Shaft power components

Chain and sprocket selection for power transmission

Fourth Quarter 2022 Shaft power components

BMG’s total plant management solutions encompass a technical advisory service for maintenance programmes that includes correct chain and sprocket selection, which is a critical factor in any power transmission system.

“We at BMG believe that by investing in quality branded power transmission chain, significant cost savings are achieved. Although the global trend is focused towards cost reduction to protect a customer’s plant availability and improve margins, it is important when it comes to procurement for maintenance that the total cost of ownership is considered above initial cost savings,” says group sales development manager, Carlo Beukes. “While some components appear to be the cheaper solution in the short term, they can easily prove expensive if regular maintenance, repair and replacement work is necessary. The key to real-world cost savings in power transmission lies in extended, low-maintenance operating cycles.

“We hear too often that when a business cuts costs, that this has been achieved by sourcing cheaper components during procurement. However, while these savings may appear advantageous in the short term, the only real way to gauge success, is to look at the total cost of the product throughout its service life. Cost of installation, maintenance requirements, downtime caused by early failure and replacement, are all hidden costs that accumulate when a budget component is specified. Our concern is that an engineer’s recommendation for a particular quality component suitable for specific performance requirements is disregarded in favour of an inferior product because of its lower cost.”

He adds that power transmission chain in particular is an area where procurement managers feel they can reduce costs by specifying budget chains. Because chain technology is perceived to be simple, with few outward differences between brands, it would be easy to assume that this is where budget components may be justified. However, the truth is very different. A chain which has been correctly specified and manufactured to stringent quality standards, using quality materials, earns its initial procurement cost back many times over when compared to a cheap, inferior quality chain.

Initial procurement is just one cost that needs to be considered when determining the TCO of power transmission chain. After procurement, there is installation time – which can vary greatly between products – as well as necessary maintenance requirements, including lubrication or the removal of links due to elongation.

The cost of replacement and plant downtime are also important considerations. A chain with a reduced service life will need more frequent replacing. This not only causes downtime, but also introduces a further round of procurement into the cost equation.

BMG offers a site visit service prior to component specification, to ensure an accurate TCO estimate. BMG’s technical team advises on the selection of the correct component for each application, and the appropriate installation and usage for optimum performance and improved safety standards. For extended service life and minimal maintenance requirements, correct lubrication methods and dust prevention care are also critical.

Tsubaki roller, engineering and speciality chains, available from BMG’s power transmission division, are designed for maximum performance in heavy-duty drive and conveying applications – particularly those operations that are subjected to both heavy and shock loads. Tsubaki chains have a special pin surface treatment to prevent pitting corrosion and offer extended service life, even in environments where there is dirt, moisture and acidity. Hardened pins permit substantial increases in acceptable load over standard chain. These chains, which have increased shock resistance and higher tensile strength, meet the demands of tough operating conditions and reduce the costs of chain replacement and work stoppage time.

Tsubaki chain, which is available exclusively throughout southern Africa from BMG, has been designed for efficient use, improved productivity, low maintenance requirements, and extended service life in many industries, including mining.

The range includes Tsubaki engineering class SJ3 sealed joint chains with improved sealing technology, designed to improve the reliability of many mechanical components exposed to harsh environments.

“An important feature of the Tsubaki SJ3 series is that extended bushing barrier seals prevent abrasive materials from entering and attacking chain joints, thus reducing wear and extending service life of chains,” explains Tsubaki product manager, Gavin Kirsten. “Tsubaki’s patented SJ3 labyrinth structure keeps each pin and bushing assembly free and clear of contaminants. This multi-seal combination inhibits fine particulates from entering critical bearing areas.”

The Tsubaki SJ3 design comprises three distinct seals. Although independent of one another, the seals complement each other to provide secure bushing and pin protection. The first seal is an industry standard extended bushing that limits the clearance between the ends of the bushings and the mating sidebars. This provides a highly effective first layer of protection.

The second seal is a polymer face seal placed around the extended bushings. These polymer face seals are available in various performance materials and can withstand temperatures up to 200°C. The final seal is a patented labyrinth seal that inhibits any remaining fine particles from entering the critical bearing area. The labyrinth is formed by a stainless steel ring attached to the pin, which rotates freely in a finely crafted groove in the bushing.

BMG’s durable Tsubaki SJ3 series has been designed for dependable operation in harsh environments, including mining, cement, paper, sugar, grain and asphalt applications. Successful installations of Tsubaki’s SJ3 technology include a synthetic gypsum feeder breaker, where the user was struggling to get more than four months of use from an OEM chain. Since the installation of SJ3 chain with stainless steel pins, service life of the chain has extended to more than 36 months.

In another application the user of a carbon coke bucket elevator initially installed a non-sealed elevator chain that lasted 12 months, and then a non-sealed chain with hardened stainless steel pins, which lasted double that period. Lifespan of the chain increased to 56 months after the installation of a Tsubaki SJ3 chain; and the chain of a potash feeder with packed joints that kinked and eventually failed was replaced with a Tsubaki SJ3 chain with stainless steel pins, and component lifespan trebled. In a fly ash bucket elevator, standard elevator chain lasted approximately 12 months. Service life of the chain has increased to more than 36 months since the installation of Tsubaki SJ3 chain.

BMG’s Tsubaki G7 ANSI RS roller chain offers double the wear life of the previous 6th generation chain and can withstand an increase of 33% in kW ratings, improved productivity and reduced downtime.

The G7 series has solid lube groove bushings, designed to retain lubrication and increase the wear life of the chain. The patented ring coin connecting link ensures that the chain can be specified to its full chain capacity. This process increases the strength of the link plate around the pin holes to make sure the link retains the same high strength and wear resistance as the rest of the chain. Other features of this pre-loaded lubricated chain include wide waist link plates, shot peened rollers, higher grade pins and oriented link plates.

There is a significant reduction in the risk of chain breakage because the specially selected steel alloy has undergone effective heat treatment. Since there is no need for external lubrication, the chain is kept cleaner, making it easier to specify and install.

As an advancement to BMG’s power transmission range, the company has improved the quality of the complete range of Fenner sprockets. The teeth of every Fenner sprocket are induction hardened during manufacture, which leads to far longer chain life (dark discolouration of the teeth indicates induction hardening). This procedure makes the Fenner sprocket superior to any other standard range of sprockets on the local market. The teeth profile remains intact for longer, which reduces strain on the chain and therefore less elongation.


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