Triplex Chains

What is triplex roller chain?

Triplex roller chain is a heavy-duty power transmission chain with three rows of rollers running side by side. It is used to transmit power between sprockets on parallel shafts, and because its load is shared across three strands, it can carry much more power than single-strand (simplex) or double-strand (duplex) chain of the same pitch. This makes triplex chain ideal for heavy-duty industrial drives where high power, high torque, or shock loads are involved, but space for larger chain sizes is limited.

Roller chain works by meshing with the teeth of sprockets. As the drive sprocket turns, its teeth pull the chain along, and the chain in turn drives the sprocket on the driven shaft. Chain drives are strong, efficient, and give positive drive with no slipping.

Triplex chain is made up of alternating inner and outer links:

• Inner links - made up of inner plates, bushes, and rollers. The rollers turn on the bushes and engage with the sprocket teeth
• Outer links - made up of outer plates and pins. The pins pass through the bushes, allowing the chain to flex as it wraps around the sprockets
• Middle plates - plates between the strands that join the three rows together and share the load
• Connecting link - a removable link used to join the chain into a continuous loop

Triplex roller chain is usually described by:

• Chain size - such as 06B-3, 08B-3, 10B-3, or 12B-3 for British Standard chain, or 40-3, 50-3, or 60-3 for ANSI chain. The 3 shows it is triplex
• Chain standard - British Standard (BS) or American Standard (ANSI)
• Pitch - the distance between the centres of adjacent pins, such as 3/8 inch, 1/2 inch, 5/8 inch, or 3/4 inch
• Length - often supplied in standard lengths, such as 5 metres or 10 feet, which can be cut to size
• Quality and material - such as standard duty, heavy duty, nickel plated, or stainless steel

For example, 08B-3 BS triplex roller chain has a 1/2 inch pitch and three strands, and is made to British Standard dimensions.

Key features:

• High power capacity - three strands share the load for maximum strength
• Compact - carries more power than simplex or duplex chain of the same pitch, without moving to a larger chain size
• Positive drive - no slipping, giving accurate and reliable power transmission
• High efficiency - transmits power with very low losses
• Handles shock loads - suitable for heavy-duty and demanding drives
• Supplied in lengths - can be cut to the length needed and joined with connecting links
• BS and ANSI sizes - to suit British Standard and American Standard sprockets

In simple terms, triplex roller chain is a strong, three-strand chain that transmits high power between sprockets in heavy-duty drives.

Why is triplex roller chain essential?

Triplex roller chain is essential for drives that need to transmit high power and torque in a limited space. Larger pitch chains can carry more load, but they need bigger sprockets and run less smoothly at higher speeds. Triplex chain allows a smaller pitch to carry much more power, keeping drives compact while still handling heavy loads, shock loads, and continuous operation.

Its main benefits are:

• Maximum power in a compact drive - higher capacity than simplex or duplex chain of the same pitch
• Smoother running - smaller pitches with multiple strands can run more smoothly than larger single-strand chains
• Positive drive - no slipping, keeping drives accurate and reliable
• High efficiency - transmits power with very little loss
• Durable - handles heavy loads, shock, and continuous operation
• Flexible layouts - can drive over long and short centre distances
• Easy to install and repair - can be cut to length and joined with connecting links
• Widely available - standard sizes make replacement chain and sprockets easy to source

Triplex roller chain is used across a wide range of industries and applications, including:

• Heavy industrial drives - high-power drives on industrial machinery
• Conveyors - heavy-duty conveyor drives
• Mining and quarrying - crushers, screens, and conveyors
• Steel, paper, and timber processing - high-load drive systems
• Agricultural machinery - heavy-duty drives on harvesters and processing equipment
• Pumps, compressors, and mixers - chain-driven equipment with high torque
• Construction and plant machinery - heavy-duty power transmission
• Oil, gas, and energy - drives on heavy equipment

The main types of triplex roller chain

Triplex roller chain is usually grouped by standard, quality, material, and finish.

By chain standard:

• British Standard (BS) triplex chain - made to British and European dimensions, such as 06B-3, 08B-3, 10B-3, 12B-3, and 16B-3. Widely used on European machinery
• ANSI triplex chain - made to American Standard dimensions, such as 40-3, 50-3, 60-3, and 80-3. Widely used on American and international machinery

British Standard and ANSI chains of the same pitch are not interchangeable, as their roller diameters, inner widths, and plate dimensions are different. They also need matching sprockets.

