When installing an anti-friction bearing, under which condition should the sleeve and hammer method be used?

The correct choice focuses on the use of a sleeve made of soft material. When installing an anti-friction bearing using the sleeve and hammer method, employing a sleeve constructed from a soft material is crucial because it helps to prevent damage to the bearing surfaces. The soft material can absorb some of the impact from the hammer strikes and distribute the force more evenly across the bearing, reducing the risk of deformation or surface damage that might occur if a harder material were used. This method is particularly important in ensuring that the integrity of the bearing is maintained during installation, as improperly installed bearings can lead to premature wear and failure.

Considering the other options, while they each describe aspects of the installation process, they do not specifically address the need for the sleeve material. For instance, using a hammer of moderate weight is important for controlling the force applied, and lubricating the bearing can facilitate easier installation and improve performance, but these factors do not directly relate to the protective aspect of the sleeve material during the installation procedure. Similarly, while operating temperature may affect some installation conditions, it is the characteristics of the sleeve material that are most critical for preventing damage during the bearing installation process.