Relative Motion
A bearing allows relative motion between two surfaces with minimal friction.
In a rolling element bearing, the primary motion is a rolling motion using a ball or roller. There is direct contact between the ball/roller and the inner and outer surfaces (races).
In a fluid film bearing, the relative motion between the two surfaces is a sliding motion on a shear of film (the lubricant). There is no contact of the surfaces except during start-up or shutdown.
Bearing Life
A key difference between rolling element and fluid film bearings is the expected life of the bearings. Rolling element bearings typically have a predictable life based on the operating conditions. Fluid film bearings, when properly designed and maintained, can operate for decades.
Waukesha Bearings specializes in the engineering, design and manufacture of hydrodynamic fluid film bearings.
| Hydrodynamic Fluid Film Bearings | Rolling Element Bearings | |
|---|---|---|
| Life Expectancy | Indefinite | Limited Life (L10) |
| Impact Loads | Excellent | Poor |
| Damping | Excellent | Poor |
| Speed Limitations | Approaches Burst Limit | Limited to DN |
| Noise | Quiet | Can Be Noisy |
| Start-up Torque | High | Low |
| Operating Friction | Low | Low |
| Lubrication | Pressure Fed | Simple |
| Cost | Low to High | Low to Moderate |
| Position Control | Fair | Good |
| Assembly/Repair | Easy to Difficult | Easy |
| Tolerance for Misalignment | Tolerant | Intolerant |
| Operating Temperature | Cryogenic to High | Cryogenic to Extreme |
| Power Loss | Moderate to High | Low to Moderate |
| Lubricant Requirements | Minimal to High | None to Low |
| Oil Quality | Moderate | High |
| Oil Pressure | Low to High | None to High |
| Natural Frequency Control | Good | Poor |
| Unbalance Response | Good | Poor |
| Stability | Good | Fair |
Journal Bearings
Waukesha Bearings custom engineers fluid film bearings in both fixed profile and tilt pad designs. Bearing geometry and materials are carefully considered to provide minimum power loss and optimum dynamic performance for the given operating conditions.
Thrust Bearings
Waukesha Bearings offers fixed profile fluid film thrust bearings for lightly loaded applications and advanced tilting pad solutions for more demanding operating conditions. Tilt pad designs may be non-equalizing or self-equalizing with flooded or ‘Directed’ lubrication to support the equipment’s unique requirements.