Publication explains factors for selecting bearings for gearboxes

RP news wires

The process of selecting bearings for all gearbox types is set to become more straightforward, structured and transparent with the launch of a new free publication, “Rolling Bearings for Industrial Gearboxes”, from NSK.

NSK supplies bearings for all aspects of gearbox operation, and the new publication reflects this in the breadth of subject matter, which is designed to help users understand all the key areas that must be considered when selecting particular bearing types for converting and translating motion.

Rolling Bearings for gearboxes extends to 31 pages and is divided into eight sections. Section one gives an overview of all current gear designs – worm, hypoid bevel, epicyclics, spur and bevel types – outlining their advantages and disadvantages. Section two then moves on to discuss the numerous factors that affect bearing performance in gearboxes; factors such as load, speed, friction, environment, shaft arrangements, lubrication, assembly space – and many more. All of these are considered individually with guidance as to the relevant questions to ask regarding each specific factor.

Section three deals with bearing types and their characteristics; here the user is helped by simple-to-use graphics; the first listing bearing types, and their capabilities, as regards loads, speeds, misalignment, and lubrication medium. The second graphic extends this information with an easy-to-read table that gives at-a-glance reference for the suitability of specific bearing types for a given set of operating parameters.

The following sections, four and five, are the most technical of the publication. The former looks at bearing positions inside gearboxes; it considers support by fixed and floating bearings, adjusted bearing support and floating bearing support. Here again graphics are used for illustration; this time in the form of a two- page table that shows most types of bearing arrangements, provides comments on them, and gives fields of application.

Next is a section that considers bearing life; this includes details on NSK’s latest optimized methods and calculation procedures such as the ABLE-Forecaster (Advanced Bearing Life Equation) software, and STIFF, a program developed by NSK that considers important parameters such as deformation of shafts and housings, misalignment, displacement of the bearing itself (and adjacent bearings), as well as internal operating cycles.

The final three sections devote seven pages to materials, lubrication, the consequences of lack of it, and proper dimensioning of bearings. As regards materials, the publication highlights NSK’s development of ground-breaking Super TF steel. This material sets new benchmarks for reliable operation in contaminated operating conditions, or applications where high stress factors are encountered. The new material can be employed in a wide range of bearing types.

The penultimate lubrication section provides a useful calculation of the quantity of oil required for optimum bearing performance; it considers whether oil or grease is best; and concludes with a graphic table giving details of damage caused by lubrication problems.

Completing what is a very comprehensive, concise publication, the final section deals with Proper Dimensioning of bearings. It gives procedures for proper fit selection, and tables detailing fits for radial bearings with housings.

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