Tapered Roller Bearings · ISO 355 / DIN ISO 355 / GB/T 297

DIN 720 31300 Series Steep Angle Tapered Roller Bearings Specification

What DIN 720 fixes, what it deliberately leaves to another document, its equivalents, and the dimensional table.

DIN 720 is the German standard for metric tapered roller bearings, covering the same 30000-series envelope as ISO 355: bore d, outside diameter D, the assembled width T and the individual cone and cup widths B and C.

Standard: DIN 720
Covers: Tapered roller bearings
Does not fix: It does not decide the mounted setting. A tapered roller bearing is adjusted against its opposing bearing to an endplay or a preload on assembly, and that figure comes from the application, not from a dimensional standard.
Equivalents: ISO 355 and its identical adoption DIN ISO 355 are the current international references; GB/T 297 is the Chinese equivalent.
Product: 31300 Series Steep Angle Tapered Roller Bearings
Governing standards: ISO 355 / DIN ISO 355 / GB/T 297

Equivalence between the ISO, DIN and GB/T documents is dimensional: a bearing made to either mounts in the same seat. It is not an equivalence of load rating, tolerance class or internal clearance, each of which is fixed by a separate standard and declared separately.

DIN 720 covers tapered roller bearings. This page sets out what the standard fixes for 31300 series steep angle tapered roller bearings, what it deliberately leaves to other documents, its national equivalents, and the dimensional table supplied against it.

DIN 720 — Scope

What DIN 720 Does Not Fix

It does not decide the mounted setting. A tapered roller bearing is adjusted against its opposing bearing to an endplay or a preload on assembly, and that figure comes from the application, not from a dimensional standard.

This division of labour is the thing to carry away from any bearing standard. A boundary dimension standard makes bearings interchangeable; it does not make them equivalent. Two bearings of the same designation from different makers mount in the same seat and are not required to have the same load rating, the same internal design, the same cage or the same speed limit.

Dimensions Supplied to DIN 720

Designation	Bore d (mm)	Outer diameter D (mm)	Assembled width T (mm)	Width B (mm)	Width C (mm)	Contact angle a (deg)	Chamfer r min (mm)
31305	25	62	18.25	17	13	28.81	1.5
31306	30	72	20.75	19	14	28.81	1.5
31307	35	80	22.75	21	15	28.81	2
31308	40	90	25.25	23	17	28.81	2
31309	45	100	27.25	25	18	28.81	2
31310	50	110	29.25	27	19	28.81	2.5
31311	55	120	31.5	29	21	28.81	2.5
31312	60	130	33.5	31	22	28.81	3
31313	65	140	36	33	23	28.81	3
31314	70	150	38	35	25	28.81	3
31315	75	160	40	37	26	28.81	3
31316	80	170	42.5	39	27	28.81	3
31317	85	180	44.5	41	28	28.81	4
31318	90	190	46.5	43	30	28.81	4
31319	95	200	49.5	45	32	28.81	4

National Equivalents

ISO 355 and its identical adoption DIN ISO 355 are the current international references; GB/T 297 is the Chinese equivalent.

This product is supplied against ISO 355 / DIN ISO 355 / GB/T 297, which names the documents it is made to.

When to Cite DIN 720

DIN 720 remains in daily use in European mechanical engineering and on legacy drawings, and it is what many German-language datasheets cite. For a new design the ISO document is the better contractual reference, with the DIN number carried alongside it so that the drawing reads the same to everyone.

Other ways to specify the 31300 Series Steep Angle Tapered Roller Bearings

The same part is also governed by ISO 355 and GB/T 297, and where two standards cover one dimension they agree — the numbers are the same, the document is not.

The same bearing can also be sized from the shaft on the 40 mm bore and 45 mm bore pages and compared by material on the Polyamide Cage and Machined Brass Cage pages.

