Using loader dump circuit to raise/lower implement - only raises... why?

TractorInnovations

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L3540
Nov 24, 2020
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Muskogee, OK
Hey Kubota Fans,

I hope somebody out there can answer a curious issue I’ve seen on my tractor, and reproduced on a half dozen other others:

My tractor: '07 L3540 with LA724 Loader

I leave my loader off most of the time for farm work, and have several implements that use hydraulic pressure, so I bought the fittings and hook them up directly to my loader connections, and run them with the loader control.

Everything has always worked perfectly on the “lift” circuit, but if I hook something up to the “dump” circuit, the cylinder goes one only way (pressure goes to the blue connector). Pushing the loader control right and left put pressure to the blue connector – so the implement turns one direction, but won’t go back. I have to shut off the tractor to relieve the pressure.

As an experiment, I hooked up the loader connections cross-ways – lift cylinders (white/yellow female fittings) hooked to dump circuit (red/blue male fittings) and it ran the loader the same way – it would only go up. I had to shut off the tractor to bring it down.

I’ve tried this on several friend’s tractors too. L series, B series, MX series… same result. Any idea why this is? I want to get a flail mower I’d like to run with both hydraulic circuits, and wonder if there’s a valve or backpressure something I could add to make it work it work right. Any ideas?



tl;dr When anything but dump cylinders are hooked to the loader dump circuit, the circuit will only push fluid in one direction. Why? How to fix it?
 

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shelkol

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bx-2200, Woods BH6000 backhoe, Tach-N-Go quick attach bucket, snow blower
Nov 12, 2015
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Westford, Massachusetts
shelkol.com
The bucket curl loader spool may be set up as a regenerative circuit ( At least that's what I think they call it). And what it is, is they connect both ports of the cylinder together when dumping. This allows the weight of what is in the bucket to make it dump faster. I have this on my BX which only has the three way valve.

The solution is to replace your existing valve with a standard loader valve or get what they call a 4-way loader valve, or just add a third function valve.
 

TractorInnovations

New member
Lifetime Member

Equipment
L3540
Nov 24, 2020
3
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Muskogee, OK
Thank you, thank you, thank you. Not what I search with the word "regenerative", I have found more reading and knowledge than I could have hoped for. Now I know how to deal with it.

I love this forum! I look like a new member, but I've been around for years. I just needed a new name, so new account. Peace!

Andy
 
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