Duplex Platewheels

What is a duplex platewheel?

A duplex platewheel is a flat, hubless sprocket with two rows of teeth, designed to run with duplex roller chain. Unlike a standard sprocket, which has a raised hub for fixing directly to a shaft, a platewheel is a plain plate with teeth around the outside and a small pilot bore in the centre. This makes it very versatile, as it can be bored to suit a shaft, welded onto a hub, bolted to a flange or drum, or built into a custom part.

Duplex platewheels are used in chain drives where duplex chain is needed to transmit more power than simplex chain can handle. Their plain, hubless design makes them ideal where space is tight, where a custom hub is needed, or where the sprocket must be fixed to another component rather than directly to a shaft.

A typical duplex platewheel has:

• Two rows of teeth - matched to the pitch, roller size, and strand spacing of duplex roller chain
• Flat plate body - a plain, hubless plate that can be machined, welded, or bolted
• Pilot bore - a small starter bore in the centre that can be machined out to the required size
• Steel construction - usually made from a strong, weldable steel, sometimes with hardened teeth

Duplex platewheels are usually described by:

• Chain size - the chain the platewheel suits, such as 05B-2 for 8 mm pitch, 08B-2 for 1/2 inch pitch, or 10B-2 for 5/8 inch pitch British Standard duplex chain
• Number of teeth - such as 10, 11, 13, or 16 teeth, which sets the size of the platewheel and the drive ratio
• Pitch circle diameter - the effective working diameter of the sprocket
• Pilot bore - the size of the starter bore
• Plate thickness - the width of the toothed section, matched to the chain

For example, a 13 tooth 08B duplex platewheel has 13 teeth and suits 1/2 inch pitch British Standard duplex chain.

Key features:

• Hubless design - a flat plate that can be bored, welded, or bolted to suit the drive
• Duplex chain compatibility - two rows of teeth for higher-power duplex chain drives
• Pilot bore - can be machined to fit the shaft or hub exactly
• Weldable - can be welded to hubs, drums, and fabricated parts
• Compact - ideal where space is limited or a standard hub will not fit
• Range of sizes - available in many tooth counts and chain sizes

In simple terms, a duplex platewheel is a flat, hubless duplex sprocket that can be machined, welded, or bolted to create a custom chain drive.

Why are duplex platewheels essential?

Duplex platewheels are essential because many chain drives need a sprocket that does not fit the standard pattern. Standard sprockets have fixed hub sizes and positions, which may not suit custom shafts, drums, or fabricated parts. Platewheels give engineers the freedom to create exactly the sprocket they need, by machining the bore, adding a hub, or fixing the platewheel directly to another component, while still running with standard duplex chain.

Their main benefits are:

• Design flexibility - can be adapted to almost any drive or mounting arrangement
• Custom bores - pilot bores can be machined to suit any shaft size, with keyways added as needed
• Easy to fabricate - can be welded to hubs, drums, and frames
• Higher power transmission - duplex teeth suit drives that need more capacity than simplex chain
• Space saving - hubless design fits into tight spaces
• Repair and replacement - ideal for replacing worn sprockets on custom or older machinery
• Cost-effective - an economical way to create custom duplex sprockets

Duplex platewheels are used across a wide range of industries and applications, including:

• Industrial drives - medium and heavy-duty chain drives on machinery
• Conveyors - conveyor drives and drums
• Agricultural machinery - drives on harvesters, balers, drills, and processing equipment
• Packaging and food machinery - drive systems on production lines
• Mining and quarrying - conveyors, screens, and crushers
• Timber, paper, and steel processing - drive systems and conveyors
• Custom fabrication - sprockets built into drums, rollers, and bespoke machinery
• Maintenance and repair - replacing worn sprockets on existing duplex drives

The main types of duplex platewheels

Duplex platewheels are usually grouped by chain standard, chain size, tooth count, and material.

By chain standard:

• British Standard (BS) duplex platewheels - suit European-style duplex roller chains, such as 05B-2, 06B-2, 08B-2, 10B-2, 12B-2, and 16B-2
• ANSI duplex platewheels - suit American-style duplex roller chains, such as 35-2, 40-2, 50-2, and 60-2

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

By chain size:

• 05B-2 (8 mm pitch) platewheels - for compact, light-duty duplex drives
• 06B-2 (3/8 inch pitch) platewheels - for compact medium-duty drives
• 08B-2 (1/2 inch pitch) platewheels - a popular size for general industrial drives
• 10B-2 (5/8 inch pitch) platewheels - for higher power drives
• 12B-2 (3/4 inch pitch) and larger platewheels - for heavy-duty drives

By number of teeth:

• Small platewheels - fewer teeth, used as drive sprockets on motors and gearboxes
• Large platewheels - more teeth, used as driven sprockets to reduce speed and increase torque

By material:

• Steel platewheels - strong, durable, and weldable, the standard choice for most drives
• Hardened tooth platewheels - with hardened teeth for longer wear life in demanding drives
• Stainless steel platewheels - for corrosive, food, and washdown environments

Related products:

• Duplex sprockets - sprockets with hubs, ready to fit directly to shafts
• Weld-on and bolt-on hubs - used to mount platewheels onto shafts with tapered locking bushes
• Duplex chain and links - matching chain and connecting links for duplex drives

How to choose the right duplex platewheel?

