I'm looking at a Zx 55 ur -3 that is periodically losing hyd. Functions. Currently all boom functions work except boom up(down works). Also no travel or blade. I can here the hoist trying but it's not moving. Can't hear engine lugging at all with blade or travel. It has also done stick in but not out. No bucket extend but curl etc. Then suddenly with a jerk the functions come back. Any ideas out there?
Good day Do you have a hydraulic schematic for your machine? Kind regards Uffex
I've emailed you the manual I have. It's for a 75 but I've found the electrical at least quite similar.
Good day Buckhorn Please post a photo of the main pumps, that way I can be more certain I am giving correct advice. Kind regards Uffex
Good day Buckhorn Your post specifies an intermittent issue on most of the functions, while a main pump fault would give this type of issue the fact that it comes and goe's makes that less of a probability. I suggest you begin by checking the servo pressure. This is the small gear pump system on the back of the main pump. The rest of the hydraulics are defendant on this mini system to operate the spool valves. An intermittent failure of this may well result in the type of problem your post describes. This could be as simple as the control lock out fault to avoid replacing unnecessarily components better work through what can be at fault. In addition to checking the servo pressure checkout the filters for any metal content and listen to the pump when you try to load a function such as boom or bucket. Your manual has not surfaced so I have taken a guess, it maybe if you tried to mail the document is too large for the provider. You can post it on a Gmail drive and post me the link then at least we will be on the same page. Come back with the results and I will try to help some more. Kind regards Uffex
Thanks for the help. I looked at the excellent links you sent. The Hitachi procedure in nolves lifting a track and running it. Both things it won't do right now. Could I tee in some where else? Or try with the track on the ground?
Good day That is to measure pilot pressure but for an example of how to mount the gauge, raising the track is not so necessary. Kind regards Uffex
So pilot pressure seems fine around 500psi. A new observation is all functions are now extremely weak. I checked load sense pressure and it was little to none. Next I checked main pump pressure and best I could get was500psi at high idle. Main pump failure doesn't seem likely but who knows. I'm wondering why the load sense isn't activating the pump. Is there a way to make the puygo to full swash to check it? Should I focus on the main valve and lack of load sense.
Good day Buckhorn I'm not sure how you measured the load sensing, at the risk of explaining what you may know the text in the manual is not so good. Load sensing is the signal going to the pump regulator controlling the swash, often this is referred to as Delta P (Differential pressure) measured across a restriction which inhibits a pressure drop. Measuring the pressure is a little tricky since you need to observe the two pressures while operating the arm, for example between end positions using set engine speed. This pressure difference can vary, however it is normally around 20 bars 285 p.s.i. The use of an electronic pressure measuring device greatly aids the process, as many have the ability to measure Delta P and retain the level in the memory. Sorry to make such a lengthy explanation, as I would not like you to condemn the pump and not move forwards. I will give your circumstances some additional consideration and come back with some suggestions. Kind regards Uffex
Almost omitted to say those photos are brilliant
I just happened to be using a tee and guagefor the pilot that happened to be the same size as the load sense. I thought I'd check it as I thought it should be within a few hundred psi of the main pressure. I was surprised to find it almost zero so I went to the main pressure line next as the functions all seemed to be struggling. Now I'm wondering if I'm losing flow somewhere stopping it from building pressure.
Good day Buckhorn Your post steers me towards intermittent loss at the control lock out, this would result in a loss of all controlled circuits. As you report the servo pressure is good, however if this is lost on an intermittent basis that would explain your post. I suggest we check out the signal to the control lock out. Not so sure how the LS came into the post. The pump according to my information is a normal variable. Can you establish where the control lock out valve is located ? Kind regards Uffex
Good day Can you please follow the line from the servo pump (Small gear wheel you have measured the pressure) it should go to a filter - relief valve and then to I am guessing to a solenoid valve. Come back with a photo of what you find.. Kind regards Uffex
Hello uffex Here are photos of the servo pump, the reducing valve after filter and solenoid lock valve. The lock valve has two solenoids for some reason but seems to work properly. No pressure with the lever up 509psi down. Also a photo of the pump showing the LS line as well as two lines coming from the reducing valve. I don't understand what they are for. It's not an intermittent problem anymore it struggles with any function very little pump output. There is one more solenoid valve at the tank with smaller lines going to it as well. Cheers Buckhorn
Good day Buckhorn My schematic shows that the track’s are manually operated can you confirm that this is the case, the tracks not working and has no dependency on servo pressure. Can you please give me a photo of the main pump label as my schematic may differ from what you have. Kind regards Uffex
Hello uffex. the tracks and blade are pilot operated as well. Today I had two guages so I tee'd one in the pilot line and one in main system pressure. I had 425psi servo pressure and around the same system pressure. I have included a picture of the tag on the pump as well as one more solenoid valve at the tank. It looks like it loops through or dumps to tank.
Good day Buckhorn We know we have both servo and pilot pressure this may add up to a intermittant relief valve issue please see attched. Kind regards Uffex