Hello everyone this is my first post and I just wanted to thank everyone ahead of time for being here and sharing the knowledge you have. I have a late 80's early 90's JD 490 Excavator, Its just a straight 490. The computer was unhooked when I got it and the wiring was butchered. It has a travel issue after you run it for 30 minutes or so it will barely move itself around. Both tracks, all other operations function properly though. I have changed the return filter and drained all the hydraulic fluid from the tank, cleaned the strainer, No chunks of metal or brass were found in either. Is there a seal in the orbitals that could be leaking when the oil gets thin? Also I cannot find a spot to hook a test gauge to see what the pump pressure is. I guess I don't know where to start with the troubleshooting. What all did the computer do on this model? It doesn't appear to have any solenoids or anything, so was it just for running the gauges and leveling? The machine has had this problem since I got it. In all the shop manuals I have read it says that it should be 24volt system but mine is 12volt and it seems to start fine. Maybe someone has changed the starter. Any help would be appreciated. Thanks for your time.
Check the swivel joint where the oil passes from the top of the machine to the lower to feed oil to the drive motors, if it's getting hot it needs resealed. Could also be relief valves or just tired motors, that machine qualifies as old now. You need to get your hands on a service manual that will give you test points, pressure specs, motor case drain flow, and procedures for testing. Hmm, what computer? I don't recall even the 490D having any computers in it, but I could be mistaken. What makes you think it's 12V? It should have two 12V batteries in series to make 24V, they never offered it in 12V and I can't imagine somebody would try to convert it.
It has 2 12v batteries hooked in parallel. Under the dash there is a silver box that has 20-30 wires coming out of it. It's back behind the seat post under the dash. It's about 8 inches tall 5 inches wide and 1 inch thick. I will get some pictures. It says 490cx on the serial tag, the guy at John deere said that it's just a straight 490. I have a service manual I'll have to read it closer about how to test the pump. Thanks.
Very strange. Okay, I see what you have there, yeah the parts book calls it "Microprocessor". Learn something new every day.
I wonder if someone hooked the batteries up wrong and possibly burned that microprocessor out maybe burned the starter up and had it rebuilt 12v it also has a one wire chevy alternator.
Yeah, I can't imagine all the things that don't work on it, wipers, lights, gauges?
Hahaha.... What gauges? I had to put manual ones in it. Is there anywhere I could find a schematic for the stock gauge cluster? I am an electrician also and I was hoping to rewire it so the stock gauges might work again at least, I can take it apart a physically trace it out, but a schematic would save a lot of time. Needless to say I'm trying to get it back to a respectable machine again.
Sounds to me like you would have to start from scratch and rewire most of the machine, every light, relay, motor, module, computer would all be 24V and even going back to 24V you might find some of those items are toast from trying to operate on 12V. There normally is a schematic or wiring diagram included in the service manual, if not your local Deere dealer should be able to provide it to you, if they're good guys. YMMV.
That's what i have done is start changing everything to 12v. Nothing on the engine is computer controlled so I will just leave it out of the equation as it would be the most costly and is most likely ruined. Not to mention all the wires are cut. It seems that most of the pump tests require engine rpm's. How can I measure that? somehow with a magnetic pickup.
The alternator may have a pulse connection, you can use a programmable tach, or there may be a port on the flywheel housing that's threaded for a pickup. I use these folks for instruments: http://www.gbinstruments.com/ Or you can always buy or rent one of those photo tach guns with a piece of reflective tape. Saw one once that had a pickup that clamped to an injector line, sensed the pressure pulse, only one I've ever seen.
Those photo tack guns are pretty cool. I worked at a factory where they used them to time steam turbines. Ive seen the injector line pulse one too.
Here's some pictures of the machine. http://i805.photobucket.com/albums/yy333/links_56/Mobile Uploads/20150804_143834.jpg Clearly this is in parallel http://i805.photobucket.com/albums/yy333/links_56/Mobile Uploads/20150804_143954.jpg Is this the top of the swivel joint you were referring to? http://i805.photobucket.com/albums/yy333/links_56/Mobile Uploads/20150804_144914.jpg And this is the bottom? http://i805.photobucket.com/albums/yy333/links_56/Mobile Uploads/20150804_144120.jpg 12v Alternator http://i805.photobucket.com/albums/yy333/links_56/Mobile Uploads/20150804_144149.jpg This looks like a 24v Starter to me though. http://i805.photobucket.com/albums/yy333/links_56/Mobile Uploads/20150804_144753.jpg Should this ring have more bolts in it? http://i805.photobucket.com/albums/yy333/links_56/Mobile Uploads/20150804_144802.jpg There are alot of holes in it but only patches of bolts. I've ordered 2 pressure gauges to see what the pumps are putting out. What does it take to rebuild the swivel joint? a few orings?
Yep, clearly 12 volt... dumb. Is the battery relay still hooked up or does it have a master switch now? Yep, swivel joint top and bottom. Fun. Starter can be the same exact frame size, in 12 or 24. It should be marked if you care to look into it further. Ummm.. WOW!!! It's a miracle the upper hasn't parted ways with the lower... Parts books says 28 bolts, the rest are either broken off or have fallen out! I would replace them all just to be safe, Gawd knows how much stress the remaining old bolts have been under. Yeah, couple O-rings and I think five high pressure seals. There are some bearing balls in there that make it turn easier, just be aware of that when you go to pull it apart.
In my tech manual it refers to that as the "center joint" but it doesn't show a diagram of it anywhere that I can find. I don't see the 24v relay anywhere, I just wired in a master switch.
Center joint, swivel joint, rotary swivel, rotary manifold, swivel assembly, Rotary assembly, there's a few more I've heard but can't recall right now, LOL! Yeah that works, the battery relay is usually right by the batteries, really doesn't matter at this point.
Thanks for the parts breakdown. Is there a cheaper place to get these seals? I have a business and order lots of parts who can i get these from at cost. It really sucks that there doesn't seem to be one wholesaler that sells everything. It's always a hunt to find parts it seems.
That's an older machine, Hitachi built I think, not a lot of aftermarket for it. On the center swivels I have always used OEM, I don't recall Deere being too pricey on them, but it's been a long time. Of course we're still just guessing your issue with travel power is bad seals, but it's a logical and common problem.
Everywhere I can find its almost 2 hundred bucks for 3 orings and 5 seals. I'm pretty sure it's leaking in that manifold.
They are high pressure seals. but yeah, pricey. If you look at: http://www.machinerytrader.com/list/PartsSearch.aspx?PartNum=th100646&btnPartSearch=Search&PST=Exact They show a couple places with stock on the old number, might be cheaper might not. Maybe if you can get one new one as a sample you can have it matched up at a seal place, I use http://www.sealsourceinc.com/ but they're out here in Oregon. I checked the new number and Singapore came up, not sure I'd want to mess with that for all the hassle of rebuilding that swivel. That's the other thing, you won't know until you get it tore down what kind of shape it's in and if it might need bearing balls and such. They tend to groove up too, let's hope yours just needs seals.
At least I have access to a lathe so I can fix that bearing surface if need be. I thought I might try out my hydraulic cylinder rebuild place and see if they can match it up.
Is there any reason I can't leave the housing in the machine and just pull the center out?
I wouldn't think so, but then again I've never done a 490, most of the ones I worked on were minis.