Double Simplex Tapered Bore Sprockets

What is a double simplex tapered bore sprocket?

A double simplex tapered bore sprocket is a sprocket with two separate rows of simplex teeth on a single body, with a tapered bore in the centre designed to accept a tapered locking bush. Each row of teeth drives its own single-strand simplex roller chain, allowing one sprocket to drive two separate chains at the same time, or to transfer drive from one chain to another along a line of shafts.

Unlike a duplex sprocket, which has two rows of teeth set close together to suit a single double-strand chain, a double simplex sprocket has its two tooth rows spaced further apart, so two independent simplex chains can run side by side without touching.

The tapered bore means the sprocket is fitted to the shaft with a standard tapered locking bush. This gives a strong, self-centring, keyed connection that is quick to fit and remove, and allows the same sprocket to suit many shaft sizes simply by changing the bush.

A typical double simplex tapered bore sprocket has:

• Two rows of simplex teeth - each matched to the pitch and width of simplex roller chain, spaced apart so two chains can run independently
• Tapered bore - accepts a standard tapered locking bush
• Half-threaded holes - shared with the bush, used to tighten the bush into the sprocket and to remove it
• Steel body - strong and durable, often with hardened teeth

Double simplex tapered bore sprockets are usually described by:

• Chain size - such as 06B for 3/8 inch pitch, 08B for 1/2 inch pitch, or 10B for 5/8 inch pitch British Standard simplex chain
• Number of teeth - such as 12, 18, 21, or 25 teeth, which sets the sprocket size and drive ratio
• Bush size - the tapered locking bush size the sprocket accepts, such as 1008, 1210, or 1610
• Pitch circle diameter - the effective working diameter of the sprocket

For example, an 18 tooth 06B tapered bore double simplex sprocket has two rows of 18 teeth, each suiting 3/8 inch pitch British Standard simplex chain, and is fitted to the shaft with a tapered locking bush.

Key features:

• Drives two chains at once - two separate rows of simplex teeth on one sprocket
• Transfers drive - passes drive from one chain to another along a line of shafts
• Keyless, self-centring mounting - fitted with a tapered locking bush for a strong, accurate connection
• Flexible shaft sizes - one sprocket suits many shaft sizes by changing the bush
• Quick fitting and removal - fitted and removed with simple hand tools
• Steel construction - strong and durable for industrial drives
• Range of sizes - available in many tooth counts and chain sizes

In simple terms, a double simplex tapered bore sprocket is a sprocket with two separate tooth rows that drives two simplex chains, and fits quickly to a shaft with a tapered locking bush.

Why are double simplex tapered bore sprockets essential?

Double simplex tapered bore sprockets are essential because many machines need to drive more than one chain from the same shaft. Fitting two separate sprockets takes up more space, needs more fixing, and makes alignment harder. A double simplex sprocket combines both drives into one compact unit, while the tapered bore makes fitting, removal, and shaft size changes simple.

Their main benefits are:

• Compact drive - drives two chains from a single sprocket, saving space on the shaft
• Accurate alignment - both tooth rows are made together, so the two chains stay correctly spaced
• Flexible layouts - ideal for line shafts, roller conveyors, and multi-shaft drives
• Strong shaft connection - tapered locking bushes clamp firmly and transmit high torque
• Self-centring - the taper centres the sprocket accurately, reducing wobble and chain wear
• Quick maintenance - sprockets can be fitted and removed quickly, reducing downtime
• Reduced stock - one sprocket can suit many shaft sizes by changing the bush

Double simplex tapered bore sprockets are used across a wide range of industries and applications, including:

• Roller conveyors - driving rollers in sequence, with chains linking one roller to the next
• Line shaft drives - passing drive along a series of shafts
• Agricultural machinery - drives on implements and processing equipment
• Packaging and food machinery - multi-chain drives on production lines
• Material handling - transfer systems and conveyors
• Industrial machinery - drives where one shaft powers two separate outputs

The main types of double simplex tapered bore sprockets

Double simplex tapered bore sprockets are usually grouped by chain standard, chain size, tooth count, and bush size.

By chain standard:

• British Standard (BS) double simplex sprockets - suit European-style simplex roller chains, such as 06B, 08B, 10B, and 12B
• ANSI double simplex sprockets - suit American-style simplex roller chains, such as 35, 40, 50, and 60

British Standard and ANSI chains are not interchangeable, so the sprocket must match the chain standard.