By quality:

• Standard duty chain - for general industrial drives
• Heavy duty chain - with thicker plates or stronger components for higher loads and shock
• Premium chain - made to tighter tolerances with improved materials and treatments for longer wear life

By material and finish:

• Plain steel chain - the standard choice for general use, usually supplied pre-lubricated
• Nickel plated chain - offers improved corrosion resistance for damp environments
• Stainless steel chain - resists rust and corrosion, ideal for food, marine, and washdown environments

Common pitches:

• 3/8 inch - such as 06B-3 and ANSI 35-3
• 1/2 inch - such as 08B-3 and ANSI 40-3
• 5/8 inch - such as 10B-3 and ANSI 50-3
• 3/4 inch - such as 12B-3 and ANSI 60-3
• 1 inch - such as 16B-3 and ANSI 80-3

Related products:

• Triplex links - connecting links, cranked links, and repair links for triplex chain
• Triplex sprockets - sprockets with three rows of teeth to suit triplex chain
• Chain tools - chain breakers and pullers for cutting and fitting chain
• Chain lubricants - to reduce wear and extend chain life

How to choose the right triplex roller chain?

Choosing the right triplex chain means matching it to the sprockets, the power, and the conditions of the drive. Work through these points in order:

• Chain standard - check whether the drive uses British Standard or ANSI chain and sprockets
• Pitch - match the chain pitch to the sprockets
• Number of strands - make sure the sprockets are triplex, with three rows of teeth
• Power and speed - check the chain can transmit the power at the drive speed, using the manufacturer’s power rating tables
• Shock loads - consider heavy duty or premium chain for drives with shock loads, frequent starts, or reversing
• Length - work out the number of links needed for the sprocket sizes and centre distance, ideally using an even number of links
• Environment - choose nickel plated or stainless steel chain for wet, food, or corrosive environments
• Lubrication - plan how the chain will be lubricated, as this has a major effect on wear life
• Quality and brand - choose chain from reputable manufacturers for accurate dimensions, strength, and long wear life

How to fit triplex roller chain

Fitting triplex chain correctly helps it run smoothly and last longer:

• Isolate the drive - switch off and isolate the machine before starting work
• Check the sprockets - make sure the sprockets are in good condition, aligned, and securely fixed. Replace worn sprockets when fitting new chain
• Cut the chain to length - use a chain breaker to remove pins and shorten the chain to the required number of links
• Join the chain - wrap the chain around the sprockets and join the ends with a triplex connecting link, fitting the spring clip with its closed end facing the direction of travel
• Set the tension - adjust the chain so it has a small amount of slack on the slack side, as recommended by the chain manufacturer
• Check alignment - make sure the sprockets are in line and the shafts are parallel, so the chain runs straight
• Lubricate - apply suitable chain lubricant before running
• Check after running - recheck tension after a short running-in period, as new chains can settle

FAQ - All you need to know about triplex roller chain

What is triplex roller chain?

Triplex roller chain is a power transmission chain with three rows of rollers side by side, giving high strength and power capacity in a compact size.

What does the 3 in 08B-3 mean?

The 3 shows the chain is triplex, with three strands. For example, 08B-1 is simplex, 08B-2 is duplex, and 08B-3 is triplex.

What is the difference between BS and ANSI chain?

BS chain is made to British and European dimensions, and ANSI chain is made to American dimensions. Even at the same pitch, they have different roller diameters and widths, so they are not interchangeable and need matching sprockets.

How do I measure chain pitch?

Measure the distance between the centres of two adjacent pins. For example, 08B-3 and ANSI 40-3 chains both have a 1/2 inch pitch.

Can I cut triplex chain to length?

Yes. Triplex chain is supplied in standard lengths and can be shortened using a chain breaker to remove pins. Join the ends with a matching triplex connecting link.

Why should a chain have an even number of links?

An even number of links allows the chain to be joined with a standard connecting link. An odd number needs a cranked link, which reduces chain strength.

How tight should triplex chain be?

The chain should have a small amount of slack on the slack side, as recommended by the manufacturer. A chain that is too tight increases wear on the chain, sprockets, and bearings, while a chain that is too loose can whip and jump teeth.

How often should triplex chain be lubricated?

It depends on the speed, load, and environment. Chains in continuous or heavy-duty use need regular lubrication, and some drives use automatic lubrication systems. Follow the chain manufacturer’s guidance.

When should triplex chain be replaced?

Replace the chain when it has stretched beyond the manufacturer’s wear limit, commonly around 2% to 3% elongation, or if links are stiff, cracked, or damaged.

Should I replace the sprockets with the chain?

It is good practice to check the sprockets whenever the chain is replaced. Worn sprockets with hooked or pointed teeth will wear new chain quickly and should be replaced at the same time.

Can I use triplex chain on duplex sprockets?

No. Triplex chain needs triplex sprockets with three rows of teeth. Always match the chain and sprockets for the correct number of strands.