A friend of mine has a mid 90's Komatsu PC-130 that is not swinging left to right. It 'tries' to swing but won't go. What sort of things can we can check to see if we can get this fixed? Link
We need to know what Dash series the machine is. It is either a Dash 6 or Dash 5. The systems work the same but the bypass switches are in different places. Do you have any codes showing on the displays? The usual suspects for your problem include the swing brake solenoid not receiving power to release the brake or the swing machinery has broken gears inside it. The swing brake is controlled by the computer which releases it automatically when a function is operated. It sets the swing brake whenever nothing is used for about seven seconds. The swing brake is also set by the swing parking brake switch. There is a bypass switch in the right side console in the cab of each machine. In the Dash 5 it is under the glove box. In the Dash 6 is is below the fuse box forward of the seat below where an operator's knee would be if sitting in the seat. There are two toggles, one for the computer/pump bypass and the other for the swing lock. Switching the toggle will throw a code on the computer. Lately I've seen bad grounds happen which will not allow current to flow through the solenoid. You should have power to the solenoid all the time on one wire and the other wire will be grounded by the computer or the swing parking brake switch to release the brake. There is a wire coupler for the solenoid and if you disconnect it you can see which wire is hot and which is ground. I've made jumpers to hook the hot side back up and then run the other wire direct to ground. If the swing works then, you know you have electric issues. I also have a tee set up to get into the hose running to the swing motor and if I get pressure and the thing is still locked up, I know I have some heavy lifting to get done. Good Luck!
Hi John. Thanks for the detailed reply. How can I tell the Dash series? The machine is about 15 mins. from my house so I can run over and check a few things and report back if that helps. I'm pretty mechanically inclined but never worked on heavy equipment. The deal is the machine can come 'live with me' if I can get it working again! : ) Link
It will say on the serial number tag. Choose your live ins very carefully. These old dogs tend to bite with big repair bills.
Any chance you know where I could find the serial tag on this PC-130? I guess the PC-130 is a European, 'gray market' version of the PC-120. Talked to its owner and he reminded me that the display is so sunfaded you can't read it. Also reminded me that there has been several other 'jumpers' made to get it to start/operate over the years. Yes, it's not the ideal live in but I don't have many friends who will let me use their excavators. Guess I should make sure we define the rules about what happens if/when it breaks at my hand!
If the monitor is sun faded there is nothing you can do to troubleshoot the machine. With a book and plenty of experience you could check components by symptom but you will be there forever and a day. A new monitor used to be around $1,500. Nowadays I can only imagine what they cost. I've got lots of years working on these dogs and without the monitor readouts I would tell people I wouldn't waste their money. In your place I'd probably thank the owner for his generous offer and walk away.
So if I am a glutten for punishment, can anyone tell me where to find the serial number the PC-130 so I can at least identify what machine we have?
Should be on the frame of the machine below where the cab mounts where the red arrow is pointing.
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Hi John. Determined today the machine is a PC130-5. Serial # K20716. We found the toggles under glove box. Changing them back and forth didn't seem to do anything. The display is sun faded but you can read it with a little spit. No errors shown. Where can I find the swing solenoid? Seems testing that as you advised above is the next logical step. I am just not sure where to look. Also, how can I tell what the fuses are for in the fuse block in the cab, below the computer? There are two 15 AMP fuses which are blown at the bottom. Going to try and find a service manual for this machine to aid in these questions. Thanks in advance. Link
As I recall the solenoids are in the pump compartment but I can't say that for sure. They are always stacked together with the two speed travel, CO cancel and two stage relief. There should be a #4 size hose attached onto the back lower side of the swing motor. You can follow that back to the swing solenoid. Let me know where you find them. John C.
Hi John. We took a photo of what I think are the solenoids. If these looks correct, how can I tell which is the right one? (trying to track down a shop manual in the mean time)
I am also attaching a photo of what I believe to be the swing motor.
Hi all I don't want to hijack the thread but I have the same problem with my PC120-5 about 1991. I have wiring issues with coroaded connectors and an inoperative control panel all I get is an beeping alarm once in a while, so no codes. The swing break has intermittenly been a pain last year the switch was bad so I bypased it and it has worked for a while now its not. My question is what solenoids need to be activated to get preasure to the swing break solenoid as I have checked the voltage and show only 2 volts at the swing break connectors. What solenoids do I need to energize to bypass the controler? I don't want to spend the money on replacing computers and controlers. Thanks Kev
OK I see two things that might help you on the 130. Your first photo shows the solenoids and just above them there is that plate where the wires disappear into. There are two bolts on that plate and you can take it off to see the connectors. Komatsu alway tags the wires with a little white wrap around tag and the one for the swing brake solenoid should say V1 on the tag. Your machine is old enough that the tag might be missing. If so you will have to follow the small hose coming out of the swing motor. That is the thing in the second photo with all the burned paint. Follow that hose back to the solenoids and it will hook into the block just opposite of the correct solenoid. Now the bad news is that the swing motor has all that burned paint. That tells me right away that someone did a nasty to the machine and overheated the motor enough that the paint changed color. It would only take a few minutes for an experienced wrench to tell you about the electrical and teeing a gauge into the swing brake port at the motor to see if that worked. With that heat indicator on the motor I can guarantee you it will have to come out for repair. They aren't bad to rebuild for an experienced wrench. I wouldn't recommend a newbie ripping one open and expecting them to get it back together right. Anyway, Good Luck!