When it comes to machinery, engines, and industrial equipment, bearings are the unsung heroes that keep everything moving smoothly. Among the many types of bearings, needle bearings hold a special place because of their compact design and ability to handle high loads in limited spaces.
If you have ever opened up a transmission, worked on an automotive engine, or handled industrial machines, you have likely seen needle bearings without even realizing it. They are small, precise, and powerful. But when it comes to replacing or designing with needle bearings, one big challenge comes up: getting the size right. That’s where a needle bearing size chart becomes invaluable.
In this guide, we will explore what needle bearings are, why size matters, common applications, and most importantly,a detailed size chart to help you find the perfect match for your project.
What is a Needle Bearing?
A needle bearing (also called a needle roller bearing) is a type of roller bearing that uses long, thin cylindrical rollers. These rollers are usually 3 to 10 times longer than their diameter, which is why they are called “needle” bearings.
Their design makes them ideal for:
Applications with limited space.
Systems requiring high load capacity but compact size.
Precision machinery where reducing weight and friction is important.
You will find them in places like:
Automotive transmissions and gearboxes.
Two-stroke engines.
Aerospace components.
Industrial machinery and tools.
They might be small, but they carry big responsibilities in keeping machines efficient and durable.
Why Needle Bearing Sizes Matter
Imagine you are repairing a motorcycle gearbox. You know it uses a needle bearing, but you don’t know the size. If you grab one that’s just a few millimeters off:
The bearing won’t fit properly in the housing.
Misalignment could increase friction and heat.
The shaft may wobble, reducing efficiency.
Worst-case scenario: the part fails prematurely.
Choosing the right size is just as important as choosing the right type of bearing. That’s why engineers, mechanics, and technicians always keep a needle bearing size chart handy.
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Types of Needle Bearings
Before we look at the chart, let’s understand the main types of needle bearings you will encounter:
Drawn Cup Needle Roller Bearings
Thin-walled outer ring.
Lightweight and compact.
Ideal for applications with small installation space.
Solid Needle Roller Bearings
Thicker outer ring.
Handles heavier loads than drawn cup bearings.
Needle Roller and Cage Assemblies
Just the cage and rollers (no inner or outer ring).
Used when the shaft and housing can act as raceways.
Thrust Needle Roller Bearings
Handle axial loads.
Often used in transmissions and gearboxes.
Each of these comes in multiple sizes, and that’s where a chart makes selection simple.
Needle Bearing Size Chart
Here’s a reference chart for common needle roller bearing sizes. Actual part numbers and availability may vary by manufacturer, but these dimensions represent widely used standards.
| Bore Diameter (mm) | Outside Diameter (mm) | Width (mm) | Typical Bearing Type |
|---|---|---|---|
| 5 mm | 10 mm | 10 mm | Drawn Cup Needle Bearing |
| 6 mm | 12 mm | 10 mm | Drawn Cup Needle Bearing |
| 8 mm | 14 mm | 12 mm | Solid Needle Bearing |
| 10 mm | 16 mm | 12 mm | Needle Roller Assembly |
| 12 mm | 18 mm | 12 mm | Needle Roller Assembly |
| 15 mm | 21 mm | 16 mm | Solid Needle Bearing |
| 17 mm | 23 mm | 16 mm | Drawn Cup Needle Bearing |
| 20 mm | 26 mm | 16 mm | Needle Roller Assembly |
| 25 mm | 32 mm | 20 mm | Solid Needle Bearing |
| 30 mm | 37 mm | 20 mm | Drawn Cup Needle Bearing |
| 35 mm | 42 mm | 25 mm | Solid Needle Bearing |
| 40 mm | 47 mm | 25 mm | Needle Roller Assembly |
| 50 mm | 62 mm | 30 mm | Solid Needle Bearing |
| 60 mm | 72 mm | 35 mm | Drawn Cup Needle Bearing |
This is just a snapshot—manufacturers like SKF, NSK, Timken, NTN, and INA publish detailed catalogs with hundreds of exact sizes.
Needle Bearing Size Chart PDF
Needle bearing size charts provide a quick reference to match bore, outside diameter, and width for precise applications. These compact, high-load bearings are widely used in engines, gearboxes, and machinery. A clear chart helps mechanics, engineers, and technicians avoid errors, reduce downtime, and select the perfect bearing for reliable and efficient machine performance.
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How to Read a Needle Bearing Size Chart
Let’s break down how you actually use the chart:
Bore Diameter (d) → The inside measurement, or the shaft size the bearing fits onto.
Outside Diameter (D) → The external measurement, or the housing size.
Width (B) → How thick the bearing is, which affects load capacity and space requirements.
Bearing Type → Helps you match the correct construction (drawn cup, solid, thrust, etc.).
Example: If your shaft is 20 mm and the housing diameter is 26 mm, you’d look at the chart and find a 20 × 26 × 16 mm bearing, usually a needle roller assembly.
