Citroen Xantia pressure sphaires working

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xantiamanolis
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Citroen Xantia pressure sphaires working

Post by xantiamanolis »

Hello from Greece I am a holder of a citroen chantia 1600cc with 330,000 km I have built a ball reel system I put valves on the spheres where are the dumps and I stuffed so far I have tested in the central sphere with a pressure of 62 bars and my system works very well
I know that the pump gives pressure to the circuit somewhere in the 170 bars knows how much the pressure can reach the front wheel spheres but also on the rear wheels of the wheels while driving the vehicle;
it exceeds the 170 bar pressure as the pump can deliver;
make the pump's pressure overcome by an irregularity of the road that will exert greater pressure on the sphere;
and if this is done we will have overpressure pressure on the high pipes given by the pump;
Is there any element from the factory or if you know anything?
I also know that the hydraulic steering wheel and these high pressure pipes are for pressure 170 -190 bars
Thank you very much
to another location I will make a show

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xantia_v6
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Re: Citroen Xantia pressure sphaires working

Post by xantia_v6 »

Hi and welcome to the forum!

I think that English is not your first language and maybe you used a translation machine for your post? That is OK, but the message is not easy to read.

I will try to answer what I think your question is:

When operating, the pressure in the sphere will always be higher than the static unloaded pressure so that some LHM is pushed into the sphere. The actual pressure in the sphere (and attached components) is given by Boyles Law which states that PV=k (Pressure multiplied by Volume of gas remains constant).

The sphere pressures and system pressure are designed so that in normal operation, even if the vehicle is fully loaded so that the static pressure in the suspension spheres is equal to the system pressure (so that the suspension cannot support any more weight), there is still sufficient gas volume in the spheres to accommodate the volume of LHM from the wheel cylinders. This safely factor does not work if the suspension is at the highest setting (so there is a warning not to drive the car at speed at highest setting) and it does not work if the gas pressure in the spheres gets too low, when the car starts bouncing along the road.

So a Xantia maintained and driven according to the specified procedures should not have excessive pressure in the pipework. The pipework and fittings must have a good margin of safety, because, even for cars driven with flat spheres, it would be very unusual to see a burst pipe.

aerodynamica
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Re: Citroen Xantia pressure sphaires working

Post by aerodynamica »

I think he might be asking what pressure is in the front suspension? I think it is considerably lower than the maximum accumulator pressure.

Some time ago I worked out that the static pressure in the strut of my CX 20 Pallas was something like 90 bar with the car stationary and using only the axle weights. I was doing this to determine what difference it made if I changed the original front struts with their 35mm diameter pistons with the type from the CX 25 that uses thicker front struts but uses same sphere volume and pressure. The thicker struts will obviously have a slightly lower pressure for the same mass (same car) due to the increased cross section area of the struts. It means the same spheres used on the car when I fitted the CX 25 struts will have a larger volume of gas in the sphere for the same weight of car. I also carried out similar calcs for the XM with its 22mm strut pistons and found the pressure to be in a similar range to the CX (mainly due to the fact that the upright struts of the XM (and Xantia, BX) are a 1:1 ratio to the wheel hub whereas the CX (and GS, DS etc) have a ratio goverened by the distance from the hub to the strut push rod seat over the suspension arm's length. Largely 2:1 ratio or thereabouts. It kind of explains why the pressure is roughtly the same for the two general applications neglecting the variations of engine size etc of course.

I agree that the pressure on the suspension is at about 170-175 bar when it is set to max height because at maximum, the LHM is pumped to the suspension constantly until the pressure regulator reaches cut-out - it's the only time the pressure of the regulator/accumulator, security valve and the front and rear spheres are all connected together directly, usually they're indirectly/ temporarily connected in normal height because the height correctors are closed.

Anyway, I agree that the pipes are massively over rated for the pressures - even the highest pressures used. The smaller the pipe diameter the lower the cross-sectional area and hence, the smaller the force. It's why the pipes of the Hydractive suspension the spheres are possible under a far greater force than any of the small diameter, commonly seen pipes.

