A tilting pad thrust bearing carries axial load from a rotating shaft through an oil film. Its separate thrust bearing pads tilt as the shaft turns, creating an oil wedge beneath the rotating thrust collar. It is a fluid-film plain bearing. Tilting pad journal bearings support radial loads and are a different design.
For a replacement Babbitt-lined pad, the part name is only a start. Pad geometry and the original lining specification define the part to manufacture.
What Parts Make Up a Tilting Pad Thrust Bearing?
The thrust collar rotates with the shaft. Opposite it, sector-shaped pads, or shoes, sit in a carrier. Each rests on a pivot or specified support and can tilt slightly. Axial force passes from collar through oil film, pad and support into the housing.
In a conventional Babbitt-lined design, a structural backing supports a white-metal running face. Pivot contact, facing geometry, lining and sensor provisions are specific to the drawing. Outside size alone does not identify a pad.
Some assemblies have equalizing links or leveling plates to share load; others do not. Machines carrying thrust in both axial directions may have separate working and counter-thrust faces. One loose pad cannot reveal the entire arrangement.
When identifying a spare, check the assembly drawing for the loaded side of the collar. A thrust pad’s broad face looks toward the collar, while the pivot geometry is on its back. Mixing those references can lead to an accurate-looking part with the wrong support position.
How Does a Tilting Pad Form an Oil Film?
As the thrust collar rotates, it draws oil across each pad. The pad inclines, creating a converging gap in the direction of motion. Oil in this gap develops hydrodynamic pressure. Under the intended operating conditions, the film separates the surfaces and transfers axial load to the pivot.
Unlike a flat, fixed thrust washer, the pad adjusts its angle with operating conditions. It cannot run dry: at start-up, shutdown or inadequate oil supply, a full film may be absent. Oil viscosity, speed, thrust, collar condition and pad geometry affect performance.
Depending on design, oil may flood the housing or be directed to the pad entrance. Equalizing features share load; oil supply feeds and cools the working faces. For a replacement, preserve specified feed features and orientation rather than copying another bearing’s groove.
Pivot position also matters. A centrally supported pad can be used in designs requiring rotation in either direction; some offset pivots favor one direction and are selected for particular loads and temperatures. Changing that location to make a worn pad easier to machine would change how the oil wedge develops.
Where Are Babbitt-Lined Thrust Pads Used?
Babbitt, also called white metal, faces many tilting pads. Bonded to a backing, it is finished to the specified geometry. During proper operation, the oil film carries the collar’s load; Babbitt lies beneath it. Our white metal bearing guide explains the alloy and layered construction.
These bearings appear in selected hydro turbine-generator units, turbines, compressors, large pumps, motors and generators. The machine name does not prove its pads use Babbitt. Some designs specify polymer, aluminum-tin or ceramic faces. A bronze wear plate is not automatically interchangeable with a Babbitt-lined thrust pad.
Steel-backed Babbitt pads are common; some engineered designs use copper-alloy backing. Neither material should be chosen by the color of a removed pad.
JEDBUSHING lists Babbitt-lined thrust pads for hydropower equipment among its custom parts. Bearing capacity, oil-system design and a change of facing material require approval by the responsible designer.
What Defines a Replacement Thrust Pad?
Begin with an approved drawing: equipment, bearing position, thrust face, pad count and revision. Specify each pad’s inner and outer radii, angular span, thickness, face profile, pivot position and rear contact geometry. Mark collar rotation as viewed from a stated shaft end. Similar outlines can conceal different pivots.
State backing material, Babbitt grade and lining thickness, plus bond or inspection requirements. Show oil-feed features, holes and sensor provisions where specified. Provide the mating collar dimensions and condition: a worn collar may affect fit even when the new pad matches its drawing.
Supply available operating data: speed, main and reverse thrust, oil type and temperature, and shaft orientation. This helps the engineer assess the request; a photograph cannot establish a new bearing rating. Identify any dimensions still unconfirmed.
Send Your Thrust Pad Drawing for Review
JEDBUSHING manufactures custom Babbitt bearing parts, including thrust pads, to agreed requirements. Send the pad drawing or available part information, quantity, backing and lining specifications, machining features, and inspection needs. Identify whether the inquiry covers one pad or a group from the same assembly. We can review the manufacturing scope and information needed for a quotation.
FAQ
Can one damaged pad be replaced while the others remain in service?
That depends on the bearing design and the condition of the complete set, pivots and thrust collar. A single pad can be submitted for a manufacturing review, but the equipment owner or bearing designer must approve whether partial replacement is appropriate.
Can replacement pads be marked by their installation positions?
Yes. Include the required position or item numbers in the order so marking and separate packing can be agreed before production.
Can you review a worn pad if the original drawing is missing?
Yes. Photos, measurements and a physical sample can begin the review. Wear may have changed the working face or pivot geometry, so the critical replacement dimensions must be verified before production.