Needle roller bearings

Frequently asked questions — Needle Roller Bearings

• When should I choose a needle roller bearing rather than a ball bearing?

  The needle roller bearing is the preferred technical solution where the available radial space is constrained, thanks to its high load capacity within a minimal radial section. It should be noted that its limiting speed is significantly lower than that of a ball bearing of equivalent diameter, typically below 30% of the latter. It is therefore only recommended where dimensional constraints take precedence over high-speed rotation requirements.
• What is the technical difference between HK and BK needle bushings?

  HK and BK needle bushings are both designed for press-fit installation into a bore machined to H7 precision. The fundamental distinction lies in their structural design: the HK bushing features a stamped base, whereas the BK bushing is without this base. The choice between these two variants depends on whether or not the end of the housing needs to be closed when fitted into the bore.
• Do I need to use an inner ring with an NK or RNA bearing?

  The NK and RNA bearing series natively incorporate a ground inner ring. This configuration is specifically suited to applications where the shaft supporting the bearing is not hardened. The use of this inner ring ensures an adequate and durable raceway surface for the needles in mechanical environments where the shaft alone would not provide the required hardness characteristics.
• How should needle bushings be correctly fitted to avoid press-fit problems?

  The fitting of needle bushings is a critical step in ensuring proper operation of the mechanism. The receiving bore must comply with H7 precision. For variants requiring a higher load capacity, increased precision of type P6 is required. Strict compliance with these tolerances is essential to ensure an adequate fit and to prevent any operational defects when the bearing is commissioned.
• What are the specific features of HF and HFL drawn cup needle roller clutches?

  Drawn cup needle roller clutches, identified by the HF and HFL series, differ from conventional bearings by incorporating a mechanical anti-reverse function. These components allow power transmission in one direction of rotation only, while permitting free movement in the opposite direction. This characteristic makes them suitable for applications requiring integrated one-way locking within a reduced radial envelope.