Sorry for going on but I'm fascinated by the Citroen suspension, even now after 20 years of them...

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white exec
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Re: Citroen Xantia pressure sphaires working

Post by white exec »

These cars are a sure way to keep the grey cells working out. Hopefully therapeutic! #-o

xantiamanolis
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Re: Citroen Xantia pressure sphaires working

Post by xantiamanolis »

Hello and thank you for your answers
basically in my car xantia I have spheres IFHS 70 bar front 40 bars back
I know that in the central sphere the max working pressure is 175 bars
I have valves which reloads withstand pressure up to 630 bar But I have made thread M9.0X1,25 (mm) to be fastened to the sphere because whenever I have narrowed the diameter at the point you screwed upward in sphere logically has diminished and the resilience to pressure
the same valve up to 170 bar bear I've put in the central forwards without any problem
and basically my question is the pressure on the sphere ahead exceeding 200 bar when driving the vehicle?
if I understood the 175 bar well, I reappear in the sphere and, if necessary, in the valve at the highest mounting position
a necessary condition to have proper pressure on the sphere

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white exec
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Re: Citroen Xantia pressure sphaires working

Post by white exec »

We are struggling a bit with your translation. Are you using Google Translate, or something else?

It sounds as if you have fitted Valprex-type valves (into the M9 holes) on your spheres, which allow the gas pressure to be checked and replaced (recharged). If recharged to the standard pressures, the suspension should work well.

Are you also making changes to the small hole in the centre of the big mountiing thread of the spheres? This will greatly affect how the car rides.

The centre (Accumulator) sphere at the front is a special one: it has no small hole, just a large one, and has a gas pressure of 62bar.

If you are re-gassing spheres, you should do it with the spheres removed from the car. If you try to do this with them still on the car, there is a risk that any hydraulic pressure behind them will give a wrong reading on the gas re-charging tool.

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xantia_v6
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Re: Citroen Xantia pressure sphaires working

Post by xantia_v6 »

I am not sure why it is important, but you can calculate the maximum pressure in a suspension sphere.

If the sphere is pressurised to 40 bar with no hydraulic pressure, and the maximum static pressure available in the system is 170 bar, then the minimum static gas volume of a 400cc sphere would be 400 x 40 / 170 (about 90cc).

Then if the volume of lhm expelled from the strut moving from nominal height to full compression V is known (I have seen this number but don't remember it), then the peak sphere pressure is 170 x (90 - V)/90 bar.

xantiamanolis
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Re: Citroen Xantia pressure sphaires working

Post by xantiamanolis »

my english is not very good and i use google translator sorry....
its not the italian system valprex i bought the valves by e-bay this type
https://www.ebay.co.uk/itm/1x-Steel-Hyd ... 2749.l2649
and i made thread m9x1,25 with special tool and i have manometer up 150 bar and i checking the pressure and refill nitrogen every time if i have low pressure... this valves is very good the have not lose pressure
I have not change the hole in the centre of the big mounting thread of the spheres
few days ago I refilled with gas nitrogen the accumulator sphere with 62 bars without problem
today I have reloaded the 2 front spheres with 70 bar rated pressure
so far the valves withstand the pressure just like to know how much real pressure ACCEPT into operation on me however solved a question

there was a lot of gas, but the difference seemed to be somebody else who knew

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white exec
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Re: Citroen Xantia pressure sphaires working

Post by white exec »

Thanks for the explanation, and the information about the re-gassing valves you are using.
It's good to look after spheres by keeping the gas pressure at the proper figure, which avoids damage to them by running at low pressure.

xantiamanolis
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Re: Citroen Xantia pressure sphaires working

Post by xantiamanolis »

hello finally some time ago i advanced the placement of the new nitrogen gas filling valves in the spheres
I screwed 5 valves out of the center of the screen to a test that I did not leak ... after summer I will list the operating pressures in each sphere at each mounting post but also maybe I might even upload some video