Introduction to
Tsubaki Attachment Chain


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Introduction to Tsubaki Attachment Chain

Attachment Chain Structure

In the world of attachment chain Tsubaki is the manufacturer you require to assure smooth operation. Whether your application requires attachments or extended pins in Carbon Steel, for the Neptune™ series, Nickel Plating or Stainless Steel, Tsubaki is your partner. Tsubaki's maintenance free solution, Lambda, is also available with a wide range of attachments. When starting with a completely new design, Tsubaki can tailor make an attachment chain for you in any specification.

1. Attachment Chain Structure

There are mainly two types of Attachment Chain: Single Pitch and Double Pitch.

- Single Pitch Attachment Chain

Single pitch attachment chains are based on roller chains with attachments added to make them suitable for conveying use. Due to the smaller chain pitch, this type of chain is ideal for short centre distances, and the conveying of small and light goods. Single pitch attachment chain has smooth transfer and low noise characte ristics and can be used at relatively medium conveying speeds. Standard roller chain sprockets can be used in most cases.

- Double Pitch Attachment Chain

This is the most commonly used attachment chain and is utilised widely in the automotive parts, electric, electronic, and precision machinery industries. Double pitch roller chain has the same basic construction as single pitch roller chain, but has twice the pitch length. A major benefit is that whilst larger conveyor lengths are possible, a double pitch chain uses only half the components of a single pitch chain in the same application, resulting in less components to wear.
The choice of sprockets depends on the roller type applied to the chain. Chain with S-type rollers can be driven by standard roller chain sprockets (> 30 teeth). The chain engages every second tooth. Special sprockets are needed when R-type rollers are used.

2. Three Basic Dimensions

Pitch, roller diameter and inner width are known as the "Three Basic Dimensions of Roller Chain." When these three dimensions are identical to the existing chain being replaced, then the roller chain and sprockets are dimensionally compatible. With attachment chain a lot of additional dimensions are important to ensure a safe replacement and carefree installation of the chain. Please refer to our dimension tables for the appropriate dimensions.

3. Basic Parts

Link Plate

The link plate is the component that bears the tension placed on the chain. Usually this is a repeated load, sometimes accompanied by shock. Therefore, the plate must not only have great static tensile strength, it must also hold up to the dynamic forces of load and shock.


The pin is subject to shearing and bending forces transmitted by the plate. At the same time, it forms a load-bearing part (together with the bush) when the chain flexes during sprocket engagement. Therefore, the pin needs high tensile and shear strength, resistance to bending, and must also have suffi cient endurance against shock and wear.


The bush is subject to complex forces from all parts, especially from the repetition of shock loads when the chain engages with the sprocket. Therefore, the bush needs extremely high shock resistance. In addition, the bush forms a load-bearing part together with the pin and as such requires great wear resistance.


The roller is subject to impact load as it mates with the sprocket tooth during engagement of the chain with the sprocket. After engagement, the roller changes its point of contact and balance. It is held between the sprocket tooth and bush, and moves on the tooth face whilst receiving a compression load. Therefore, it must be resistant to wear and still have strength against shock, fatigue and compression.

There are two types of rollers, S-roller (standard) and R-roller (oversized). The S-rollers are used in short-length and slow-speed conveying. The R-rollers are most commonly used for longer conveying applications.
(RS35 is a bush chain and does not have rollers).

Roller Link

Two bushes are press fi t into two roller link plates and rollers are inserted to allow rotation around the outside of the bushes during operation. This is the same for single and for multi strand chains.

Pin Link and Intermediate Plate

The pin link consists of two pins that have been press fit into two pin link plates. In case of multi-strand roller chain up to size RF08B, an intermediate plate is added to the pin link. In case of multi strand roller chain above size RF08B, two intermediate plates are added to the pin link. The intermediate plates are slip fit for standard attachment chain.

Spring Clip and Cotter Pin

The spring clip prevent the link plate from becoming detached, with the cotter pin type being as an added security measure where there is as possibly of the clip being removed due to interference from chain guides or some other aspect of the application.

4. Assembly Parts

Roller chains are usually made up of a number of inner and outer links in an endless formation. Although offset links can be used when there is an odd number of links in the roller chain, it is better to use a design that requires an even number of links-thus eliminating the use of offset links.

Connecting Links

There are two types of connecting link: spring clip connecting link and cotter pin connecting link. It's common to use slip fit spring clip connecting links for small size attachment chains. Cotter pin connecting links are used for large size attachment chains and on customer request.

Offset Links

An offset link is used when an odd number of chain links is required. The pin and two plates are slip fit. The fatigue strength is 35% lower than that of the chain itself.

Other Chain Types

In addition to standard single and double pitch attachment chain, two other chain types are commonly used for conveyance purposes: Hollow Pin Chain (HP) and Curved Chain (CU).

Hollow Pin Chain (HP)

This particular design of chain has a hollow bearing pin allowing for the installation of various attachments. Usually these chains are used for conveyors. The advantages of installing attachments into the hollow pin include the following:

  • The hollow pin is at the centre of articulation, and always keeps the pitch length. Regardless of whether the chain is straight or wrapping around the sprocket, the centre distance of attachments is always the same.
  • With a cross rod over two chains, the load from the attachments is distributed equally between the link plates. The chain can fully utilise its strength and will not twist.
  • It is easy to change, maintain, and adjust attachments.
  • Standard sprockets are used for the single pitch series. For double pitch series, standard sprockets for double pitch roller chain are used.

Curved Chain (CU)

Due to Tsubaki's exclusive pin and bushing structure and the wide plate to plate clearance, this roller chain has a large side flex radius. The basic dimensions of this chain are the same as ANSI standard roller chain. The ability to use ANSI standard sprockets makes curved transmission simple. Guides are required for all curved areas.