Needle roller bearings are essentially cylindrical roller bearings except that their cylindrical rollers have a length 3 to 10 times their diameter (versus less a length less than 3 times their diameter). Therefore, the ratio of the bearing outside diameter to the inscribed circle diameter is small, and they have a rather high radial load capacity.
Precision needle roller bearing have a one-piece, channel-shaped outer race of bearing quality steel, and are heat treated to provide maximum bearing capacity and life. Precision grinding assures optimum roller load distribution within the bearing.
The heavy duty race permits assembly into housings with either a slip fit or a press fit, as required by the application. Single row bearings are available in inch dimensions and metric dimensions, some double row metric sizes are available.
Precision roller bearings offer the following advantages:
- Very high capacity
- Moderate cross section
- Permits installation in split housings
- Long, no maintenance service life when properly lubricated
- Excellent service at high rotational speeds
- Easy installation
- Superior anti-friction performance
- Excellent shock resistance
Precision needle roller bearings have a steel cage which provides inward retention of the needle rollers. The design provides maximum cage strength consistent with the long life requirements.
The retainer is radially located by the outer race flange and contacts the rollers only near the ends and at the roller pitch diameter, where accurate guidance is obtained with minimum effort. Pitch line guidance at the roller ends results in minimum stress on the retainer and assures roller stability. Contact area and force required for effective roller guidance are reduced, thus minimizing drag between retainer and rollers. The design leaves the center area of the retainer open to enhance circulation of lubricant.
For more information, CAD models and AST’s catalogue on precision roller bearings, follow this link. For more information on this, or any bearing-related product, click here to contact an AST engineer.