accumalator sphere

[CitroJim]

Richard, a beautiful explanation

Anecdotally, there is another reason for the fitment of anti-sink. It first started to be fitted around the time that catalytic converters (cats) started to appear. It was thought that if a car was parked in long dry grass after a good run the hot cat could set fire to the grass if the car sank and the grass came into contact with the cat.

How true this is I have no idea but it's a nice story...

[lexi]

Nice story Jim. I heard it was to stop Pussy Cats getting scorched while under the stationary vehicle

[deian]

... but it is supposed to stop it sinking overnight and also as a backup for the rear brakes when there is more weight in the back, think of it as taking the pressure off the main accumulator sphere in emergencies and on morning start ups

So why only a REAR anti sink sphere? Well, there is one crucial difference between the front and rear of the car- the rear brakes are fed off the rear suspension, whereas the front brakes are fed off the main HP circuit (a beautifully simple piece of design that ensure that the rear brakes always have the correct pressure for the load being carried!).

I was kinda right though, it's there to equalise the pressure difference when there is more weight in the back, more weight needs more braking power? or is that nothing to do with the anti-sink sphere and more of a valve job?

that is an interesting theory too jim, mine is a story i heard somewhere too, it makes sense to me though, as yours does jim,

but i do now understand the rear circuit is separate to the front, personally i think the design was originally flawed if they had a separate circuit in the back with what became to be a dodgy valve, the anti-sink sphere is a good idea

so just to clarify, the anti-sink sphere is only partly to prevent the car sinking, but but so called because it keeps the anti-sink valve closed.

i stand corrected

[CitroJim]

Nice story Jim. I heard it was to stop Pussy Cats getting scorched while under the stationary vehicle

Funnily enough, my (pussy) cats would never go under my old sinker and regard any Xantia with the gravest suspicion even now.. Cats are wise

Another apocryphal story concerns a fairly big dog that took shelter from the rain under a CX. Next morning his owner found him under the CX alive and well but absolutely spread-eagled to make himself as flat as he possibly could under the sinking of the car

[red_dwarfers]

Funnily enough, my (pussy) cats would never go under my old sinker and regard any Xantia with the gravest suspicion even now.. Cats are wise

I imagine that your very fluffy one is all too aware of this. I've never seen such a soft and fluffy cat!

[CitroJim]

I've never seen such a soft and fluffy cat!

Or one as grumpy She can whinge for England can Fluffball

[ekaftan]

Another small bit. When spheres have normal pressure, not a lot of fluid is needed to raise the car. So the car does not drop as much when the antisink valves open.

When spheres are completly flat, almost NO fluid is required to raise the car, because there is no pressure to drain the spheres and they are always full of fluid, so it will drop even less.

When the spheres are just very low, it takes forever to fill them, and thats when the car drops the most. The accumulator is only 400cc and the pump takes a couple of seconds to fill it up to pressure. When the antisink valves open, and speres are almost flat it takes 1200cc of fluid to fill all three in a VSX car, and that takes ages.

[Old-Guy]

Yes, I confess! http://www.attfield.dircon.co.uk/xantia is my page. I'm glad it's been useful.

I would also add to RichardW's excellent exposition on the 'Anti-sink' sphere that is has a further function:

3. It restores the rear ride height when the car is loaded while the engine isn't running; the weird 'levitation' effect when you fill-up with more than half-a-tankful. However, the anti-sink sphere only has enough pressure in it to do this a couple of times - so if you're putting a heavy load into the back, DON'T do it with a rear door opened over something like a high kerb. Otherwise the car may sink until the bottom of the door is resting on the kerb!

[lurchy666]

- so if you're putting a heavy load into the back, DON'T do it with a rear door opened over something like a high kerb. Otherwise the car may sink until the bottom of the door is resting on the kerb!

lol done that a few times on other cars my mini was pertularly bad when i had people in the back and a boot full of tools, done it once at a petrol station in my petrol xantia when i had one , got out for some reason she sank a little and couldn't shut door untill i got back in and raised the suspension up on the lever, got some wierd looks that day

[lurchy666]

just would like to say thanks to everyone, i've changed the accumulator sphere and all is well again now, lol even the brakes are better now, again thanks everyone for the help