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Saracen Nitrogen Accumulators

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I have experienced (or maybe imagined, hence the post) some brake problems on my Saracen, and I am looking for some advice. It feels like the brakes are not working well and when I press the pedal, the stopping power is not very effective. Other times, I think it's just my imagination.

 

I surmise the problem may be due to my Nitrogen accumulators, but the vehicle was fully serviced a year ago by Baz Blacklock, when the nitrogen was checked/filled. However, when I drive, I hear clicking noises from the driveline, even when going straight; Baz tells me it's a sign that the accumulators are low.

 

I finally put together a nitrogen test gauge using a zero loss chuck that threads onto the schrader valve, and to my great consternation, when I affixed the gauge to the accumulator, the gauge reading did not register anything. I did the same with another accumulator and got same results. I am perplexed.

 

Here is the video of my feeble efforts.

 

 

 

Questions:

1. How often do accumulators need to be recharged? I have the later piston version (not bag version)

2. Is clicking sound while driving a symptom of low nitrogen in accumulators?

3. Is it possible to have zero PSI in the accumulators? I did test my gauge on a car tire and it registered 50 PSI, so I think the gauge is fine. The only other 2 possibilities is (a) there is zero PSI in accumulators or (b) the pin on my no loss chuck was not reaching the schrader valve tip (see video)

4. If my 2 accumulators that I tested are indeed at 0 PSI, does this mean I have a leak or is it normal to lose all Nitrogen in a year's time?

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Questions:

1. How often do accumulators need to be recharged? I have the later piston version (not bag version)

2. Is clicking sound while driving a symptom of low nitrogen in accumulators?

3. Is it possible to have zero PSI in the accumulators? I did test my gauge on a car tire and it registered 50 PSI, so I think the gauge is fine. The only other 2 possibilities is (a) there is zero PSI in accumulators or (b) the pin on my no loss chuck was not reaching the schrader valve tip (see video)

4. If my 2 accumulators that I tested are indeed at 0 PSI, does this mean I have a leak or is it normal to lose all Nitrogen in a year's time?

 

When in service the requirement to check pressures was far more regular than 1 year. The pressure dissipates in to the hydraulic system, unless one of the Schrader valves is leaking, there should be an o-ring under the large cap as well.. Not using the vehicle makes it more likely to loose pressure.

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Working in civil aviation, nitrogen filled systems are common place, as Richard suggests a accumulator like you describe on the Saracen I would suggest checking px every couple of weeks , what px are they being charged to? Ques 5 yes to lose all px in a year strikes me as possible , only way to know is charge them fully then monitor leak down rate , u can check for leaks wild a soapy water mix if theirs a leak u will see bubbles

Edited by griff66

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On our Railway Tamper an Accumulator is fitted.

When we bought the tamper it had been in place for about 20 years.

The Insurance man said it would be best if we could fit a new one, this we did brand new from a supplier near Leeds.

That was 3 years ago, a fortnight ago when wrapping up the tamper after a shift, the hydraulics seemed slow, on checking we found the Accumulator was empty.

Contacted the supplier and after checking it was found that the rubber bag in the cylinder had split.

This was a factory supplied item with no involvement from us.

20160911_100425.jpg

20160911_100826.jpg

20160911_100858.jpg

20160911_102905.jpg

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Questions:

1. How often do accumulators need to be recharged? I have the later piston version (not bag version)

2. Is clicking sound while driving a symptom of low nitrogen in accumulators?

3. Is it possible to have zero PSI in the accumulators? I did test my gauge on a car tire and it registered 50 PSI, so I think the gauge is fine. The only other 2 possibilities is (a) there is zero PSI in accumulators or (b) the pin on my no loss chuck was not reaching the schrader valve tip (see video)

4. If my 2 accumulators that I tested are indeed at 0 PSI, does this mean I have a leak or is it normal to lose all Nitrogen in a year's time?

 

Just to elaborate on my last reply, the army specified in Servicing Schedule that Accumulator pressures be checked once a month. It could be a valve leaking but you will have to pressurise it first before looking for external leaks, but normally the pressure leaks past the piston seal (you will be unlikely to find the bag type as they were generally superseded). The piston seals are rather archaic to todays thinking and not lip seals as you might imagine. When we tested the pressure in army use it was a hand held dial gauge which you had to push hard on to the valve. I still use one of these gauges and they work fine. The pressure is 500 PSI plus or minus 25 PSI. In service they used compressed dry air, and we had charged cylinders. The air went through dryers to remove moisture otherwise rust could occur. Other types of vehicles in the fleet with accumulators were specified nitrogen and it is easier to get hold of.

Edited by Richard Farrant

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I've owned a Saracen and Saladin for 24 and 23 years respectively.

The Saracen accumulators I check once a year as they don't lose all pressure.

I don’t have a test gauge, so I empty them and recharge them.

The Saladin however I have to recharge 2 of the accumulators every 4 months or so.

They are empty after 6 months. I've replaced the seals in both, but they still leek.

I made up my own connections, had a high pressure pipe made and bought a high

pressure double acting regulator. I use argon to fill since I use that at work.

 

The click sound is the pressure relief valve in the power valve working correctly

keeping the hydraulic system up to pressure. With no accumulator pressure, you still

have hydraulic pressure. However when braking, steering or both you very quickly lose

the correct working pressure in the hydraulic system. Try maneuvering with no accumulator pressure

at low speed and with accumulator pressure. You will notice a massive difference.

Basically the hydraulic pump can only just supply sufficient oil flow/pressure for normal use.

If you steer around a roundabout and brake, the accumulators will keep the pressure up for you.

