Understanding Axial load vs radial load is important for building machines that work well and last long. These forces affect parts like bearings and shafts, so knowing the difference helps you pick the right parts for your project.
In this guide, we’ll explain what axial and radial loads are, how they’re used, their main differences, and how to choose the right one. Whether you’re a professional engineer or a curious hobbyist, this will help you understand these important forces and make smarter design choices.
Definitions and Basic Concepts
Axial Load (Thrust Load)
An axial load is a force that pushes or pulls along the length of a part. It either squeezes the part together (compression) or pulls it apart (tension).
Everyday Examples:
Elevator Cables: The cables pull the elevator up by applying a pulling (tension) force along their length.
Hydraulic Presses: These machines push down on materials, applying a squeezing (compression) force.
Building Columns: Columns hold up the weight of the building above by carrying a pushing (compression) force straight down.
Common Parts That Handle Axial Loads:
Thrust Bearings: Made to carry pushing or pulling forces along the axis in machines.
Screws and Bolts: Tightening them creates pulling (tension) forces along their length.
Pistons: In engines, pistons get pushed and pulled along their length during operation.
This explains axial loads and their use in everyday machines and structures.
Radial Load
A radial load is a force that pushes sideways on a rotating part, like a shaft or bearing. Instead of pushing along the length, this force presses outwards from the center, hitting the sides of the part.
Examples:
Conveyor Belt Rollers: When materials sit on a conveyor belt, their weight pushes down on the rollers from the side, creating radial loads.
Gearboxes: The gears inside push sideways on shafts and bearings as they turn, causing radial loads.
Vehicle Wheels: The weight of a car pushes sideways on the wheel bearings as the wheels spin.
Common Parts That Handle Radial Loads:
Radial Bearings: Radial bearings are designed to support sideways (radial) forces, allowing machines to rotate smoothly and last longer.
Shafts: Shafts support rotating parts and must handle the sideways forces from things like gears or pulleys attached to them.
Pulleys: Pulleys feel radial loads from the belts or ropes pulling sideways on them.
This explains side forces (radial loads) and why parts must be strong to handle them.
Key Differences Between Axial and Radial Loads
Direction of Force
Axial Load: The force pushes or pulls along the length of the shaft (parallel to it).
Radial Load: The force pushes straight toward the center, at a right angle (perpendicular) to the shaft.
Bearings for Each Load
Axial Load Bearings: Thrust bearings (like thrust ball bearings and tapered roller bearings) handle axial loads. Some angular contact ball bearings can handle both axial and radial loads.
Radial Load Bearings: These include deep groove ball bearings, cylindrical roller bearings, and needle roller bearings. They are designed to handle forces that push from the side, across the shaft.
Typical Applications and Scenarios
Axial Load Applications:
Elevator cables and pulleys.
Hydraulic presses.
Structural columns in buildings.
Automotive transmissions.
Radial Load Applications:
Conveyor belt rollers.
Gearboxes.
Vehicle wheels.
Linear motion systems.
Bearing Types and Their Load Capacities
Angular Contact Ball Bearings
Load Handling: Designed to support both radial and axial loads simultaneously. The ability to handle axial loads depends on the contact angle.
Contact Angle: The contact angle determines the axial load capacity. A larger contact angle increases the bearing’s ability to handle axial loads.
Applications: Commonly used in machine tool spindles, pumps, and electric motors.
Tapered Roller Bearings
Load Handling: Capable of supporting high radial and axial loads in one direction.
Contact Angle: The axial load capacity increases with the contact angle. Bearings with larger contact angles can handle higher axial loads.
Applications: Widely used in automotive applications, such as wheel hubs and gearboxes.
Thrust Bearings
Load Handling: Specifically designed to support axial loads.
Contact Angle: Thrust ball bearings typically have a contact angle greater than 45°, enhancing their axial load capacity.
Applications: Used in applications where axial loads are predominant, such as in vertical shafts.
Deep Groove Ball Bearings
Load Handling: Primarily designed for radial loads but can accommodate some axial loads in both directions.
Contact Angle: The contact angle is relatively small, making them suitable for applications with low axial load requirements.
Applications: Commonly used in electric motors, household appliances, and automotive applications.
Common Bearing Mistakes and How to Avoid Them
Mixing Up Load Types Causes Failures
Problem: Choosing the wrong type of bearing because you didn’t correctly identify whether the load is pushing along the shaft (axial), sideways (radial), or both.
Fix: Take time to understand how the load acts on your component. For example, use angular contact ball bearings if the load is both axial and radial. Use deep groove ball bearings if it’s mostly radial.
Why it matters: Picking the wrong bearing can cause it to wear out or fail quickly.
Ignoring Loads Acting Together
Problem: Bearings often face both side (radial) and lengthwise (axial) forces at the same time. If this is ignored, it can put too much pressure on the bearing and cause it to fail.
Fix: Choose bearings that handle combined loads well, like angular contact ball bearings or tapered roller bearings. Check the bearing’s load ratings to match your needs.
Why it matters: Bearings must be able to handle both side and lengthwise forces as they happen in real use. Designing for only one type can lead to damage or failure.
Skipping Maintenance and Monitoring
Problem: Not regularly checking bearings or missing signs of wear can lead to sudden failures.
Fix: Set up a regular maintenance plan—lubricate bearings, check alignment, and use tools like vibration analysis to spot problems early.
Why it matters: Early detection helps prevent costly breakdowns.
Conclusion: Choosing the Right Load Type for Your Design
Understanding the difference between axial load vs radial load is essential for building reliable, long-lasting machines. These forces affect parts like bearings, shafts, pulleys, and structural supports—so choosing the right type for your application ensures safety, performance, and durability.
In real-world systems, components often face both types of loads at once. That’s why it’s important to:
Identify the dominant load direction in your design.
Select bearings and parts built to handle those specific forces (or both).
Avoid common mistakes like mismatched bearing types or skipping maintenance.
Whether you’re designing a motor, elevator system, gearbox, or anything in between, understanding how axial and radial loads work helps you make smart, informed decisions—and avoid unnecessary wear or failure. Always match your load requirements to the right components to keep your systems running smoothly.