My Komatsu PC340LCD-7 has been down due to a hydraulic issue for the last two weeks, the tracks and boom slow down to an almost stand still and the hydraulic controls in the drivers cabin become hard after the machine working for only 5 minutes, they then start to work at normal performance speed after a few minutes and then the issue comes back after another 5 minutes. I have had a Komatsu engineer over here, in Ghana, look at it but at the time he could not find the fault and since then he has not been able to look at the machine so I got another engineer, who usually works on Cats, to look at it and he believes it is due to a faulty Pilot pump or Pilot Filter. I'm not convinced because I cannot find a Pilot pump or Pilot Filter in the service manual or parts book. Does anyone know if PC340LCD-7 have a Pilot pump or Pilot Filter? Also is anyone familiar with this sort of issue? What are the best troubleshooting steps I should take when trying to locate fault causing hydraulic issues like this? Sorry if my description has not been clear I have only just recently got in to the plant business so my mechanical knowledge is very limited. Any tips will be greatly appreciated. thanks
dash 7 series don't have a pilot pump, they use a pressure reducing to to make pilot pressure. the pressure port is situated at left side control valve near the engine/control valve pannel. First thing check the return filter for contamination. plug a pressure gauge and see what happends when the trouble occur. hope it helps.
Hi Steve, Thank you very much for replying to my post\questions, It ‘s 5am and I’m just getting ready to travel the 3 to 4hr trip through the mosquito infested jungle to my machine to try your suggestions long with the tips I've been given by a Komatsu engineer from the UK below, what are yours or anyone else feelings about his comments below? Fingers crossed my machine will be operational later today… Thanks again Trev..AKA Jungledigger UK Komatsu Engineer suggestion/comments below: The Pilot System on the PC340-7 machines in governed by a SRPV ( Self Reducing Pressure Valve ). Main Pump outlet pressure is reduced to a 32 – 35 bar feed for the machine pilot controls and EPC Valves ( Electronically Proportional Control Valves ) for pump control. If the levers are getting stiff, it would suggest that either too higher pressure is being generated or an abnormal back pressure is building up in the solenoid return lines. I have attached some SRPV information and the procedure for testing Pilot source pressure on the machine. There is no cartridge / element type filter devoted solely for pilot system. The machine main filter and the parts pages attached show the machines inline strainers and high pressure filters on the hydraulic system. Please be aware these parts pages are for a PC340LC-7 serial number range K45001 –up. There is no cartridge / element type filter devoted solely for pilot system. The machine main filter and the parts pages attached show the machines inline strainers and high pressure filters on the hydraulic system. Please be aware these parts pages are for a PC340LC-7 serial number range K45001 –up.
It sounds like he's narrowed it down pretty well. If you have the gauges and fittings to test pressures, and you can find the filters/screens, you should be able to find the problem. Is there any part of the instructions you don't understand?
Does the machine travel straight? Are there any added attachments that have motor drives, compactor, breaker, mulcher and so on? Are there any fault codes on the computer? These are just a few things that would help in troubleshooting.
I had one that had a plugged LS lines (small lines on pump that Control swash plates) the junk plugged em right at the elbow on the pump itself. My suggestion would be to give it a hydraulic tune-up but more than likely if reliefs are already maxed out you have pumps going south on you. How's the controls feel ? Are they heavy and or sluggish to respond ? Edit; I'm not sure a plugged filter would bother anything as it it probably setup with a bypass system Pj
Try installing a guage on the PRV and also one on the front pump output and the rear pump output. Watch the ones on the pump closely. When controls go neutral and idle drops down on ethier auto idle or by turning the fuel knob you may see the pressures drop. I have noticed this 3 times on the rear pump. (Furthest from engine) it sounds like the swash plate is coming back further than it should causing your issue.
Everyone thanks for you reply’s After 3 days in the bush, almost being ripped off by Ghanaian cowboy mechanic, who had been recommend to me by the caretaker of my machine and a well known respected excavator operator, and also knocking myself unconscious for several seconds, by missing a step on my excavator and falling number of feet landing flat on my back knocking my head on the floor (I now have whiplash and really sore back) I located the source of the levers stiffing up and the hydraulics slowing down. I traced the problem to an Elbow connecting the Solenoid Valve to the return line, as was suggested by the UK Komatsu engineer. The Elbow had been replaced by another dodgy local mechanic because of a leak, at the time he did not have the right connections so he did some dodgy welding modification, pls see picture below. The dodgy welding must have been causing some blockage because since I replaced it the hydraulic issues are no more… If you ever plan to bring plant equipment to Africa Avoid the local mechanics at all costs..I got a lot more to say on that one but I’ll be here all day…. The only other problem that has now appeared is that one of the tracks is running slower than the other, especially when working in the deep thick mud, the operator is reporting that at times he needs to use the arm to assist to move the machine because it’s moving so slow, any ideas what could be causing this? Thanks again ..Jungledigger Trev..
Check the tracks for anything that might be causing a drag on the side that's not pulling before you start tearing into the hydraulics. Good luck with it.
D9gdon, thanks for replying I thought this might be due to a warn sprocket, which a Komatsu engineer recently told me needs replacing, however the machine operator does not think this is the cause, i'm not sure that he is right, is there anyway of confirming a sprocket fault?
Lift the track off the ground with the stick and move the track forward and backward while someone is watching it. I would be looking for a carrier roller that's locked up or maybe a bottom roller that's bad. Could also be an idler bushing out. Any problem should be visible and easy to spot. I don't think it'd be just a bad sprocket, but your final drive might be going out. Check for any wobble by prying with a big bar against the sprocket.
Isn't there a crossover valve somewhere on the system to time the tracks and merge the pumps flows together ? My guess is a Week pump or bad crossover or weak relief valve, swap relief valves on the two pumps with each other and see if the problem changes track sides......I wouldn't think it would be anything mechanical like a roller or idler since it just developed the problem when you fixed the hyd problem. but I may be wrong Pj
Is it only that one track going slow or any other functions going slow as well. If one side going slow check the drive motor directly measure the case drain oil and compare with the other side.I have met many machines with this problem of one side going slow mostly one related to arm,swing and one track. I may not have good experience as per say(local mechanics do funny things) am african mechanic but not (doggy). Check the EPC-PC related to the track, spool valve that gets stuck.