Podcast: Absorbing the Shock

You’re listening to the four questions with an engineer podcast, the show that brings you bearing insights from CCTY Bearing. Today we are talking about shock absorber bushings with Corey Helgeson.

Cory, what are the types of bearings used on shocks?

So typically with the shock absorber there’s two locations for the bushings. One is in the eyelet and the body cap and the other is in the piston the bearing housing. Basically inside the shock absorber. Those are the two locations we generally talk about.

What is the purpose of the bushing and each of these applications?

So in the eyelet and the body cap, basically if you can picture shock with the hole on top and bottom of the shock. its purpose is to facilitate the connection between the shock and the vehicle. And then in the piston and bearing housing, the purpose is to be the contact and surface between the piston and the housing during shock movements, vibrations and things like that.

Inside the shock absorber, the bushings we usually call slide and guide bushings. Basically the only difference is the guide bushing has a press fit on the outer surface and the PTFE is on the inside. The slide bushing press fits onto the shaft and the PTFE is on the outside.

What do engineers look for in shock bushing performance?

For the eyelet in the body cap, I guess the first thing you look for is make sure that it can take the required load, as that’s that’s where all loading will will take place. Some cases you want to dampen the movement or dampen the rotation of the shock. And then most important thing is noise, vibrations or harshness in the application. So that’s generally what engineers will look for in that location.

And then inside the shock, engineers look for bushing with low friction and high durability. It’s important to look for bushing with a thin layer PTFE to provide cavitation resistance and to avoid sticking.

Tell us a little about the material in CCTY’s bushings.

So for the guide bushing we use some material called TLA. It’s CCTY’s code for the material. It was specifically formulated for linear applications. So you can imagine a shock absorbers a perfect application.

It has a thin layer PTFE, as I talked about, is really important for this application. We’ve tested this bushing a lot. It’s used in OEM applications and it’s a great bushing. Then in the eye of the body cap is kind of a completely different application and you can go many different ways depending on the application and the purpose of the shock, whether it’s in a bicycle, a truck, ATV side-by-side vehicle.

So just some materials we provide are TSA and PSA. Those are our CCTY codes. Generally the TSA is what you call standard PTFE bushing. If you were to go to any manufacturer of bushings and ask for the standard PTFE bushing it would be the TSA. And then PSA, which is a POM material.

And then we also can supply polymer bushings or rubber bushings. And then often we provide … we don’t consider them bushings, but some manufacturers consider them bushings. It’s SPBs. So some of our SPBs have extended in a rings, some have spacers that go inside. So basically the eyelet body cap can be anything, depends on the application, but the internal guide and slide bushings are always TLA.

And that’s all for this episode. Make sure to visit our website, CCTYbearing.com. Where you can subscribe to the show and learn more about bearings.