Spherical plain bearings, as a variant of deep groove ball bearings, distinguish themselves from traditional bearings with their unique outer ring design. Its outer diameter surface is spherical, which can fit with the concave spherical surface inside the bearing housing, thereby achieving the self-aligning function. This design enables the spherical plain bearing to demonstrate its superiority in multiple application fields.
Compared with ordinary deep groove ball bearings, spherical plain bearings are more convenient to use. This is mainly reflected in the simplicity of the loading and unloading process and its excellent self-centering ability.
In addition, the standard tolerance of this bearing follows the principle of “adding inside and subtracting outside”, that is, the inner diameter is designed with an added tolerance, thereby ensuring a light and smooth fit with the shaft. Spherical plain bearings are usually not used alone but are installed as a whole with the bearing housing. Due to the various shapes of bearing housings, they can be applied to multiple structural positions after overall coordination.
Sealed Bearings with Seat
Function: Sealed spherical plain bearings are engineered to minimize the ingress of contaminants into the bearing’s rotating surfaces while retaining lubricant within the bearing assembly.
Temperature Range: The sealing components are effective within a temperature range of –10°F to +250°F. For applications involving temperatures beyond this range, specialized seal materials are available upon request.
Heavy-Duty Spherical Plain Bearings with Seat
Design Features: Compared to the standard series, the heavy-duty series offers larger inner and outer ring diameters and increased outer ring width for the same bore diameter option. This design enhances the surface contact area, enabling the bearing to support higher loads.Load-Carrying Capacity Improvement: On average, heavy-duty spherical plain bearings provide approximately 25% greater load-carrying capacity than their standard-duty counterparts.
Extended Inner Ring Spherical Plain Bearings with Seat
For applications requiring additional axial space, we offers extended inner ring spherical plain bearings. This design eliminates the need for external spacers on both sides of the inner ring, simplifying assembly and improving system compactness.
Self-Lubricating Bearings with Seat
Self-lubricating bearings (as illustrated in Figure 6) do not require external grease or oil for lubrication. Instead, they incorporate a liner system bonded to the internal diameter of the outer ring. The inner ring or ball is manufactured from heat-treated, high-strength steel and features chrome plating on its outer diameter. This chrome plating provides a durable, low-friction surface that interfaces effectively with the liner system. These bearings are also equipped with seals to prevent contamination ingress. Self-lubricating bearings are particularly suitable for applications involving unidirectional loading, as such conditions prevent conventional lubricants from migrating into the load zone, whereas the integrated liner ensures consistent lubrication under load.
Angular Contact Bearings with Seat
Angular contact bearings are ideally suited for applications involving unidirectional thrust loads. Under reversed thrust loading, these bearings may separate axially. Therefore, for applications subject to alternating thrust loads, it is recommended to use a matched pair of angular contact bearings. For applications requiring greater moment flexibility, a face-to-face (“DF”) arrangement is advised. Conversely, for applications demanding high moment rigidity, a back-to-back (“DB”) configuration is preferred.
Fractured Outer Ring Assembly Process
As part of the manufacturing process for spherical plain bearings, the outer ring is split (fractured) to facilitate assembly. At National Precision, high-quality steel is used, and the bearing rings undergo a controlled heat treatment process to achieve a hardness of Rockwell C 58. The bearing rings exhibit a 0.2% yield strength of 320,000 psi and an ultimate tensile strength of 450,000 psi. With precise assembly controls, the inner ring can be press-fitted into the fractured outer ring .
Dimensional Tolerance
Except for self-lubricating bearings, all outer rings and balls are treated with a phosphate coating for corrosion resistance. The spherical surfaces are further coated with molybdenum disulfide. The nominal thickness of this dry-film coating is 0.0002 inches. Depending on the internal clearance or preload between the outer ring and the ball, the fractured outer ring may slightly open prior to installation into the housing. Consequently, all dimensional tolerances specified in the catalog apply to bearing components prior to outer ring fracturing and application of the dry-film coating. LZ spherical plain bearings meet or exceed the requirements of ISO 12240-1 and ANSI/ABMA Std. 22.2.