Re: Hydraulic Tip \'N Tilt
Harv - I think you'd definitely find the official Kubota "Workshop Manual" worth the money. It's pretty good - at least the L-series version is. While it's definitely not "Tractors 101", it's still got enough theory and detail that you can figure out what's going on.
As for the discrepancy you found between the drain plug discussion and the photo, you're not the first to notice it. It's the age-old catch-22: Let the engineer write it, and no one has a clue what he's talking about. Hire a technical writer to do it, and everyone can understand him, but he doesn't know what he's talking about. Hire anybody else who'll take the job, and nobody understands what he's talking about, but it's a good thing, because he doesn't either.
I'll try my hand at some definitions for you, and you can try to figure out for yourself which of the above three categories I fit into /w3tcompact/icons/wink.gif:
spool, valve, etc. - First, an example: That black thing on your loader frame that the joystick and all those hoses are connected to is the loader valve. The black metal part is the valve body. The shiny rods that the joystick moves in and out are the spools. That particular valve is called (are you sitting down for this one?) a two-spool valve because (drum roll, please) it has two of those spools in it.
Power Beyond - Most valves and hydraulic distribution blocks (which is just what it says) have a port labelled "PB", or sometimes just "P", which is known as a Power Beyond port. It's purpose is to allow you to plumb in additional hydraulic circuits. It's there so you can add stuff that needs hydraulic power more easily. Most hydraulic systems these days are known as "open center" circuits, which means that the valves in them must pass the fluid back to sump (the transmission case) when in the center position (i.e. not actuated). This means that there's a constant flow of fluid from the hydraulic pump through the system and back to sump, even when no work is being done (i.e. no cylinders are being moved). Also, the fluid is in this case situation under little or no pressure because there's no resistance to its flow. For example, if you look at the pictures and discussion in my "
L4310 Enhancements" thread in the "Tractor Modifications" topic, you'll see that I've got a hydraulic pressure gauge on my tractor. When the tractor is running and all hydraulic valves are "centered", or not actuated, the pressure runs about 100 psi (I don't remember off-hand, but I'll check it). This is due to the normal resistance to flow of the hoses and valves in the primary circuit. But when I actuate one of the valves, the pressure on the gauge is whatever is necessary to move the cylinder. This is why, for example, you can use this gauge to determine how much something weighs. But anyway, back to Power Beyond: Its purppose is to allow you to add hydraulic circuits without modifying or tapping into the primary circuit. FWIW, apparently a hydraulic distribution block providing a Power Beyond port is optional on the B-Series, as Bird found out.
Hydraulic block/distribution block - Simply a "junction box" for hydraulic connections. There are many different designs and types, but they simply provide a means of plumbing hydraulic circuits. Some of them handle only the pressure side, providing a pressure in port and pressure out and power beyond ports. Some of them are simply "tees" for receiving fluid to be dumped to sump, also known as return lines. Some have ports for both pressure and return lines and handle both.
Open center has been discussed above. If you search, this has been discussed in some detail at least once, though it may be in the archives.
Control valve section/assemblies - Some valves are not made up of a single block with two or more spools in them, but are made only in single-spool blocks that are "stackable", i.e. they can be bolted together and connect to one another hydraulically by ports in the side of the blocks. A single one of these is sometimes called a control valve section. Multiple sections can be bolted together to form an assembly.
It is not necessary to drain the system to do anything we've discussed in this thread, though you will certainly lose some from hoses draining, etc. and need to "top off" when you're done.
HTH. Everything I've said may be wrong. Your mileage may vary. Don't do anything 'cause I did it or said it was safe. You know, all the usual disclaimers. /w3tcompact/icons/smile.gif
MarkC