Every size in the range sits in one table on the full 31300 series steep angle tapered roller bearings table. For the duty rather than the dimension, see where 31300 series steep angle tapered roller bearings are fitted.

Technical Drawing

Customize the parameters below — every spec field is editable, and the drawing redraws to match the values you choose. Changing the designation snaps the other fields to that size's standard values; you can then override any individual value.

Sends the selected values to the quote form below.

Our facility

Held in production, not just on paper

The tolerances above are decided on the grinding and superfinishing lines in our own plant, and gauged on every ring rather than on a sample. A dimension is only worth quoting if it survives the process that produces it.

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The form below follows the current technical drawing configuration. Change the drawing values above and the request details update automatically.

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Specification

Item / category Standard Size(s) / designation Material / seals Quantity

Business Information

Company * Contact Name * Email * Phone (with country code) Country / Region

Notes

Dimensions & Specifications (ISO 355 / DIN ISO 355 / GB/T 297)

Designation	Bore d (mm)	Outer diameter D (mm)	Assembled width T (mm)	Width B (mm)	Width C (mm)	Contact angle a (deg)	Chamfer r min (mm)
31305	25	62	18.25	17	13	28.81	1.5
31306	30	72	20.75	19	14	28.81	1.5
31307	35	80	22.75	21	15	28.81	2
31308	40	90	25.25	23	17	28.81	2
31309	45	100	27.25	25	18	28.81	2
31310	50	110	29.25	27	19	28.81	2.5
31311	55	120	31.5	29	21	28.81	2.5
31312	60	130	33.5	31	22	28.81	3
31313	65	140	36	33	23	28.81	3
31314	70	150	38	35	25	28.81	3
31315	75	160	40	37	26	28.81	3
31316	80	170	42.5	39	27	28.81	3
31317	85	180	44.5	41	28	28.81	4
31318	90	190	46.5	43	30	28.81	4
31319	95	200	49.5	45	32	28.81	4

Video: DIN 720 31300 Series Steep Angle Tapered Roller Bearings Specification

Third-party video, selected automatically for this topic. It is not produced by Bushing Bearings and is not a specification source — use the tables on this page for dimensional data.

Frequently Asked Questions

Does DIN 720 mean two bearings are interchangeable?

Dimensionally, yes — that is what a boundary dimension standard is for, and a bearing of the same designation from any maker mounts in the same shaft and housing seat. Functionally, not necessarily: the load rating, the internal design, the cage, the clearance group and the speed limit are decided by the manufacturer and by other standards, and two bearings with the same number are not required to match on any of them.

Does DIN 720 fix the load rating?

No. DIN 720 does not set load ratings. Basic dynamic load ratings are calculated to the method of ISO 281 and are declared by the manufacturer; the static rating follows ISO 76.

Which edition of DIN 720 does this table follow?

The table reproduces the dimensions we supply 31300 series steep angle tapered roller bearings to. We do not publish an edition year against it, so where the edition is contractually significant, cite the edition you require on the enquiry and we will confirm it against the table before quoting.

Can I cite the GB/T number instead of the ISO one?

For the boundary dimensions, yes — the GB/T standards restate the ISO dimension plan and a part made to either mounts in the same seat. The safest drawing note gives both, because it stays legible if the supply moves between a Chinese, a European and an international manufacturer.

How do I request a quotation?

Use the technical drawing on this page to pick the exact configuration, then submit it with the quote form. We respond within one business day.

DIN 720 — Scope

What DIN 720 Does Not Fix

Dimensions Supplied to DIN 720

National Equivalents

When to Cite DIN 720

Other ways to specify the 31300 Series Steep Angle Tapered Roller Bearings

Technical Drawing

Held in production, not just on paper

Request a Quote

Request a Quotation

Dimensions & Specifications (ISO 355 / DIN ISO 355 / GB/T 297)

Video: DIN 720 31300 Series Steep Angle Tapered Roller Bearings Specification

Frequently Asked Questions

Related Pages

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