Girth Gears

Investment in the most advanced machining and gear cutting technology, along with development of new materials used in the manufacturing process, has enabled David Brown to rewrite the rule book on girth gears.

Industrial girth gear

The result is a radical reduction in lead times and the ability to achieve standards of accuracy to AGMA Level 13 and beyond. Custom-designed multi-axis CNC machinery dedicated to mill gear production, temperature-controlled gear-cutting facilities, automated and optimised design and a unique carburising capability alongside induction hardening and tempering furnaces ensure David Brown retains its position at the industry's leading edge.

Primary Applications

AG/SAG Mills – Autogenous and semi-autogenous mills generally operate with large diameter gears of >7m. These are generally used in ‘hard rock’ mining applications, to extract copper, gold, platinum and other precious metals or diamonds. David Brown has a unique capability to machine up to 14m diameter, high integrity girth gears to AGMA level 13 or beyond. David Brown recommends two technologies for these applications, which require the highest integrity in materials and precision machining.

  • Cast girth gears
  • Fabricated Girth Gears – David Brown uses a unique welding process to fabricate large gears to ensure material hardnesses are maintained but with the highest weld integrity demanded by these heavy duty applications. Fabricated gear technology, provides shortened lead times for critical project time lines but retains precision engineered excellence.

Ball Mills and Rod Mills

Often also referred to as tube mills, these horizontal mills are used in a wide number of applications such as:

  • Pelletizers for iron ore processing
  • Mineral processing in ‘hard rock’ mining applications
  • Primary grinding or ‘raw mill’ grinding in cement manufacture
  • Coal pulverisation in thermal power plants
  • Limestone grinding to produce lime slurry for Flue Gas Desulphurisation (FGD) plants in thermal power stations

Many of these mills will use girth gears of <7m and in some instances, application duties are relatively light. In these instances, David Brown can offer a lower duty girth gears matched closely with the application needs, but still ensuring the highest reliability and durability at a price to suit. David Brown recommends the following technologies:

  • Traditional casting and machining techniques to suit most light to medium duty applications.
  • Fabricated gears, with advantages in shorter lead-time, combined with greater material integrity for medium duty applications.

Kiln Drives and Cooler Drives – widely used in the cement manufacturing industry and also in iron production, these drives will generally utilise smaller diameter girth gears of <6m. David Brown can offer new and replacement girth gears for these applications:

  • Traditional casting and machining techniques.
  • Fabricated gears, with advantages in shorter lead-time

Mill drive reduction boxes – for all mill types, from AG/SAG mills to kilns and coolers, David Brown offers mill drive primary reduction gear units in both single and double reduction configuration depending on space envelope constraints. Mill drives are offered with barring drives and inching capability as required.

Powerful Brands

Screw Jack Products Benzlers Accudrive Products Cone Drive Benzlers and Cone Drive are sister companies of David Brown, also part of the Textron family. Working together enables us to offer a full range of gear products and provide global services and support.