CASE 580D backhoe with weak hoe

[mEl]

The secondary reliefs are all above main relief pressure except doom down, being above main relief, they have no effect on digging performance, the secondaries are adjusted by removing them and putting them in a special fixture designed for that purpose and pumping against them with a handpump. By turning them randomly you have possibly created a situation where hoses could be blown, cylinder tubes split or get yourself in a dangerous situation, secondaries work by getting rid of pressures that are created by mechanical forces pushing back against the cylinders and creating excessive pressures. If you marked the screw heads so you could return them to that point I would advise that.

 

[booneyboy]

The secondary reliefs are all above main relief pressure except doom down, being above main relief, they have no effect on digging performance, the secondaries are adjusted by removing them and putting them in a special fixture designed for that purpose and pumping against them with a handpump. By turning them randomly you have possibly created a situation where hoses could be blown, cylinder tubes split or get yourself in a dangerous situation, secondaries work by getting rid of pressures that are created by mechanical forces pushing back against the cylinders and creating excessive pressures. If you marked the screw heads so you could return them to that point I would advise that.

Yes, I marked them and turned half turn clockwise, checked pressure, turned another half turn, checked pressure etc.. no change at all so I put it back to the original setting. When you mention the secondary relief valves, are you talking about the two valves located on the top and bottom of each spool? I know on my older case 580 ck the main relief valve would bypass at 3000 and someone had set the stabilizer relief valves (bypass valves) higher. I was able to bring them back down to a lower pressure by unscrewing them as we mentioned above.

 

[mEl]

Yes, secondaries are top and bottom by the spools, the proper settings are stamped into the flats in the hex. I have heard people say they have jacked the main pressure up and then set the secondaries, That scares me a bit but I had the proper tooling at my disposal. If that were done it would have to be at the lowest throttle setting to maintain rpm as secondaries are not high-volume reliefs. they are simply to control short bursts of pressure. Being higher than relief they do not contribute to digging force directly except they allow a bit higher pressure if the system is being forced by another systems leverage. The early Cs did not have enough boom down for an experienced operator to raise the hoe with the boom down pressure to swing himself over a ditch, so I increased boom down secondary to cure that problem. I did that in the field on road service.

 

[cumminstinkerer]

Yeah I've never set one by jacking the main up either, we had the test blocks to set them, I also used the flow meter when setting the main to get crack and full relief dialed in. It's been too long but pretty sure you set main, then steering, I don't recall an unloader valve but maybe that is a D thing and didn't work on very many of them, I was on more K's and newer.

 

[mEl]

CT, Case was my life from 62 till 14 in the same dealership till I retired. Many years after I retired, one day my old employer called and asked if I wanted the old flowmeter I used during my career, an OTC 75 GPM electronic job. I made it a labor of love to restore it, and it is in my shop ready to go, I am set up to do the backhoes and can put quick couplers on to test ag tractors hydraulics and powershift leakage through the remotes. You know from experience the value of a flowmeter, there are ways to narrow things down but if one wants to be precise with your diagnosis one is a necessity, many do not know the difference in cracking pressure and full flow. with my OTC I can see a 1/2 gal minute internal leakage in a cylinder. During the peak power shift years, I had calls from Racine to discuss power shift problems and some service bulletins were prompted by info from our shop.

 

[cumminstinkerer]

I was there from 2000 to 2008, had some great guys I worked with and an awesome service manager, Obie Bowen, I ended up in some deep conversation with TSG on some weird ones, went to a training in Racine with a guy from TSG once, we got to be buddies so he was my go too. I think that old flow meter you have is the same that we had can't recall for sure the model number, we also had a bigger version, I think it went to 100GPM, only got close to the max once on it, it was a cx240 that we put a special HKX hydraulic kit on to run a Tree cutter, took around 85 GPM at 5000 psi, that was wicked setting the flows and pressures on that one, that dang flow meter would float up off the cart around 4500 psi! To bad you are so far away, I'd sure by a meal and swap stories, I might need your input if ever I get time to delve into my 1370 fix whatever is up with 2nd and 3rd PS, but thats a topic for elsewhere>

 

[mEl]

That flow and pressure is scary stuff, I have never had to deal with those figures, it was standard procedure to flow all new pieces pre delivery and record the results, bailed us out a few times with customers who said their machines were not right, pull out the predelivery sheet, retest and compare flows. My flowmeter is a Y94A OTC, I believe the later Digital version of the same machine was 4221 IIRC.

 

[cumminstinkerer]

same for us, we flowed, pressure tested, set RPMS, all that right when it came off the transport, saved our bacon a few times too!