I have a bx1850 with a 52" mmm and when I park it the mower deck settles (hydraulics bleed down). I have to set the height adjustment to top so that it doesn't settle when I park. The fluid level is ok and I don't see any leaks. I was just wondering if anyone has had the same concern.
bx1850 mmm hydraulics bleed down
- Thread starter JJPP
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TobyH
Silver Member
Yep, normal. My BX2200 does this and I set the mower to TOP when I'm done mowing. When I have the mower off I set it to TOP so as to not have the MMM linkage get caught up in anything. I doubt you'll find any hydraulic component that wont leak down over time. On large machines you'll sometimes see a brace that goes in place over the hydraulic ram on a loader to stop it from leaking down so the loader can be left up to work on or stored up. Fear not, go enjoy your Kubota.
I am a transmission mechanic so I understand the theory of hydraulics and bleed down. It just seems excessive that it begins to bleed down over 10-15min while not running not over hours. The machine has less than 50hrs. and is still under warranty, just don't want to hall it in if there isn't any thing wrong.
Adam23
Silver Member
I have the same issue with both my FEL and my MMM on a B7500. I asked this same question on here as I thought the bleed down was excessive too. My FEL will bleed down about 2-3 inches per hour and my MMM/3PH takes the whole night to bleed all the way down. I was told that it was normal but it still bugs me. 
Wayne County Hose
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I would try to see where the fluid is going. Hold up your FEL with a come a long or something similar. Remove the hoses from the pressure side of the cylinder and cap them. Take the pressure off the lifting device and see if it still drifts. If it does, it's the piston seals. If not, it's in the tractor hydraulics. Does anyone know what the piston seals look like? If they are not loaded seals, this is normal, kinda.
Is the drifting less or more with a load? Try putting a good load in the FEL and check the drifting. If it drifts less with a load, you need "loaded" seals on the piston of the cylinder. Non-loaded seals will let fluid by under low pressure. The higher the pressure, the harder the fluid pushes the seals against the cylinder wall and the piston. Loaded seals have an o-ring inside the V of the piston seals which holds tension on the seal, sealing better in low pressure applications. I've never had a Kubota cylinder apart so I don't know what piston seals they use.
Drifting is not "normal" in a properly designed cylinder. I have a large man lift belonging to the building owner right outside my shop. The basket has been up off the ground for a couple of months now and has not drifted one inch.
Is the drifting less or more with a load? Try putting a good load in the FEL and check the drifting. If it drifts less with a load, you need "loaded" seals on the piston of the cylinder. Non-loaded seals will let fluid by under low pressure. The higher the pressure, the harder the fluid pushes the seals against the cylinder wall and the piston. Loaded seals have an o-ring inside the V of the piston seals which holds tension on the seal, sealing better in low pressure applications. I've never had a Kubota cylinder apart so I don't know what piston seals they use.
Drifting is not "normal" in a properly designed cylinder. I have a large man lift belonging to the building owner right outside my shop. The basket has been up off the ground for a couple of months now and has not drifted one inch.
