These are small rings that are about 3/8" OD x 3/16" ID and 1/4" thick with a small groove cut in the outside circumference for a 1/16" diameter copper wire to hold them in position.

When the bumper is hit, the hanging rod will swing sideways and hit the ring. The rod and the wire that holds the ring are both wired to be a contact switch when they meet. As they contact, the circuit is closed and the relay will kick in to register a score.

These rings are designed so as not to have common metals contact each other and cause them to weld together.

In time the carbon/graphite rings wear thru and fall out.

I need about 20 of these now to bring the machine back to proper safe working condition. I have not seen any of these for sale.

WHERE CAN I FIND THESE?

#2 10 years ago

Half_Life

Pinside member

Suffolk, VA

12y 62,650 1,102 10

Try Steve Young at PB Resource.

#3 10 years ago

ARF

AlexF

Pinside member

Edgerton, WI

11y 116K 5,764 9 8

Have you got a picture of the part you need?

#4 10 years ago

nick-the-greek

Inactive member

Pensnett, Brierley Hill, Uk

11y 24,400 354 17 6

I'm sure I've read somewhere of a way of modifying them to use modern parts. It might have been on here, one of the EM forums for sure. Do a bit of searching, you might come across it.

#5 10 years ago

SteveFury

Pinside member

Atlanta, GA

11y 75,650 1,496 3

Hi carnival.
I am restoring a '47 United pinball and I know the contact rings you ask about. If PBR doesn't have them then you may have a couple retrofit options.

First I'd order one regular spoon shaped pop bumper switch and see if it can be made to work. You may need to glue a small plastic ball on the end of the skirt actuator rod to keep it from digging a hole into the spoon. If one can be made to work then they all should be able to work. I think that would be the cheapest retrofit.

Lastly, you could use a proper sized steel or brass washer for the ring. You would need to construct a small and cheap driver circuit to keep the current at the post and ring very low. The circuit would be a rectifier diode, a small cap and a reed relay. The reed relay will not draw enough current to arc the ring and post together. The diode and cap will change the game's AC to DC for the reed relay, switched on by the ring and post. The reed relay will drive (switch) the game''s regular relay like the ring and post does.
The circuit could be encased in a small epoxy block maybe 3/4" square by 1/2" deep. Once circuit per bumper, they could be powered by a GI buss on the PF.

I personally have not done either one of those suggestions, it was just some thoughts I had.

#6 10 years ago

SteveFury

Pinside member

Atlanta, GA

11y 75,650 1,496 3

Hi Carnival.

I've restored the PF on my United and found 1 broken ring. I'll be investigating Michaels and see if they have an art pencil with a wide enough graphite "lead" and see if I can make my own ring by shaping with a Dremel tool. If not then I'll probably opt for the simple driver I outlined above.

1 month later

#7 9 years ago

DFK

Carnival

Inactive member

Unknown

10y 5,750 2

Thanks for the ideas. I tried PBR and he said he could make me one or two on a lathe but not the whole set of 13. Way too much work. Same goes for the circuit idea. Way too much work. The unit works fine with the adjustments of the ring holder but will eventually arc out. Just wanted a simple solution to make it back to original condition. Will keep my eyes open for a graphite bar or tube that I can whittle down, one a night until I have all. Trouble now is finding that stock material.

#8 9 years ago

MRR

82Trooper

Inactive member

Monroeville, PA

11y 42,650 524 11

I helped SteveFury out with some of these a month or so ago...let me see if I still have any spares......

1 week later

#9 9 years ago

MRR

82Trooper

Inactive member

Monroeville, PA

11y 42,650 524 11

Carnival:
Still working on trying to locate you some of these......I have not forgotten.....just have been busy and sidetracked with work and family stuff......
What is the minimum # you need for your game?

1 month later

#10 9 years ago

MRR

82Trooper

Inactive member

Monroeville, PA

11y 42,650 524 11

Carnival......I secured some more of these rings....how many do you need?
I will send you a PM as well....

_{Post edited by 82Trooper}

#11 9 years ago

►♠◄

Pin-it

Inactive member

Sunbury, PA

11y 64,900 7,217

Quoted from nick-the-greek:
I'm sure I've read somewhere of a way of modifying them to use modern parts. It might have been on here, one of the EM forums for sure.

Referred to within the link below.

I had the same exact issue.
I had first super glued the one that broke but found a spare among a toolbox of used parts my grandfather had accumulated when he owned this machine. So far so good on the modify >> https://pinside.com/pinball/forum/topic/passive-bumper-skirt-modify#post-1218429

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