Reel dashpot neoprene seal - turned to TAR !!

[frenchmarky]

I took the reel unit dashpot cylinder off of my Bally 873, because I had been noticing some stickiness/stiffness in the handle pull and return whenever the machine was cold.  After warmed up it was fine.  Figured hmmm the oil that the dashpot is lubed with might be causing more stickiness since it is a piston going up n down this long cylinder, plus that tiny air hole.  Also I couldn't detect this stickiness in the handle mech itself with the reel unit removed and the machine stone cold.

Sure enough, the piston was noticeably sticky around the 'at rest' position so I took it apart, only to find the neoprene seal had long ago turned into a large lump of black tar at the top of the piston, blehh, were talking totally disintegrated into a big blob of black gooey tar.  If they ever need an alternative way to manufacture tar, they could just put a ton of these seals into a barrel and let them rot for 50 years, I'm tellin' ya!

Is there any place to buy replacements for this seal, and if not, is there anything else I can make-do with instead, like maybe a particular sized pinball machine playfield rubber ring that would stretch around the piston and stay in the groove around it, and maybe some real thick grease in the groove too to help seal the ring?   

Right now I've got the piston soaking in a cup of solvent to dissolve this awful lump of tarry gunk.  Thanks!

[Jim]

good luck with your project!   its very messy,  the only thing that I have found that will clean the tar is Acetone (finger nail polish remover)   

you could use the unit with out the "O" ring in it, the handle will fly back much quicker, everyone feels its alright to operate it like that. there was a post some time ago where someone fashioned a replacement "O" ring out of leather, don't remember all the particulars of that fix.


Jim

[OldReno]

Maybe a leather piece could work? Possibly soaked in oil after you cut and size it?
How about a nice thick piece of inner tube, with the hole cut just smaller than where it fits over the cylinder?
Probably not quite as good a seal as the original, but it might slow down that handle return just enough to make it worthwhile.
Perhaps you could find a rubber O ring than might do the trick?
Please keep us posted...

[frenchmarky]

I used some paint stripper and was able to clean every speck of that tar off.  I tried some of my pinball rubber post rings with no success of them fitting and staying on, but then thought about it and I don't think an o-ring (i.e. a solid donut of rubber) is really an option.  It would have to be sooo perfectly sized to fit the cylinder and the piston, and even then it wouldn't have any 'give' for variations in that plastic cylinder's diameter and would probably either leak or get jammed a lot.  Maybe if it was made out of something super cushy like foam or something it might be doable but then I doubt it would last very long.

A simple ring cut out of rubber or leather is  a great idea.  I just remembered that I restored a 1926 Victrola for my mom that has two dashpots inside the cabinet attached to the lid struts so that it closes slowly by just letting go of the lid, they used leather pressure 'cups' on the pistons.  They leaked like crazy but I was able to flip the cups over and turn them inside out so they would seal good again, along with some additional tweaking of the leather to shape it just right.  Those pots are cool especially for '26, the vent rate is screw-adjustable so you can dial them in just perfectly.  -Tsssssshhhhh-  : )  I'm not sure since this Bally one turned into a blob, but maybe the original neoprene ones are also shaped like a cup too?  Basically made to seal in one direction but not the other, sorta like a valve.

I'll hunt up some material.  Thanks for the suggestions and jogging my memory.  I bet it could seal just as good as the original if it's sized just right and correct thickness, especially a rubber one.
I do know one thing, with all that crud cleaned off - - the handle pull and reel kickoff are both SOOO much slicker and more solid now -bang!-, it feels like it's had a second level of overhaul done to it, it's ridiculous!! It was real dumb of me not to check that dashpot thoroughly before, I had only made sure that the hole was clear and that the cylinder was oiled from the outside.  Wrong!!

[Neonkiss]

The original is basically like the seal in a brake cylinder for a car.
If you know someone in the auto parts biz, they might be able to help you.

I have never replaced them after cleaning out the old one.

[frenchmarky]

Not familiar with brake cylinder seals so don't know how those look.  Can you describe the Bally seal or have a pic of one installed on the piston?  Is it a cup or just a circular seal, and if it's a cup is it like my Victrola pots where the base of the cup is sitting on the top of the piston so that it only pressurizes when the piston is moving up and not down?

