How do I get to this thing, It must need a rebuild.... tracks are super slow, but it digs like a mother....
What method of trouble shooting did you use to determine the center joint is bad ? Just curious.
Just from investigating other threads about Excavators and their symptoms... At first I thought it might be the Hydraulic Pump, so I bought a new one (small fortune), but then didn't install it yet, because it grabs and digs so well, I figured it probably wasn't the pump....it goes fast enough with both tracks moving in the same direction and in second gear, its do-able...... and of course on pavement or the like , it'll spin like a top (metal tracks).....but get me in any loose soil ,rocks,mud etc etc...it won't spin to save my life, totally bogs down...to zero value, I have tightened/loosened tracks, I have changed out the lube in the tracks.... anyway...what do you think it could be...besides that ;-)
Raise one track off the ground at a time and find out what cycle time spec is. Travel is pump flow. The more flow the faster the circuit. Do both sides and compare to spec. After that I would look into travel motor case drain at the motor. Again get the spec and put the drain hose in a covered container and run it. If case drain is say 3 GPM, run it for that length of time and see how much oil comes out. As a last suggestion, if everything else is good, get a center joint schematic and find the port on it that is the port either above or below the traavel port. Remove the hose and run the track to determine if it is a seal in the joint.
Anyone know where I can buy a repair book for this rig ????? It came with an operations and maintenance book, but doesn't have any spec stuff !!!!!
Service CD http://www.ebay.ca/itm/Komatsu-PC50...6784?pt=AU_HeavyMachinery&hash=item4177a63a10 Parts Manual http://www.ebay.ca/itm/PC50UU-1-KOM...321?pt=LH_DefaultDomain_0&hash=item3cceed2f01
I just need to throw in my two cents since a couple of other Greg's already answered too. PC50UU-1's must be a "Greg" thing. I've got one of these. The ebay CD is the only game in town for the manual. They're available other places, but they're all the same. From what I've been able to find, this is the only manual ever made available in English. Cycle times are all listed in there, as well as a decent trouble shooting section. The travel motors are controlled through the 6 spool valve, same as your digging functions. If your digging is strong, probably your relief pressures are OK. The case drain test recommended above is a good bet. Greg, too
Thank You Brother ;-)
Hey... my middle name is Greg..... just kidding ;-) I just ordered the CD and I called Modern Machinery and ordered the Paper Copy also (118.00 dollars) "If your digging is strong, probably your relief pressures are OK. The case drain test recommended above is a good bet. " I will have to wait to get a manual, before I will be able to figure out how to accomplish this, but you think something here would slow down the tracks ???
I'm no expert, but I've spent a lot of time working on mine. The tracks are driven by hydraulic motors (final drives), one for each track. If the motors are worn enough, they'll bypass enough oil to get weak. Particularly more so as the oil heats up and thins out. If yours work well cold, when you first start in the morning, and get progressively worse the more you travel, you may have worn motors. PC50UU-1's as far as I've seen, all use Hy-Dash final drives. I'm not sure they're even available any more as exact replacements. There's a helpful member on here by the user name finaldrives that I think is the only Hy-Dash distributor in the U.S. Maybe he'll chime in in a minute. Somebody might be able to rebuild yours if you can find the parts. All of that is assuming the drives are at fault..... you might get lucky and find something simpler and cheaper. The case drain test will tell you how much oil is bypassing the track drive motors. Compare that to the allowable spec in your new manual and you'll get an idea how much wear you've got. I hope that's all accurate, please someone correct me if I've misled him. Greg
APM wrote : Particularly more so as the oil heats up and thins out. If yours work well cold, when you first start in the morning, and get progressively worse the more you travel, you may have worn motors. I didn't think that could be true of my tracks , so I just went out and fired up the beast, walked it about, 50 feet to a level gravel surface (relatively compacted surface), and proceeded to spin her left and then spin her right, as previously said, she will spin like a top on asphalt or concrete (no resistance and because she has steel tracks), but as soon as I had built up 3" of gravel/dirt, she won't spin , left or right.....as soon as this happens , my "workaround" is too , move her forward or reverse until she is free from the debris, and then turn her..... it sucks , I need her to spin...help.......
