SN DWGCWLAWHD1010141 Anyone out there in the kind-hearted land of Heavy equipment have a PDF of the service manual they could share? Or at least a schematic? Mostly interested in the starter wiring. Operator complaint: Was just tooling along like Saturday night cruising Broadway, then the machine dies and now got no key action at all. No starter action. Nothing obvious like broken/loose/burned wiring. Battery good and hot. Not sure about any anti-start or anti-theft safety devices that may be on the machine, hence my preference for a manual or complete schematic. We have 5 of these, and so far they seem pretty solid until recently. That's about all I can add at this point. TIA for any help given.
Hi Tony, the only thing I got is a description of electric system of a Daewoo MEGA200V. Might this help?
Hey Bigbert.....it sure couldn't hurt. I've been putting this one off for a while, but eventually I'll have to get into it, so anything even similar might help. I appreciate it!
Funny thing about fuses. Some people check them good and.....some find the bad ones. This one turned out to be the trans controller fuse. Simple 10A ATC fuse and it was off and running. But of course I know that fuses rarely blow themselves, so I fully expect a repeat and a deeper dive. We shall see. Thanks Bigbert!
https://mega.nz/file/udsFnZ6Y#Rex12hsqw0GLnF_Vfbu-faAOMFV9lhET4ZlbpwBjkck
Thank you very much, Mohamed Mostafa El Haddad. That should prove helpful. Many thanks! What I seem to be stuck with is a group of 5 DL250 family loaders, some -3 and one -5, but much should be the same. Some of the model years overlap, so those - numbers could mean anything. The one that blue the controller fuse is still up, so for now I'll have to call it fixed.
I have a situation on hand with the -5. Despite the plethora of information in the manual, much of the -5 is not covered, or detailed sufficiently to diagnose this problem. The complaint seems a bit odd to me, but I have suspicions. I'd like to hear you guys' thoughts on it. Here's what the operators say: When turning, if your turn is slow and gentle (meaning moving the steering wheel slowly), everything is fine. However, if you are navigating and need a sharp, quick turn (think collision avoidance) the steering wheel nearly locks up, obviously losing whatever assist that should be on the turn cylinders. It seems that it should have a priority valve to allow steering to have all the volume and pressure available on demand, regardless of the rate of rotation on the steering wheel. Yet in that manual, I have not located it, nor has the senior tech in the shop. So either it's just not covered in that manual, or there is another management system in play here. Open for any help on this one!
So I know nothing about dooson but ran into this identical problem on a John deere 744h a few years ago took a while to figure it out long story short ended up being pump control
Yeah, it does seem like a valving issue to me, but I haven't dug in too deeply yet. i studied the steering and hydraulic sections of the manual I was sent, but nothing jumped out at me as a likely cause. One of our guys took the priority valve down and cleaned it, expecting to find a blocked orifice or broken spring, nut nothing. Not sure I see the difference how turning the steering fast or slow should matter. Now if the pressure was really low, or the volume restricted...maybe I could see a problem.
Does the machine have a steering accumulator?
I don't believe so. It uses a system that uses a "cushion valve" that allow sudden changes in pressure to be allowed to flow back to the reservoir. I'm not completely clear on how that works as opposed to an accumulator. I have had only a brief look into this one myself, just got pulled in today. I'm struggling with another project, which I'm about to post out of desperation. It's actually a truck, so I'm just hoping to maybe just get pointed some direction.
Does the steering system have its own pump or does it run off a single hydraulic system pump? Is it a hydrostatic machine? Most of the hystats I've put eyes on had a dedicated steering pump which kept high pressure on tap all the time.
John, this machine has a stack of three pumps. I believe the first is the main loader pump, the second, slightly smaller pump is dedicated to steering, and a third, smaller yet pump runs the fan, pilot system and brakes. The only accumulators it has are for brakes and pilot.
Maybe the system during a hard steer is demanding oil capacity that isn't available. Have the pump flows and pressures been checked?
I've seen Komatsu and Hough loaders with a steering demand valve where all the steering pump oil goes to that valve first and any that isn't used goes to the implement valve. They ran gear pumps in my time so the system was open center the priority was always to steering. Don't know what Doosan is. I'm just talking in generalities. Stack pumps are usually gear of vane types.
John, I'm not sure on this machine just how that is structured. Talking with the guy in the shop who started working on this mentioned something related to what you said that jogged my memory. He said when you lift the bucket and turn the steering, it's difficult even when turning slow. His reasoning was that there should be a priority valve that would supply steering pressure at all times, so the assist should be there even when turning slow, and raising the bucket. That makes me think the bucket would be slow to raise if there simply was insufficient flow/pressure if both the bucket was slow and turning was hard. I don't think that has been tested that way yet though. VeTech, no, we have not hooked up the flow meter to anything yet. This one is pretty fresh in the shop, so still looking for the obvious and trying to sort out the -5 info from the manual that was linked above. Not everything is identical on the DL250-X machines, but most of the basics. That would be a good next step. The pilot pressure, on another pump, must be ok since all the other functions work fine, so this is something to do directly with flow control to the steering cylinders. IIRC, that is a dedicated pump, so it's high on the suspect list. Then the valving. Steering valve is suspect as well. There is also something they call a "cushion valve". It's purpose is described as: "The cushion valve absorbs any excessive peak pressure that maybe generated during initial movement of the steering wheel or during a change in steering direction. The cushion valve also prevents excessive high-pressure and shock that can result from steering load inertia." I would take that to mean that the operator would not feel (as strongly perhaps) any feedback or kick from dropping a wheel into a hole, or running it up against an immovable object, but I suppose since it plays a role in pressure management it has to be suspected as well.
This is my exact problem with a 250-5 right now as well! What did you ever figure out here??
It's been a while now, but as I recall, we tore down that cushion valve and cleaned it, polished any moving parts. I didn't do this one myself so I don't remember that anything specific was found, but other than a filter service, nothing else was done. The complaint disappeared. I'll look up who was assigned that work order and see if they can add to it. These days we are keeping more specific notes on fixes, but 2+ years back...not so much.
Tony, yes please keep me posted and yes I just started a book/log to track all the different equipment we have as well. Thankful for these posts with some great insite and fixes...the posts that leave you hanging are a bit frustrating haha. James
My 250-5 is having the exact same problems as Tonys in reference to the no steer assist feeling, just looking at mine vs the manual shared here and each steer cyl does have an accumulator. Not seeing the cushion valve at all. Any ideas here?