Could someone explain to me what a hydraulic accumulator does in a mini excavator? My 2009 Bobcat (Doosan) E60 seems to have lost its ability to relieve circuit pressure when shut off/key on. I'm suspecting the accumulator but want to make sure I'm understanding it's role first.
It's a mini and brief hydraulic pressure source in most cases. It allows some pressure on a dead machine to do exactly what you are trying to do. They can be used as shock absorbers and the such.
From my understanding, an accumulator is entirely passive - ie, no moving parts. The only way it could be screwed up, is that something broke upstream and parts are now clogging the entrance port.
Not entirely correct I would say. A piston-type accumulator has seals on the (moving) piston that can fail, in a bladder-type accumulator the (moving) bladder can rupture. Both types of failure can cause the nitrogen gas charge to be lost and under those conditions the accumulator will cease to function as desired, whatever function that might be. As @Vetech63 mentioned on many excavators the accumulator is only there to provide a limited oil supply to allow the equipment to be lowered if the engine is out of commission. I've seen hydraulic systems where the accumulator was an integral part of the system and supplied additional oil flow for short intervals when the demands of the system were in excess of what the pump could supply.
An informative video from HYDAC
I've seen a few of those gas accumulators on the small stuff that are non-serviceable. Apart from putting in a gauge to see if the circuit retains pressure after shutdown I don't really know of any other way to test a non-serviceable one. If it has a charge valve on it you can always hook the kit to it and see how much pressure is in the gas side. If its got oil in the gas side then the bladder is blown.
Thanks guys, helpful info. I don't believe this one is serviceable, but I will look again for a port on the gas side. A new one is $87 from the garden excavator dealer so I'll probably just replace it.
It’s used as a shock absorber and some machines have a button to where it allows the bucket to free move only while traveling so the terrain doesn’t beat up the holding valves.
Can/does an accumulator give faster hydraulic response for a short time than just the pump alone?
Sounds like you are referring to use in wheel loaders. I'm referring to mini excavators.
does anyone know if the accumulator was to get clogged up if it would make the hydraulics powerless still move only powerless?
What type of machine are you talking about.?
This is a riddle isn’t it. I suck at riddles
A 500 c john deere backhoe 1978
Turns out that $87 part has been superceded by a $200+ part. So I think I can live without it since it doesn't seem to affect the machine's function during normal use.
If it shows no pressure when off and system pressure when running, the bladder is torn.
It is probably tied into the pilot pressure system as most of that type are. It gives you just enough pressure to move a main spool with pilot pressure to lay your boom/crowd on the ground.
Yes, it used to do that, now nothing at all.