Choosing the right duplex platewheel means matching it to the chain, the drive ratio, and the way it will be mounted. Work through these points in order:

• Chain standard - check whether the drive uses British Standard or ANSI duplex chain
• Chain size - choose a platewheel that matches the chain pitch exactly, such as 08B-2
• Number of strands - make sure the platewheel is duplex, with two rows of teeth
• Number of teeth - choose tooth counts on the drive and driven sprockets that give the required ratio. As a guide, larger tooth counts give smoother running and less chain wear, especially at higher speeds
• Pitch circle diameter - check the platewheel fits the available space
• Bore - check the pilot bore can be machined to the required shaft or hub size, leaving enough material for strength
• Mounting method - decide whether the platewheel will be bored to fit a shaft, welded to a hub, or bolted to a flange or drum
• Load and speed - choose a chain size and tooth count suitable for the power and speed of the drive
• Material - choose steel for general use, hardened teeth for longer wear life, or stainless steel for corrosive environments
• Quality and brand - choose platewheels from reputable suppliers for accurate tooth profiles and reliable performance

How to fit a duplex platewheel

Fitting a platewheel correctly helps the drive run smoothly and accurately:

• Machine the bore - bore the platewheel to the required size, keeping the bore concentric with the teeth, and add a keyway if needed
• Or weld to a hub - if welding to a hub, align the platewheel carefully, tack it in several places, and weld in short runs on alternate sides to reduce distortion
• Or bolt to a flange - if bolting to a flange or drum, drill accurate bolt holes and make sure the platewheel sits flat and true
• Check run-out - make sure the platewheel runs true, without wobble or eccentricity
• Fit to the shaft - secure the platewheel or hub to the shaft with a key, set screw, or tapered locking bush
• Align the sprockets - make sure the drive and driven sprockets are in line and the shafts are parallel
• Fit the chain - fit the duplex chain and set the tension, leaving a small amount of slack on the slack side
• Lubricate - apply suitable chain lubricant before running

FAQ - All you need to know about duplex platewheels

What is a duplex platewheel?

A duplex platewheel is a flat, hubless sprocket with two rows of teeth, designed to run with duplex roller chain. It can be bored, welded, or bolted to suit the drive.

What is the difference between a platewheel and a sprocket?

A standard sprocket has a raised hub for fixing directly to a shaft. A platewheel is a flat plate without a hub, giving more flexibility to bore it, weld it to a hub, or bolt it to another part.

What does the pilot bore mean?

The pilot bore is a small starter hole in the centre of the platewheel. It is designed to be machined out to the required shaft or hub size.

Can I weld a duplex platewheel?

Yes. Steel platewheels are usually weldable, so they can be welded to hubs, drums, and fabricated parts. Weld carefully to avoid distortion, and check the platewheel runs true afterwards.

How do I mount a platewheel to a shaft?

You can bore the platewheel to fit the shaft and add a keyway, weld it to a hub, or bolt it to a hub or flange. Weld-on and bolt-on hubs with tapered locking bushes give a strong, removable mounting.

What does 08B mean on a duplex platewheel?

08B is the British Standard chain size for 1/2 inch pitch chain. A duplex platewheel marked 08B suits 08B-2 duplex roller chain.

Can I use a duplex platewheel with simplex or triplex chain?

No. Duplex platewheels have two rows of teeth and are designed to run with duplex chain only.

What is the difference between BS and ANSI platewheels?

BS platewheels suit British Standard chain, and ANSI platewheels suit American Standard chain. They have different tooth dimensions and are not interchangeable.

How do I work out the drive ratio?

Divide the number of teeth on the driven sprocket by the number of teeth on the drive sprocket. For example, a 13 tooth drive sprocket and a 39 tooth driven sprocket give a 3:1 ratio, reducing speed to a third and increasing torque.

Should I replace platewheels when I replace the chain?

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

As with the triplex page, the intro describes platewheels as large-diameter sprockets for reduction, but the range includes small tooth counts too. Something like “These duplex platewheels are commonly used in chain drive systems, to provide a hubless sprocket that can be bored, welded, or bolted to suit the drive” would cover the full range better.