I ran a tractor PTO chipper via a SSQA-to-three-point adapter with a hydraulic motor for the 540 r/min PTO for a couple hours and it seems like this was a mistake (I have, in the past, only used this chipper on my tractor). Afterward, my 2020 John Deere 325G boom/bucket/aux functions all are slow and weak. For example, at idle, it now takes 40 seconds to raise the boom fully without an attachment. At max throttle, it takes about 10 seconds. With an attachment, at idle, the machine will not even raise the boom fully. Bucket curl, at idle, without an attachment, is about 10 seconds. Track speed/power seems completely unaffected/normal, which is good. I ran boom/bucket calibration with only minimal perceptible change. Unlike another active thread, this unit does not have bucket self-leveling, so there's one less factor. For those unfamiliar, a PTO chipper has a large spinning mass, so there is a huge amount of inertia at play (it rotates for a long time after shutting off power). There were several starts/stops and I think one stall during my chipping session, and the chipper was much less powerful than I am used to having with my 50 hp tractor. The cheap Chinese SSQA-to-three-point adapter does have some sort of shunt between the hydraulic lines, but it has no label on it, so I am not certain what its purpose is. I thought that it was designed to protect the loader in the event of back-driving the adapter's motor. So, what did I damage with my unwise venture into cross-platform chipping? Your input would be greatly appreciated.
Any idea how hot the hydraulics were getting, during the chipping operation? While I have had the desire to try out a 3pt conversion set up and running a chipper and a couple of other things, I always shy away as I’m unsure that the hydraulics could withstand the continuous use like a tractor. I have used attachments like a shredder and a log splitter but set up for my auxiliary hydraulics and had no issues.
I checked the hydraulic oil temperature somewhere in the middle and at the end; it was fine. I don't remember exactly, but maybe 160-165 °F, or so? Surprised me that it wasn't higher. I did notice that the aux cooling fan did cycle on and off during the session. I think that there is plenty of cooling capacity on the machine, so long as the cooler is kept free of debris. Tangentially, the log splitter... do you have a hand-operated valve and is it just dumping to case drain whenever it's not cycling? Just curious.
Yep, was a 2 way splitter. I set up a separate case drain, to keep the heat off and the speed up. Was thinking of buying it but lucked into an estate sale and got one with a Honda gas engine and like it better. Was thinking of buying a 3pt hitch chipper as I could really use one. Want something bigger than a gas job but really can’t stand the idea of chipping with my Kubota running 1500 rpm all the time. Still looking but have recently been seeing quite a few of the 3 pt hitch conversions around. Would rather have a 5” chipper on the front of my skid.
Splitter: Ah, ok. Nice. Chipper: Yeah, I can see why it's tempting. I have been much more impressed with the performance on the tractor, though... My unit could use some tweaks to improve efficiency, but the biggest drawback is that the feed drum is manually-driven. Hydraulic feed would be much better.
If it helps, this was the first time that I ran this 3-pt/PTO adapter. I did do some grapple work beforehand, but I believe that everything was working normally after that.
Today I tested the hydraulic charge pressure at the test port on the filter base at 380 psi at 1200 r/min, 420 psi at 1700 r/min, and 525 psi at 2700 r/min. I think that these are all appropriate. I checked the main pressure relief valve after a bit of running and it was not hot. I'm waiting on some plumbing to check the loader pressure, but I expect that it's going to be low. I also plan on pulling and cutting open the hydraulic filter. Any other diagnostics that I should be performing? This is most likely a problem with the high side of the gear pump, correct?
Some more data: Pressure, cold, measured at the auxiliary output is approximately 1000 psi at 1200 r/min and 2500 psi at 2700 r/min. Pressure, warm (~130 °F), approximately 600 psi at 1200 r/min and 2300 psi at 2700 r/min. Spec is 3450 psi, I believe. The fluid smells cooked and has fine metallic particles in it. The filter housing has both coarse (mostly brass) and fine particles (mostly steel). The filter is full of fine particles. Here are some photos... So, as before, are there any other diagnostics that I should be performing? This is most likely a problem with the main section of the gear pump, correct? Thanks again for any input that you may have on this.
First question I always ask (after I ask for the machine's serial number) when there is a hydraulic performance issue with these machines, was the cooling fan turning? Check the fitting and return filter below for debris. How bad is it? Was the hydraulic pump flow tested?
Serial number: Haha (PMed with the ask for the hydraulic schematic a few days ago; thank you very much for that). Yes, the cooling fan is turning. I believe that it was cycling (probably high and low speed; I don't think that it ever stands still) during the operation in question. I remember hearing deliberate changes in fan noise on/off at least thrice. Since Hydrau is expensive, I was waiting to check the two screens until I don't need to do any other diagnostics with the machine running (then drain the hydraulic oil). I am very curious, myself. I have not flow-tested the pump because I don't have specialized plumbing/tooling, but maybe there's an easy way?
I finally drained the hydraulic oil and pulled the return screen in the reservoir (I'm not sure how to get at the case drain one under the hydrostatic pump; the access is challenging... but this is the more pertinent one, anyhow). A portion of one side (< 20% of the area of the total area of the screen) was covered in metal flakes, mostly steel, but some brass and maybe a little bit of aluminum: There was also a little bit of seal material. Please ignore the blue flecks (glove fragments) and rust color (contaminant from the outside of the fitting washed off). My takeaway is that there has probably been major component failure, either on the track loader or an attachment, but that the oil flow was not obstructed. What do you think? What else can be learned from this? Thanks for your input.
I usually remove the whole thing. It is a pain, but easier than trying to get the screen out in place. That material is probably hanging up your spools in the control valve.
Case drain manifold return screen: Ah, ok. Yeah, not ideal. Control valve: I understand that shunting, such as with a stuck spool, could cause all functions to be weak, but shouldn't there be a hot spot on the valve body and wouldn't I expect there to be some drift in at least one of the functions? Of course, I also don't want to pull out my entire valve body and break it down, so there's bias here... Separate question: The drain plug for the reservoir is not on the bottom of the tank, so I expect that there is some old oil and probably lots of metallic particles on the bottom. Without a flush/filter rig (there's probably a name for this), what are some options for cleaning it out? I have considered an oil extractor and a magnet on a stick, but maybe there's better?
Unfortunately, you are in for a major cleaning if that kind of metal went through the system. The source needs to be determined to prevent future failure. That is why it is important to inspect that case drain screen as well. As far as the reservoir, a filter caddy with a wand that can reach the bottom will usually pick up most of the debris. Using a magnet may get the steel, but not the brass and aluminum. The pressure should be close to system pressure at the lower rpm's. This tells me there is leakage somewhere. Did you remove and inspect the system relief valve? Probably has some of that debris in it.
After an extensive cleanup and a couple of hydraulic oil changes, the machine is back up and running. The case drain screen and system relief valve were clear. The gear pump ("external hydraulic gear pump") had failed. Cold auxiliary hydraulic pressure is now 3100 psi at 1200 r/min and 3250 psi at 2700 r/min. Warm (~135 °F) auxiliary hydraulic pressure is 3050 psi at 1200 r/min and 3200 psi at 2700 r/min. I think that the slight deviation from spec is due to a cheap gauge; this is much more like what I would expect. Thanks, again, for the help.