Versatile girth gears

Electrical switching & drive systems & components

4th Quarter 2014 Electrical switching & drive systems & components

SEW-Eurodrive has developed a flexible range of girth gears to assist with the transfer of drive torque from the gearmotor to the rotary cylinder, thereby simplifying manufacturing, transport and installation. General manager for sales and engineering, Conrad Pilger notes that the company provides entire drive packages, including girth gears. This includes the basic gear units, as well as the drive pinions, a base, housing, and any other parts that are required.

“When supplying girth gears, the process involves machine designers and users in order to determine the best technical and economic solution for the desired application. SEW-Eurodrive specialists support the process from the consulting stage right through to the assembly and start-up,” he explains.

Girth gears are used to drive large, rotating systems such as dryers, rotary kilns or horizontal mills. They are installed around the circumference of these systems and transfer the drive torque from the gear motor to the rotary cylinder. Pilger states that traditional girth gears generally consist of two to four segments that are assembled together for processing. “This requires large and expensive machines for production, handling and heat treatment. The size of component parts also creates disadvantages with regard to casting and heat treatment.”

In contrast, SEW-Eurodrive girth gears are split into several identical segments in order to keep the component parts short and easy to handle. “We use austempered ductile iron (ADI) for girth gears, which boasts unmatched tensile strength compared to other materials,” he adds.

The decreased size of the girth gear segments reduces the cost for the scrapping of blanks. These blanks can be used without additional welding or oversizing. In addition the use of ADI lowers the weight of the girth gears and features an above average contact fatigue strength, thanks to its cold work hardening properties.

Pilger observes: “These cold work hardening properties, when combined with an appropriate girth gear size, allow for a more compact and lighter gear design than traditional solutions. This low weight is important for the handling and assembly of the girth gear, as well as for achieving circumferential velocity.”

The segmented design simplifies handling at the construction site. Due to this design, there is no need for special transportation. The segmented design also guarantees an initial pitch accuracy of ISO 8, which minimises vibrations. Pilger points out that a benefit of the segmented design is that if a segment or part is damaged, it can easily be replaced without the need for dismantling the entire ring. In addition, with the correct dimensioning, alignment, load and lubrication, an ADI girth gear is almost wear-free.

The SEW-Eurodrive girth gears are suitable for use in a variety of sectors. These include the energy sector, the pulp and paper industry, mining, the steel sector, and the cement industry.

For more information contact René Rose, SEW-Eurodrive, +27 (0)11 248 7000, [email protected], www.sew.co.za

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Tel:	+27 11 248 7000
Fax:	+27 11 248 7289
Email:	[email protected]
www:	www.sew-eurodrive.co.za
Articles:	More information and articles about SEW-EURODRIVE

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Electrical switching & drive systems & components

Versatile girth gears

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