can react against a stiff part of the machine.
Ambient, Dust, Moisture, and Washdown
Describe ambient temperature range, humidity, dust concentration, chemical exposure, outdoor exposure, washdown pressure, and cleaning chemicals. These conditions influence enclosure, sealing, breather location, coating, and lubrication.
The RFQ should state what happens if sealing fails. In a dry packaging cell the consequence may be a cleaning delay. In sludge dewatering or a coastal plant, leakage can create corrosion, slip risk, and environmental findings.
Inputs Seven and Eight: Duty Cycle and Documentation
Annual Hours and Load Spectrum
Annual hours, shift pattern, load spectrum, reversing frequency, and idle time allow the supplier to assess thermal life rather than a single operating point. A drive that operates at moderate load for 6,000 hours per year may need a different review from one that sees high load for 500 hours.
The load spectrum can be a simple table of time at low, normal, and high load. It does not need to be perfect, but its assumptions should be visible. That record also supports later maintenance planning and spare-parts stocking.
Certification and Inspection Requirements
State whether the project requires CE marking, ISO quality documentation, material certificates, traceability, non-destructive testing, or third-party inspection. Do not assume that every supplier interprets a general quality claim in the same way.
For exported machinery, the buyer should identify the applicable directives and the party responsible for the declaration. A certificate list is evidence of a management system or product approval only when its scope and validity are checked against the exact item.
Inputs Nine and Ten: Acceptance Criteria and Commercial Constraints
Test Records and Acceptance Tests
Define the tests required before shipment. Typical items may include no-load running, direction check, vibration or noise screening, leak inspection, brake function, insulation resistance, and dimensional verification. The RFQ should specify which records must be delivered with the unit.
Acceptance criteria should be measurable. A statement such as smooth operation is difficult to verify without a method and limit. The buyer and supplier should agree on the test condition, instrument, sample, and record format.
Lead Time, Spare Parts, and Warranty Terms
Commercial terms belong in the technical comparison because they affect lifecycle risk. Ask for lead time after drawing approval, packaging details, spare-part recommendations, warranty start date, and the process for a field failure. Clarify whether replacement parts are standard or project-specific.
A quotation that excludes drawings, test records, or commissioning support may appear cheaper while creating later cost. The buyer should compare the complete scope and state which commercial assumptions are fixed and which remain open.
A Weighted Completeness Matrix for RFQ Review
Criteria and Weights
The completeness matrix tests whether an inquiry gives the supplier enough evidence to quote and whether the reply closes each interface. It uses four dimensions and a 1-to-4 evidence score. The weights express the relative cost of an unresolved gap in each category.
| Dimension | Weight | Evidence expected | Decision rule |
|---|---|---|---|
| Mechanical duty definition | 35% | Torque, speed, service factor, starts, duty profile | No approved quotation without all governing values |
| Physical and environmental interface | 25% | Drawings, loads, mounting, temperature, sealing | Resolve before drawing approval |
| Electrical and control definition | 25% | Motor data, control method, protection, destination requirements | Confirm with automation and electrical teams |
| Documentation and commercial closure | 15% | Tests, certificates, lead time, spares, warranty | Attach to purchase specification |
Reading the Result
A dimension scores 4 when complete, consistent evidence is available; 3 when one minor clarification remains; 2 when multiple material items are open; and 1 when the requirement is undefined. Multiply each score by its weight to produce a relative completeness value.
The matrix should be applied twice: once to the outgoing RFQ and once to the supplier reply. A strong inquiry paired with a vague reply is still incomplete. The closure target is not a perfect score for its own sake, but no unresolved item that can change the model, interface, or acceptance result.
Common Gaps in OEM Gearmotor Inquiries
The same gaps recur across otherwise professional projects. They are easy to remove when the RFQ is reviewed as an engineering document rather than a purchasing form.
- A power value without output speed or torque.
- A required ratio without the actual motor speed at load.
- A service factor without the shock or starting condition that justifies it.
- A shaft drawing without radial-load magnitude, direction, or distance.
- A mounting orientation without a service-clearance envelope.
- An environmental note such as wet area without temperature, chemicals, or washdown details.
- A certificate request without model scope, issuing body, or acceptance document.
- A delivery target without drawing approval and inspection milestones.
Application Notes: Where the Ten Inputs Change
Mining and Heavy Conveyors
Heavy conveyors require explicit shock, jam, belt-pull, and restart data. Radial loads and foundation stiffness can decide the frame as much as average torque. The RFQ should identify the torque-limiting method and the inspection records required before dispatch.
Packaging and Light Assembly
Packaging cells often prioritize compact right-angle installation, repeatable stopping, and frequent starts. The RFQ should define acceleration, brake logic, guarding, and the space needed to remove the motor without dismantling the line.
