Hi guys, I’m new to this forum, but I really don’t know much about hydraulics. Unfortunately I have a 2020 Sunward excavator that I bought from a guy who rolled it on its side. It had a couple of issues from broken hydraulic lines to broken radiator lines, but I repaired everything all of a sudden one day everything was working all right, and I went out to go start the excavator and my stick would not boom out. It will come in, but it will not boom out. The only thing I’ve noticed is that the solenoids that are on the pilot control valve one of them seems to get very hot. I don’t know if that would do anything. What do you guys think? Where should I start? Yes, some of the hydraulic lines were switched around when I bought it and I have since put everything back where I think they should go.
Maybe try starting at the cylinder and check that oil is not bypassing internally. Does the system sound like it loads up when trying to operate the arm/stick out function?. Pilot control solenoids can feel hot to touch when operating so that could be normal. For additional help from other members on this site you would need to give some more details on the machine such as model and serial number. Best regards
it does sound like it’s struggling when I actuate the lever 2020 sunward Swe35uf 250 hours on the machine
It will move about 1 inch then stop completely
I can only get it to move once then if I shut it off release all the pressure in the lines by actuating all the other hydronic functions and I start it back up I can get it to move another inch
All other fiction work as they should
If possible try and install high pressure gauges on the arm/stick cylinders high pressure hose connections so that you can see if there is pressure on both sides of the cylinder when operating the stick out function. There may be a lock valve causing the cylinder to become hydrostatically locked. If you are able to install gauges just remember to watch out for stored high pressure fluid in those lines as when released it can cause high pressure injection into the body and the stick may drop if it is still in suspension.
Welcome to the world of Chinese machines. The problem is that few people have worked on them. So first off please take some pictures of the machine. That way we can get an understanding of how the machine is set up. We can determine if there is burst valves installed. Chinese machines tend to have either every add on ever thought of or nothing at all. Burst valves are adjustable and will lock out a function exactly as you are describing. Relief valve might be set to low and relieves before moving the weight of the stick. Also possible a cylinder is bypassing. The bypass would cause a lot of heat in cylinder so should stand out. Also could be mechanical. Binding pins or bent boom may cause this but should be obvious. Heat in the pilot valve could be debris jaming spool so well worth pulling apart and investigating
Could have broken sping in pilot valve
Sounds like it could have bent cylinder shaft or pulled the piston off the shaft.
I will take a couple of pictures to start and look into finding a high-pressure gauge that I can hook up. I don’t believe anything‘s bent. It looks to be running smoothly. Just the cab is damaged and possible hydraulic components could be damaged. I replaced quite a few bent fittings And hydraulic hoses
I know the function is a pretty slow function when it is working I would say it’s about half to 2/3 of the speed of the stick in function
Just to clarify, “stick wont boom out” doesn’t make sense. The upright arm attached to the main frame is called a “Boom”. The arm the attached to the top is called a “stick” or “dipper”. What wont move again?
Boom won’t drop
I went back out there today, and I was able to run it for about five minutes and then it slowed down to a crawl on the dropping of the boom where it was almost not working at all
Your boom won’t drop. My boom won’t raise.
Them blue pills will fix you, Chinese excavator probably no fix. Joe H
Problem with the load holding valve maybe?
I’m going to start with testing the pressure I’ll post the findings
Turn the adjuster bolt under the top nut on the silver block on the side of the boom cylinder in half a turn.
The boom or the stick isn't moving? Picture is of the boom cylinder but you said the stick isn't moving. The boom looks to have a pilot operated "load hold" valve, same on the stick? Also called counterbalance valve, dump valve, and I guess burst valve. (Had to look that one up, never heard it before!) I'm not seeing solenoids in the pics, you sure it's electric over hydraulic? Or do you mean the valves. Also called cartridges. Least I've always used solenoid for electronic controlled hydraulic valves.
Without this connected, the boom will not lower.
Usually it's just 1 line to run the load hold valve. Total of 3. Pilot line, pressure line, and line to cylinder. That looks to be the check valve/relief.
All the lock valves on my equipment have 2 pilot lines.
Just wanted to re-clarify the issue. I’m having while I wait for my hydraulic gauges to show up the issue. I’m having is the boom down function moves slowly after starting it up and letting it warm up for about two minutes it functions but just very slowly, all other operations function normally at a normal speed After about five or 10 minutes of using the boom down function it’s slowly gets worse and worse until it comes to a very slow crawl maybe 1 inch a second Any suggestions would be great while I wait 2020 Sunward SWE35uf I do have a service manual PDF
forgive me I know nothing about hydraulics
I don’t think that line was ever hooked up, but it’s possible the previous owner capped after he rolled the machine I’ll try hooking it up
Long story short. The cause is the block on the side of the boom cylinder. (Burst protection valve or drop/hold valve) Possibly cause, hose not connected, out of adjustment or failed internally. Solution, hook up hose, adjust or take it off and hook hose directly to cylinder.
Under the first cap is a JIC fitting is that for pressure testing? When I remove the second cap, the one with the two arrows it has an Allen head underneath of it that looks like hydraulic fluid flows through it, but looks like an adjustment. I don’t think that hose was ever connected to this as it is the wrong fitting to fit on any of it. That test port fitting is JIC , the hose is Bspp (British) thirdly if I bypassed the whole system what do I do with the hose on the side? Do I just cap it?
Id have to go look on my excavator. I'm more familiar with the ones on forklifts.
Ok, so boom, not stick. My thoughts... and not an expert on.hydraulics, just know enough to be dangerous haha. If you crack open the pilot line and try to lower the boom, is there flow at that line? That is what opens the load hold valve and allows flow. If there's flow, I'd pull the cartridge out (should be able to pull the poppet) and inspect for debris or damage. Could also pull the guts out and put it back so it seals and that would "bypass" the load hold. Should lower then... If not, it's an issue somewhere else. Edit... The other photo just loaded.. potato speed internet... it shows that capped line hooked to the capped port... I'd try that first. You said someone goofed with lines, and you fixed it... that to me looks like part of the goofed lines. Maybe worked fine with however they has the lines going.
I guess I should clarify that the valves with pilot lines have two lines, but some of the valves on my Mecalac don't have any pilot lines. But as far as I know on both my Bobcat and Mecalac, any holding valves that have lines have two.
Ok, so I think all is working. I removed the one line that was not hooked up and repaired the end fitting and reinstalled it. then hooked it up to the open port it seems to be working for now but only ran it up and down five or so times I’ll let you guys know if anything changes