Hey guys! I would like to ask for help with a Komatsu PC 110 R frame break. I've heard that this is a common fault with these machines, but I couldn't find any information about it online. Has anyone had a similar problem or experience with this? I'll try to take photos of it tomorrow. The "Y" frame supporting the boom is broken under the cab and the fuel tank. I bought the machine a few days ago at a good price and it is in pretty good condition. Any little help or information can be useful, thanks in advance! Zsolt from Hungary.
Hi everyone. I started to disassemble the machine to get access to the broken frame..
If your an experienced welder then you know what to do, if your not, get an experienced welder. This is not an easy job and if not done correctly will likely break again and be harder to fix.
Yeah, that's a pretty big repair job. Not a DIY job unless you have a lot of welding experience. First thing you need to do is get all the hoses and wires well out of the way. You may have to dismantle part of the machine to have enough room to do the welding. May help to drill holes at the ends of the crack. Everything will have to be beveled for full penetration welds or a section cut out so an inner backing plate could be inside and then filled up with weld. It also looks like the wide part of the crack needs to be pushed together. The problem there is if it's pushed together and welded there will be a big stress build up because the weld won't be able to contract naturally when cooling off. You'd need to stress relief it to get the best strength. Preheat and peening every pass will help along with post heat and slow cooling with a welding blanket or some kind of insulation. You could put some reinforcing plates on but make them oval and don't weld all around the ends. It would be good idea to drill a hole or leave a small section unwelded if the assembly is boxed in. This will stop the heat from welding building pressure inside. Let it mostly cool off and then weld the hole or finish the weld. The pressure build up inside a smaller box section can be enough to cause the weld to crack as the pressure is trying to escape. I'm not sure if the entire broke section could somehow be removed? It would certainly make it a whole lot easier. It's a big repair and not worth doing unless you try to do it as well as possible.
Hello Lagwagon, Hello Dave, Thanks for the info and advice. I appreciate! Yes, I have experience in this field and can also weld. I also have tools. I am not saying that I am the master of such repairs, but I judge myself that it will work. Of course, more specialists and more experience can always be a good help. Of course, I will share more photos of the work process with you. Dave, I see you have a lot of experience in this field, can I contact you in a private message to analyze a detail or two?
Just ask on the forum. It's a big repair so there are no dumb questions. There might be good ideas from others. You can PM me if you'd like though. I will say you need to use 7018 electrodes or an equivelant to do the welding. I know 6013 is common in Europe but it is not suitable for this type of repair. I'm just posting established good welding practices. A needle scaler or even a dull chipping chipping hammer to peen the welds while hot would help relive some stresses.
Hello Dawe, ok. Unfortunately, I do not speak English and I use the Google translator for communication, which does not always give a clear translation. That is why I may ask you several times about the same topic, so I ask for your understanding and patience. Thanks.
Thank you for your advice regarding the preparations, (dismantling, grinding, preheating, slow cooling...) this is fine. I have a personal relationship with a welding shop, where they help me choose the right welding rod. For me, what is still not clear is the stress relief after welding, could you explain the technique of this in more detail? I would like to repair the broken frame with an "X" welding seam, and then strengthen it on both sides with webbing. (See photos) what do you think about this?
I don't think you need to apologize for not speaking English anymore than we need to apologize for not speaking your language. I will probably never be involved attempting a repair like this but still like to hear about it and learn the process.
I don't think you could do a double bevel X style set up. You can't weld from the inside. You need to do single bevels from the outside to get 100% penetration or leave a gap where you can fit a backing plate inside. Don't need to worry about U groove. U grooves are used on thick vessels/plates to reduce the amount of filler metal required. You just want a good sound weld. The heat from welding and then cooling can create a lot of stress in the metal. Stress relieving gets rid of that stress. It's done on large excavator booms, dragline booms, critical pressure vessels and pipe and other weldments. The steel around the weld including the welded area is heated to a specific high temperature and then carefully slow cooled. Large furnace rooms or induction heating blankets are used. I think the temp. for steel is 1400- 1650F deg's. but would have to look it up. I'm not sure if you'd really need it if you peened the welds and slow cooled them.
A few photos of the demolition process...
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Is the broken piece solid? or hollow?
Solid.
I thought there was a boxed in section. Now I'm thinking the cracks are a result of bad steel or fabrication techniques. Maybe wasn't preheated and crack started in heat affected zone of weld. I can't see the pics. good enough on my phone. I'll look on the computer when I get home. Is the crack(s) anywhere close to the edge of a weld?
