345bl negative flow right valve bank.....

[rmllarue91]

Hey hef got a good one machine is a basket case i diagnosed weak pumps last year upper pump was like 2k psi lower maybe 3k psi right track and bucket ( upper pump useless )they had another mechanic change o rings between main control valve half's recently. they had issues and had like 5 pilot lines crossed.... Sorted that out they ran machine Lil bit but said its time for pumps..... I put used Dyno tested pumps new oil and filters and main relief... The replacement pumps both build 5k psi when booming up and it counter rotates well when tracking seems like decent pumps. BUT the bucket and right track are totally destroying pump by way of less than 150 psi negative flow to upper pump as soon as pull a function . Lower pump left valve bank stays up about 500 psi under same single track function..... Any thoughts welcome

 

[rmllarue91]

Ok i thought I was getting some where but i cap the negative flow line on upper pump regulator and it's the same slow and only builds 1200 psi bump and onther function comes right to life and builds 5k psi ?

 

[Chrisso]

Well if both pumps are building about 5k psi at some point that's a good sign.

Cat made 8 variations of a 345B L. I'd love to look at a schematic. For that I need a s/n... otherwise I need to check all 8 to give reliable information.

The replacement pumps both build 5k psi when booming up and it counter rotates well when tracking seems like decent pumps.

So as it sits right now what is the machine not doing properly (from an operators perspective)?

BUT the bucket and right track are totally destroying pump by way of less than 150 psi negative flow to upper pump as soon as pull a function

Where are you taking these pressure readings from?

 

[rmllarue91]

Ags2426
Symptoms are bucket and right track slow stalling at 1200 psi ish i was thinking almost totally neutral pump swash angle....
If you bump any other function it comes right to life and will build relief pressure taking pressure on pump ports thanks for looking into it

 

[rmllarue91]

Machine will counter rotate strong and track up hill good the pumps are able to work. Weird part is it's exactly the same if i cap negative flow line to regulator......

 

[funwithfuel]

Have you gauged the pressure to the pump controllers? Could it be you've got a corrupt signal from the MCV? Bucket and track are single pump functions. That makes sense. You could have one pumps signal doing double duty by stroking the second pump by being siphoned off a left stick function that demands 2 pump flow. I would swap signal lines first, see what if anything changes

 

[funwithfuel]

BTW, i have no intimate knowledge on Caterpillar equipment. I'm speaking from a general point of view. Serial numbers will be required for the Cat guys to supply the correct schematics and pictures always seem to speak much better than words. That way we are all on the same page.

 

[Chrisso]

Sounds like you already know this, but a zero negative flow signal to the pump regulator (on the side of the pump) means pump should go to max displacement.

The pump regulators both receive a common signal (which I think is #40, but not entirely sure) from the Proportional Reducing Valve (PRV) in the pilot manifold. So if at least one pump works we can rule that out. Now it's just a question of whether something is going on within the pump regulators themselves or the negative pressure signals not being correct.

The upper and lower pump regulators both receive their own negative flow signals from each side of the main control valve (#11 & #42). As funwithfuel suggested, I think we need to swap these and look for a change.



If there is a change, well... each negative flow signal has it's own relief in the main control valve.

Come to think of it, you said you found five pilot lines routed incorrectly a while back. Sure these neg flow signal hoses are in their correct spots?...



I could be wrong but shouldn't #7 & #9 match up to #11 & #42 above? Think it's worth swapping them anyway to see if that fixes the problem.

 

[rmllarue91]

Thanks for all the input should get back to machine later in week they are running it say it's running pretty good......
I did check routing of negative flow line and it's in the right ports. As far as other pressures I'm go to start from scratch and record findings I'll get an update when i know more thanks again