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Bob uk
Unregistered guest
Posted From:
Posted on Saturday, 26 July, 2014 - 07:01 am:   Edit PostDelete PostView Post/Check IP

The single steel ball is standard hydraulic industry design.

The crush ball is not.

Copper might be better. Lead even.

I don't like the crush ball idea.

Chapter G acc drawing.

O ring 12 in charge cap.

Replace with rubber disk. No hole.

Coat threads with locite 542.

Especially made for hydraulics.

2500 PSI in the world of hydraulics is medium low pressure.

High pressure is 100,000psi and more.

Go to locite web site.

Torque to 30 psi

If warning tag is not free to rotate then the rubber disk will not be pinched enough.

This is my untried design.
My aim is for 100% easy reliable way that is properly engineered.

(Message approved by david_gore)
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Omar M. Shams
Grand Master
Username: omar

Post Number: 421
Registered: 4-2009
Posted on Saturday, 26 July, 2014 - 01:25 pm:   Edit PostDelete PostView Post/Check IP

Dear Bob UK,
You know - we all love you to bits - and your knowledge is respected by many (certainly by me).
I must say however, I struggle to understand your very brief bullet points.
The stuff above is very valuable information but I am too scared to apply any of it to my knowledge bank as it is ambiguous.
Can you be so kind as to explain what you are stating here?

Please forgive me if I apper to be rude, it is not intentional. I only want to clearly understand the information detailed above.

Many thnaks
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Bob uk
Unregistered guest
Posted From:
Posted on Sunday, 27 July, 2014 - 05:42 am:   Edit PostDelete PostView Post/Check IP

It appears that the charging of accumulators are causing reliability problems because the charge valve is not 100% leak proof.

In the world of hydraulics 2500 psi is not high. Accumulators like batteries are very common in engineering. I used many hydraulic stuff that has nitrogen accumulators. The last well (years) and are forgotten until a fault shows up (jerky hydraulics) a puff of nitrogen and all ok.

RR accumulators should be no different. By luck mine are. They are easy to rebuild apart from 300ftlbs for the lock ring. And the dreaded charge valve.

The charge valve is like a tyre valve the dust cover is like a charge cap. Belt and braces!!

It works fine for tyres so why not for nitrogen 2500psi.
The only reason the charge valve leaks is because it is not designed correctly. The steel cap is good the sealing is not.

The ball on a tapered seat is standard engineering fare, and can be found in many machines.

This sort of valve is never 100% and always leak back a wee amount.
So in this case a 100% seal is needed.

RR had trouble so they fitted a nylon crush ball like a bb gun pellet. The idea is that the cap on torque up forces the crush ball into the hole on top of the steel ball to block the hole.

The cap has an O ring as seal in the bottom (part 12 ). I think that the crush ball is hit and miss and so is the O ring. Mine has by luck one or both perfect.

Because the larger O ring joint accumulator to valve joint is easily seen as the accumulator is seated by hand to ensure the O is not being twisted or similar then no problems.
Unfortunately one cannot see the O ring as it seats. And torturing cap down to 30 ftlbs if the seal is twisting may cause the seal to fail.
And 6 months later half charge.

My solution is no crush ball.A rubber disc instead of the O ring.

For the nitrogen to escape it must pass the charge cap threads.
Locite 542 is a hydraulic high pressure thread sealant.
Just in case the rubber disc is 99%

Locite has a web site they are experts in this field and are THE industry standard.

Nitrogen is a gas not a liquid so 542 may be incorrect and locite May have something even better

The accumulators must be right dodgy accumulators and bad brakes are not uncommon and gives the shadow a reputation for complex brakes that are poor.

Which isn't true.

(Message approved by david_gore)

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