How to determine the size of an unknown chain

Why this is needed

In a warehouse or during repairs there is often an unmarked chain: a spare one, from an old mechanism, from a mixed batch. To replace it or order an analogue, you need to identify the size — the set of link parameters. Under our TUs (class 3 and T8 lifting) the size can be reconstructed from four simple measurements.

Four parameters and how to measure them

• Gauge d — the diameter of the rod the link is made from. Measure with a caliper on a straight section of the link, not at the weld and not at the bend: the metal can be thicker there. The nominal value is stated in mm with a tolerance.
• Pitch t — the internal length of the link. The distance between the inner surfaces of adjacent links. It is more reliable to measure 10 links at once and divide by 10 — then the error of a single measurement will not distort the result.
• Width b — the outer width of the link: from the outer surface of the link to the outer one, with a caliper.
• Weight per 1 metre. Weigh a section at least 1 m long (the longer, the more accurate) and divide the weight by the length. The weight per metre quickly separates adjacent sizes and is a good check on the other measurements.

Example

Suppose the measurements are: d ≈ 8 mm, t ≈ 24 mm, b ≈ 26 mm, weight ≈ 1.4–1.45 kg/m. This set corresponds to:

• A1-3-8×24×26 — a calibrated short-link class 3 chain to our TU 25.93.17-001-06515248-2020 (weight ≈ 1.45 kg/m);
• 8×24-T8 — a class 8 lifting chain to our TU 25.93.17-002-06515248-2026 (weight ≈ 1.4 kg/m).

Both options match in link dimensions, but they are different chains for different purposes — the choice depends on the assembly in which the chain works: a lifting device or a traction mechanism. If the chain worked in a lifting device (for example, a hoist), choose the class 8 version and a specialist's confirmation — more details in the article Chain slings and class 8 lifting chains.

Online tool

Enter the measurements into the Chain identification by measurements tool — it will show the closest sizes of both TUs with deviations for each parameter and links to the item cards. The exact match and tolerances will be confirmed by a manager based on your measurements.