Preload with a constant force

In precision, high-speed applications, a constant, uniform preload is important. To maintain the proper preload, calibrated linear springs are typically used between the bearing outer ring and housing shoulder (fig. 1). With springs, the kinematic behaviour of the bearing does not influence preload under normal operating conditions. However, a spring-loaded bearing arrangement has a lower degree of stiffness than an arrangement using axial displacement to set the preload. The spring preload method is standard for spindles used on internal grinders.

Guideline values for the most common spring-loaded bearing arrangements are listed in table 1. The values apply to single CE and ACE design bearings. For bearings in tandem arrangements, the values should be multiplied by a factor equal to the number of bearings preloaded with the spring force. The specified spring preload forces are a compromise between minimal difference in operating contact angle at the inner and outer ring raceways, and axial rigidity at high rotational speeds. Heavier preloads lead to higher operating temperatures.

For additional information, contact the SKF application engineering service.

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