PB spherical plain bearings use a steel/bronze sliding interface rather than a steel/steel or PTFE-lined contact. They are useful when a metallic liner is preferred, motion is slow, and a planned lubrication route can be maintained.
PB series construction
The PB family combines a spherical inner ring with a bronze-lined outer-ring sliding surface. The series is greaseable, so oil grooves, grease access and the maintenance plan remain part of the joint design. The current range covers PB5 through PB30.
PB series technical data
| Part No. | d mm | D mm | B mm | C mm | d1 mm | Cr kN | C0r kN | Weight g |
|---|---|---|---|---|---|---|---|---|
| EP-PB5 | 5 | 16 | 8 | 6 | 7.7 | 3.3 | 7.8 | 9 |
| EP-PB6 | 6 | 18 | 9 | 6.75 | 9 | 4.3 | 9.8 | 13 |
| EP-PB8 | 8 | 22 | 12 | 9 | 10.4 | 6.8 | 16 | 24 |
| EP-PB10 | 10 | 26 | 14 | 10.5 | 12.9 | 10 | 23 | 39 |
| EP-PB12 | 12 | 30 | 16 | 12 | 15.4 | 13 | 31 | 58 |
| EP-PB14 | 14 | 34 | 19 | 13.5 | 16.9 | 17 | 40 | 84 |
| EP-PB16 | 16 | 38 | 21 | 15 | 19.4 | 21 | 50 | 111 |
| EP-PB18 | 18 | 42 | 23 | 16.5 | 21.9 | 26 | 61 | 160 |
| EP-PB20 | 20 | 46 | 25 | 18 | 24.4 | 31 | 73 | 210 |
| EP-PB22 | 22 | 50 | 28 | 20 | 25.8 | 38 | 88 | 260 |
| EP-PB25 | 25 | 56 | 31 | 22 | 29.6 | 47 | 110 | 390 |
| EP-PB28 | 28 | 62 | 35 | 25 | 32.3 | 59 | 138 | 530 |
| EP-PB30 | 30 | 66 | 37 | 25 | 34.8 | 63 | 148 | 610 |
What the bronze liner changes
A bronze sliding surface offers a different wear and lubrication behavior from the other families in the catalogue. It remains a serviceable metallic sliding pair, so it should not be treated as equivalent to a dry-running PTFE maintenance-free bearing.
Typical applications
- Low-speed pivoting machinery where a grease route is already part of routine maintenance.
- Agricultural or construction mechanisms using compact pivot joints.
- Industrial supports and linkages where a bronze sliding interface is specified by the machine design.
PB vs GE..C vs GE..E
| Feature | PB | GE..C | GE..E / ES |
|---|---|---|---|
| Sliding pair | Steel / bronze | Steel / PTFE composite | Steel / steel |
| Routine relubrication | Required | Not required by liner | Required |
| Sealing in reference family | Open | Open | Open; 2RS available in ES family |
| Primary decision | Metallic bronze liner | Maintenance-free compact joint | Conventional greaseable radial joint |
Cross-reference and replacement
A PB marking may have brand-specific equivalents or near-equivalents, but replacement should still be checked by bore, outside diameter, width, liner type and lubrication arrangement. Use the Cross-Reference tool as an identification lead rather than automatic interchange approval.
How the PB size range develops
The PB series grows from a 5 mm bore to 30 mm while outside diameter, width and load rating increase with size. That makes the table useful for early packaging studies, but the designer should not select only from the highest C0r that fits. Pin diameter, housing stiffness, articulation, grease access and bearing width all belong in the same decision.
Lubrication and wear behavior
A bronze liner is a metallic sliding interface, so the condition of the lubricant strongly affects service. Fresh grease separates the sliding surfaces and helps carry contamination away. Infrequent service, contaminated grease or a blocked lubrication path can create accelerated scoring. When replacing a PB bearing, inspect both the liner and the spherical inner surface; damage on one usually means the mating surface has also been affected.
What to inspect on an old PB joint
- Bronze discoloration, scoring or transfer material on the sliding surface.
- Groove and lubrication-hole blockage.
- Pin corrosion or fretting at the inner-ring bore.
- Housing wear that lets the outer ring move in the bore.
- Shoulder contact that may be limiting articulation.
Why PB is not simply a lower-cost substitute
The PB family represents a distinct maintenance and material choice. If the machine specification was written around PTFE maintenance-free operation, moving to bronze changes service requirements. If it was written around a greaseable steel/steel joint, bronze changes the sliding pair and wear behavior. Use PB because the bronze interface fits the duty, not merely because the dimensions are close.
Need a PB size checked?
Send the old marking and d / D / B / C measurements. EVER POWER can compare the PB range and alternative constructions.
