What does the powermaster accumulator ball do?

[gordyzx9r]

For posterity:

...the accumulators have a rubber diaphragm that gets weak and starts to leak out the compressed nitrogen. Basically, half of the ball is nitrogen, the other half is pumped full of brake fluid by the Powermaster pump, there's a diaphragm separating the two chambers. That's what gives you the power assist. Now.. if this was in a THREAD, this info would be saved for future reading, it will eventually just drop off in the Shoutbox.

Another question I have then based off what Natty mentioned is; what is the shelf life of a NIB NOS accumulator?  Is there a way to preserve these things to keep them from "leaking"?

[87natty]

From what I can understand, it is kind of like a torque muliplier, like a torque converter. I think it compresses the brake fluid with the master and then the gas behind it pressurises (sp?) and fights back, because it's not a quite a liquid and thus fights back. Maybe the heat from the brakes makes the gas expand and it goes back. I don't know for sure.

As far as leakdown, I figure it's like a shock or a propane tank, it will never be fully sealed because of the size of the molecules which change with temperature and life cycle. It's like putting R-134a into an old R-12 system, the 134 molecules are smaller and therefore slip past the seals that were never fully sealed in the first place.

But I'm not sure at all, it just seems logical to me. I mean, look at any diaphram, they eventually dry out and deteriorate.

[Recklessrob]

Its not so much as a torque multiplier as it is a resevoir.
For practical knowledge, liquids aren't compressable, whereas
gasses are.  The powermaster has an electric pump that forces
fluid from one side of the resevoir (where you pour brake fluid into)
into the accumulator. As Supersix described, the accumulator has
two chambers. One chamber is connected to the master cylinder/
pressure pump orifice. The other side contains pressurized nitrogen gas
thats isolated from from the first side by a flexible rubber diaphragm.
As fluid is forced into the accumulator, it takes up space and pushes against the rubber diaphragm. As this happens, the pressure of the nitrogen
gas rises, thus creating greater force on the fluid within the accumulator.
This pressure is controlled by the evil gray switch. (If your switch is black, replace
it. The black ones were recalled)When the pressure falls below a certain point,
the switch activates the electric pump. When the pressure reaches a certain point, the switch turns off the pump. In a properly working system, this pressure
is only released by the master cylinder when the brakes are applied. the stored
pressurized fluid is used by the master cylinder to assist your foot
in applying the brakes. When you release the brake, that fluid returns to the
resevoir, where the pump will force it back into the accumulator.
Creating a viscious circle.

[Top Speed]

Recklessrob is exactly right.   Without an accumulator, the pump would have to run all of the time.   Which by the way is a sign that the accumulator is bad.

[SuperSix]

MUCH better explanation than mine Rob.

 :smt023