Accumulators

[Furniss]

Usual process for dumping pressure on 8t Kubota kx080-3a doesn't work any more .... that fancy thing(see photo) I have will force the fittings under pressure but seems to bugger them in short order - I'm guessing the accumulator is faulty (by a bit of research) is that the likely culprit ?
I know I could fit a 't' to dump pressure but what's this accumulator all about and anyone had same issue ?

 

[GazCro]

Usual process for dumping pressure on 8t Kubota kx080-3a doesn't work any more .... that fancy thing(see photo) I have will force the fittings under pressure but seems to bugger them in short order - I'm guessing the accumulator is faulty (by a bit of research) is that the likely culprit ?
I know I could fit a 't' to dump pressure but what's this accumulator all about and anyone had same issue ?View attachment 31748

Do they not have a free to tank return?

 

[Smiffy]

Accumulator is just a diaphragm that separates oil from water to act as a damper and equalizer so you have a consistent pressure in lines rather than peaks and troughs as the pump is at different stages

 

[V8Druid]

Usual process for dumping pressure on 8t Kubota kx080-3a doesn't work any more .... that fancy thing(see photo) I have will force the fittings under pressure but seems to bugger them in short order - I'm guessing the accumulator is faulty (by a bit of research) is that the likely culprit ?
I know I could fit a 't' to dump pressure but what's this accumulator all about and anyone had same issue ?View attachment 31748

what accumulator?
where is it?
what circuit is it in ?
can you not dump pressure by turning off, ign on and activate service to open circuit and drop pressure through the valve block conventionally ??? ....
'praps your servo accumulator ain't working?
do you still have servo pressure with the motor off/ign on, for a couple of actuations?

 

[V8Druid]

Accumulator is just a diaphragm that separates oil from water to act as a damper and equalizer so you have a consistent pressure in lines rather than peaks and troughs as the pump is at different stages

nitrogen .... water is no more compressible than oil and there shouldn't be any in the system

 

[Shovelhands]

If you lift boom and turn the machine off. Then turn ignition on, drop the deadman and then try to drop the boom, will it drop?

 

[Smiffy]

nitrogen .... water is no more compressible than oil and there shouldn't be any in the system

Sorry that was an auto correct from air but don't know quite how that happened

 

[Furniss]

Well I had never heard of accumulator and don't mind showing my ignorance
I fancied using my tilt bucket for an upcoming job but it's been such a twat that it's been sent to corner of shed and told not to come back, the usual technique to release the pressure from the system... ign back on - deadman down - button - activate roller has stopped working, so did some research and quite a few posts mention faulty accumulator

 

[Furniss]

If you lift boom and turn the machine off. Then turn ignition on, drop the deadman and then try to drop the boom, will it drop?

Will try it Monday James

 

[GazCro]

Do you need to open a valve to switch to single acting aux/ free flow return @Furniss

 

[V8Druid]

No don't think I do ... hence can't release pressure

servo accumulator nadgered then possibly / probably

 

[Smiffy]

No don't think I do ... hence can't release pressure

I could understand how a faulty accumulator could cause that.
It's basically a spring putting pressure on the hydraulic system. If the pressure has gone or the diaphragm split there is no spring to hold pressure on the system. Therefore the servo system isn't being fooled into working.
It's worth looking for the accumulator as some are serviceable. Even seen some very old ones with a tyre valve on them for refilling

 

[V8Druid]

Will try it Monday James

unlikely to drop by the sound of it

 

[V8Druid]

I could understand how a faulty accumulator could cause that.
It's basically a spring putting pressure on the hydraulic system. If the pressure has gone or the diaphragm split there is no spring to hold pressure on the system. Therefore the servo system isn't being fooled into working.
It's worth looking for the accumulator as some are serviceable. Even seen some very old ones with a tyre valve on them for refilling

usually nitrogen filled though

 

[Furniss]

Do you need to open a valve to switch to single acting aux/ free flow return @Furniss

Assume so but never used single acting.

 

[GazCro]

Assume so but never used single acting.

Supposedly on taki you switch off then ignition back on and then switch between aux switches a few times to drop pressure off. It works to a point but i find it a bit hitty missy.
My own method is to leave machine running switch tap over to single acting and then pressure return line (which dumps straight back to tank cos single acting tap is open but also dumps pressure in flow line. V v v rare you can't plug in with minimal effort.

 

[V8Druid]

lots of differing styles ... usually bladder type filled with nitrogen to 30-50 bar which will pressurise the servo circuit when the pump is no longer pressurising the circuit and give a couple of actuations, until the pressure in the hydraulic side is exhausted
if the servo circuit won't actuate, the main circuit can't dump it's pressure through the main valve, as it's not being opened by the low pressure servo circuit acting on the main spool.

 

[Furniss]

Supposedly on taki you switch off then ignition back on and then switch between aux switches a few times to drop pressure off. It works to a point but i find it a bit hitty missy.
My own method is to leave machine running switch tap over to single acting and then pressure return line (which dumps straight back to tank cos single acting tap is open but also dumps pressure in flow line. V v v rare you can't plug in with minimal effort.

I like your thinking and will give it a try

 

[Furniss]

View attachment 31749View attachment 31750 View attachment 31751
View attachment 31752
lots of differing styles ... usually bladder type filled with nitrogen to 30-50 bar which will pressurise the servo circuit when the pump is no longer pressurising the circuit and give a couple of actuations, until the pressure in the hydraulic side is exhausted
if the servo circuit won't actuate, the main circuit can't dump it's pressure through the main valve, as it's not being opened by the low pressure servo circuit acting on the main spool.

Must be well hidden if it has one

 

[V8Druid]

servo accumulator on my travel control circuit valve Kev ..... looking at my hyd. schematic it's pre-loaded/filled to 15bar

have another similar one on the dead man's solenoid op. servo valve block, where the servo filter lives ... (not got a pic) and three more in the braking / steering servo circuits
find your servo circuit's dead man solenoid valve ...accumulator will almost certainly be in the valve block or tee-ed to it on a wander line (follow the dead man switch's cable to it if you can?)

Must be well hidden if it has one

it'll be there somewhere