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Expertise 10.09.2018

Drive chains, connecting links and reducer links


Chains have been used for propulsion for decades. Hence the logical name, drive chain. Since 2017, you can find drive chains, locking links and drop links in our range at Dema.

Drive chains

As mentioned earlier, chains are used to drive, or rather to transmit power. But this is not the only function of a chain. Transport is another and this chain is called... yes indeed... the conveyor chain. But let's stick to drive chains this time because there's a lot to be said about them. Conveyor chains will be explained at another time.

Different types

Roller chain

One of the most common drive chains is the roller chain. This chain consists of internal and external links of which the internal links consist of plates with hollow bushes pressed into them. Around these bushings is a roller that can rotate freely. The outer links consist of plates in which pins are pressed into these hollow bushings. If you use external links with one internal link, this is called a single or simplex chain. If you use external links with longer pins, you can use several internal links next to each other, giving you a wider and stronger chain. If these inner links are double, this is called a duplex chain. If it is triple, it is called a triplex chain. With these chains, extra plates are placed between the internal links to increase the strength.

Determining the type

A number of dimensions are important in determining the type of roller chain. Firstly, the pitch (p), which is the centre-to-centre measurement of both the pins and the bushings. Usually this is expressed in inch sizes in tables, because chains were originally made according to British Standard (BS). The internal link width (b1) and roller diameter (d1) are also two important sizes, as these sizes must match the sprocket used. The plate thickness (T) and the height (h2) of the links are also decisive. Finally, the pin diameter (d2) can indicate the type, especially if a chain needs to be lengthened.

Long-distance chain

For low-speed and light-load applications, there is a chain with a pitch dimension that is twice as long as the standard. All other sizes are the same as the standard chain. The big advantage is that this chain is lighter and can run on the same sprockets. A long pitch chain is also often used as a transport chain.

Side bow chain

Most chains are quite stiff in the sideways direction. This is because the slack in the chain is minimal. However, it is important for certain applications that the chain can make a turn and this can be achieved in two ways.

1. The thin pin

By inserting a thinner pin into the bush, there is enough play to allow the links to move relative to each other.

2. The curved pin

The rounded pin is used in the more expensive chains. Due to the sub-optimal construction, this type of chain is less strong and requires good lubrication.

Kinds of links

To make a customized chain, there are different links available. At Dema, we have the locking link with slider (SCL) or pin (CCL) and the half link or drop link (OL) in stock in both normal and reinforced versions.


During the standardisation process, two different standards remained, the European standard, DIN/ISO (DIN 8187, ISO 606) and the American standard, ANSI (DIN 8188). By checking the aforementioned dimensions against tables, you can therefore determine which chain is in use. For new applications, the DIN/ISO version is recommended because it is the best available in Europe.

Would you like more information?

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