Selecting the correct chain is key to transmission component reliability, says Chris Rice, and by taking all factors into account, a reliability figure of 100% is achievable.

Roller chain has to perform as a highly efficient and reliable component of a transmission system; however, what constitutes 'reliable' varies greatly from company to company, and from engineer to engineer. There are many factors that influence chain performance and by taking each one into account, and addressing it through correct specification and maintenance, Tsubaki believes that 100% reliability is achievable. Reliability is becoming more important in modern manufacturing as faster machine speeds and higher production capacities result in short, infrequent maintenance windows and increasingly expensive downtime.

Fitting quality chains and sprockets that are appropriate to the task in hand has to be the first step in increasing reliability and eliminating unplanned stoppages due to chain failure.

Chain elongation due to component wear, fatigue failure (particularly common on connecting links), corrosion, and overload conditions are all possible causes of chain failure.

Fitting a quality engineered high performance chain has been found to be an essential requisite to offering the best line of resistance to these routine but demanding conditions for a roller chain.

Chain quality begins with the manufacturing process, Tsubaki has been a pioneer of chain research and development for close to a Century, and believes that without doubt, the use of high quality materials and manufacturing processes is the foundation of long term transmission reliability.

The company exercises total 100% control over the grade of raw materials used, the critical heat treatment process and surface hardening of components, through to the assembly of a chain drive to ensure consistency of the mechanical properties throughout all components.

Good design and continuous innovation is also crucial to reliability.

Through extensive research and analysis of any chain failures it found, Tsubaki identified that the connecting links are often the weakest component and subject to fatigue failure, due to their slip fit.

Tsubaki then developed the patented ring coining process to overcome this problem, ensuring that the connecting link in Tsubaki roller chain is as strong and durable as any other, providing 100% fatigue strength throughout the whole drive and minimising the possibility of unexpected breakages.

* Overloading - in operation, overload situations are sometimes unavoidable due to other equipment failing or process inconsistencies, and a chain cannot be totally resistant, but high quality components ensure the chain is less likely to fail in an overload situation.

In the event it is important to know that an overload situation has occurred as the chain may look fine on the surface but might be damaged internally.

A symptom such as bearing pin rotation is a good sign.

Tsubaki has thought of this as well, and on the BS drive chain has designed indicators on the rivet pin that will show rotation and so action can be taken before failure occurs.

Maintaining chains correctly is another cornerstone of reliability, effective lubrication being first on the list.

Lubrication is essential for avoiding excessive chain wear, which results in reduced chain performance and eventual seizing of components.

Tsubaki know that in an ideal world, every engineer would ensure chains are properly lubricated but understand that in reality, operating conditions and pressures of production output do not always make this practical.

* Lubrication - Lambda Lube free was Tsubaki's answer to chain applications where ideal lubrication was not possible or practical.

The first generation of Lambda was also the first self lubricating chain available on the market and the company has continued its technical development ever since.

Within heat and load tolerance Lambda is always perfectly lubricated so can greatly extend chain life.

Chain is inevitably a wear component in a transmission system and accurate prediction of replacement times is crucial.

The linear wear pattern of Lambda makes it possible to predict when the chain will need replacing with a high degree of accuracy.

Roller chain with irregular lubrication will display a sporadic wear pattern and so be difficult to predict, as will poor quality chain with inconsistent material and construction quality.

The material consistency and production accuracy in Tsubaki standard chain make it far easier to measure wear and schedule replacements with confidence.

Simple chain gauges have been developed to track the wear, and an occasional check is all that is required, but it is a major weapon in the fight to ensure maintenance is kept at a required minimum and cost is tightly controlled.

* Environment considerations - operating conditions such as dusty, wet or dirty conditions and corrosive environments can reduce chain life and therefore operating performance.

Tsubaki have many off the shelf and application specific products to improve the life of chains in such environments.

Plenty of communication between the manufacturer and the applications engineer will ensure that the right chain selection is made.

The end result is that with the right quality, specification and care, 100 per cent reliability is possible.

* About the author - Chris Rice is with Tsubaki UK.