Water Treatment and Sludge Dewatering
Water-treatment drives need a clear description of moisture, washdown, chemical exposure, and maintenance access. Sealing and coating requirements may outrank a small difference in nominal frame weight. Acceptance should include the records needed to confirm protection before installation.
Document Package Checklist
The quotation package should be reviewed as a set. Missing documents create a false sense that the technical scope is closed.
| Document | What it should confirm | Buyer review action |
|---|---|---|
| Duty calculation sheet | Torque, speed, service factor, ratio, and governing case | Recheck units and assumptions |
| General arrangement drawing | Envelope, shaft, flange, mounting, service access | Compare with machine layout |
| Motor and accessory data | Voltage, efficiency, control, brake, protection | Confirm with electrical design |
| Inspection and test plan | Tests, acceptance limits, records, witness points | Approve before production |
| Commercial schedule | Lead time, packaging, spares, warranty, delivery terms | Attach to purchase order |
Frequently Asked Questions
Q1: What is the minimum information for an initial gearmotor RFQ?
A: Provide output torque, output speed, service factor, duty cycle, starts per hour, mounting orientation, motor supply, environment, shaft loads, and required documents.
Q2: Why are ten inputs needed instead of a model number?
A: A model number may describe a family but not the duty. The inputs show whether the frame, ratio, motor, mounting, and documentation fit the machine and destination.
Q3: Should peak torque or continuous torque lead the frame check?
A: Both must be recorded. The governing value depends on the application. Thermal duty and mechanical peak capacity can lead to different frame decisions.
Q4: How complete should the shaft drawing be?
A: It should show dimensions, tolerances, key or spline details, flange pattern, mounting orientation, load direction, load distance, and the available service envelope.
Q5: Can a supplier quote before environmental details are known?
A: A preliminary price may be possible, but the selection is conditional. Sealing, coating, lubrication, and enclosure can change after temperature, chemicals, and washdown are defined.
Q6: What makes a quotation comparable?
A: Comparable quotations use the same duty calculation, scope, documents, tests, accessories, delivery basis, and warranty terms. Technical assumptions should be visible.
C
onclusion
A complete OEM gearmotor RFQ is a risk-control document. It connects machine duty to frame selection, defines the physical and electrical interfaces, and records the evidence required for acceptance. The ten inputs do not remove engineering judgement; they make that judgement visible and repeatable.
Buyers should send the duty data, drawings, environment, and document requirements together, then use the reply to test whether every assumption has been closed. This approach supports faster quotation without sacrificing technical control and gives SLTM's KC series helical-bevel geared motor, or any comparable product, a fair basis for evaluation.
References
Sources
- U.S. Department of Energy, Motor Systems
https://www.energy.gov/cmei/ito/motor-systems
Note: Offers public guidance on motor-system efficiency, load management, and the value of matching equipment to actual service demand.
- European Commission, Electric Motors Product List
https://energy-efficient-products.ec.europa.eu/product-list/electric-motors_en
Note: Provides regulatory and efficiency context for industrial electric motors used with geared units in European and export projects.
Related Examples
- SLTM KC Series Helical-Bevel Geared Motor
https://www.chinagearmotor.com/products/helical-bevel-geared-motor
Note: Presents the KC model range, published torque limits, ratio coverage, mounting forms, and inspection sequence used as the case example.
- SLTM Industrial Drive Applications
https://www.chinagearmotor.com/pages/application
Note: Connects geared-motor designs with conveyors, sludge dewatering, lifting, pumps, and other industrial duty profiles relevant to OEM RFQ preparation.
- SLTM Frequently Asked Questions
https://www.chinagearmotor.com/pages/faq
Note: Adds supplier-side clarification of quotation, delivery, customization, and product-information practices that buyers can test during procurement.
- NORD Helical-Bevel Geared Motors
Note: Provides an additional manufacturer example for comparing right-angle geared-motor architecture and published selection information.
- NORD BLOC1 Bevel Geared Motor
Note: Shows another compact right-angle product family and helps readers benchmark the information a technical product page should expose.
- Bonfiglioli RAN Series Industrial Gearmotors
Note: Adds an industrial right-angle gearmotor example for checking torque, ratio, mounting, and application documentation.
- Bonfiglioli 3-H Series Heavy-Duty Right-Angle Gear Units
Note: Provides a heavy-duty reference point for shaft loads, service conditions, and the documentation expected in demanding applications.
Further Reading
- Right-Sizing Gearmotors for Green Manufacturing
https://www.worldtradhub.com/2026/10/right-sizing-gearmotors-for-greener.html
Note: Explains how oversizing and poor duty matching create hidden energy losses and supports the article argument for evidence-based frame selection.
- KC Helical-Bevel Gearmotor Sizing Hub
https://www.chinagearmotor.com/pages/kc-helical-bevel-gearmotor-sizing-hub
Note: Organizes the eight practical inputs, inline versus right-angle layout decision, KC37 to KC187 range, and mounting choices used in the selection review.
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