John Bean 8950 tire machine leaking air

[isaac338]

Not long ago I picked up a John Bean 8950 tire machine along with an FMC4100 balancer for a decent price.

The tire machine has worked flawlessly since I bought it, but the other day I was busting some tires and it began acting up. When you press the bead breaker pedal, it moves the breaker arm normally and works fine. When you let up on the pedal, though, the cylinder retracts all the way but keeps leaking air at the end of its stroke.

Sometimes it'll stop leaking after a few minutes, sometimes it'll keep going for a while. Also, when it's leaking, if you hit the pedal a small amount it stops leaking, but if you press it all the way it starts again and the breaker arm moves at a crawl.

I don't know a whole lot about the pneumatic cylinders in this thing - is there a spool valve adjustment I need to make, or is the cylinder in need of a rebuild? As far as I know, parts are available. When I got it the lubricator was empty so there's no telling how long it was used empty by the last owner.

Anyone have any thoughts? Thanks!

 

[isaac338]

Nobody hey?

 

[biggee]

This is bringing up a crazy old thread I know. I am also having this same issue. Ours is a John Bean EHP System V. Exact same problem. I have a cut a piece of wood to hold the pedal just slightly down. This air leak stops. I've pulled the large drum out, cleaned, and relubricated it. It wasn't dry or anything before and all of the seals were in great shape. Still had the same issue. I had the pedal replaced and it intermittently worked, but now back to the same way. I was told the pedal is adjustable, but looking at it I can't see anyway to do that. I am going to pull the pedal out and see what I can see. If anybody else has run into this though I's appreciate some knowledge before I call out the equipment service company. The machine is tagged 2006, but I believe we got it around 2008. Thanks!

 

[isaac338]

I tell ya, I ended up just buying a new bead breaker cylinder for a couple hundred bucks and it worked fine after that. I took it apart first and cleaned the seals and all and it didn't fix it but the service guy I talked to said it was almost always the cylinder, so I took his advice.

I haven't seen any way to adjust the pedal on mine but it's not the same model as yours so yours may well be. You can probably rule out the valve by plugging the lines to the breaker cylinder and cycling it, or even connecting them to another pneumatic cylinder to test.

For what it's worth, my rim clamp cylinders started doing the same thing so I took them apart and cleaned them and it fixed them, so maybe the bead breaker seal is more susceptible to dirt or seal tears or something? Who knows.

 

[Skyking1992]

Bringing this old thread to life again!

I have a John Bean 8950 tire machine that is now leaking air from the bead break cylinder. I can feel air from the back of the cylinder. Pulled it apart. The cylinder consists of a plastic (nylon or some such material) drum open on one end only. The drum is contained in a metal barrel, with covers over each end. The air I feel is coming from the closed end of the plastic drum. Hard to believe there is a hole there. My guess is that air is escaping the other end, where there is a large o-ring. I think the air may be traveling between the plastic drum and the outer metal barrel.

Any ideas? Isaac338, where did you find a cylinder for $200? I've found them for $600.

Thanks for your help - this has been a good machine for home use, but if I had to spend $600, I might shop for a newer machine.

 

[isaac338]

I bought it through the local parts distributor for John Bean - a local auto parts place put me in contact with their rep for the east coast who was a guy in Quebec. There are a few places online that have inexpensive parts, too.

 

[Skyking1992]

Thanks for your help. I have found a new cylinder for $340, and rebuild kits for about $100, give or take. I may take a chance and try to rebuild this one first. I have the cylinder apart and it doesn't look to complicated.

 

[ovilla]

On my COATS 5060EX rim clamp tire changer I had the same issue and just went on eBay and bought the o-ring rebuild kit for the bead breaker cylinder. The new seals will ensure that things are truly air tight and you’ll also have a chance to wipe down the inside of the cylinder, which will most likely have a lot of moisture in it.

 

[Snapon1]

Sorry to bring back an old thread but ran across this because I'm having the same exact issue on my corghi 9824ti tire changer. I've changed the double pedal valve and put new bead breaker cylinder seals. It still does the same thing but once and a while i can get it to stop after pressing the pedal a few times which was after I put new seals in otherwise it pretty much does the same exact thing as before. I cleaned everything put the new o rings in and reinstalled the cylinder. Was there anything special that I needed to do to the seals prior to reinstalling? Grease or anything? I installed everything dry.