Global Gear Couplings

Standards & Specifications

AGMA 9002 vs DIN 5480 vs IS 12405: which standard governs your coupling?

Of the documents compared here, only IS 12405 governs a whole gear coupling. AGMA 9002 governs the bore and keyway, DIN 5480 the spline and ISO 6194 the seal. Treating them as a three-way choice is how a drawing ends up citing all of them and satisfying none cleanly.

Author
Priyansh Thummar, Editor
Dates
Published · Last updated
Reading time
3 minutes

1. Scope of each document

AGMA 9002 is a bore and keyway practice: inch-series bore tolerances, fits and keyway dimensions for flexible coupling hubs. It governs the shaft-hub interface and nothing else — not the rating, the tooth form, the material or the balance.

DIN 5480 and ISO 6194-1 are component standards, not coupling standards. DIN 5480 specifies involute splined connections, an alternative to a keyed bore at the shaft-hub interface. ISO 6194-1, with DIN 3760 as the aligned German document, sets the dimensions and tolerances of rotary shaft lip seals. Neither addresses torque rating, balance, or the coupling as an assembly.

IS 12405 is the Bureau of Indian Standards specification for gear type flexible couplings. It addresses the coupling itself: its Type A and Type B designs, tabulated ratings and dimensions, hub and sleeve material, sealing, lubrication and marking.

1.1 Shaft-hub interface

Inch and metric practice genuinely differ here. AGMA 9002 works in inch-series tolerances and keyway dimensions. Metric bores are specified with ISO 286 fits — commonly an H7 bore — and metric parallel keys to standards such as IS 2048 or DIN 6885: a different tolerance grammar, not a stricter or looser version of the same one. DIN 5480 offers a third option at this interface: a splined connection engaging many teeth around the bore, generally specified where torque density in a limited bore diameter matters more than ease of disassembly.

1.2 Sealing practice

IS 12405 addresses sealing rather than leaving it open: its Type A design uses integral O-rings and its Type B design a detachable seal, with felt or lip seals as options agreed between supplier and user. AGMA 9002 says nothing about seals. Where a lip seal is specified, ISO 6194-1 and DIN 3760 are the general-engineering references for its dimensions. DIN 3761, which still appears on some drawings, is the series for seals in automobiles.

2. Clause comparison

Table 1 — Scope comparison: AGMA 9002-B04, DIN 5480 / ISO 6194-1, and IS 12405:1988
AspectAGMA 9002DIN 5480 / ISO 6194-1IS 12405
Primary subjectBore & keyway dimensions, inch seriesSplined interface (5480) / lip seal (6194-1)Gear type flexible couplings
Governs whole coupling?No — shaft interface onlyNo — component onlyYes
Shaft-hub interfaceKeyed, inch seriesSplined (5480), where specifiedMetric (dimensions in mm)
SealingNot addressedLip seal dimensions (6194-1)Type A O-rings; Type B detachable; alternatives by agreement
Rating / service factorNot addressedNot addressedRatings tabulated by coupling number; service factor table from the manufacturer
Typical useInch-series catalogue couplingsCited alongside any whole-coupling documentGear couplings to Indian specifications
DIN 5480 and ISO 6194-1 are cited alongside a whole-coupling standard, not instead of one. Always verify against the revision named in the purchase order.

3. Rating and service factor

None of these documents supplies a service factor. Service factors for flexible couplings come from AGMA 922-A96 or from the manufacturer, and IS 12405 requires the manufacturer to provide its service factor table. IS 12405 does tabulate ratings, but for its own coupling numbers — a manufacturer’s own size series may not follow them. Citing DIN 5480 or ISO 6194-1 contributes nothing to the torque rating.

3.1 Selection torque

Tsel = (9550 · Prated / n) × Kf × Kt

Selection torque in N·m, where Prated is driver rated power in kW, n is speed in rev/min, Kf is the service factor for the load class — from AGMA 922-A96 or the manufacturer’s table — and Kt is any temperature derating the manufacturer applies. Neither AGMA 9002 nor the DIN and ISO component standards supply a term in this formula.

3.2 Tooth geometry under misalignment

Tooth geometry is common to any gear coupling regardless of which standards are cited, because it is a property of the crowned-tooth mechanism itself. Crowned external teeth accommodate angular misalignment by rolling the contact point along the crown as the shaft rotates. Sliding velocity at the tooth flank, not transmitted torque, usually sets the practical misalignment limit: above roughly 1.5° per mesh the lubricant film becomes difficult to maintain and wear turns progressive rather than run-in.

