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Radial vs. Axial Load: Understanding the Differences

Radial vs. Axial Load: Understanding the Differences
Radial vs. Axial Load: Understanding the Differences
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Radial and axial loads apply force in different directions, and using the wrong bearing type can lead to premature wear, system inefficiencies, or failure.

Understanding these fundamental forces is key to selecting the right bearings, improving system performance, and extending component lifespan. 

Whether you're troubleshooting failure points or optimizing custom bearing designs, this article will help unravel the complexities of bearing loads so you can make informed decisions.

 

Understanding Radial Loads

Radial load is one of the most common and one of the two primary force directions that bearings must accommodate, the other being axial load.

Selecting the correct bearing type and accommodating radial forces is essential for maintaining performance, reducing wear, and ensuring system durability.

 

What is Radial Load?

Radial load is a type of centrifugal force acting perpendicularly to the axis of a rotating shaft or component, directed towards its center.

In bearings, it's the load carried at right angles to the rotation axis.

 

Examples of Radial Load Applications

Radial loads are typical in rotating applications such as car wheels, machine shafts, electric motors, pulleys, and gearboxes.

For example, a car's wheel bearings experience varying radial loads dependent on the vehicle's speed and weight.

 

How Radial Load is Transferred Through the Bearing

In a bearing subjected to radial load, the load is transferred from the inner raceway through the rolling elements (balls or rollers) to the outer raceway.

The force is distributed over several rolling elements simultaneously, depending on the bearing design and the size of the load.

Radial Load

 

Impact of Radial Load Distribution on Rolling Elements

Radial load distribution impacts bearing performance and longevity.

Proper distribution prevents over-stressing individual elements, ensuring balanced wear.

However, uneven distribution can cause premature bearing failure due to excessive stress on certain elements.

 

Suitable Bearing Types for Handling Radial Load

Various bearings handle radial loads, including deep groove ball bearings for their versatility, cylindrical roller bearings and needle roller bearings for heavy loads, and self-aligning ball bearings for misalignment scenarios.

Each type is selected based on the application and load magnitude.

 

Understanding Axial Load

Unlike radial loads that push perpendicular to the shaft, axial loads push or pull in line with the shaft’s centerline.

These forces are crucial to consider when designing components that experience significant end-to-end pressure, as choosing the wrong bearing for axial forces can lead to decreased efficiency, faster wear, or premature failure.

 

What is Axial Load?

Axial load, synonymous with thrust or parallel load, is the force that acts parallel to the shaft's axis.

Simply put, it's a force that's exerted along the lines of the center, or axis, of an object.

 

Examples of Axial Load Applications

Axial loads are prevalent in various sectors, including automotive axles, aerospace jet engines, wind turbines, and industrial conveyor systems.

They also occur in pumps and compressors, and screw drive systems due to forces exerted by fluid, gas, or mechanical movement.

 

How Axial Load is Transferred through the Bearing

Axial load transfers through a bearing's raceways and rolling elements.

In thrust ball bearings, the load passes from one washer to another via balls aligned parallel to the rotation axis, enabling high axial load capacity.

Tapered roller bearings handle axial and radial loads, with their tapered design facilitating axial load transfer along inclined surfaces, thereby improving load distribution and reducing stress.

Axial Load

 

Balanced Load Distribution in Axial Load Scenarios

Achieving balanced load distribution in axial load scenarios is key for optimal bearing performance, durability, and smooth operation.

Ideally, axial loads are equally shared among all rolling elements, minimizing wear and enhancing bearing efficiency.

Factors such as misalignment or uneven loading can disrupt this balance, increasing stress and potentially leadinng to premature failure.

 

Suitable Bearing Types for Handling Axial Load

Thrust bearings are the go-to choice for handling axial loads due to their design that accommodates forces parallel to the axis.

Types include thrust ball bearings for lighter loads and thrust roller bearings for heavier loads. 

Angular contact ball bearings can manage combined radial and axial loads, provided the axial component is significant.

 

Comparison of Radial Load and Axial Load

Differentiating between radial and axial loads, or understanding the concept of radial vs axial load, is vital for the optimal selection and use of bearings.

The primary distinctions lie in the direction of the force applied - radial loads act perpendicular to the shaft's axis, and axial loads act parallel to it.

The type of bearing used also varies between these loads.

While deep-groove ball bearings are better equipped to handle radial loads, thrust ball bearings are designed for axial loads.

However, it's essential to note that most bearings, such as angular contact ball bearings, can handle both radial and axial loads.

For a more comprehensive understanding, let's look at a comparative table:

  Radial Load Axial Load
Force Direction Perpendicular to the shaft's axis Parallel to the shaft's axis
Load Distribution Distributes force across the circumference of the bearing, Distributes force along the bearing's axis
Bearing Examples Deep-groove ball bearings, cylindrical roller bearings, needle roller bearings Thrust ball bearings, tapered roller bearings
Typical Applications Rotating Machinery, Wheels, Conveyor belts, electric motors, gearboxes, etc. Vertical shafts in transmissions, helicopters, Wind Turbines, etc.

 

 

 

Combined Loads in Real-World Applications

In most situations, bearings aren’t subjected to just radial or just axial forces, but rather a combination of both (sometimes, moment loads as well).

These combined loads require bearings that can handle forces from multiple axial directions at the same time, so careful selection, load calculations, and engineering are needed. 

Angular contact ball bearings and tapered roller bearings are examples of bearings designed to handle dual forces.

Understanding combined loads is key in applications like automotive wheel hubs, industrial gearboxes, and turbines, where unbalanced or mis-calculated forces can cause premature wear and failure.

There are also non-roller style bearings (i.e., telescopic rails) with individual balls that move along their surface.

These are most commonly used for cabinet drawers and machinery that extends and retracts loads during operation. 

 

 

How Load Type Affects Bearing Life

The type of load (i.e., radial, axial, or a combination) determines which bearing is best for a given application.

Bearings are engineered for specific load directions and capacities, so selecting the wrong one can result in reduced performance or failure. 

For example, deep groove ball bearings handle mostly radial loads but can handle some axial loads, while angular contact bearings are for applications where both radial and axial loads are high.

Matching load to bearing design is critical for system reliability, safety, and longevity.

 

 

Practical Considerations

Assessing radial and axial loads in real-world applications demands attention to various aspects such as operating speed, load magnitude and direction, and the operating environment. 

Carefully balancing these loads can lead to a noticeable improvement in bearing performance and life.

A case study worth mentioning is in the realm of automotive wheel bearings. 

These bearings need to handle both radial loads (from the vehicle's weight) and axial loads (from cornering forces).

The delicate balance and distribution of these loads are crucial for the smooth and efficient operation of the vehicle.

Additionally, the bearing's material selection, like Chrome Steel or Stainless Steel, also plays a significant role in handling radial and axial loads.

Chrome Steel, for instance, is often used for its high load capacity and wear resistance, making it suitable for applications with high radial and axial loads.

 

Choosing the Right Bearings for Radial, Axial, and Combined Loads

Understanding and managing radial vs axial load can greatly enhance bearing performance and longevity.

Selecting the right bearing, based on the load nature, can boost your machinery's efficiency.

At LILY Bearing, we provide a wide range of bearings to meet varied load needs.

Our expertise and quality commitment assure optimal performance and extended machinery life through our tailored bearing solutions. 

Explore our full selection of bearings designed for radial, axial, or combined load support.

 

 

 

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