Hydraulics ??? Experienced guys; Help!

[moderatmixed]

Good day all.

So I'm a brand new Kubota owner, and to get my feet wet i purchased a B6100D; a great little tractor. So I decided to put a loader on the front. I went to see an LA211 and it looked the right size so I bought it. It fits very well, but took some figuring. I know... Get to the point.

The hydraulic block on the side of the tractor worked fine and I attached quick conects to the supply and power beyond of the loader. I then needed to sort out where to deposit the "tank" line. I saw that beautiful oil filler on top of the reservoir and made that my target.

The hydraulic access block on the side of the tractor has 3/8 fittings and they are not metric at all. But the 90 degree reducing fittings (3/8 female to 1/2 male) that I attached to the 3/8 nipples were sloppy on the 1/2 end. The 1/2 end had o-rings so when I tightened the quick coupler onto the 1/2 end it was a sloppy fit until the o-ring was met; then things tightend nicely. I rigged everything and started the tractor. The quick coupler blew off like a bullet from the 1/2 end! I went back to the store and of course nobody knew anything about hydraulics...... I purchased 1/2 plugs with 3/8 holes (different style reducers). The 1/2 inch side was tapered slightly and tightened beautifully into the quick couplers, and several other spots in the system including the oil port on the B6100.

So my questions...

Are some hydraulic fittings metric, or are the tapered fittings the solution for off sizes? What are the fittings then that have a 1/2 inch end listed on the packaging but are slightly undersized (the ones with the o-ring) for? What are the standard fitting sizes for Kubota hydraulics? The supply line appears to be 3/8 inch and the return 1/2 inch is that correct or are they metric too?

Next issue... Loader operation

When I tilt the bucket (curl it) all the way up, if I don't release the control it really bogs the engine down at low rpm's, to the point where it will stall the engine. I havent tried it at high rpm, but is there some sort of relief valve (internal) the the loader should have or that I should instal to safeguard that? I just dont want to damage anything... Or... is it ok in a hydraulic system to in essence bog things down? I understand that it what I am doing is restricting the flow, but is that just a property of hydraulics?

Anyone who wants to chime in I'd be glad for your comments and experiences. I purchased a book on hydraulics and have read it cover to cover and it didnt speak much to my questions. If any of you could offer some hydraulics 101, I'd be grateful.

Cheers.

 

[Marty394]

Well I can't tell you much about the size of the fittings on the particular tractor, but when it comes to some of the fittings you are dealing with, here's some info. If the thread appears to be tapered it is a pipe thread "NPT". It could also be a metric pipe thread "MPT". Noe way to know the difference except to compare to a known fitting. As far as the o-ring fitting, there are some metric thread pitches that will thread into SAE fittings. But if they wobble or feel loose they are not correct. Have seen some brake line fittings like this as well. They thread together just fine. But when you torque them down "good-n-tight" the will either strip out the threads or slightly "cock" and leak. Find yourself a good hydraulic shop and have them identify the fittings. The life you save may be your own!!!!!!

Bob

 

[Kubota Newbie]

Hydraulic fittings that you buy at your typical farm parts department or TSC etc here in the US in 1/2 inch will typically be either NPT as mentioned (Pipe Thread) or 1/2 inch O-ring fittings. They WILL thread together BUT they do not interchange since the O-ring fittings have a "straight" thread, just like a bolt, whereas the NPT threads taper, getting bigger at the back of the threaded area. Sounds tile you had a O-ring male end threaded in a NPT hole. You just need to check to make sure which you have, usually same price, good idea to keep a couple extra O-rings around. Can't answer your other question. RC

 

[Bulldog]

Two different hyd fittings. NPT (pipe thread) and the O-ring fitting is JIC. You just need to adapt the JIC to a NPT.

 

[J252]

Check and be sure your loader control valve is schematically after the tractors factory relief valve or else has its own relief valve set to the same system pressure.

I am not familiar with your B6100 but i can just comment on the two Kubota's we have owned.

Our old 1980's L345 has the relief valve at the back of the tractor just before the 3PH control valve. That means, if one were to make a custom tie-in and cut into the hard line ahead of this and route the fluid through the loader and PB back out to the 3PH, that loader control valve must have a relief valve or else the system will hydraulically lock up when reaching end of stroke or overloaded.

Our newer L3400 has the relief as the first thing after the pump at the distribution block at the middle of the tractor. Anything downstream (loader/3PH/remotes) is protected by this relief.

 

[kubotaman]

make sure you have the lines plumbed correctly to the loader . there is a designated in port and a designated out port . i accidentally connected mine backwards during a power steering install and experienced the same bogging you describe . do not run it under this condition . it will ruin the pump and is very costly . 500.00 worth in my instance