A road map is presented listing critical considerations and optimal use of materials and methods in the construction of large gears. The purpose of any gear mesh is to transmit rotary motion and torque from one location to another at a consistent rate. Various rating practices from AGMA, ISO and others go into great detail about the tooth proportions, accuracy requirements, material selection and cutting methods to produce a tooth that satisfies the requirements of the application. However, standards do not provide all the information necessary to ensure the torque at the gear tooth is actually moved to the piece of driven equipment, i.e.- gear blank design. In most enclosed drive applications, a disk of the same face with a bore and keyway is sufficient. Yet, in the realm of large gears - defined as three meters (10 feet) in diameter and above - a solid blank fulfills the design engineer's maxim of making the part difficult to manufacture and impossible to install. Blank design needs to be driven by the application and the range of materials available to ensure that sufficient stress capacity is available at the teeth - as well as the ability to connect with the driven equipment. This paper covers these issues in a specific area of use: gearing for cylindrical grinding mills and kilns.
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