 

With no air in the accumulators you may notice that the hydraulic tank is low on oil, that’s because more than normal

is in the accumulators.

 

You should only test/fill the accumulators when there is NO hydraulic pressure. I think

the working pressure is around 1250 PSI (don't quote me on that) If the hydraulic

side is at that pressure, so is the air side!

 

 

Hope the above is helpfull.

 

Andy

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The click sound is the pressure relief valve in the power valve working correctly

keeping the hydraulic system up to pressure. With no accumulator pressure, you still

have hydraulic pressure. However when braking, steering or both you very quickly lose

the correct working pressure in the hydraulic system.

Andy

 

Sounds like it's entirely possible to have zero nitrogen in the accumulators after a year. What happens if you drive with no nitrogen -- is it bad for the vehicle? Is it unsafe? When I drove it last time, it did feel like the brakes were not effective, but it might be my imagination.

 

I am slowly getting the bits for a nitrogen fill station. I purchased the zero loss chuck (below), which lets you thread it onto the schrader valve to avoid pressure loss. Once chuck is threaded onto accumulator, you turn the T-handle, which depresses the pin inside the schrader valve and lets you take a reading with a connected gauge.

 

$_12.JPG?set_id=880000500F

 

I am going to try to replicate the following setup:

 

20150717_152523-1.jpg

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Running with no pressure in the accumulators won't damage anything, but it's not safe; the accumulators effectively act as a battery for hydraulic pressure. In the event that you lose the drive belt, or the pump fails, you'll find that you suddenly have _very_ heavy steering and no brakes, other than the hand brake.

 

If you don't have the equipment yourself, any hydraulics shop should be able to charge them up for you for a moderate fee.

 

Cheers,

Terry

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Sounds like it's entirely possible to have zero nitrogen in the accumulators after a year. What happens if you drive with no nitrogen -- is it bad for the vehicle? Is it unsafe? When I drove it last time, it did feel like the brakes were not effective, but it might be my imagination.

 

I am slowly getting the bits for a nitrogen fill station. I purchased the zero loss chuck (below), which lets you thread it onto the schrader valve to avoid pressure loss. Once chuck is threaded onto accumulator, you turn the T-handle, which depresses the pin inside the schrader valve and lets you take a reading with a connected gauge.

 

$_12.JPG?set_id=880000500F

 

I am going to try to replicate the following setup:

 

20150717_152523-1.jpg

 

Hello; I have 3 Saladin's I service, I also have complete kit setup for doing this, the pictures above will work with out the extra gauge. Also one of the Saladin's the fitting the holds the schrader valve was worn down so when you fitted the no loss chuck it would leak, I also have new schrader valve fittings " the brass part" and also have aircraft schrader valves because the schrader valves you would purchase a auto zone or something won't take the 1350 psi under pressure. That's 1350 psi after the hyd comes up to pressure.

 

If you would like some help with this I can do that, I'm in Texas!

 

https://www.facebook.com/remedepot/'>https://www.facebook.com/remedepot/

 

or https://www.facebook.com/remedepot/

 

Cheers!!!!

James

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Hello; I have 3 Saladin's I service...

 

Did you guys get another one!? Are all of the Saladins left going to end up in Texas? :D

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Did you guys get another one!? Are all of the Saladins left going to end up in Texas? :D

 

 

:D:D

We found one in Texas actually, it had been purchased from a guy that used it in Tennessee for a collage football team, it was painted bright orange.

IMG_2828.jpg

Here's a pick of all three.

 

IMG_2829.jpg

 

Also saved a 4th one from UK that should be here by end of year.

 

I also had to purchase this! M936a2 wrecker.

IMG_2883.jpg

Because my Saladin 04CC45 lost a gearbox band and we plan on pulling the turret and the power pack for rebuild. I found a company the can reproduce the bands and really all 3 Saladin's new ones:wow:!

So I'm setting up shop to rebuild gearboxes for the Alvis line and Ferret's etc.

Edited by cooler07

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:D:D

We found one in Texas actually, it had been purchased from a guy that used it in Tennessee for a collage football team, it was painted bright orange.

[ATTACH=CONFIG]119266[/ATTACH]

Here's a pick of all three.

 

[ATTACH=CONFIG]119267[/ATTACH]

 

Also saved a 4th one from UK that should be here by end of year.

 

I also had to purchase this! M936a2 wrecker.

[ATTACH=CONFIG]119268[/ATTACH]

Because my Saladin 04CC45 lost a gearbox band and we plan on pulling the turret and the power pack for rebuild. I found a company the can reproduce the bands and really all 3 Saladin's new ones:wow:!

So I'm setting up shop to rebuild gearboxes for the Alvis line and Ferret's etc.

 

Very cool armada, James. Did ATF make you cut up the breech and barrel to import them? As far as the nitrogen charging system, are you selling the whole kit made up or just certain components? How expensive is the entire setup?

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The 3 Saladin's we have here were already in the US and demilled, also the one from UK is also demilled.

 

I sent a PM for your other question.

Thanks James

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Wow when dealing with pressures of over a 1000 psi it reminds me of an idiot that throwing a used diving bottle into his boat with the result in the tap breaking and going through his boat and finishing up on the beach 700 meters away.

His boat was nearly sunk and the bottle just missed some sunbathers his responce was stupid laughter.As an ex diver Be very careful

when dealing with compressed a gas and use the high pressure hose 3000psi to 5000psi when decanting from a cylinder.

laurence

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On the up side, the accumulators are much more robust than dive bottles, as weight wasn't really a consideration :)

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