Cross-section diagram of a crowned external gear tooth meshing with a straight internal sleeve tooth, with the angular misalignment between hub and sleeve centrelines marked by dimension arcs and a magnified detail of the contact point
Figure 1. Contact migration across a crowned tooth flank at angular misalignment, independent of which standards govern the coupling’s bore, seal or interface.

4. Deciding which applies

Deciding is three separate questions, not one three-way choice.

Table 2 — Three independent decisions, not one
QuestionOptionsDecided by
Which document governs the coupling and its rating?IS 12405 / ISO 14691 or ISO 10441 / named purchaser spec and manufacturer's catalogueMarket, service class and the purchaser's specification
How is the shaft-hub interface specified?Inch keyed bore (AGMA 9002) / metric fit and key (ISO 286, IS 2048 or DIN 6885) / spline (DIN 5480)Shaft standard, torque density and disassembly frequency
What seal is specified?O-ring / lip seal to ISO 6194-1 or DIN 3760 / manufacturer's standard practiceLubrication method and contamination risk
A drawing can correctly cite a whole-coupling standard, a bore standard, DIN 5480 and ISO 6194-1 together — they answer different questions and do not contradict one another.

Frequently asked

Is AGMA 9002, DIN 5480 or IS 12405 the right standard for my coupling?
The question contains a false premise: they are not versions of the same document. AGMA 9002 governs the bore and keyway at the shaft-hub interface. IS 12405 governs a gear coupling as a product. DIN 5480 governs an involute spline and ISO 6194-1 a lip seal — components a coupling may contain. A drawing can cite a whole-coupling standard, a bore standard and the component standards together without contradiction, because they answer different questions.
Can a coupling specified to AGMA 9002 be supplied against IS 12405 instead?
Not by substitution. AGMA 9002 works in inch-series bores and keyways; IS 12405 is a metric standard, and metric bores are specified with ISO 286 fits and metric parallel keys. Converting between them by rounding a dimension is a common way a bore mismatch reaches site. If the governing document changes, re-specify the bore and keyway in the new system rather than translating them.
Which document should a purchase order name?
The one that governs the thing being bought. Name the whole-coupling standard the coupling is to be manufactured to, then name the interface standard the bore and keyway are to be machined to, and name the seal or spline standard only if you are specifying that component. Citing them all as though they were alternatives is what produces a drawing that satisfies none of them cleanly.
Do any of these standards fix the coupling's torque rating?
Only IS 12405, and only for its own coupling numbers: it tabulates ratings and dimensions for its Type A and Type B designs and requires the manufacturer to supply the service factor table. AGMA 9002, DIN 5480 and ISO 6194-1 say nothing about rating. For a manufacturer's own range the rating comes from the manufacturer, and service factors from AGMA 922-A96 or the manufacturer's table. A specification that names a standard but no required torque, speed and misalignment has not specified a coupling.

References

  1. AGMA 9002-B04, Bores and Keyways for Flexible Couplings (Inch Series). American Gear Manufacturers Association.
  2. AGMA 922-A96, Load Classification and Service Factors for Flexible Couplings. American Gear Manufacturers Association.
  3. DIN 5480, Splined connections with involute splines based on reference diameters. Deutsches Institut für Normung.
  4. ISO 6194-1, Rotary shaft lip-type seals incorporating elastomeric sealing elements — Part 1: Nominal dimensions and tolerances. International Organization for Standardization.
  5. IS 12405:1988 (reaffirmed 2006), Specification for gear type flexible couplings. Bureau of Indian Standards.
  6. AGMA 9008-B00, Flexible Couplings — Gear Type — Flange Dimensions, Inch Series.
  7. Correction, 15 September 2026: earlier editions of this article named IS 3238 as the Indian gear coupling standard and DIN 3761 as the shaft seal standard, and treated AGMA 9002 as a whole-coupling standard carrying a service factor. We could find no Bureau of Indian Standards record of IS 3238; the standard is IS 12405:1988. DIN 3761 is the lip seal series for automobiles; general engineering uses ISO 6194-1 and DIN 3760. AGMA 9002 governs bores and keyways only, and service factors come from AGMA 922-A96 or the manufacturer. The comparison has been rewritten accordingly.

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