By chain size:

• 06B (3/8 inch pitch) sprockets - for light and medium-duty drives
• 08B (1/2 inch pitch) sprockets - a popular size for general industrial drives and conveyors
• 10B (5/8 inch pitch) sprockets - for higher power drives
• 12B (3/4 inch pitch) and larger sprockets - for heavier drives

By number of teeth:

• Small sprockets - fewer teeth, used where space is limited or as drive sprockets
• Large sprockets - more teeth, used to reduce speed and increase torque, and for smoother running

By bush size:

• Small bush sizes - such as 1008 and 1108, for smaller sprockets and shafts
• Medium bush sizes - such as 1210, 1610, and 2012, for general industrial drives
• Large bush sizes - such as 2517 and above, for larger sprockets and shafts

Related products:

• Tapered locking bushes - required to fit the sprocket to the shaft, chosen to match the bush size and shaft diameter
• Duplex sprockets - sprockets with two closely spaced tooth rows for double-strand duplex chain
• Simplex chain and links - chain and connecting links for each of the two drives

How to choose the right double simplex tapered bore sprocket?

Choosing the right sprocket means matching it to the chains, the shaft, and the drive. Work through these points in order:

• Chain type - make sure each drive uses simplex chain. For a single duplex chain, choose a duplex sprocket instead
• Chain standard - check whether the drive uses British Standard or ANSI chain
• Chain size - choose a sprocket that matches the chain pitch exactly, such as 08B
• Number of teeth - choose a tooth count that gives the required ratio and fits the space. Larger sprockets give smoother running and less chain wear
• Chain spacing - check the spacing between the two tooth rows suits the layout of the drive and the sprockets it connects to
• Bush size - check the sprocket’s bush size and choose a tapered locking bush with a bore that matches the shaft
• Shaft size - make sure the shaft diameter is within the bore range of the bush size
• Load and speed - check the chain size and sprocket suit the power and speed of each drive
• Quality and brand - choose sprockets from reputable suppliers for accurate teeth and reliable bush fit

How to fit a double simplex tapered bore sprocket

Fitting the sprocket correctly helps both chains run smoothly:

• Isolate the drive - switch off and isolate the machine before starting work
• Clean the parts - clean the shaft, tapered bore, and bush, and remove any oil or grease from the taper
• Fit the bush - place the bush into the sprocket, line up the half holes, and insert the screws loosely
• Fit to the shaft - slide the sprocket and bush onto the shaft with the key in place
• Align the sprocket - position the sprocket so both rows of teeth line up with the sprockets they drive
• Tighten the bush - tighten the screws evenly and alternately to the recommended torque, rechecking alignment as you go
• Fit the chains - fit both chains and set the tension, leaving a small amount of slack on the slack side of each
• Check the drive - turn the drive by hand to check both chains run smoothly, then lubricate before running

FAQ - All you need to know about double simplex tapered bore sprockets

What is a double simplex sprocket?

A double simplex sprocket has two separate rows of simplex teeth on one body, allowing it to drive two independent simplex chains at the same time.

What is the difference between double simplex and duplex sprockets?

A duplex sprocket has two closely spaced tooth rows for a single double-strand duplex chain. A double simplex sprocket has two tooth rows spaced further apart, so two separate simplex chains can run side by side.

Can I use a double simplex sprocket with duplex chain?

No. Double simplex sprockets are designed for two separate simplex chains. Duplex chain needs a duplex sprocket.

What does tapered bore mean?

A tapered bore sprocket has a tapered hole that accepts a tapered locking bush. The bush clamps onto the shaft when tightened, fixing the sprocket securely and centring it accurately.

Do I need to buy a tapered locking bush separately?

Usually, yes. Choose a bush that matches the sprocket’s bush size, with a bore and keyway that suit your shaft.

What are double simplex sprockets used for?

They are often used on roller conveyors and line shaft drives, where each sprocket receives drive from one chain and passes it to the next shaft with a second chain.

What does 06B mean?

06B is the British Standard chain size for 3/8 inch pitch chain. A double simplex sprocket marked 06B suits two 06B-1 simplex chains.

How do I remove a tapered bore sprocket?

Remove the screws from the bush, insert them into the removal holes, and tighten them to push the bush out of the taper. The sprocket can then be removed from the shaft.

Should I lubricate the taper?

No. The tapered surfaces should be clean and dry so the bush grips correctly. Only the chains need lubrication.

When should I replace the sprocket?

Replace it if the teeth are hooked, pointed, or worn, as worn sprockets quickly wear new chains. It is good practice to check sprockets whenever the chains are replaced.