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  1. #1
    Platinum Member Tom_Veatch's Avatar
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    Oct 2003
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    516
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    Wichita, Kansas
    Tractor
    Yanmar 2220D

    Default Yet another FEL Joystick Question

    Out mowing the other day and after a couple of hours, happened to lay my arm on the housing for the FEL joystick. Wow, was it HOT! And it's in a convenient place to rest the forearm.

    The FEL is an aftermarket addon package installed by the dealer when I bought my grey-market Yanmar. Looks like it was plumbed by cutting the supply line from the pump and rerouting the flow through the FEL valve and back to the supply line. I guess that makes it an "open-center" or maybe an "open-center power beyond" valve installed in series if I understand what I've been reading.

    My question is, why couldn't the valve be replaced by a "closed-center" valve and the series arrangement be changed to a parallel configuration. Insert tees in each of the supply and the return lines and plumb from the supply to a closed-center valve. Return flow from the valve would be plumbed to the tee in the tractor's return line.

    Sorry to bring this up again since I've read in other threads that such a parallel circuit would stop everything from working because of free flow through the parallel branch. But, those other threads seemed to assume the parallel branch is through an open center valve. What if the added/replacement valve were closed center?

    A point made in one thread was that in such a parallel arrangement, at least part of the flow would be diverted from downstream uses when the FEL was actuated. But, even in a series arrangement, the flow energy used by the FEL won't be available downstream since it's the lower pressure return from the FEL that is being supplied to the downstream applications. Obviously there's something I'm not understanding.

    As is probably very obvious, there isn't much hydraulic oil soaked into my hands. About all I know is what little I've read, and I'm not real sure I understand that. All I'm sure about is that FEL control housing was uncomfortably hot and it would probably be much cooler if the full output of the hydraulic pump didn't constantly flow through it. (Also wouldn't have to worry about quick-disconnects deadheading the pump output if/when the FEL is dismounted)
    Tom Veatch
    Wichita, KS
    USA

  2. #2
    Gold Member
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    Jul 2005
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    pa
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    Kubota L48 Kobelco sk100 Kobelco sko35 case 450 Mack R600

    Default Re: Yet another FEL Joystick Question

    If you use a closed center valve and just try to hook it up by teeing in to the lines you will never get any flow to the valve the oil will always go to the path of least resistance (ie) to tank if you try and just use a closed center valve and run through it you will deadhead the flow and burn up the pump

  3. #3
    Platinum Member Tom_Veatch's Avatar
    Join Date
    Oct 2003
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    Wichita, Kansas
    Tractor
    Yanmar 2220D

    Default Re: Yet another FEL Joystick Question

    Of course! That would have to be the case now that I think about it. The downstream loop would have to be open center or the pump would be deadheaded if all controls were at neutral. The downstream loop would be just like a dead short in an electrical circuit. As soon as the FEL were actuated, there would be resistance in the FEL loop and all the flow would, like you said, take the path of least resistance through the downstream loop. The pressure across the FEL loop would not exceed the flow resistance in the rest of the system. Now, it's so darned obvious that I'm a little embarrassed for displaying my ignorance for the whole world to see.

    Thanks for the reply!
    Tom Veatch
    Wichita, KS
    USA

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