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Question for Link Belt/Case/Sumitomo gurus!
- Thread starter TVA
- Start date
I stated about stumbling on some hidden ECM strategies before!
For example: Cat ( at least 312/315C) when ECM reads more then 1000 psi discharge pressure, and no function pressure switch is ON - it will reduce the pumps flow through EPPRV but will maintain that 1000 psi pressure.
And you not going to find this information in the repair/service manual in the appropriate section! I stumbled upon this, breefly mentioned in totally different section, because I got frustrated and just started reading through that damn manual!!!
These sort of things!
For example: Cat ( at least 312/315C) when ECM reads more then 1000 psi discharge pressure, and no function pressure switch is ON - it will reduce the pumps flow through EPPRV but will maintain that 1000 psi pressure.
And you not going to find this information in the repair/service manual in the appropriate section! I stumbled upon this, breefly mentioned in totally different section, because I got frustrated and just started reading through that damn manual!!!
These sort of things!
LACHAU
Senior Member
funwithfuel
Senior Member
Good point Lachau, didn't even consider wiring. I let myself get focused towards hydraulics.
Lynch VP-HV!
Basically two pressure compensated priority valves ( One for each for each pump), relief and flow control for controlled flow port.
Takes flow for Hammer/mower first, and diverts rest further down to machines MDCVs!
Installed in series between pumps discharge ports and MDCVs inlet ports!
I know few people who bought these things to avoid paying more for PTO gear ( in case of Kawasaki tandem pump) and dedicated PTO pump to run attachments.
It seems to run OK on Hitachi/Deer, but people with NFC machines have lots of problems with those!
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Yeah! That’s the next thing I want to interrogate that guy on?!
How in the hell they wired that thing!!!
funwithfuel
Senior Member
And, I would think this priority acts as a control in that it generates LS signal to pumps? Is that correct.
Well! The priority valve has LS port ( as well as G port for gauge) connected to a CF port, so it is basically reads mowers main pressure, but mowers DCV also has LS port which supposed to read the pressure on the “working” side of the spool to control just regular open loop piston pump like A10VO or Sauer Series 45, or Oil gear PVG ( that’s what mostly runs on forestry attachments) with LS controllers.
So you are right about this one!!!
funwithfuel
Senior Member
That and whether or not you need bi-directional flow, return through the control valve or straight to tank.
I’m pretty sure it is straight to the tank!
Wonder weather they wired Priority valve solenoid to pilot valve solenoid circuit, and “robbing” pilot solenoid amperage while priority solenoid is ON!
Just texted him this question!
If they wired priority solenoid straight to lock out switch, and used thicker gauge wire then one that going to pilot lock out solenoid - this may be the problem!
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So if LB LX line similar to Case CX line - then LB Quantum line similar to Case 90**B?
Is it so?!?!
Because as far as I remember the first gen. of Case 90 series was a Drott excavators.
And 88 series - Poclains.
GaryHoff
Senior Member
From my understanding, your are connected straight to the mower through a priority valve from the pumps. There is a specific priority valve available from Case for these types of applications that require constant flow. I'm assuming you did not plumb the mower through the aux valve due to flow fluctuations. I believe you likely have a wrong priority valve installed (or miss adjusted) , and its messing with your pumps. Any pictures or part numbers available?
It is not me, but someone I try to help who installed this on that machine without knowledge of NFC system.
Unfortunately I think I am not getting good feedback, and last two days I am not getting feed back at all!
Don’t really know the reason why they didn’t plumb it through Aux. Circuit!
In my understanding the NFC should self adjust its flow while using mower, because flow drop to MDCV also drops the NFC pressure because there will be no flow to resist to to induce the pressure!
But the mower circuit will induce discharge pressure plenty enough to provide for swash plate movement of the pumps. So the whole set up should automatically adapt it self to satisfy mowers demand for flow, plus to build enough NFC pressure to de stroke the pumps at new position.
But all of that is only true if everything is plumbed and adjusted right!
Here is all the information I have on that priority valve:
Attachments
funwithfuel
Senior Member
That looks like a bunch of extra garbage when the auxiliary spool could have easily satisfied the needs of the implement. It's like it's own control valve . If the machine has a supposed 74 GPM available why couldn't one pump supply the 34 needed for the attachment? I always like to use factory add-ons where possible. I think a foot pedal control and the aux spool would have more than sufficient for his application. That also would reserve P2 for basic functions
Well!
“And the mystery of that is great!!!”
Frankly - I think they should have used dedicated PTO pump for that, if they went to the trouble of buying and installing the mower! Because with the mower you need the almost full functionality of the excavator less digging power, manipulating around the trees and shrubs. And with set up like this you greatly reducing that capability!
But I know some scrap yard people who try to run hydraulic gensets for magnets through those things, have bunch of problems with it also!!!
That one is total oxymoron, because I don’t think that hydraulic genset is a lot more cheaper then the diesel one!
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John C.
Senior Member
Typically diverters were on each pump for mower service as they didn't want all the flow coming from a single pump. That is what allows operation of the machine at the same time as the mower. Diverter valves have to have orifices installed to set the flow to the mower. That takes a flow meter and plenty of experimentation to set up.
On a negative flow control, you have to tee into the NC lines and dump it to tank in order to get the pumps to stroke up when running the mower. The problem is what little control that the NC does provide as far as load sensing is then gone as the pumps then try to over load the engine. Then you get to play around trying to find the right size orifice again to limit the amount of NC oil into the drain circuit.
As far as the pilot circuit goes, there is a pilot tie in at the pumps which is used as one of the balance functions in the pump control valves. That shouldn't affect anything else. That someone could hear pilot oil through the joy sticks indicates a plumbing problem. You can put a gauge on the pilot circuit and watch the pressure go away to check that. I've not worked on that series of Link-Belt and can't confirm if the system is Negative Control or not. It may be something totally different now.
On a negative flow control, you have to tee into the NC lines and dump it to tank in order to get the pumps to stroke up when running the mower. The problem is what little control that the NC does provide as far as load sensing is then gone as the pumps then try to over load the engine. Then you get to play around trying to find the right size orifice again to limit the amount of NC oil into the drain circuit.
As far as the pilot circuit goes, there is a pilot tie in at the pumps which is used as one of the balance functions in the pump control valves. That shouldn't affect anything else. That someone could hear pilot oil through the joy sticks indicates a plumbing problem. You can put a gauge on the pilot circuit and watch the pressure go away to check that. I've not worked on that series of Link-Belt and can't confirm if the system is Negative Control or not. It may be something totally different now.
I had an idea of pilot operated pressure reducing valves installed in to both NFC lines and adjusted just enough of NFC pressure drop to run the mower. Those will drop the pressure only when there will be a pressure signal from priority valve. For the same reason - didn’t want to push all the available flow through the system and overload!
But then decided to check out things on pilot side before proceeding!
This priority valve uses adjustable flow control instead of orifices to adjust for the needs of different attachments.