Double direction angular contact thrust ball bearings are manufactured so that they have a suitable operating preload when mounted.
Bearings in the BTM series are available with different preloads:
- light preload, designation suffix DBA
- heavy preload, designation suffix DBB
The preload is obtained during manufacturing by precisely adjusting the standout of the shaft washers / inner rings relative to their housing washers / outer rings. The preload values are listed in the product table and apply to new bearings prior to mounting. Bearing components and bearing sets must be kept together as supplied and mounted in the indicated order. For additional information, refer to Markings on bearings.
Effect of interference on preload
When double direction angular contact thrust ball bearings are mounted onto a shaft seat machined to the recommended h4 diameter tolerance, a transition fit, which can be either a loose or an interference fit, will result. A loose fit will not affect preload. An interference fit increases preload. For additional information, contact the SKF application engineering service.