Hey all, I’m looking at a komatsu 300 LC -7, I believe. Serial #A90215. I believe I am dealing with a lot of leakage/ priority issue. The main complaint is that you cannot perform two functions at the same time. If you raise boom and bucket the boom will pretty much stop same for bucket and stick. It’s almost like when resolvers go out in a back hoe or a motor grader. I am not too experienced with komatsu or these pilot operated systems even though that’s what a majority of them are. I got into this trade about two years ago and have a lot to learn. I know my way around electro- hydraulic systems but those are simpler. I know they are similar and I’m assuming this system is using two way two pump flow for most actions I need to verify what pumps, reliefs, bypass, valves are associated each function that way I can find a common denominator. Can someone provide me with a schematic or systems op so I can think my way through this? It’s kind of hard to figure out where to start. I don’t have any bypassing cylinders, oil is good, I believe pilot pressure is good, I believe main pump pressure is good but it seems like there is a signal leakage or something is not telling the pumps to either upstroke or sending flow the wrong way. I also observed a very weird action; when you would stall bucket curl in after you let go the swing would turn to the right a little! Lol this thing is a work of art but I want to learn more about it and i feel like if I can get a schematic and some help I can find the common denominator. I believe there is also an active code for bucket curl sensor but I’m not sure if that would cause all these issues. Any help is appreciated, thanks View attachment IMG_1909.jpeg
Last edited:
