The dynamic clearance of rolling element bearings is higher than that of journal bearings?

The statement is accurate; the dynamic clearance of rolling element bearings is generally lower than that of journal bearings. This is primarily due to the different mechanics involved in how these types of bearings operate.

Rolling element bearings rely on rolling motion between the balls or rollers and the raceways. This design typically results in a tighter fit and less clearance during operation because the rolling elements maintain a specific contact pattern with minimal displacement, thereby reducing the gap or clearance required for effective lubrication and operation.

In contrast, journal bearings function based on sliding motion, where a shaft rotates within a sleeve or bushing. These bearings often require greater dynamic clearance to accommodate variations in load, thermal expansion, and other factors. This sliding mechanism inherently involves more clearance than rolling bearings, to ensure smooth operation and prevent contact between the moving parts.

Therefore, understanding that rolling element bearings operate with higher precision and tighter tolerances clarifies why the statement regarding dynamic clearance is accurate.