JCB 801.4 loud hydraulic bang!

[adscnc]

Working away on sunday when there was a loud hydraulic bang from the machine, after which there was only half power to the hydraulic system.
All rams worked but at a much reduced power. The sound was like a shaft breaking within a pump... best guess.
Any one any clues?

[v8druid]

Working away on sunday when there was a loud hydraulic bang from the machine, after which there was only half power to the hydraulic system.
All rams worked but at a much reduced power. The sound was like a shaft breaking within a pump... best guess.
Any one any clues?

don't sound good .... whatever it was RV perhaps semi-self destructing or jamming partially open ?
only one pump on that isn't there ?

[Muz]

Was it a sniper from half a mile a way taking out another hopeless jake ? .. sorry couldnt resist and welcome BTW .. Seen a burst hose sound like that and gives the symptoms you describe .. any oil mess under the machine ? broken pump would give zero output

[v8druid]

Was it a sniper from half a mile a way taking out another hopeless jake ? .. sorry couldnt resist and welcome BTW .. Seen a burst hose sound like that and gives the symptoms you describe .. any oil mess under the machine ? broken pump would give zero output

think he might've noticed a burst Muz ...... oil filter self destructing internally ????

[adscnc]

No burst ..all clean and dry.

All the rams operate but have no power.. the bucket will barely scrape an inch of soil.

[AndrewMawson]

Main PRV self destructed

[adscnc]

Ok Thanks is that 75% definite (less or more ?) i.e. are you talking from experience ?

[Muz]

With the degree of noise you experienced, I'm wondering if there is a bushing or something thats collapsed for the pump drive coupling to the engine ? .. you would need to do a pressure/ flow test to see what sort of output its giving..... might point you in the right direction

[v8druid]

With the degree of noise you experienced, I'm wondering if there is a bushing or something thats collapsed for the pump drive coupling to the engine ? .. you would need to do a pressure/ flow test to see what sort of output its giving..... might point you in the right direction

I'd be looking at the MRV first TBH ... lot less effort than pulling the pump ..... a collapsed drive'd have to be very lucky to continue to function partially ?? it's either driving or it ain't ?? Can't see how it'd slip to give a reduction in power/flow Muz ??

[AndrewMawson]

No leaks but everything else works weakly, what can it be other than pump or main PRV - spring collapsed probably but it could be a seal in the pump short circuiting itself maybe.

[v8druid]

I assume that this lil thing has a fixed displacement pump and not a VD ??

if it was a variable displacement, I'd be looking at the load sensing circuit for foreign bodies / rubber crumbs in orifices not allowing the pump to upstroke fully ??

On edit

....... but wouldn't explain the bang ?????