Fortunately, there is no box, by removing the cab you can easily access it from all sides. I also thought a lot about what could have caused this break?! The machine is 15 years old and has 8,100 working hours and is in very good condition. It was owned and operated by the same person. (unfortunately, I didn't know him) If it was a material defect, it should have broken already. There are no signs of excessive force on the devices that come with it. Yes, the cracks start at the end of the stiffener plates. Material size 40x250mm (1.6"x10")
I don't think the entire frame is preheated before welding during series production. It was produced in northern Italy and it is possible that the production took place in the colder winter period when the raw material was colder and the welding cooled down faster?!
Was a hydraulic hammer run on that machine? That is just plate steel and yes the gussets, where they end is what killed it. That or it was rolled off a trailer. Not to hard to X weld that and add in some strengthening plates on both sides, well past that brace, only need room for the pump. Not really into the turn table. Those welds were done with high nickel sub arc welding. I would root pass with a mig and stick weld from there making sure to rotate sides to keep an even temp and cover as it cools. Peening will help. Whatever you do, don’t let it cool off fast.
The heat from welding the stiffener plates could have contributed to the cracking. It's not a big excavator so it's doubtful if any special welding procedures or higher nickel filler metals would have been used. Likely no preheat either which may have prevented the failure, especially if the weld on the stiffener started at the same place the crack started. Instant quenching effect. Even slight undercut from the weld on the stiffener could be where the crack started. It may even be case where the end of stiffener would have been better left un-welded. The same reason you don't typically weld across the boom on excavators. I don't know if the steel was cut from plate or was made as a long bar. Bar stock typically has the grain structure going lengthwise where plate has the grain structure going in multiple directions. Basically if pieces are cut from plate they will have equal strength no matter what position they are placed in. Pieces cut from flat bar only have max. strength in the direction of the grain structure. For a lot of stuff it won't matter but will on more critical weldments. Preheat before starting the repair.
Unfortunately, I don't know the history of the machine. The machine is in very good condition, the included spoon does not show any damage.
The structure is cut out of board material, not fiber material. Special material, the material of the cut welding root sounds like the blade of a sword!
He got a little further in the repair over the weekend. I cut out and ground out the broken welds and tried to pull the frame of the machine back to its original position. Unfortunately, it won't be as simple as I thought. I lifted almost the entire machine with a 50 Ton Hydraulic Jack, but still there was a difference of 4 and 9 millimeters in the frame. Photos..
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I managed to get a special welding electrode for welding the frame, and a shielded gas welding wire with higher tensile strength for welding the belt plates.
I have no idea what you mean by board and fiber material?? The 680 S is a high strength stainless based rod. A little bit overkill since you aren't welding an exotic unknown steel but still a good choice albeit a very expensive option. The wire is standard ER70S-6 Mig wire, nothing special. Not sure what you mean by belt plates but if they help hold the frame together, I wouldn't use Mig. I'd only use Mig on non critical stuff or in spray mode in the flat position. Looks like you want about 300F preheat (since it's low to medium carbon steel) and then wrap the weld with welding blankets or insulation. You also don't want to get it super hot when welding. That probably won't be an issue though. They don't recommend post heating just slow cooling. It will be critical you have complete fusion with no flaws on the bottom of the frame welds. Any flaws there could cause it to crack again. The top is easy to see but the bottom you may need a mirror to look for flaws or confirm it's a good sound weld. If you see a flaw you may have to grind the weld out and redo it. When welding the bevels, do 1 or 2 passes on one side and then grind into that weld from the other side to insure 100% penetration. As far as the gaps you want to get them about half the distance back together. They don't have to be pulled tight together. I'd guess 3 to 4mm gap would be good. The weld will shrink/contract upon cooling. You want the weld to have room to contract. Pulled tight and welded would create internal weld stress. When doing high pressure piping they normally add about 1/8"(3mm) to the pipe measurements and after welding it shrinks/contracts about half of the gap to the proper dimension. Larger pipes with bigger weld gaps will contract a little more. You may need to weld some brackets on the frame and use some big bolts to pull the sections together. Good luck with the repair. Take your time and don't try any short cuts. Just use sound welding techniques. https://www.castolin.com/sites/default/files/products/docs/EutecTrode-680.pdf
Hello Dawe, thanks for the further professional advice! The project has stopped a bit, unfortunately I don't have enough related time (at least a full weekend) to complete this work calmly and professionally, possibly with possible problems. A couple of answers to your question: The material of the frame is not fiber material - flat steel, but is cut out of board material with a flame cutter. The tightening of the strap that I talked about earlier: You can find the photo below. Have a nice day. I'll be back later.