They were never really meant to counterrotate the tracks unless in low mode on the travel. The proper way to test these things is to walk them up a hill with both pedals at max and then see if the machine veers off to one side of the other. If it will walk straight you could check your pressures and if those are right there most likely isn't anything wrong at all. I haven't worked on one of these machines this small so could use some more information. Does it have gear pumps or a piston one?
John, the PC50UU-1 uses a fixed displacement gear pump, no pilot controls, no electronics, etc. Just plain, old fashioned hydraulics. Three chamber pump. Greg
John said "there most likely isn't anything wrong at all." AAARRRGGGGHHHHHHHH ;-) That would be a terrible reality.... those of you who have the same rig, please tell me you have enough power in your tracks , to move about as desired. As I age , my memory fades ;-) But... I remember a time when nothing could stop these tracks when the pedal was to the floor...nothing....even if I hit a wall, the tracks would just continue to churn away. My thoughts on when this started was when I lost a lot of hydraulic Fluid, I was perched on top of what I thought was a mound of dirt and debris and was trying to grab a 6' wide rock ....I kept moving around trying to grab a "lip" so I could yank it up..... well ...all of a sudden I am smelling Hydraulic Fluid, the "mound" I was sitting on ... turned out to be a 1' tall x 2" tree trunk that had been cut down and covered with dirt, the week before, after I had wiggled around a bunch, trying to get the rock, the trunk got up into my swivel joint and busted off a nipple ....OY VEY.... I crawled off the tree trunk and ordered a new nipple....and my excavator has never been the same since.....
Sorry guys, no Komatsu fan here. Work on one you`ve worked on them all. There are only so many ways to dig a hole in the ground. My color of choice ? Hitachi for about 12 years
Somebody....Get a rope ;-)
Hey Greg, Whats up with this Hitachi.... it seems the logo is upside down and the cab is on the wrong side ????
That`s for the Australia market, you didn`t know that ??? Upside down and backwards.
;-)
Were you able to figure it out? Sorry guys, Old thread. Just curious if you ever got your pc50uu-1 turning again? I have the same machine and the same problem. One final drive was replaced by previous owner, the replacement is stronger but slower, but still stalls out when turning. The machine will push anything going straight but doesn't like to turn either direction without whining and stalling the track. Sometimes it will almost get a second life and counter rotate both tracks better than it will spin just one, but not usual. Relief pressures are good on all three relief valves (set at 3100psi). cycle times are quicker on the original final drive (more loose) than the newer final drive but still not up to spec. This could also be due to different flow rates on each gear pump as well, but i don't have access to flow meter. I was also considering replacing the slipper seals as they're a lot cheaper than replacing the pump (which seems impossible to find, where did you find yours?) Hopefully replacing the slipper/center swivel seals helped you out? I've heard they usually start to fail around 5000hrs...i'm up to 5200hrs. Thanks guys, Nick :Banghead
Hey Ruffles a new pump fixed me up, http://www.whitehouseproductsltd.com/
Hey Guys/Gregs, Reviving this old thread again...Not sure if any of you guys still have your PC50uu-1, but you seem to be the experienced bunch. My pc50uu-1 had the center swivel seals fail (lost final drive power almost entirely). When we got it torn apart the swivel/slipper seals were all in pieces. I've replaced them once before so no big deal replacing. I got the previous seal kit from "fridayparts" which probably last about 500hours. So I ordered another set from them (i think $100 for the whole kit vs $800+ from komatsu). My problem is that after I installed the last kit it blew out the bottom oil seal and leaked everywhere, I assumed I scratched a seal or put the oil seal in backwards or something simple.... Took it all apart again, replaced all the seals again (with a seal kit from ebay), tested the tracks in place before i bolted it all back together- seemed fine no leaks. Go to work on a trail and oil is pouring out the bottom of the swivel joint again! I'm thinking either 1. The center swivel drain line is plugged with pieces from the previously failed swivel, causing the oil seal to blow out each time. 2. The swivel joint is marred on the inside of the swivel causing the final drive pressure to bypass the bottom slipper seal and blow out the bottom oil seal 3. Or i got two bad sets of slipper seals from the aftermarket dealer -which seems unlikely (the fridayparts seal kit felt like i had brand new final drives) (the ebay/motrol kit didnt feel quite as tight, but still moved fine). Please let me know if you guys have any ideas or if i'm missing something? Where did you guys get your slipper seals from? are the komatsu seals worth the $800? TIA -Nick