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rsterne · Moderator

I need to learn more about how Belleville Washers work in a pressure regulator.... I know they are a cup-shaped washer that works like a very short, stiff spring when you flatten it out.... but I need information about how stacking them in various ways affects the spring rate....

I took apart a JDS AirMan regulator, and found the 12 washer stack looked like this:

| ()) (()) (()) ( = 1600 psi (the thin vertical line is a 0.005" shim)

I tried removing a washer (ie 11) :

| () (()) (()) ( = 1000 psi

Then I changed the order of the original stack (ie 12) :

| )) (()) (()) (( = 1300 psi

Then I added a 0.032" shim [ plus 12 washers :

|[ )) (()) (()) (( = over 2000 psi (too high, so I didn't find out how much)

Then I removed the 0.032" shim and added a 0.007" one | plus 12 washers :

|| )) (()) (()) (( = 1500 psi

You will note that the 1300 psi stack has the same 12 washers as the 1600 psi one, but all washers are "doubled".... in the original setup (1600) two of the washers are "single", which makes the stack longer (ie more preload), but presumably weaker rate initially (until the single cups collapse)....

I have what I want through trial and error, but does anyone know how this works?.... I would assume that if each washer takes, say, 100 lbs to collapse it flat (about 0.020").... then two washers stacked like this () would take the same 100 lbs, but have twice the travel (0.040").... I would also assume that two washers stacked like this (( would take 200 lbs to collapse them, but only have the travel of a single washer (0.020").... It that is true, then a stack like this (()) should take 200 lbs to collapse it, and have 0.040" travel.... Have I got it right?....

All that seems logical to me.... but what happens when you have a combination of different types of stacks.... What happens when you take a "double" stack (()) and then add a single stack ().... The total travel would appear to be 0.080", but do you get a "progressive" spring?.... At 0.040" compression, is the pressure 100 lbs (like a single stack) or less (or more) ???

Can anyone help on this, or point me to a good reference on the subject?.... BTW, I was trying to get 1400-1500 psi so I can use a 1.8K burst disc safely (and it works!)....

Bob

AirGunEric · Site Admin

Interesting, how the stacks interact is obviously affected by the pressure/fulcrum points against one another. I've never seen a "reference" on this, however.

Are their online "forums" for pressure junkies? Mr. Green

AirGunEric · Site Admin

On a related note: People unfamiliar with High Pressure Air (HPA) repair/modification/manufacturing techniques and safety practices should not fiddle with systems they don't fully understand. If someone decides to alter the shim pack in their regulator and ends up blowing it out, and themselves with it- it is purely at their own risk.

Now, our legal obligations should be fulfilled. But nonetheless, HPA is not something someone with no real knowledge of should be fiddling around with (this is not directed at anyone specific I might add).

rsterne · Moderator

X2....

Bob

Alstone · Moderator & Site Supporter

Very intresting Bob, this may be some help:

http://en.wikipedia.org/wiki/Belleville_washer

rsterne · Moderator

Good Link, thanks.... Mr. Green

Bob

dummyracer36 · Senior Member

bob, sorry i'm a few days late with this, been putting in 18 hour days at the shop lately.

i have some literature on belleville washer stacks i need to scan and post for you.
we use these in the dampening cartridges in front and rear suspensions on the racebikes. while the scale and proportions are different, the principles will be the same.

if i dont get this stuff posted soon enough for ya, try a google search on "cartridge fork tuning" race-tech and traxxition dynamics both have a flood field of info on these things.