The large gears found in mining, steel, construction, off-road, marine and energy applications—massive and robust in nature—need to tackle the greatest production demands. This, in turn, means that a special emphasis must be put on the heat treating methods used to increase the wear resistance and strength properties of gears this size.

In the wide, wide world of moving parts, the gears required for the big jobs—the really big jobs—often experience big problems. Proper lubrication of these gears is paramount in industrial applications such as wind turbines, kilns, sugar mills, crushers, heavy construction, offshore drilling rigs, mining and quarrying.

In this article, the authors calculated the numerical coordinates on the tooth surfaces of spiral bevel gears and then modeled the tooth profiles using a 3-D CAD system. They then manufactured the large-sized spiral bevel gears based on a CAM process using multi-axis control and multi-tasking machine tooling. The real tooth surfaces were measured using a coordinate measuring machine and the tooth flank form errors were detected using the measured coordinates. Moreover, the gears were meshed with each other and the tooth contact patterns were investigated. As a result, the validity of this manufacturing method was confirmed.

Meeting the many challenges of large gear inspection.

Most research on micropitting is done on small-sized gears. This article examines whether those results are also applicable to larger gears.

Indexable carbide insert cutting tools for gears are nothing new. But big gears have recently become a very big business. The result is that there's been a renewed interest in carbide insert cutting tools.

Gary A. Bish, director of product design technology for Horsburgh & Scott, discusses his role as chairman of the AGMA mill gearing committee.

Quality, materials and technology continue to challenge the big gear manufacturing market.

Natural resources—minerals, coal, oil, agricultural products, etc.—are the blessings that Mother Earth confers upon the nations of the world. But it takes unnaturally large gears to extract them.

The complete product news section from the January/February 2009 issue of Gear Technology, featuring giant-sized David Brown girth gears, gear inspection up to 4.5 meters and the latest Gleason gear grinder.