Weird Hydraulic Issue cat 315CL

[funwithfuel]

There ya go again, as I sit here lazy as can be. But, in my defense, its cold outside.

 

[funwithfuel]

Have you checked your hoses to and from pumps for "flappers" ?
When the inner jacket starts to separate and folds over causing an obstruction. Just something to be mindful of.

 

[floridamechanic]

I would not get my butt up if it was cold outside, come on down need plenty good mechanics here,

All functions drop to zero---swing both directions--curl both directions----stick both directions---tracking both directions---boom up--- only 4$#@%%^% boom down will not drop

Started to check hoses like you said but swapped hoses at valve and did not change on gauges

 

[TVA]

Me an wife swapped out rear idler and loaded for job tomorrow, needed too do something in our spare time this morning, hope this Taiwan made idler last

Both of you just a “beasts” to pull off heavy job like this in your age!!!

 

[funwithfuel]

Just went back and realized I skipped a few replies. Boom down is the only function without neg control drop to 0. That's fine. Unless you're hanging over an edge 30 feet deep you're never going to realize max demand without tipping the machine up on her butt. You have to see a load comparative with the drop in control. The only other way you could see this is to cap the hoses to the head or rod end of your cylinders. If you do this, and lean in on boom down, a couple things happen boom 2 shifts for added flow taking barrel side oil and shuffling to rod side. It makes up faster than pump can deliver when working with gravity. This will happen in the blink of an eye, cuz no make up is needed. Now the valve is gonna "think" you're digging in clay cuz it stopped moving, the pressure rise is gonna come in , the horsepower limiter is going to kick in . Your spool will be shifted all the way, you have a wide open path from pump to boom hoses, the oil is not moving, your negative control should be at near 0 for a moment before the pump destroke. As you play with the joystick from neutral to boom down, you should be able to view this phenomenon repeatedly. It will happen fast. No need to "slam" stick forward. That does nothing but abuse the swash plate and regulator.
I copy and pasted the boom down function in totality from the info Nige afforded us early on. It tells you exactly what is happening and why. What spools and circuits are exercised and why.
Are you still tracking straight, are your standby pressures equal? If the baseline is incorrect, nothing else will cooperate.

 

[funwithfuel]

Reply 377 check it out. Its clearer than I can explain off the cuff.
I think that with a better understanding of how the regulators work, thanks to mobiletech and establishing your standby & servo pressures is going to serve you well.
Good luck.

 

[John C.]

Did you trace both those lines back to the pump? Usually one pump is on the outlet side of the main control valve and the other pump NC is on the other end of the main control valve block. Can you confirm that? So far you haven't confirmed anything about the fittings or where you have installed the gauges.

You keep jumping to other stuff without completing the thought process on what you just did. Slow down some and think about what you have seen in the gauge tests and make an interpretation of what might be happening. You are waiting for someone to solve your problem for you and there are multiple voices here that are only confusing the process. Both funwithfuel and mobiletech provide good information but you jumped off track without thinking about the information that you were provided.

 

[floridamechanic]

have hose coming off each pump accuator they go to the left side of main block as pic shows, before they go into block I teed in for gauges,

 

[floridamechanic]

here is pic I posted showing hoses coming off pump, #4 hard to see letter 4 b/c light and #5 both go to main valve block, in pic to follow,

 

[floridamechanic]

top one is forward most pump that runs boom and curl, bottom line comes from rearmost pump,

 

[floridamechanic]

Reply 377 check it out. Its clearer than I can explain off the cuff.
I think that with a better understanding of how the regulators work, thanks to mobiletech and establishing your standby & servo pressures is going to serve you well.
Good luck.

Still left with pump chirp the way it all started before, gauge is screwed into valve body, line from pump screwed into gauge bottom line from rear pump reads 450, top fitting in valve body has gauge screwed into it and line into gauge, top line shows 900 at idle, switch lines and pressures DO NOT switch, the bottom line to rear pump was reading 450 move it to top fitting now reads 900, move top line reading 900 to bottom it will now read 450, top port on valve and bottom port on valve keep same pressure not pump,

 

[floridamechanic]

gauge hookup, so 1100 lbs of nc pressure does not have to be regulated down?

 

[funwithfuel]

Not necessarily , yet. But more importantly post 393, how'd it go.

Measuring pump pressure, do it at the pump. You have test fittings there for pump A&B . That's where you measure. Servo pressure correct to spec? Are working pressures correct? Do you have equal servo pressures to either side of boom 1 spool? If the spool is not shifting fully, not receiving the correct oil pressure , of course the control pressure is not going to drop off correctly
Boom down , again , controls 3 functions boom 1, boom 2 and boom drift reduction valve.(some folks call it load holding or load check) if any of the three are allowing servo to drain off, or there is a restriction , your spool will not fully shift.
BTW has this behavior started recently, something you've been living with ? I'm wondering if you have an option for grading that may have been inadvertently turned on.

 

[funwithfuel]

The only pressure we should be measuring at the MCV is servo oil apply to boom 1&2.

 

[floridamechanic]

See this is where i am struggling, can do whatever you direct me to do to gather information but i have been lost and learning as we go with this unit, this is my first ever excavator event, when I get back off dozer tomorrow will get each pump pressure , you want them at idle? full throttle? working? No it started month ago with slipper noise and had to finish job and got worse so I am one who tore pump up, that is why when I hear noise now I cringe, pump was rebuilt and sold along with a bunch of other closing inventory, spoke with guy who closed his business and sold it all to the guy I bought it from, pumps are stronger than ones on unit when I bought it, way stronger at low rpm tracking etc. where is grading option?

 

[TVA]

The only pressure we should be measuring at the MCV is servo oil apply to boom 1&2.

He is talking about reducing Negative Flow Control pressure in general, on a the pump that has 900-1000 psi.

 

[TVA]

Not necessarily , yet. But more importantly post 393, how'd it go.

Measuring pump pressure, do it at the pump. You have test fittings there for pump A&B . That's where you measure. Servo pressure correct to spec? Are working pressures correct? Do you have equal servo pressures to either side of boom 1 spool? If the spool is not shifting fully, not receiving the correct oil pressure , of course the control pressure is not going to drop off correctly
Boom down , again , controls 3 functions boom 1, boom 2 and boom drift reduction valve.(some folks call it load holding or load check) if any of the three are allowing servo to drain off, or there is a restriction , your spool will not fully shift.
BTW has this behavior started recently, something you've been living with ? I'm wondering if you have an option for grading that may have been inadvertently turned on.

Someone said here yesterday that pilot pressure has nothtto do with this problem when I proposed to check it!!!

 

[TVA]

The only pressure we should be measuring at the MCV is servo oil apply to boom 1&2.

The only pressure we should be measuring at the MCV is servo oil apply to boom 1&2.

He teed in to NC lines at MCV, and unless there’s flapper in the hose I don’t see the difference where it is tapped to - it is all the same hose from MCV to pumps controller.

 

[TVA]

Plus swapping the NC hoses proved that source of high pressure is in the MCV and not wrong setting of Standby Flow by pumps regulator.

 

[funwithfuel]

Please don't interpret my statements. I meant servo. The oil that acts on the end of the spool to actuate a function. We are trying to establish whether the MCV is the problem or is one of the other 3 parts of the boom down circuit suffering a loss. If we can verify pressure changes as I have described in both directions, we can move on. Otherwise we'll have to pursue where the oil is going.
I'm a simple guy. I started learning this reading Case manuals back in the 80s. One thing stuck out. This manual is written in CASE, clear and simple english. I have always tried to explain things in that same way.