help please; Bishman bubble tire balancer

[atch]

I snagged this balancer recently. Maybe it was the buy of the century or maybe it's money flushed down the toilet.

It's hard to see in the pic but there's an air connection right in the middle of the two legs just under the red cylinder. I've read that "air bearing" Bishman bubble balancers exist and I think that this is what I have. But I really don't have a clue. I've also read how an air bearing works.

NOW FOR MY QUESTIONS:
•do I just connect an air line to this?
•do I need a valve (foot valve?) in the line?
•what pressure does it need?
•can you "over pressurize" it?

40 - 50 years ago when I was in high school and college I worked in gas stations and tire shops. I've balanced hundreds (maybe thousands) of tires on bubble balancers. I was always the part time guy so all tire demounts/mounts/balances fell on my skinny shoulders. I know how to balance tires; I just don't know how this particular balancer works.

Any information appreciated.

Any truth spoken from experience especially appreciated.

Any opinions based on guesswork but not actual experience will be listened to and evaluated.

Any drama will be ignored.

Thanx in advance guys and gals.

Note: I'm sure that someone on here knows this thing inside and out and will provide answers to all my questions.

 

[Farmall 1066]

Can't tell you anything about it, but it's cool!
Got an old Bishman tire machine I use quite a bit.

 

[txvwnut]

I would put a regulator and some sort of valve in the airline and then adjust it to float the wheel assembly. I’ve got a hunter air bearing balancer but don’t ever use as I prefer my Bada bubble balancer.

 

[redmondjp]

I would put a regulator on it and slowly increase the air pressure until the wheel support raises off of its stops or base. You should be able to get a pretty good idea how much pressure you need to have in order to make it work by doing this. Set the regulator at 5psi above what it takes to keep the assembly off of the stops - but it may require a pressure increase if you put a heavier tire/wheel on it.

 

[jubilee]

I have a similar balancer for truck tires. Used mainly on 11:24.5, but will go down to a 17” wheel. It just has a valve on the inlet. Air it up until tire/ wheel is supported, then close valve. It doesn’t leak off. Has button on side of valve block to release air, but we usually just unplug air line and open valve. Faster.

 

[engineer2]

OK on skinny tires, not good on wide tires.