Hello all, Working with an early 80's Deere 410. I'd like to add a valve to operate a grapple on the loader. I know this machine has closed center hydraulics which I know little to nothing about. If it's possible to add a valve like this, what type of valve? Size? How would I go about plumbing it in? Thanks guys.
In some way's it's easier than open center hydraulics. You can tee into the supply line, go to a new closed center valve, and tee the return into any of the returns. Most/some? open center valves can be converted to closed center with a simple kit. 1/2" is kind of the standard size, no reason to go with anything else unless you have one already. As far as adding another section to the valve bank, I'm sure it's possible, but I don't know what it would take.
Thanks for the reply. Correct me if I'm wrong... Does the size of the valves/fittings/hoses determine the volume of flow in a closed center system? If I read correctly, a variable displacement pump only moves as much oil as is demanded or can actually flow through a given size orifice. In other words, a "small" hose say 3/8" will only flow a certain volume of oil while a "larger" 3/4" hose will flow more. I suppose my question is; Will installing relatively small hoses for this application safely limit the speed of the grapple cylinders? 38 gpm of oil on two 2 1/2" x 16" cylinders will cause them to extend in ~ 1 second. That seems dangerously fast.
To add to the above post: The valve I'm looking at is rated for 12 gpm with a maximum flow of 16 gpm. If the pump is rated for 38 gpm (max) will installing a valve such as this cause any damage? Again, I am not very familiar with closed center hydraulic systems. I know that, in open center systems, pushing a given volume of oil through an orifice that isn't capable of handling it results in heat.
Yes, the size of the hoses and valves and fittings will determine the flow. You have smaller hoses on the stabilizers than on the main boom cylinder because it's a smaller cylinder and they didn't want it to operate too fast. No, a small valve will not cause any problems, the valves in a closed center are all "wired" parallel, the brakes, steering, diff lock (in other applications), are all small valves that see full supply pressure all the time.
This type of closed center system, the pump always tries to maintain maximum pressure, when you shift a valve spool, the spool meters oil to the work port, the pump will pump whatever flow it takes to keep the pressure up, up to it's maximum flow. Oil lonly flows when it's doing work, so no heat is generated unless work is being done. One thing you can do is put some needle valves in the work port lines, get the ones with the free reverse flow check in them so they only meter one way. I would suggest meter out, just adjust the needles way down to start, open them up until you get a comfortable speed, and usually the needle valve will have a tiny allen set screw to lock the adjustment. OR, put a flow control valve, either needle or pressure compensated (better) in the pressure line to the new control valve, will limit flow to both directions with one valve. Bailey Hydraulics or Surplus Center should have what you need I think. http://www.baileyhydraulics.com/Pressure-Compensated-Flow-Control-Valves http://www.surpluscenter.com/Hydrau...M-CLOSED-CENTER-LOG-SPLITTER-VALVE-9-8021.axd http://www.surpluscenter.com/Brands...NCE-WFC-800-IN-LINE-FLOW-CONTROL-9-7960-8.axd http://www.surpluscenter.com/Hydrau...s/HYD-FLOW-RESTRICTOR-VALVE-SAE-10-9-1212.axd
Thanks again guys! Referencing your above quote, "no heat is generated unless work is being done" - My machine valves become warm, sometimes hot to the touch while the tractor is idling (warming up). This happens without moving any valves or doing any work. Is this normal? I've never physically touched the loader valves however I have touched the backhoe valves while the tractor is warming up. I can't say they were 'burning hot' but they were/are getting rather warm. Again, normal or is something wrong?
I would think with a machine that old you're getting some internal bypass, maybe from spool wear, etc, or maybe one of the spools isn't centering exactly. That's one of the drawbacks of this type system, constant max pressure. If you can get your hands on one of those heat sensing guns, you might try to see if one section or another is hotter than the rest.
Great idea! I have a laser thermometer. I'll fire her up and give it a try. I replaced the o-rings on the loader valve spools. It still leaks down so I'm thinking I need to rebuild the cylinders. Is it possible for the spools themselves to be worn to the point of leaking, even with new o-rings? If so, are replacement spools available?
Probably cylinder packing, but even new they will drift some. Usually the tolerances are so tight that each spool is individually fitted to it's bore, so you have to replace the whole section if it's too worn, they don't sell the spool or the section housing separate. In the case of the loader boom once you're sure the cylinders are in good shape and the valve section seals and port relief valves are not leaking, if you still have too much drift you can use a lock or counterbalance valve between the loader valve and the cylinders to lock the cylinders in position. Mind you, you won't be able to easily lower it down without the engine running to apply pressure to the rod end of the cylinders, but that's just a tradeoff.
One last question then I'll leave you guys alone... for now Is there a reliable online source for the cylinder rebuild kits or should I head on over to the local JD commercial dealer and lay out the $$$?
Hercules is a big seal place. I can't tell you if they will be cheaper than the dealer or not, you might be surprised how competitive the dealer is on SOME parts.
Just called my local JD dealer. They're telling me $250 per boom cylinder and $220 per bucket cylinder. Ouch...
OUCH! That's crazy talk....
I just ordered the kits from Hercules. $113 for all four including shipping. Thank you Hercules!