10 Costly Mistakes In Pump Bearing Selection

Adnan Siddiqui
Apr 25
5 min read

Updated: Apr 29

Choosing the correct bearing type is critical for the optimal performance and longevity of pump systems. When the wrong bearings are used, it can lead to a range of operational issues, from inefficiency to catastrophic failures. This blog outlines ten common and costly examples of how incorrect bearing types can cause problems in pumps. We present detailed explanations and solutions for each scenario.

Axial Versus Radial Loads

Before diving into bearing selection, it’s important to understand the two primary types of loads that bearings are designed to handle. The diagram below illustrates these fundamental concepts:

Diagram of a shaft showing axial and radial forces, with arrows indicating direction. Blue grid background. Text: "Figure 1 Shaft forces/loads." — Axial vs Radial Loads on Bearings

Axial Loads – Axial loads act along the length of the shaft, pushing or pulling on the shaft ends. These forces follow the centerline of rotation and can be in either direction—compressing or tensioning the shaft.
Radial Loads – Radial loads act perpendicular to the shaft's axis, pushing the shaft away from the center of rotation. These forces can deflect the shaft upward, downward, or side-to-side—always perpendicular to its length.

10 Costly Problems in Pump Bearing Selection

1. Radial Loads on Thrust Bearings

Drawing of a tapered thrust bearing on graph paper, labeled "Figure 2: Tapered Thrust Bearing" in blue. — Tapered Thrust Bearing

Thrust bearings are designed to handle axial loads, but when subjected to significant radial loads, they can fail prematurely. This mismatch often occurs when pumps are designed or repaired without proper attention to load direction. Radial forces on thrust bearings lead to uneven wear, overheating, and potential deformation of bearing components.

Symptoms: Uneven wear, overheating, potential deformation of bearing components, increased vibration, and noise.
Consequences: Operational inefficiency, premature failure.
Financial Implications: Increased maintenance and replacement costs, potential downtime.

Over time, this can result in increased vibration, noise, and operational inefficiency. Proper selection and application of radial-specific bearings, such as deep groove ball or cylindrical roller bearings, can prevent these issues. Ensuring the right bearing type is critical to maintaining pump performance and reliability.

2. Thrust Loads on Radial Bearings

Blueprint sketch of a roller bearing labeled "Figure 3" on a grid paper background. Blue ink with detailed shading effects. — Roller Bearing

Bearings for radial loads, like deep groove ball bearings, are designed to handle loads perpendicular to the shaft. When axial thrust loads are applied to these bearings, their rolling elements and raceways experience stress concentrations, leading to premature wear and failure. This issue often arises when axial loads are underestimated during pump design or retrofitting.

Symptoms: Increased friction, overheating, and bearing seizure.
Consequences: Premature wear and failure.
Financial Implications: Costly repairs, downtime.

To avoid these problems, thrust-specific bearings, such as angular contact or thrust ball bearings, should be employed where axial loads are present. Proper alignment and load analysis are essential for long-term performance.

3. Using Ball Bearings Instead of Roller Bearings

Ball bearings are ideal for applications with moderate loads and high speeds but may fail under heavy radial loads. Roller bearings, such as cylindrical or spherical types, are better suited for high-load scenarios.

Symptoms: Rapid wear, deformation of the balls, and pitting of the raceways, increased vibration.
Consequences: Operational downtime.
Financial Implications: Increased maintenance costs.

This often results in increased vibration and operational downtime. Selecting roller bearings for heavy-load applications ensures even load distribution and durability, minimizing maintenance costs and extending the pump's service life.

4. Improperly Sealed Bearings

Unsealed or poorly sealed bearings can allow contaminants like dirt, dust, and moisture to enter, leading to premature failure. This is particularly problematic in pumps operating in harsh or wet environments.

Symptoms: Abrasive wear, corrosion, and lubrication degradation, resulting in higher friction and overheating.
Consequences: Premature failure.
Financial Implications: Increased maintenance and replacement costs.

Properly sealed bearings, such as those with rubber or metal shields, provide a barrier against environmental contaminants. Regular inspection and proper sealing material selection ensure reliable performance and extend the pump's lifespan, especially in challenging conditions.

