Chain & Sprockets

Roller Chain Pitch Reference — Quick Reference

Roller chain selection turns on standard (BS / ASA), pitch (distance between roller centres), configuration (simplex / duplex / triplex), and matching sprocket. BS chains are dominant in Australian industrial plant; ASA is common in US-imported and agricultural equipment. Mismatched chain ↔ sprocket = rapid wear.

Critical: BS and ASA chains with the same pitch (e.g. 08B vs #40) are NOT interchangeable — different inner plate widths and roller diameters. Match sprocket teeth count to drive ratio + minimum 17T to reduce polygon effect. Use simplex for light drives, duplex/triplex where torque or shock load demands. Brands: KCM, SY Chain, Tsubaki. Companion: roller chain, sprockets, connecting links, taper lock bushes, roller chain guide.

Roller Chain & Sprockets: BS, ASA Drive Chain, Connecting Links and Taper Lock Sprockets

Roller chain and sprocket drives are among the most reliable power transmission solutions in industrial use — delivering high efficiency, positive drive, and long service life when correctly selected and maintained. AIMS Industrial supplies hundreds of chain and sprocket products from KCM, SY & Tsubaki, including British Standard (BS) and American Standard (ASA) simplex, duplex & triplex roller chain, pilot bore sprockets, taper lock sprockets, weld-fit sprockets, connecting links, and tensioner idlers.

The AIMS Chain & Sprockets Range

Our range covers both BS (most common in industrial Australian plant) and ASA (common in imported US equipment & agricultural equipment) drive systems.

• KCM BS Roller Chain (Simplex/Duplex/Triplex): British Standard (BS) simplex roller chain is the dominant chain standard in Australian industrial plant. KCM BS roller chain is available in standard simplex or multiple strand with connecting links, offset/half (crank) links, and full box quantities for maintenance and replacement applications.
• KCM ASA Roller Chain (Simplex/Duplex/Triplex): American Standard (ASA/ANSI) roller chain for imported US-specification equipment and machinery. Available in connecting link and full-box configurations.
• Pilot Bore Sprockets (BS & ASA): BS and ASA pilot bore sprockets in simplex, duplex & triplex strand configurations allow custom bore and keyway machining to suit your specific shaft dimensions. Hardened tooth for abrasive and high-cycle applications.
• Taper Lock Sprockets: BS taper lock sprockets accept standard taper lock bushes for rapid shaft mounting and demounting without shaft machining — the preferred configuration for maintenance-friendly drive system design.
• Weld-Fit Sprockets: BS and ANSI weld-fit sprockets with hardened teeth for permanent shaft welding in drives where taper lock or pilot bore is impractical. Common in conveyor and agricultural applications.
• Tensioner Idler Sprockets: Tensioner idler sprockets maintain correct chain tension across the span, extending chain and sprocket life and preventing jump-off under variable loads.

Chain Drive Maintenance & Selection

• Chain Matching: Chain sizes are identified by pitch: 06B/ASA35 (3/8"), 08B/ASA40 (1/2"), 10B/ASA50 (5/8"), 12B/ASA60 (3/4"), 16B/ASA80 (1"), 20B/ASA100 (1-1/4"). Always replace chain and sprockets together when either shows wear — mixing new chain with worn sprockets accelerates re-wear of the new chain.Note that even though BS & ASA chain have the same pitch, other dimensions differ slightly, so it is important to find chain/sprocket identifying markings or measure multiple dimensions carefully.
• Lubrication is Critical: Unlubricated roller chain can lose 30-50% of its theoretical service life. See our lubrication range for chain oils and lubricants appropriate for your operating temperature and environment.
• Expert Support: Need help selecting the right chain pitch, strand count, or sprocket bore for your drive? Contact our team or request a quote for drive system specification support.
• Australian Business, Local Supply: As a proudly Australian business since 1988, we stock locally and work with trusted local Australian manufacturers and distributors to ensure fast, reliable supply.

Also see our sprockets, industrial V belts, V pulleys, and bearings and bushings for complementary power transmission components.

People Also Ask — Roller Chain and Sprockets

Q: How do I identify the chain size and pitch I need?

