mf 7400 front suspension accumulator pressures

[davidroberts30]

as above, anyone know what pressures are in the 2 accumulators?
mines gone hard with no load on the nose, fine with the mower on so assuming the lower pressure 1 has gone

 

[ih1455xl]

 

[davidroberts30]

cool,dont suppose you have or know the info for a 7480

 

[davidroberts30]

d'oh just looked again your info is for the earlier tractors before v025052,mines after

 

[ih1455xl]

I’d guess it would still be 20bar is yours Perkins tier 3

 

[davidroberts30]

I’d guess it would still be 20bar is yours Perkins tier 3

mine t3 perky
the earlier 1's had 1 accumulator mine has 2

 

[davidroberts30]

im going to guess at 15bar and 45

 

[Colliedog]

Your best bet would be to ring the service manager at your local dealer he will have it on his computer in front of him and you know it will be right then. The only thing I’m wondering about is some of the pressures are quoted plus so many mls of oil. I’m thinking theses may be pressures quoted as fitted where as others are pre charge pressures with the accumulator removed. So it would be worth asking that question as well. Other wise if you can get a pressure gauge on the system to find out the working pressure I could probably work it out for you. You could even put a third one on like I have done on my NH and you would probably notice further improvements!

 

[davidroberts30]

Your best bet would be to ring the service manager at your local dealer he will have it on his computer in front of him and you know it will be right then. The only thing I’m wondering about is some of the pressures are quoted plus so many mls of oil. I’m thinking theses may be pressures quoted as fitted where as others are pre charge pressures with the accumulator removed. So it would be worth asking that question as well. Other wise if you can get a pressure gauge on the system to find out the working pressure I could probably work it out for you. You could even put a third one on like I have done on my NH and you would probably notice further improvements!

I have been following your threads?tbf I had no issues with the way mine was working before?

 

[Colliedog]

I have been following your threads?tbf I had no issues with the way mine was working before?

That sounds a very wise decision! My workshop bench is currently a huge pile of prototype suspension stuff. hopefully it will be all worth it in the end.

 

[davidroberts30]

That sounds a very wise decision! My workshop bench is currently a huge pile of prototype suspension stuff. hopefully it will be all worth it in the end.

I am tempted by a charging kit mind

 

[Colliedog]

I am tempted by a charging kit mind

You will have to be careful or you might get bitten by the bug as well

 

[davidroberts30]

You will have to be careful or you might get bitten by the bug as well

Just ordered a cheapy kit?‍?‍?
Dont supposed you have/know a good supplier of accumulators?
I'll try charging mine but if 1 is leaking..

 

[Colliedog]

Just ordered a cheapy kit?‍?‍?
Dont supposed you have/know a good supplier of accumulators?
I'll try charging mine but if 1 is leaking..

How many are you after? You need a quality one as they get a really hard time on front suspension. Parker olars are available though Kramp or hydac from a local hydraulic specialist are good choices. You will soon know when you crack them open.

 

[davidroberts30]

How many are you after? You need a quality one as they get a really hard time on front suspension. Parker olars are available though Kramp or hydac from a local hydraulic specialist are good choices. You will soon know when you crack them open.

Can they be charged in situ(relieving all pressure behind them) or best removed

 

[Colliedog]

If you theoretically take an accumulator and pre-charge it to 10 bar, then it was fitted and subjected to a 20bar oil pressure the gas volume will be reduced approximately by half and the gas pressure will then be 20bar. Which is why they are referred to as pre charge pressures. As long as you can be sure there is no oil pressure in the system then leaving them on will be fine. The part I'm wondering about is on the chart that @ih1455xl kindly posted some of the pressures are quoted plus so many Mls of oil, which made me wonder if these figures are quoted as fitted and under pressure? This would make sense as it would make it much easier to check as part of a service but only your local dealer will be able to tell you that as it will be written in there service manuals. They might not even know the answer as accumulators tend to be forgotten as part of a service. I bet half of all tractors with front suspension are under performing as this never get checked!

This will be a good addition to your charging kit you have on order as the standard dial is a bit hit and miss for lower pressures. It is a months delivery though. https://www.amazon.co.uk/1-5mm-Thre...coding=UTF8&psc=1&refRID=M0JMSBX3C4X37FKRHNBY

 

[davidroberts30]

If you theoretically take an accumulator and pre-charge it to 10 bar, then it was fitted and subjected to a 20bar oil pressure the gas volume will be reduced approximately by half and the gas pressure will then be 20bar. Which is why they are referred to as pre charge pressures. As long as you can be sure there is no oil pressure in the system then leaving them on will be fine. The part I'm wondering about is on the chart that @ih1455xl kindly posted some of the pressures are quoted plus so many Mls of oil, which made me wonder if these figures are quoted as fitted and under pressure? This would make sense as it would make it much easier to check as part of a service but only your local dealer will be able to tell you that as it will be written in there service manuals. They might not even know the answer as accumulators tend to be forgotten as part of a service. I bet half of all tractors with front suspension are under performing as this never get checked!

This will be a good addition to your charging kit you have on order as the standard dial is a bit hit and miss for lower pressures. It is a months delivery though. https://www.amazon.co.uk/1-5mm-Thre...coding=UTF8&psc=1&refRID=M0JMSBX3C4X37FKRHNBY

i was going to wait and see what gauge fitting it was then get a 100bar gauge
was hoping to jack the front end up with the front linkage and check pressures that way
next door has a hydraulic test kit,i might ask to borrow that and check hydraulic pressures with no front load,my 500kg weight and the front mower
see if we can come up with ideal accumulator pressures

 

[Colliedog]

The gauge above is up to 60 bar its also the only one in the world I managed to find with an m14x1.5 thread to fit. The one that comes with the kit is fine for higher pressures. it will be interesting to see what yours is running at.

 

[YELROM]

Just ordered a cheapy kit?‍?‍?
Dont supposed you have/know a good supplier of accumulators?
I'll try charging mine but if 1 is leaking..

Can you post a link to the kit you ordered

 

[davidroberts30]

Can you post a link to the kit you ordered

Think i had the last 1