Custom Spiral Bevel Gear RFQ Checklist: Drawings, Ratings, Tolerances and Samples

The largest delays in custom gear procurement frequently occur before the first chip is cut. Buyers and suppliers exchange emails about missing tooth data, unidentified material standards, uncertain assembly positions and unclear acceptance criteria. A structured request for quotation (RFQ) avoids many of these loops.

This guide explains what to include, what can be estimated initially and which information must be finalized before manufacturing.

State whether the request is for (a) a new gearbox design, (b) a replacement crown wheel and pinion, (c) one member of an existing pair or (d) a prototype for testing. These scenarios need different evidence. A new design can be optimized. A replacement must respect the existing gearbox's interfaces and often requires a close match to original geometry.

Include equipment model, OEM part number if available, photos of both sides of the gear, and details of why replacement is needed. For a failed gear, photographs of damaged teeth before cleaning can be diagnostically useful.

A dimensioned 2D drawing plus 3D CAD geometry is ideal, but tooth-surface data may require more than a generic STEP solid. Specify the controlling design system, datum scheme and drawing revision. Important fields include:

Do not infer spiral hand from a photograph if the image orientation is ambiguous. Ask the manufacturer to confirm it against the drawing.

For new designs, supply power, speed, torque, load spectrum, reversing frequency, lubrication and service target. Where the output torque is not known, a simple preliminary estimate is:

For example, a 15 kW drive at 900 rpm has nominal input torque of approximately 159 N·m. A 3:1 reduction would ideally yield 300 rpm and approximately 477 N·m at the output before accounting for losses. This is an illustrative power/torque conversion, not a bevel gear strength calculation. Startup shock, overload factors and duty cycles can dominate design requirements.

If the customer cannot supply torque, request motor data, gearbox drawings, duty description and any observed overload history; do not invent load ratings to complete the form.

A drawing that says “alloy steel, HRC 60" may still be incomplete. Clarify the material designation/standard, surface hardness range, heat-treatment type, effective case depth if relevant, core properties where required and allowable distortion/finishing route.

A combination that works for a small case-carburized pinion may not be appropriate for a very large wheel. For replacement projects, seek historical material certificates or conduct suitable testing when the composition is unknown.

Mark critical bearing journals, locating faces, bore fit, bolt pattern and related datum features explicitly. “High precision" is not an acceptance criterion. Define the agreed geometry and inspection standard, tolerance class or individually measurable limits.

Ask what measurement data the supplier can furnish at the component level and what will be evaluated as a pair. A rolling test may provide contact evidence, while dimensional/geometry inspection confirms other critical features. They are complementary.

Quantity alone does not define the order. State whether the quotation includes tooling or first-article inspection; whether a gear set is supplied matched and labeled; which documents are mandatory; packaging requirements; delivery terms and requested shipment date. Also state whether the supplier can propose alternatives or must quote to-print without deviations.

Useful RFQ email fields: project/equipment; use case; drawing revision; wheel teeth/pinion teeth; nominal speed; torque or power; material; heat treatment; accuracy; quantity; acceptance records; destination; needed date; contact person.

A reverse-engineering enquiry should ideally include the failed component, undamaged mating component, mounting hardware and any housing dimensions. Measurements may recover physical dimensions, but they do not automatically recover the original design intent, heat-treatment history or loaded contact behavior.

Ruida describes gear surveying and mapping as part of its technical services. Discuss the feasibility of reconstructing the pair, the limitations of worn samples and whether a replacement should be matched to an existing pinion.

• Are the quotation and approved drawings on the same revision?
• Is the gear-pair configuration unambiguous?
• Are material and heat-treatment requirements measurable?
• Are inspection and documentation deliverables defined?
• Are exclusions and permitted deviations recorded?

A technically complete RFQ will not eliminate all risk. It does, however, provide the foundation for a traceable quotation and prevent many avoidable disputes.

An initial feasibility RFQ can be sent with incomplete information when it clearly labels unknowns and seeks guidance. A firm technical quotation should have an agreed design basis and defined commercial scope. A production-release package should contain the final drawing revision, approved deviations and inspection plan. Confusing these levels is a frequent source of disputes: a budget price based on photographs should not be treated as approval to cut a custom tooth form.

Imagine a replacement wheel with 64 teeth and a matching 16-tooth pinion. The ratio is 4:1, but the tooth counts alone cannot establish whether a replacement will fit. The buyer must also provide the mounting geometry, face width, bore/shaft interfaces, tooth system and the mating gear condition. If the original drawing is missing, measurements of the existing pair and housing may be needed, with feasibility reviewed before committing to a final price.

Optional attachments that help: a video showing the original gear pair's assembly orientation, annotated dimensions of the housing, photos of identification stamps and the machine's maintenance history. Avoid sharing only a file named 'gear_final.dwg' without a revision record.

Request a quotation: Send complete drawings or samples to Ruida, together with the application conditions and acceptance requirements. Engineering will need to confirm manufacturability before an order is finalized.

Technical editorial review required before publication.