Real-World Example: Motorcycles
Motorcycles often use needle bearings in their engines and transmissions because of the compact design. For instance:
A gearbox shaft might require a 15 mm bore × 21 mm OD × 16 mm width solid needle bearing.
The clutch assembly may use thrust needle bearings for axial loads.
By checking the chart, a mechanic can quickly identify which replacement fits best without guessing.
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Factors Beyond Size
While size is key, choosing a needle bearing also depends on other factors:
Load Capacity
Heavy-duty gearboxes → Solid needle bearings.
Light-duty, compact spaces → Drawn cup bearings.
Speed
High-speed applications need precision and proper lubrication.
Space Limitations
If you’re tight on space, drawn cup bearings are usually the go-to.
Alignment
Misalignment tolerance is limited—needle bearings need precise installation.
Lubrication
Oil bath or grease lubrication ensures long life.
Benefits of Needle Bearings
Why are needle bearings so popular?
Compact design – Handles high loads without taking much space.
High load capacity – Better surface contact than ball bearings.
Efficiency – Reduces friction, improving machine performance.
Durability – Works well in tough conditions when maintained properly.
Versatility – Available in many designs for radial or axial loads.
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Maintenance Tips for Needle Bearings
Even the right size won’t perform well without care. Here’s how to extend their lifespan:
Proper lubrication – Always follow manufacturer specs.
Keep clean – Dirt or debris can quickly ruin precision rollers.
Inspect regularly – Check for unusual noise, heat, or vibration.
Avoid overloading – Never push them beyond rated capacity.
Correct installation – Misalignment shortens lifespan dramatically.
Industries That Rely on Needle Bearings
Needle bearings are not limited to just cars or motorcycles. They’re everywhere:
Automotive – Transmissions, universal joints, engines.
Aerospace – Flight control systems, jet engines.
Industrial machinery – Pumps, compressors, conveyors.
Medical equipment – Compact machines where precision is key.
Power tools – Handheld drills and grinders.
This versatility is why engineers love needle bearings, they combine compactness with strength.
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Conclusion
A needle bearing size chart is more than just a table, it’s your roadmap to finding the right part, avoiding costly mistakes, and ensuring machines run efficiently. By matching bore diameter, outside diameter, and width, you can confidently select the correct bearing.
Whether you are a mechanic fixing a motorcycle, an engineer designing aerospace parts, or a technician maintaining industrial equipment, needle bearings play a crucial role. Their ability to fit into tight spaces while handling heavy loads makes them invaluable.
So the next time you are working with a shaft or housing, do not guess. Pull out a needle bearing size chart, check your measurements, and choose the bearing that fits like a glove. It’s the simplest way to ensure smooth, reliable performance in any machine.
FAQs About Needle Bearing Sizes
What is a needle bearing size chart?
A needle bearing size chart is a reference guide showing bore diameter, outside diameter, and width for different needle roller bearings. By using the chart, mechanics and engineers can quickly identify the right bearing for their shaft and housing size. It helps reduce guesswork, prevent fitting issues, and improve machine reliability and performance.
Why is it important to use the correct needle bearing size?
Choosing the correct needle bearing size ensures proper alignment, smooth motion, and load distribution. If the bearing is too small or too large, it can lead to overheating, excess friction, and even machine failure. The size chart helps avoid costly mistakes and ensures long-lasting, efficient performance in engines, gearboxes, and other industrial applications.
How do I read a needle bearing size chart?
To read a needle bearing size chart, focus on three main dimensions: the bore diameter (shaft size), the outside diameter (housing fit), and the width (thickness). Match these numbers with your actual measurements. Once identified, you can confirm the bearing type, whether it’s drawn cup, solid, or thrust, based on the requirements of your application.
Where are needle bearings commonly used?
Needle bearings are widely used in automotive transmissions, motorcycles, aerospace parts, medical devices, and industrial machinery. Their slim profile allows them to fit in tight spaces while still handling heavy loads. You’ll often find them in gearboxes, universal joints, clutches, compressors, and even handheld power tools where both strength and compact design are essential.
What is the difference between a needle bearing and a roller bearing?
The main difference lies in roller shape and size. Needle bearings use very thin, long rollers, making them ideal for compact spaces. Regular roller bearings use larger cylindrical, spherical, or tapered rollers and handle heavier radial loads. Needle bearings save space without sacrificing strength, while standard roller bearings are often bulkier but support greater load capacity.
How do I know if my needle bearing needs replacement?
You may need to replace a needle bearing if you notice unusual noise, vibration, or overheating during operation. Visible wear, cracks, or damage on the rollers or cage are also warning signs. If the bearing feels rough when rotated by hand or shows excess clearance, it’s time for a new one to prevent equipment failure.
Can I interchange needle bearings of different brands if the size matches?
Yes, in many cases you can interchange needle bearings across brands as long as the bore, outside diameter, and width match. However, quality, material, and tolerance standards may vary between manufacturers. For critical applications, it’s safer to choose a trusted brand or confirm compatibility in the catalog to ensure performance, durability, and long-term reliability.