How to Choose the Right Thrust Bearing Washer: A Simple Guide to AS Series vs. LS Series

Have you ever wondered how machines handle heavy pushing forces? Or what keeps parts moving smoothly when they are squeezed together? The answer often lies in a small but mighty component called a thrust bearing washer.

Think of a thrust bearing washer as a super-strong, flat ring. Its job is to handle "thrust" or pushing forces between rotating parts, protecting them from wear and tear. Choosing the wrong washer is like wearing sneakers for hiking—it might work for a while, but it will likely fail when things get tough. Today, we’ll break down two popular types: the AS Series and the LS Series. By the end, you’ll know exactly how to pick the right one for your project.

What is a Thrust Bearing Washer?

A thrust bearing washer is a key part of a thrust needle roller bearing. These bearings are designed to handle heavy loads pushing in one direction (axial loads) while taking up very little space. They are common in everything from car transmissions and farm equipment to electric tools and industrial machinery.

The washers are the flat discs that the rolling elements (like needles or rollers) run against. They must be strong, hard, and precise to work correctly.

Meet the Two Main Contenders: AS Series vs. LS Series

Although there are several types, we will focus on the two that often cause confusion: the AS thrust washer and the LS thrust bearing washer. They are made differently and used for different jobs.

1. The AS Series: The Flexible Protector

⦁ What it is: The AS washer is like a precision stamping. It's made from high-quality spring steel, usually 0.8mm or 1.0mm thick.

⦁ Key Feature: It is not super hard itself, but it is very rigid and accurate.

⦁ Best Used For: Its main job is to protect other parts. Use an AS washer when the machine parts next to the bearing (like a housing or shaft) are not hardened. The AS washer sits in between, taking the load and preventing the soft adjacent parts from getting damaged. It acts as a durable, replaceable shield.

⦁ Simple Rule: Think "Protection for Soft Parts." If the surrounding metal can't be hardened, you need an AS series thrust bearing washer.

2. The LS Series: The Hardened Workhorse

⦁ What it is: The LS washer is a solid, thick disc made from hardened bearing steel.

⦁ Key Feature: It is very hard and durable from the inside out.

⦁ Best Used For: It is designed to be a direct, long-lasting contact surface for the rolling elements. An LS washer is typically used together with a thrust cylindrical roller and cage assembly. It’s used when the surrounding structure is also rigid and can support it fully. It's built to handle direct, heavy loads for a long time.

⦁ Simple Rule: Think "Direct Contact for Heavy Duty." When you need a super-hard surface right where the rollers push, you choose an LS series thrust bearing washer.

Side-by-Side Comparison

What Happens If You Choose Wrong?

Picking the wrong thrust bearing washer can lead to big problems and costly downtime:

Using an AS Washer in an LS Application: If you use a thinner AS washer as a direct raceway for heavy rollers, it will wear out or deform quickly. The hard rollers will dig into it, causing the whole bearing to fail and creating metal debris that can wreck other parts.

Using an LS Washer in an AS Application: If you force a hard, thick LS washer against a soft, unhardened housing, the problem reverses. The hard washer won't get damaged, but it will embed itself into the soft metal of your machine part! This ruins the housing or shaft, which is often much more expensive and difficult to replace than the washer itself.

How to Make the Right Choice: A Quick Checklist

Look at the Neighbors: Are the parts touching the washer (shaft and housing) hardened steel? If NO, you likely need an AS Series washer to protect them.

Check the Assembly: Are you using a complete thrust roller and cage assembly? If YES, you will likely need a hardened LS Series washer (or its partners, WS/GS) as the raceway.

Consider the Load: For very high loads and direct force, the hardened LS type thrust bearing washer is the standard choice. For moderate loads where protection is key, the AS thrust washer is perfect.

Conclusion

Choosing between an AS and an LS thrust bearing washer isn't about which one is better—it's about which one is right for the job. The AS is the protector, ideal for shielding softer machine parts. The LS is the direct contact champion, made to withstand relentless force from rollers.

Understanding this simple difference saves time, money, and prevents machine failures. Always remember: match the washer to the hardness of the parts around it and the type of rolling element assembly. When in doubt, consulting with a bearing expert is the best next step to ensure your machinery runs smoothly and reliably for years to come.