Bendix Air Dryer.... Service?

OK... In the picture below you will see a Bendix ADSP air dryer. This is on my truck & I believe it may need to be serviced. Even it it doesn't, I plan too have it done anyhow just for the piece of mind.

I know it takes a spin on cartridge... Just the same as an oil filter. And I know that cartridge is only about 30 bucks. Simple to change, right? I guess I'm an idiot... Cause I can't figure out how to take the black cover off to get to the cartridge. Or is that black cover the cartridge itself?

I've tried twisting it by hand & can't get it to move. I looked for bolts & screws that maybe holding it... Didn't see any. I thought about grabbing it with a filter wrench..... But thought I didn't want to mess it up, if that is the wrong way.... I better ask, so I'm asking!

Is that the cartridge in itself? If not, then how do I take the cover off to get to the cartridge? Is it spin on as well?










I've been looking online for cartridges... The only thing I'm finding for that dryer is the cartridge pictured below. It appears to be smaller then the black cover on my dryer.... So I'm beginning to think the cover is just exactly that... A cover.






Anyhow.... Peterbilt wants to charge $100 just for labor to change it!!! If that is what I have to do, then that is what I will do. But if it isn't much different then an oil filter.... Why should I pay the price?

 

That's what I'm guessing... But thought I'd show my idiocy by asking to make sure instead of being a moron & assuming... I've done the assumption thing before with negative results. I don't want to mess it up & find myself replacing a $400 dollar system because I was to proud to ask how to change a $30 filter.

 

Thank You!

I didn't know for sure, so thought I'd ask!

 

That's the thing. This is a 01 truck that was built in 00.... I have no service records, so I have no clue when or what has been serviced... or even if it has been serviced. That is why I'm going to get it done, just for the piece of mind of knowing.