A single-row angular contact ball bearing is generally applied to support the main shaft in machining tools. Although it is categorized as radial bearing, axial load must be applied as a preload to support the radial load by increasing the rigidity of the bearing. There are two kinds of preloading methods: position preloading and constant-pressure preloading. The position preloading is commonly because of the simplicity of the required mechanism. However, this method is sensitive to dimensional changes. Therefore, in this method, the amount of preload changes when dimensional change, such as thermal expansion, occurs owing to heat generation by the bearing. In this study, the axial load applied to the single-row angular contact ball bearings 7306 under operation with a fixed position preload was measured. As a result, it became clear that the amount of preload during rotation increases by about 30% of the initial amount of preload. In addition, “preload loss” occurs after several hours of rotation; it will not occur if preloading is repeated with an axial load smaller than the previous load.

The purpose of our research is to install the handrail in the sliding doors used in hospitals and nursing facilities to support the senior and handicapped persons to walk by themselves. The semi-automatic lifting equipment is utilized for the storable handrail to make sure the bad health persons are able to open the door using a weak force. In this study, stress analysis and fatigue experiment were conducted to confirm the safety during 20 years. Also, the FEM results showed that the maximum stress is small enough. And, the experimental observation confirmed that no significant damage can be seen by the compressive and alternative stress.