The chain pitch is the centre-to-centre distance between adjacent pins, and it's the primary identifier. Imperial chain uses ANSI codes like 40 (1/2 inch pitch), 60 (3/4 inch), 80 (1 inch). Metric chain uses ISO codes like 08B (1/2 inch pitch), 10B (5/8), 12B (3/4). Measure pitch with calipers across multiple pin centres for accuracy. The sprocket must match the chain pitch exactly — wrong pitch causes premature tooth wear and chain failure.

Q: Should I replace just the chain or chain and sprockets together?

When the chain has stretched beyond its wear limit, the sprocket teeth have usually worn to match — a new chain on worn sprockets accelerates wear on both. Best practice: replace chain and sprockets together unless the sprockets are clearly within acceptable wear. The cost saving from reusing worn sprockets is rarely worth the shortened life of the new chain.

Q: What's the difference between ANSI and ISO roller chain?

ANSI is the American standard, ISO is the international (metric) standard. They have slightly different pin and roller dimensions even at the same nominal pitch — they're not interchangeable. ANSI 40 chain won't run cleanly on an ISO 08B sprocket and vice versa despite both being half-inch pitch. Check which system the equipment uses before ordering replacement components.

Q: How tight should a new roller chain be tensioned?

Most drives need 1-2 percent of centre distance as free sag in the slack side — too tight loads the bearings and stretches the chain prematurely, too loose lets the chain jump or whip. Vertical drives need less sag, horizontal more. Tensioner sprockets or idlers on the slack side keep tension consistent as the chain wears. Re-check tension after the first hours of operation when the chain has settled.

Q: When should a worn chain be replaced?

When the chain has elongated more than 3 percent from its new pitch length — measure across a known number of pitches and compare to spec. Visible signs: links no longer seat fully on the sprocket teeth, the chain rides up on the teeth under load, or sprocket teeth show hooked or pointed wear. Running a worn chain destroys sprockets fast and risks sudden failure.

Q: What's the difference between simplex, duplex and triplex roller chain?

Simplex is a single strand of roller chain — the workshop standard for general drive work. Duplex is two strands running side by side on a common pin, near-doubling the load capacity. Triplex is three strands, near-tripling capacity. Duplex and triplex chains need matching duplex or triplex sprockets — the tooth face is wider to carry all strands. Choose multi-strand chain when a single strand at higher pitch would give unacceptable centre distance, sprocket size or drive envelope. Common in mining crushers, agricultural balers and heavy conveyor drives.

Q: How does sprocket tooth count affect chain life?

More teeth means smoother running and longer chain life. As a rule, run at least 17 teeth on the drive sprocket for standard service and 21 or more for high-speed or high-cycle drives. Below 17 teeth, the chain articulates through a larger angle at each tooth engagement, increasing wear on the pins and bushes. For step-up drives (small driver, large driven), keep the driver above the 17-tooth minimum even if this means a physically larger driven sprocket to hit the required ratio.

Q: What are hardened teeth sprockets and when should you use them?

Hardened teeth sprockets have induction- or flame-hardened teeth (typically 45-55 HRC) with a softer core for shock resistance. Standard sprockets have through-hardened teeth or plain steel construction. Choose hardened teeth for high-cycle drives, shock-load service (crushers, mills), or where sprocket replacement is difficult and long life matters. Standard sprockets are adequate for general workshop drives and low-cycle service. Hardened sprockets also resist wear from abrasive contamination better.

Q: Why is chain and sprocket alignment critical?

Even small angular or parallel misalignment between drive and driven sprockets accelerates chain wear dramatically — the chain runs at an angle across the sprocket teeth, wearing the sidebars and rollers unevenly. Check with a straight edge across both sprocket faces (angular alignment) and confirm shafts are parallel (parallel alignment). Aim for total misalignment below 0.5 degrees. Poor alignment is a common cause of premature chain and sprocket failure in field installations — worth 15 minutes with a straight edge before commissioning any new drive.

Q: What lubricant should be used on roller chain drives?

Roller chain needs a lubricant that penetrates between the pin and bush — the primary wear surface. General workshop practice: a medium-viscosity mineral oil (ISO VG 46 to 100) applied to the inside of the chain where it wraps the smaller sprocket, letting centrifugal force carry it into the pin joints. For high-speed drives, an oil bath or drip feed system delivers continuous lubrication. Chain sprays with PTFE or moly additives work for occasional maintenance. Avoid heavy greases — they cannot penetrate the pin joint and just coat the outside. See our chain lube guide for lubricant selection by drive type and service condition.