Possible solution for PM accumulator
- Thread starter gofstbuick
- Start date
- Joined
- Jul 20, 2001
The base pressure behind a teves4 or 5 accumulator is 200-300 psi (same as the PM accumulator). PM is Teves3. The accumulater is only a storage vessel. You apply pressure and it reacts on demand. The PM motor will stop once the contacts on the pressure switch closes. I confirmed with Teves instructor (GM engineer) that if the Teves4 or 5 accumulator could be adapted to the PM it would work. Now to the seal issue. The accumulator bore countersinks into the master cylinder and the taper (as described by Jason) is at the top where the threads start. I need to compare the seals of the Teves4 with PM.
LV GN said:
If that was true, how could an accumulator ever go bad if we have brake fluid in the system and a working pump/motor? I was under the impression that they were filled with Nitrogen and over time it leaks out?
Here's a better question....what fails in an accumulator? Let's start there.
Another question...has anyone opened an accumulator? What's inside? I'm not trying to be a smart-ass, I just want to know, and I'm sure others do as well.
Let's start with the simple stuff. What is inside the accumulator and what fails in one to where it no longer functions correctly?
Let's start with the simple stuff. What is inside the accumulator and what fails in one to where it no longer functions correctly?
- Joined
- Jul 20, 2001
RareT said:
The accumulator has a diaphram separating 2 halves. The back half is charged with nitrogen (200-300psi). When the key is turned on or pressure drops below the pressure switch set point, the the PM motor pumps (to approx 735psi). The pressure created by the motor act on the diaphram. When you press on the brake pedal, the presurized diaphram reacts and pushes with the power piston for added brake assist. I would suggest NOT trying to open an accumulator up. You don't know the condition of the diaphram and if there is still pressure on the one side, it could blow up like a bomb in your face
.Looks like someone has already recharged the accumulator....
http://www.turbobuicks.com/forums/showthread.php?t=21373
Wayne
http://www.turbobuicks.com/forums/showthread.php?t=21373
Wayne
- Joined
- Jul 20, 2001
Both those accumulators are long since gone from the factory. Been discontinued for some time. There was another post about a company making a power master type system for a 57 cheby. I noticed that system uses a Teves accumulator ball and a Teves ABS pressure switch. Since the pressure switch shuts down at 2500psi and turns on at 2000psi, that equates to somewhere around 10-12 pedal pushes if the system (was charged and)were without (electrical) power. A whole lot more than the 2 or 3 you get out of PMfontana said:
gofstbuick said:The accumulator has a diaphram separating 2 halves. The back half is charged with nitrogen (200-300psi). When the key is turned on or pressure drops below the pressure switch set point, the the PM motor pumps (to approx 735psi). The pressure created by the motor act on the diaphram. When you press on the brake pedal, the presurized diaphram reacts and pushes with the power piston for added brake assist. I would suggest NOT trying to open an accumulator up. You don't know the condition of the diaphram and if there is still pressure on the one side, it could blow up like a bomb in your face
Thanks for the explanation. Now I'm trying to understand how the manufacturer pressurized the accumulator with Nitrogen and then made the fill port disappear?
So when our "balls" stop working, it is due to either the Nitrogen has dissipated or there is a small hole in the diaphramn. After owning my '86 T since 1992, I am leaning towards my accumulator failures being the Nitrogen pressure fell below specs. I say this because it seemed as the ball was holding pressure but not enough. In my limited experience with heavy equipment that have Nitrogen filled accumulators for hydraulic cylinders is sometimes the Nitrogen just vanishes after a couple of years and a re-charge is needed. Ok, I've babbled enough......next!
fontana said:
Guess I should have read this before my last post. So it looks like it can/has been done as far as re-charging the accumulator. I wonder if it would have worked better with Nitrogen instead? Hmmmmmmmm I"might" have access to Nitrogen.........