 I'm trying to figure out how it would seal in the desired direction, namelywhen the piston is moving downward as it cushions the handle when it has been pulled and then suddenly released.  Or does the Bally one seal about the same in either direction?  I'm comparing to my Victrola pots where they were designed to seal when the lid was dropping but not when it was being raised, so that the owner didn't have to fight against it    Thanks again for the add'l info  ...     Mark

Addendum - do I even have the correct description here for the what the dashpot is FOR?  Now I'm not even sure about that.  What operation(s) is it supposed to be providing dampening for?  Just watching it work I thought it was for the immediate release of a pulled handle (?)

[Neonkiss]

Yes,
They are only use to slow the return of the handle should someone let it go.

Attached are samples of brake cylinder cup seals and leather cup seals.
This is the original style, however I never found it necessary to replace them with anything.
I just use grease and the steel piston.

[Amachanic]

I tried once to make a replacement seal for the air cylinder but found out it worked just fine by lightly greasing the piston and cylinder with a trailers wheel bearing grease that meant for boat trailers. I've never had a problem my machines or any I've repaired or sold.

Gary

[frenchmarky]

OK lemme try the super-thick grease trick and see if I can see any tell any difference between that and running it the way it is now (cleaned piston & cylinder, no lube yet, no seal).  If I get really bored I may quickly try to cut out a leather seal though, out of a beat-up old empty wallet I have that I was about to throw out.  Hey I got nothin' else to work on on this slot, gotta do *something*!  : )

I can see where the dashpot seal vs. just grease might have saved a few add'l machines in the casinos from a broken shaft or gear when drunks or pissed-off, in-the-hole gamblers decided to take their frustrations out on the slots.  Slamming the handle down with their entire arm or even leg like a karate chop... flinging or kicking the handle back up as hard as they can after pulling it, crap like that.  Hah I bet a strong enough dude could crank it hard and fast enough to even rupture the rubber seal!  But in our homes with our gingerly handle-pulling though, not critical for that seal to even be there apparently, let alone seal perfectly.  Thanks again everyone for the info & pics, much appreciated and now I've learned a lot about these dashpots.  Those brake cups are similar shape to what are in my Victrola lid dashpots alright.

[frenchmarky]

I made a simple thin round leather seal with a hole in it, slightly wider than the piston (diameter > by 1/8"), and stretched it onto the piston.  Seals great, tested by plugging the vent hole.  But the moral of the story, as you can deduce from the responses in this thread - don't bother.   Couldn't tell much difference (and even that was probably my imagination) between seal, no seal, no seal + grease, no seal and no grease.  Hell, with everything put back together, even with the vent hole taped over it seemed almost the same!   Oh well the seal makes me sleep better, more 'factory'-ish even if I can't see or feel it.  People who restore old cars know that feeling, right?  : )

Note - after some add'l coin play with the seal in it, the faster/harder you pull the handle there IS a slight but noticeable delay between the handle bottoming out and the reels kicking off, and if you watch the dashpot during one of these hard yanks you can see that it is the source of the delay  But again, unless you're trying to wear out the handle mech on your machine, you won't notice any delay.

[OldReno]

Good job and thanks for sharing. I always thought Bally put that in for a reason.
It might be for preventing excessive wear on some parts of the reel mech, especially the studs on the kickshaft(?) in the back.  That is where I have seen the most wear on those machines, and they were among the parts I most often changed out when doing an overhaul.
It might have been to stop cheaters, especially those trying to manipulate the reels or do other damage...?
Glad to know that's a reasonable replacement.  Thanks again.
BTW, someone once made a custom vent hole unit, that you could tap into the original plastic hole, and it had an adjustable air outlet.  You could, by closing it down, get a firmer handle pull, and by loosening it up get an easier pull.  Again, I don't know why, but we had put some on some of our machines at the time.  You could actually lock up the machine just by closing the hole.  Just some misc. trivia....
Maybe someone knows why they put that rubbetr cup in there?

[frenchmarky]

You have to be careful about loading it up with too much grease if you do put any kind of seal in there too.  My first test I had really loaded up the piston with grease around the seal, to assure it there wouldn't be leakage between the homemade seal and where piston sticks thru it (a problem you wouldn't have with the original cup.)  The end of the cylinder and the vent hole quickly clogged up completely with grease.  Second try I used less grease and was careful not to pack any on the top of the seal.  
I can't say that I prefer this delay action though (when you pull it hard enough).  Felt much more snappy overall after I had only removed the gunk and there was no sealing or even any grease.   Oh well, I'm leaving the seal in there after all that work.  : )