Roller Chain Pitch Guide

What chain pitch means in practice

Pitch (P) is measured pin centre to pin centre along the chain length. It defines how far the chain advances per tooth on the sprocket and determines roller diameter, plate height, and breaking load for a given series.

When you order chain, you specify pitch plus strand count (simplex, duplex, triplex). When you order sprockets, you specify the same pitch plus teeth count and bore. Pitch never changes when you increase strand count — only width and load capacity increase.

If pitch is wrong, the rollers will not seat correctly in the sprocket tooth gaps. Symptoms appear within hours: rattling on engagement, visible wear on tooth flanks, and elongation measured far above normal limits.

Common BS (European) pitches

BS roller chain follows ISO 606 naming. The number in the designation relates to pitch expressed in the BS sizing convention — for example, 06B has 9.525 mm pitch and 08B has 12.7 mm pitch. The B suffix indicates European/British Standard roller and plate dimensions.

These pitches cover the majority of conveyor drives, packaging machinery, agricultural equipment, and light-to-medium industrial power transmission found in UAE factories and free-zone assembly plants.

ANSI (American) pitch equivalents

ANSI chain uses a different numbering system where the number relates to eighths of an inch pitch (e.g. #40 = 4/8 inch = 1/2 inch = 12.7 mm). ANSI 40 is often compared to BS 08B because pitch is similar, but they are not always fully interchangeable.

Equipment imported from North America frequently carries ANSI markings. European and Asian OEM equipment typically uses BS/ISO designations. Mixed fleets across Dubai, Jebel Ali, and KIZAD industrial zones often require cross-reference support.

BS vs ANSI — when they are not interchangeable

Chains with the same pitch number do not automatically fit the same sprockets. Roller diameter, pin diameter, plate thickness, and tooth profile can differ between BS and ANSI series even when pitch matches.

Using ANSI sprockets with BS chain (or vice versa) may cause rough running, premature tooth wear, or fit that appears acceptable at rest but fails under load. Always identify chain from the stamping on the outer link plate and match sprockets to the same standard.

If the chain marking is unreadable, measure pitch across several pins (centre to centre over multiple links and divide), roller diameter, and plate width. Provide photos and measurements on RFQ for engineering confirmation.

• Read stamping on outer link: e.g. 08B-1, 10B-2, 40-1, 50-2
• Count strand count from suffix: -1 simplex, -2 duplex, -3 triplex
• Note manufacturer if visible — premium brands may have proprietary treatments but standard pitch
• Never assume #40 chain equals 08B sprockets without verification

Strand suffix and load capacity

Strand count multiplies power capacity without changing pitch. A 08B-2 duplex chain uses the same 12.7 mm pitch as 08B-1 simplex but has two rows of rollers sharing the load.

Sprockets must match strand count — duplex sprockets are wider with two tooth rows aligned to each roller row. Ordering a simplex sprocket for duplex chain will not work.

Identifying pitch on worn or unmarked chain

On older chain, stamping may be worn away. Measure pitch by marking several pin centres and dividing total distance by number of pitches measured — accuracy improves when measuring over 10–20 links.

Compare measured pitch to the tables above. Also measure roller outer diameter and inner width between inner plates — these help distinguish close pitch variants.

Chain elongation affects pitch measurement on worn chain. If elongation exceeds 3% (manufacturer limit varies), replace rather than re-measure for like-for-like ordering. Elongated chain will cause incorrect length calculations on replacement drives.

Ordering and RFQ information

For fastest turnaround from UAE stock or import supply, provide pitch, strand count, link count or cut length, connecting link type, and application duty (conveyor, elevator, drive, etc.).

If upgrading pitch for higher load, both sprockets and chain must change together — never mix pitches on the same drive. Engineering review is recommended when changing pitch or teeth count on existing centre distance.

• Chain designation from link plate (e.g. 12B-1)
• Number of links or overall length (mm)
• Connecting link: spring clip, cotter pin, or riveted endless
• Sprocket teeth count on driver and driven if replacing as a set
• Environment: dusty, wet, food-grade, high temperature

Common mistakes to avoid

• Ordering 08B chain for #40 sprockets without confirming tooth form compatibility
• Confusing pitch with roller diameter — they are related but not the same specification
• Replacing only chain on severely worn sprockets — new chain on hooked teeth fails quickly
• Ignoring strand suffix: ordering 10B-1 when existing chain is 10B-2
• Measuring pitch on elongated worn chain and ordering to the stretched dimension
• Assuming all 12.7 mm pitch chain shares identical plate and roller dimensions across brands

RFQ checklist

• Chain designation from outer link stamping (e.g. 08B-2)
• Pitch (mm) verified by measurement if marking missing
• Strand count: simplex (-1), duplex (-2), or triplex (-3)
• Total link count (must be even for standard connecting link)
• Connecting link type required
• Sprocket teeth counts if ordering matched set
• Application and environment (indoor, outdoor, washdown, dusty)
• Quantity and urgency (stock vs project lead time)