The translation is kind of cloudy in reference to fiber and board material and I don't know what the word in the pic. means. I think if you can pull it close and get a sound 100% penetration weld you should be OK.
Me means that it was cut from plate, not flat bar.
That's kind of what I thought but didn't know if the frame rail was straight like bar stock.
Yes, thanks for your help Old Growth
The word in the picture: Belt plate.
Reinforcing plates. You have to be careful welding them. You don't want to weld straight across the ends of the plates. Lengthwise is fine. The ends need to have a curve or V shape and don't necessarily need to be fully welded. Very similar to the way excavator booms have reinforcing plates welded on.
Yes, I also thought of cutting off the end of the reinforcing plate as a "swallowtail" V, and welding with a thinner seam.
Hey guys. The frame has been pulled back, straightened, and welded. Belt plates arrived last week and their welding was completed. If the weather permits, I'll paint it today and we'll repaint the cab and the boom at the weekend
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.. I wish everyone a nice day.
Nice job! Is there any way to stress-relieve the welds? Maybe peening with an air hammer?
That is an impressive repair job.
Yes it looks really good and very impressive. Can't tell if it was hot MIG welded or Metal-core but was done by an experienced welder. Normally I wouldn't use MIG for such a repair but it was done at high amps to ensure good penetration and no lack of fusion. Great job pulling it back together! Stress relieving would be nice but peening needs to be done when the welds are still hot. Done after cooling can add stress. I think you'll be good though. You added a lot of reinforcement. I can't see the machine pulling itself apart again. I'm still thinking the steel may have had a defect for it to break in the first place. Excellent repair job!
Thanks. Yes, I de-stressed it with a jackhammer after welding.
Hi Dave, Thanks. Yes, after welding I de-stressed with an air hammer as you recommended. I welded it with MIG Hopefully it won't break again here. A crane truck will arrive today and we will reinstall the boom and cab.
A couple of photos of the painted state. As new, it was still new.
If you peened it while hot is good but I didn't notice any peening marks. Regardless it looks very professional.
If you zoom in, you can see the trace of the flattening on both sides of the weld.
Wow. I've seen some pretty good repair jobs over the years here on HEF, and until now that draft ball repair on a grader was at the top of my list. This has just surpassed it. The amount of effort to completely dismantle the machine to get to this is frightening. Well done. You obviously have laid down a bead or 100 with a welder.
Hi everyone. Here I am sending the missing photos of the assembly and commissioning - The machine has already been put to work, technically everything works well, but the pump is "crying". It knows the operating pressure of 300 bar, but it is very likely that the control valve will open earlier. Does anyone have experience in this area?
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If the noise is coming from the pump maybe it is leaking air on the inlet side in the line to the reservoir or there is a restriction in the suction line to the reservoir that is causing cavitation
What a pain if you needed to change a hose on that manifold. You'd have to take off several or a lot of the other hoses off to be able to get the bad one off. Your machine is looking great though!
Awesome! That tangle of hoses in your hand is frightening. Amazing work getting it all sorted out. Thanks for sharing it all.
The noise is only above a certain load. It's not permanent. I can't measure the bucket from solid ground in one go. The machine does not raise itself completely when I raise it by leaning on the boom. Would you downgrade earlier than you should?!
Hi Dave, thanks. And I would like to thank you once again for your professional help and advice. Yes, there are many hoses, but now I have more experience. Maybe a hose change wouldn't be a problem.
Thanks Gary, surprisingly I only had two bad hose connections because the degreaser washed off the numbers.
It may be air in a cylinder. Dead heading cylinder will bleed it. Also check your hose orientation. One may be mixed up. As above, suction leak is the likely cause and will normally turn hydraulic oil milky or foamy. If oil is clear and you have a hydraulics pressure gauge, maybe measure the relief pressure. When a new problem appears after a repair is is almost always related to the repair.
Greetings to all. I'd like to share with you some photos of my first work. The machine works great! Thanks to Weder Dave and everyone who helped me with good advice to restore the machine!
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