| 摘要 |
PROBLEM TO BE SOLVED: To realize a double row ball bearing device capable of stably imparting a desirable pre-load even in of a small device. SOLUTION: The number of active coils of a compression coil spring 20 for giving a pre-load is set at a three or less so as to reduce the axial directional dimension of the compression coil spring 20. The relation between the axial directional length L20 of the compression coil spring 20 and the elastic force thereof is measured to obtain a value of the axial directional length L20 capable of obtaining the elastic force for obtaining a required pre-load. A spacer 18a of a pair of spacers 18a and 18b is selected among plural spacers having a different axial directional length, and assembled between the compression coil spring 20 and a second outer ring 15 so as to regulate the axial directional length L20 of the compression coil spring 20 at the described value. As a result, even the compression coil spring 20 having three or less of the number of active coils and easy to generate the unevenness of the elastic characteristic can stably impart the pre-load.
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