Bearing materials and service conditions: Tin-based white metals (Babbitt alloys) are typically selected for bearings operating under which combination of load and pressure conditions?

Introduction / Context:
Bearing material choice balances conformability, embeddability, fatigue resistance, and friction. Tin-based white metals (Babbitts) are classic bearing linings known for their soft, conformable matrix with hard intermetallic phases that support load over a hydrodynamic oil film.

Given Data / Assumptions:

• Application is a hydrodynamic journal bearing with adequate lubrication.
• Tin-based Babbitt lining over a stronger backing (e.g., steel/bronze shell).
• Normal operating temperatures and good oil cleanliness.

Concept / Approach:
White metals provide excellent embeddability and conformability but limited load-carrying capacity compared with bronzes or high-strength overlays. They are therefore favored where unit pressures and loads are modest, misalignment must be tolerated, and seizure resistance is important.

Step-by-Step Solution:
Identify key properties: soft matrix, good seizure resistance, embeddability.Map properties to service: suitable for light-duty bearings with low P and low W.Avoid high-temperature or severe load applications where fatigue life is limiting.Select the condition 'Low pressure and low load'.

Verification / Alternative check:
Manufacturer handbooks rate Babbitt linings for relatively low specific pressures; heavier-duty bearings often use copper–lead or aluminum–tin alloys with higher fatigue strength.

Why Other Options Are Wrong:
High pressure/high load: exceeds Babbitt fatigue capacity.

High temperature: risks softening of the matrix and reduced film strength.

Large surface wear: while conformable, Babbitt is not a wear-resistant hard-facing material.

Common Pitfalls:

• Assuming Babbitt alone carries the load; it is a lining supported by a stronger shell.
• Ignoring lubrication; boundary conditions can rapidly damage soft linings.

Final Answer:
Low pressure and low load