Pitch first
The pitch is the distance between the centres of two neighbouring rollers. The number gives it in inches: 08B is 8/16 inch (12.70 mm), ANSI 40 is 4/8 inch.
Reference tool — not inspection
Identify the chain before it goes in an RFQ.
Roller chain
Pitch, roller, width.
Enter the pitch (or the length over several pitches), the roller and the width. Below the examples, an offered chain designation can be checked against the reading: pitch, roller, width, strands and series. The drawing and the RFQ line update with every change.
Examples:
Replacement check
Against your reading and the tables alone: the data of the chain maker and the sprocket decide.
All 130 engineering tools
A roller chain is ordered by its number, and three readings find the number: the pitch, the roller diameter and the width between the inner plates. The A (ANSI) and B (British) series share pitches and differ in the roller and the width, so the tool shows both and says which fits.
The table sizes are nominal; a worn chain stretches and reads a longer pitch, so measure over many pitches. The marking on the plates and the sprocket settle it.
How chains are told apart
Pitch, series, strands.
A or B series
At one pitch the series differ in roller and width: 16B has a 15.88 mm roller and 17.02 mm width, ANSI 80 has 15.88 and 15.88 mm. The width decides.
Strands and length
-1, -2 and -3 are simplex, duplex and triplex. The length goes in links or metres, and the connecting link separately.
| Chain | Series | Pitch, mm | Roller, mm | Width, mm |
|---|---|---|---|---|
| ANSI 25 | A (ANSI) | 6.35 | 3.30 | 3.18 |
| ANSI 35 | A (ANSI) | 9.525 | 5.08 | 4.78 |
| ANSI 41 | A (ANSI) | 12.70 | 7.77 | 6.38 |
| 08A / ANSI 40 | A (ANSI) | 12.70 | 7.92 | 7.95 |
| 10A / ANSI 50 | A (ANSI) | 15.875 | 10.16 | 9.53 |
| 12A / ANSI 60 | A (ANSI) | 19.05 | 11.91 | 12.70 |
| 16A / ANSI 80 | A (ANSI) | 25.40 | 15.88 | 15.88 |
| 20A / ANSI 100 | A (ANSI) | 31.75 | 19.05 | 19.05* |
| 24A / ANSI 120 | A (ANSI) | 38.10 | 22.23 | 25.40* |
| ANSI 140 | A (ANSI) | 44.45 | 25.40 | 25.40* |
| ANSI 160 | A (ANSI) | 50.80 | 28.58 | 31.75* |
| ANSI 200 | A (ANSI) | 63.50 | 39.68 | 38.10* |
| ANSI 240 | A (ANSI) | 76.20 | 47.63 | 47.63* |
| 05B | B | 8.00 | — | 3.00 |
| 06B | B | 9.525 | 6.35 | 5.72 |
| 08B | B | 12.70 | 8.51 | 7.75 |
| 10B | B | 15.875 | 10.16 | 9.65 |
| 12B | B | 19.05 | 12.07 | 11.68 |
| 16B | B | 25.40 | 15.88 | 17.02 |
| 20B | B | 31.75 | — | 19.56 |
| 24B | B | 38.10 | — | 25.40 |
Widths marked * come from one source. ANSI 25 and 35 have a bush instead of a roller. Rollers of 05B, 20B and 24B are not given: the sources do not confirm them twice.
Sources
A series: Tsubaki Europe’s ANSI G8 table, checked against the ANSI table in Wikipedia’s "Roller chain" article (pitch, roller; widths 25 to 80); size 180, on which they differ, is left out. B series: Tyma’s DIN 8187 table (pitch, inner width) and U.S. Tsubaki’s BS/DIN chain table (08B to 16B, in inches), with the Tsubaki 05B, 06B, 20B and 24B listings at RS Components and Acorn. 08A as ANSI 40: Tyma and Wippermann listings.
Before you send the chain
Questions about chains in an RFQ
How do I measure the pitch?
From the centre of one pin to the centre of the next. A worn chain reads long, so measure over ten pitches or more and divide: over ten pitches a new 08B chain measures 127 mm.
Is 08B the same as ANSI 40?
No. Both have a 12.70 mm pitch, but 08B has an 8.51 mm roller and 7.75 mm between the inner plates, ANSI 40 a 7.92 mm roller and 7.95 mm. Measure the roller and the inner width, and name the series in the request.
What do -1, -2 and -3 mean?
The number of strands: simplex, duplex and triplex. 16B-2 is a two-strand 16B chain.
What should the request include?
The chain number and strands, the length in links or metres, the connecting link wanted, and a photograph of the plates with any marking on them. Where the old chain is worn, send the sprocket tooth count as well.
Chain identified?
Send the line with the photograph.
An identified number is a cross-check on your reading, not proof. Attach photographs of the plates and the sprocket, and Vessel Core checks them against each other before an offer goes back.
Buyer tools
