Hydraulic cylinders put spherical plain bearings in a demanding combination of high load, low-speed articulation and changing alignment. The bearing may sit at the cylinder base, the rod-end connection or another clevis joint, and the machine load path can be concentrated through a relatively small pin.
Where the bearing sits in a hydraulic cylinder assembly
- Base or clevis mount: carries reaction force between the cylinder body and machine structure.
- Rod-end connection: transmits cylinder force into the moving linkage.
- Trunnion or auxiliary pivot: accommodates motion while the cylinder changes angle through the stroke.
Start with force, then evaluate static rating
The design load comes from the hydraulic system and machine geometry. If a project design basis applies a static safety factor of 3 to a 100 kN joint load, the resulting target would be 300 kN. In the current range, EP-GEG25ES has a C0r value of 310 kN, but that simple comparison is only a screening step; shock, side load, pin bending, bracket stiffness and articulation still need review.
Recommended series to compare
| Joint condition | Series to compare | Reason |
|---|---|---|
| Heavy, exposed clevis | GEG..ES 2RS | Wider heavy-duty envelope plus face sealing |
| Heavy, serviceable protected joint | GEG..ES | Wider greaseable heavy-duty envelope |
| Moderate compact joint | GE..ES / GE..ES 2RS | Smaller radial envelope |
| Poor grease access | GE..C or GE..ET 2RS | Maintenance-free liner systems |
Installation and fit
The housing and pin should be measured before assembly, especially during replacement work where wear can enlarge the clevis bore. Use the fitting-tolerance reference as a dimensional aid, then apply the approved machine fit for the actual load direction and housing stiffness.
Sealing and maintenance
2RS is useful when dirt, water or spray can reach the bearing faces. A sealed greaseable bearing still needs the lubrication strategy intended for the joint. If service access is the real problem, a maintenance-free liner may be more relevant than simply adding seals.
What to send with an RFQ
- Existing bearing marking or clear photo.
- Pin diameter and d / D / B / C measurements.
- Maximum cylinder force or joint load case.
- Articulation, contamination and lubrication access.
- Bracket or clevis drawing when available.
Cylinder force is only the first load input
Hydraulic force can be estimated from pressure and effective piston area, but the bearing can see more than the pure axial cylinder force. Machine linkage geometry can magnify force, side load can appear when pivots are misaligned, and shock can occur when the mechanism reaches a stop. The clevis plates and pin support also affect how evenly the spherical contact is loaded.
Clevis geometry and pin support
A long unsupported pin span bends more than a short, closely supported pin. That bending can tilt the inner ring and push load toward one side of the spherical contact. When a hydraulic bearing shows edge wear, inspect plate spacing, pin diameter and bracket distortion before increasing bearing size.
Grease path design
For a serviceable GEG or GE bearing, the grease passage should remain accessible after the cylinder is installed. A fitting that becomes hidden behind a frame member is not a practical maintenance route. In dirty service, grease should also have a path to purge contamination rather than trapping it behind damaged seals.
Overhaul checklist
- Measure the clevis bore for ovality.
- Inspect pin hardness/finish and look for a wear step.
- Check whether the old bearing could articulate freely at full stroke.
- Verify the cylinder rod and base pivots are aligned.
- Confirm the replacement seal and lubrication strategy before assembly.
Discuss your hydraulic-cylinder bearing requirement
Send the cylinder joint drawing, load and existing part number to compare GE and GEG alternatives.
