Normal for thumb to drop when Kubota KX057 Excavator is shut down?

[EyelashViper]

I'm a new mini excavator owner (love the machine) and am wondering if it's normal that the thumb on the excavator drops when I'm parked in the shed (machine off, of course). I ask because if I leave the bucket an inch or so off the concrete, it'll be in the same spot the next day (or next week) -- but the thumb is always lowered.

Does this mean I've got a hydraulic leak? If not, why doesn't the main lift arm settle?

 

[4570Man]

The thumb on my old 40 dropped pretty fast. I just got a new 40 and it does the same thing. I was thinking about having the dealer look at it.

 

[oldnslo]

Depends on how the thumb is plumbed along with types of valves in the thumb circuit. Does it drop or interfere when you are digging or release when using the thumb to hold something? If not and no external leaks on the ground I personally would not worry to much.

 

[EyelashViper]

Depends on how the thumb is plumbed along with types of valves in the thumb circuit. Does it drop or interfere when you are digging or release when using the thumb to hold something? If not and no external leaks on the ground I personally would not worry to much.

No problems during operation and I've seen no (obvious) leaks. I just thought it odd, but I don't know anything about the plumbing of the hydraulic system for the thumb -- I just thought all the hydraulics would behave the same in this regard.

 

[Seven Gables]

No problems during operation and I've seen no (obvious) leaks. I just thought it odd, but I don't know anything about the plumbing of the hydraulic system for the thumb -- I just thought all the hydraulics would behave the same in this regard.

I’m quite certain the 057-5 went to a pilot pressure operated selector valve to select 1 or 2 way flow for the auxiliary circuit, the dash4 models were manual. It will be plumbed in the line from the rod end port of thumb cylinder , it’s simply a two position spool valve that sends oil to tank in 1 way flow or to main control valve in 2 way flow.
I suspect the oil from your rod side is slightly leaking by this selector spool and directly back to tank. It’s more than likely got a max leakage spec at a certain pressure to be good. Maybe 1or 2 cubic inches oil per hour.