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If you try to put a rivet in an inner link of a roller chain, you realize that it works only with force. Although the nominal chain pitch of the DIN ISO 606 standard should be the same, here the theory differs from practice. Why there are obviously two graduation measures in a roller chain and what that means for the user, knows the Propulsion specialist Tsubaki.

The answer lies in the task that the bolt-bushing connection has to fulfill: it forms the chain link and as such has to be movable. This is made possible by a joint play. Through the game turn the axis centers of bolt and bushing are offset in a chain under load to each other. Thus, there are two individual graduation measures in the chain, in order to finally reach the nominal graduation in the DIN ISO 606 standard.

The structure of a roller chain makes this clear: It consists of inner and outer plates, rollers, bushings and bolts. Inner links, bushings and rollers form the inner links, outer links and bolts the outer links. Inner and outer links result in alternately installed the roller chain.

What's up with the chain pitch?

In the DIN ISO 606 the dimensions are listed to the established ANSI (American) standard and European standard chains. The size of a chain is defined by the chain pitch in both standards. For example, a roller chain of the designation 08B made according to European standards has a pitch of 12,7 mm. If now this pitch for the inner link (bush center to bush center 12,7 mm) and the max. permissible joint gap of 0,05 mm (minimum bushing inside diameter 4,50 mm, max bolt diameter 4,45 mm) is granted, for the outer link a structural correction of the individual pitch is required, so that the tensioned chain later equidistant in the pitch circle of the sprocket.

For a majority of users, this information is irrelevant. For the chain manufacturer, the Einzelteilungsmaß is of course very important and for the user knowledge about it then relevant, for example, if extended bolts are used for attaching Beistellteilen with a narrow fit. It is important to pay attention to which pair of bolts that Beistellteile to be attached. It makes sense to use only the pair of bolts of an outer link and not the bolts of two outer links. Because the articular surfaces wear out inevitably during operation of the chain, so that the bolt centers always further away from the socket centers. If one measures the division of the individual links in an already in use chain with advanced wear, the Einzelteilungsmaß the inner links is usually still very close to the nominal dimension, while the Einzelteilungsmaße the outer plates exceed the nominal size recognizable. Thus, the power transmission has been partially relocated to the Beistellteile.

Note the retro-fit

If chains from different manufacturers are used in the course of an exchange, it is advisable to check the accessories for compatibility and possibly even to adjust them. The leading manufacturer of powertrain products Tsubaki always pays attention when it comes to such a chain change. For 100 years, the company has been successfully implementing a wide variety of customer requirements, resulting in countless success stories that ultimately save TCOs of the order of magnitude. And so it is not surprising that end users often switch even in the described application on a premium chain of the drive specialist, if the previous chain had performance problems.
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