Why Do Thrust Bearings Fail? 5 Common Causes and How to Fix Them

The components of thrust bearings can occasionally fail; when this occurs, the entire production line may come to a standstill. This article explains the 5 most common reasons why a thrust bearing fails. More importantly, you will learn how to fix and prevent these problems. We will also look at signs of damage, simple maintenance tips, and answer common questions.

Common Causes of Failure

A thrust bearing is tough, but it is not invincible. Here are the top five reasons they fail:

Poor Lubrication

This is the #1 cause. A thrust bearing needs a thin layer of oil or grease to keep metal parts from touching. When there is too little lubricant, or the wrong type, the thrust bearing overheats. The metal surfaces grind together, causing scuffing and then seizure. Always check your lubricant levels and quality.

Overloading

Every thrust bearing has a maximum load rating. If you push it beyond that limit, the internal parts can deform. For example, the thrust bearing washer  may get dented or cracked. Overloading leads to early metal fatigue and sudden failure. Make sure you select a thrust bearing with the correct capacity for your application.

Misalignment

A thrust bearing is designed to handle pure axial forces. But if the shaft or housing is bent or not centered, side forces appear. This puts uneven pressure on the thrust bearing washer and the rolling elements. The result? Premature wear on one side. Proper alignment during installation is critical.

Contamination

Dirt, dust, water, or metal chips are enemies of any thrust bearing. These particles get inside and act like sandpaper. They scratch the smooth surfaces of the thrust bearing washer and the needle rollers. Even a tiny speck can cause big damage over time. Keep your work area and lubricants clean.

Improper Installation

A thrust bearing is not a "drop-in" part. If you hammer it or press it incorrectly, you can dent the raceways. Also, remember that the shaft washer (WS) and seat washer (GS) are hardened steel – they need a proper housing that is also rigid. Always follow the manual.

Signs of Bearing Damage

How do you know if a thrust bearing is failing? Look for these red flags:

▸ Unusual Noise: Grinding, squealing, or rumbling sounds from the bearing area.

▸ High Temperature: If the housing feels too hot to touch, the thrust bearing is likely overheating.

▸ Vibration: The machine shakes more than normal, especially under load.

▸ Metal Debris: You find fine metal powder or flakes in the lubricant.

▸ Poor Performance: The machine loses precision, or it takes more power to run.

If you see any of these signs, inspect the thrust bearing immediately.

How to Prevent Failure

Preventing thrust bearing failure is easier than fixing it. Follow these steps:

1. Choose the right bearing. Use our online tools or talk to an engineer to match the thrust bearing size and type to your real load and speed.

2. Use high-quality lubricants. Select oil or grease that is made for thrust bearing applications. Consider synthetic options for high-speed or high-heat environments.

3. Install correctly. Always support the thrust bearing washer fully. Never use a hammer directly on the bearing. Use a proper press or fitting tool.

4. Keep it clean. Seal the housing well. Change lubricants on a schedule. Filter the oil in circulating systems.

5. Monitor regularly. Use temperature sensors or vibration analyzers if possible. But even a weekly visual check and listening to the machine can catch problems early.

Maintenance Tips

Regular maintenance extends the life of any thrust bearing. Here is a simple checklist:

▸ Weekly: Listen for noise. Check seals for leaks. Feel the housing temperature.

▸ Monthly: Take an oil sample and look for metal particles. Inspect the thrust bearing washer if easily accessible. Re-tighten mounting bolts.

▸ Yearly (or per machine hours): Replace the lubricant completely. Disassemble and inspect the thrust bearing and washers for wear patterns. Replace any part that shows pitting, scoring, or color change (a sign of overheating).

Remember: A clean, well-lubricated thrust bearing is a happy thrust bearing.

FAQ

Q: Can I reuse a thrust bearing after disassembly?

A: Generally, no. Once a thrust bearing is removed, the rolling elements and thrust bearing washer may have settled into a specific wear pattern. Reinstalling it usually leads to early failure. Always use new parts if you open the assembly.

Q: What is the difference between a thrust bearing and a thrust washer?

A: A thrust bearing usually includes rolling elements (needles or balls) plus washers. A thrust bearing washer (like the AS or LS series) is a flat ring that provides a smooth surface for those rolling elements. You often use them together.

Q: How tight should I hold a thrust bearing in its housing?

A: The housing should support the thrust bearing washer fully but without squeezing it. For a solid washer (WS/GS/LS), the housing fit is usually a light press or slip fit. For an AS stamped washer, the housing must be perfectly flat and rigid. If you overtighten, you can distort the washer.

Q: What happens if I put a thrust bearing in backward?

A: The thrust bearing will fail instantly or within hours. Most thrust bearing designs can handle force in only one direction (or both, but with a specific orientation). Always check the marking on the thrust bearing washer or the cage.

Q: How long should a thrust bearing last?

A: With proper selection, installation, and lubrication, a thrust bearing can last thousands of hours. But in dirty or overloaded conditions, it might fail in days. Quality matters. For example, our AS/LS/TRA series washers are made from hardened bearing steel or spring steel, which gives them long life under normal conditions.

By understanding these five common causes of thrust bearing failure, you can keep your machines running smoothly. Remember: pay attention to lubrication, load, alignment, cleanliness, and installation. And always choose the right thrust bearing for the job.