5. Under-Sized Bearings

Diagram of a steel roller bearing adjacent to a selection chart with bearing numbers, radial load, and max speed on a grid background. — Example Bearing Selection Chart

Installing under-sized bearings in pumps often leads to excessive stress, as these bearings cannot handle the required load capacity. Bearing specifications are based on static along with dynamic loads at a given rotational speed. Failure to specific the appropriate bearing can result in fatigue, overheating, and early failure. Under-sized bearings are typically chosen due to cost constraints or incorrect load calculations. Over time, this compromises the pump's efficiency and increases maintenance frequency.

Symptoms: Fatigue, overheating, and early failure.
Consequences: Compromised pump efficiency.
Financial Implications: Increased maintenance frequency, unnecessary downtime.

To avoid such issues, ensure accurate load and operational condition analysis during the design phase. Selecting appropriately sized bearings prevents unnecessary downtime and ensures reliable pump operation.

6. High-Speed Applications with Low-Speed Bearings

Pumps operating at high speeds require bearings designed to handle the associated rotational stresses and heat generation. Low-speed bearings in high-speed applications can overheat, causing lubricant breakdown, deformation, and eventual failure.

Symptoms: Increased vibration, noise, and bearing seizure.
Consequences: Lubricant breakdown, deformation, and eventual failure
Financial Implications: Increased energy consumption and wear.

High-speed bearings, and the associated tighter tolerances, are also designed with optimized geometries, materials, and lubrication systems are essential for these scenarios. Properly matched bearings improve performance, reduce energy consumption, and minimize wear.

7. Use of Single-Row Bearings in Dual-Row Applications

Single-row bearings are not designed to handle the combined radial and axial loads that dual-row bearings can support. When single-row bearings are used in applications requiring dual-row capabilities, misalignment and failure often result. This mismatch increases vibration, reduces efficiency, and shortens bearing life.

Symptoms: Misalignment, increased vibration
Consequences: Reduced efficiency, shortened bearing life
Financial Implication: Increased costs, failures in pump systems.

Dual-row bearings, such as angular contact or tapered roller types, offer greater load-carrying capacity and stability. Proper load analysis and bearing selection are key to preventing such failures in pump systems.

8. Misalignment Issues with Spherical Bearings

Non-self-aligning bearings used in applications with shaft misalignment can lead to uneven load distribution and stress concentration. This causes accelerated wear, vibration, and operational inefficiency.

Symptoms: Uneven load distribution and stress concentration, accelerated wear, vibration
Consequences: Operational inefficiency.
Financial Implications: Increased maintenance costs

Spherical bearings, designed to accommodate misalignment, prevent these issues by allowing self-alignment under load. Common causes of misalignment include improper installation and thermal expansion. Regular alignment checks and the use of self-aligning bearings where necessary ensure smooth operation and reduced maintenance costs.

9. Incompatible Material Bearings

Bearings made from materials unsuited for the pump’s operating conditions, such as high temperatures or corrosive environments, degrade quickly. For example, standard steel bearings in acidic environments corrode rapidly, leading to premature failure.

Symptoms: Degradation
Consequences: Premature failure
Financial Implications: Increased costs

Bearings made from stainless steel, ceramics, or other specialized materials offer superior resistance to corrosion, heat, and wear. Understanding the operating environment and selecting materials accordingly ensures long-term reliability and efficiency.

10. Inadequate Lubrication Design

Using bearings that rely on incompatible lubrication systems can result in insufficient lubrication, causing overheating, wear, and failure. For example, grease-lubricated bearings may fail in high-speed applications where oil lubrication is more effective. Conversely, oil-lubricated bearings may be unnecessary for low-speed or low-load applications.

Symptoms: Overheating, wear
Consequences: failure
Financial Implications: Increased operational costs.

Regular lubrication checks, using the correct lubricant type and quantity, and implementing proper lubrication systems are critical to maintaining bearing and pump performance. Proper lubrication design reduces friction, extends bearing life, and minimizes operational costs.