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Cat 312b pump loading engine.

TVA

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Well! NFC. At neutral supposed to be equal or slightly lower then stand by, and both pumps supposed to have the same!
And that’s supposed to be around 400 psi!

If you pretty sure it is Mitsubishi that might be something different, but I doubt it!
There should not be 900-1000
Psi at neutral anywhere in that system!
 

TVA

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It’s right pilot pressure for CAT!
What about you stand by?
 

TVA

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If your stand by on front pump is 1000
Psi then most likely someone was messing with minimum displacement set screw! Or the bracket is not tight on Servo piston and backed off or something else is seriously wrong with that regulator! It’s too high of a stand by pressure caused by way too much stand by flow!!!
 
Last edited:

Tyler d4c

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Mar 2, 2016
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Salix Pa
What should the pressure be? I also for got to state in the original post that at time the pump would stay stroked after you let go of the control. The Stand by of the other pump was also 1100 or 1200
 

TVA

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Stand by should be 380-400, at least for C series, and I don’t think it is much different for B series!
If you have the same stand by for the back one, but zero NFC, then remove and plug the nfc line and see if you have the same pressure as stand by! If you do - then pumps regulator dumps the stand by flow to case!
If not, then you need take NFC relieve valve in Main Control valve and look what the hell is going on there!
 

Tyler d4c

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I've checked both nfc relieve valves both looked good springs looked good orfacies clear even switched them had the same result. I'll get back on it in the morning a see where I get
 

TVA

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With the rear one having zero NFC pressure she is the one having too much flow! And pumps interconnected between regulators!
I would start with solving the back pumps issues, and after that is fixed and you still having original problem - proceed to fix that!
Basically if you have 400 or close to it on NFC port - your pump is at minimum displacement! If you have zero NFC your pump is at full flow ( unless Power Shift destrokes her )!
 

TVA

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Well good night sir! I had a hard day, moving, brush cleaning along the chain link fence and grass trimming of my 5 acres!
 

Tyler d4c

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Mar 2, 2016
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Salix Pa
Front pump stand by is 1200 psi with the nfc line plugged. The book I have for the machine doesn't call out the minimum displacement screw. What would happen if the fork is out of place
 

TVA

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Messages
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Actually you supposed to plug rear pumps NFC line to find out why you have no pressure there! Either it’s leaking out or not even getting there!

With fork out of place the pump will not know at what angle the swash plate is! And the whole Torque Limiting ( It has bunch of different names: TVC, Power Shift, etc.) like a boxer or a fighter who just gotten KO wouldn’t know where it’s at and do crazy and goofy things!

Today I having an event, and not going to able to hang out on here! But you seem like bright fella and can figure it out, this should help:

http://www.madillequipment.com/dealerportal/Madill Portal Files/MASTER PARTS MANUAL 800 - 2007-11/Section 11/K3V112DT-165R-manual Section 11 Service Info.pdf

953 and 955 is displacement limit screws! And one thing you got to remember is - pumps mounted back to back, and “flipped” in relationships to each other!
 

TVA

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953 is your minimum! Last time I’ve seen too high of a stand by flow was 531 was loose on 532 and backed off, it’s supposed to be all the way to that bigger diameter shoulder and Lock-tited!
 

Tyler d4c

Senior Member
Joined
Mar 2, 2016
Messages
1,750
Location
Salix Pa
Actually you supposed to plug rear pumps NFC line to find out why you have no pressure there! Either it’s leaking out or not even getting there!

With fork out of place the pump will not know at what angle the swash plate is! And the whole Torque Limiting ( It has bunch of different names: TVC, Power Shift, etc.) like a boxer or a fighter who just gotten KO wouldn’t know where it’s at and do crazy and goofy things!

Today I having an event, and not going to able to hang out on here! But you seem like bright fella and can figure it out, this should help:

http://www.madillequipment.com/dealerportal/Madill Portal Files/MASTER PARTS MANUAL 800 - 2007-11/Section 11/K3V112DT-165R-manual Section 11 Service Info.pdf

953 and 955 is displacement limit screws! And one thing you got to remember is - pumps mounted back to back, and “flipped” in relationships to each other!
Hope you have a good time. I've seem to got it fixed. Pull the control off the pump. Pulled it apart cleaned it up reassembled it and presto it works must have had something sticking in it. Thanks again for the help.
 
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