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General Components · GB/T 78 / ISO 4027

T 78 Engineered Component Dimensions

T 78 Engineered Component Dimensions reference image

Specification summary of T 78 as applied to engineered component: the dimensions the standard controls, the tolerance and product grades it defines, the full specified size range, and the equivalent DIN/ISO/ASME designations.

T 78 — Scope

T 78 specifies the dimensions and tolerances of engineered component — gb/t 78 / iso 4027 (series 025). Material, property class, surface finish and packaging are governed by separate documents in the same standards family (for example ISO 898-1 for the mechanical property classes of bolts and screws).

Tolerance & Product Grades

T 78, alongside the related GB/T 78 / ISO 4027 entries on this site, specifies product grades (typically A or B for fine work and C for general engineering) and tolerance classes for the controlling dimensions. Choose the grade against the precision your application requires.

Dimensions Specified by T 78

Size designationOuter diameter / width (mm)Length / height (mm)Bore / thread (mm)MaterialReference standard
Size 110206C45 carbon steelGB/T 1804-m
Size 212258C45 carbon steelGB/T 1804-m
Size 3163210C45 carbon steelGB/T 1804-m
Size 4204012C45 carbon steelGB/T 1804-m
Size 5255016C45 carbon steelGB/T 1804-m
Size 6326320C45 carbon steelGB/T 1804-m
Size 7408025C45 carbon steelGB/T 1804-m
Size 85010030C45 carbon steelGB/T 1804-m

Equivalent Standards

Where direct equivalents exist (ISO ↔ DIN, ISO ↔ ASME), they are listed on the parent Engineered Component — GB/T 78 / ISO 4027 (Series 025) page. Always confirm against the dimensions on this page, since some "equivalent" standards differ in tolerances and head geometry.

Companion Standards

T 78 controls only the geometry of engineered component — gb/t 78 / iso 4027 (series 025). The mechanical strength is set by ISO 898-1 (bolts and screws) or ISO 898-2 (nuts); the surface finish is governed by separate finish standards (e.g. ISO 4042 for electroplating). For corrosion testing, the relevant document is ISO 9227 (neutral salt spray).

Technical Drawing

Customize the parameters below — every spec field is editable, and the drawing redraws to match the values you choose. Changing the size will snap 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.

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Specification
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Dimensions & Specifications (GB/T 78 / ISO 4027)

Size designationOuter diameter / width (mm)Length / height (mm)Bore / thread (mm)MaterialReference standard
Size 110206C45 carbon steelGB/T 1804-m
Size 212258C45 carbon steelGB/T 1804-m
Size 3163210C45 carbon steelGB/T 1804-m
Size 4204012C45 carbon steelGB/T 1804-m
Size 5255016C45 carbon steelGB/T 1804-m
Size 6326320C45 carbon steelGB/T 1804-m
Size 7408025C45 carbon steelGB/T 1804-m
Size 85010030C45 carbon steelGB/T 1804-m

Frequently Asked Questions

Can I substitute T 78 for the corresponding DIN standard on a drawing?

On modern drawings the ISO standard is the master reference; the older DIN equivalent is a cross-reference. For most dimensional purposes the parts are interchangeable, but check tolerance grades and the head height — these are the most common points of divergence.

When did T 78 last revise its dimensional table?

ISO standards for engineered component — gb/t 78 / iso 4027 (series 025) are reviewed on roughly a five-year cycle. Always reference the latest published edition (or the edition cited contractually); the dimensional table on this page reflects the current commercially-supplied form.

What does T 78 specify for Engineered Component — GB/T 78 / ISO 4027 (Series 025)?

T 78 specifies the dimensions and tolerances of engineered component — gb/t 78 / iso 4027 (series 025). Material and property class are governed by separate standards in the same family.

What product grades does T 78 define?

T 78 typically distinguishes product grades for precision (A/B) and general engineering (C). The selection for Engineered Component — GB/T 78 / ISO 4027 (Series 025) depends on the precision your application requires.

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.