We have a PC400 that the boom moves slow in any and all directions. We replaced all the solenoids but still the same. Any advice is greatly appreciated.
You need to provide more information. What Dash series is it. How many hours on it? What was it doing when it first happened. Does it only affect the boom? What have you done so far to check out the problem?
Sorry about the lack of information, dash series? where would i find that? We just purchased the komatsu and it was supposed to be in good working condition but when we tested it, it all works just the boom moves slowly but also it seems to bogg down under load meaning when it starts to dig into the dirt seems to struggle engine seems like its bogging down. We replaced all the solenoids that work the travel up down left right swing etc all on one block or valve. we also replaced the idle actuator motor that supposed to rev the engine up when its under load but still the same. We also acquired the repair manual to properly follow the test procedures but still seem to have the problems. Some of the cylinders are leaking but the operator says it should still work faster and not bogg down under load. I will check the hours tomorrow and try to find the dash series you requested. I do apologies for the lack of technical terms as im a car mechanic trying to help out my father in law as where we live we dont really have a heavy equipment mechanic/technician.
You should be able to look at the serial tag on the cab under the boom to find the serial number and the dash series, it will be something like: pc400lc-7. Does the engine not rev up all the way when no load is applied ? You will need some way to read engine speed , easiest way is through the machine monitor if yours is capable of displaying rpm, if not a photo tach or diesel pulse reader. Follow the procedure in the book for a PM tune up it will give you a series of tests and positions and values for each test. You will also bed done way to read hydraulic pressure a 0-10,000psi gauge and some test fittings. Your book will give you the locations to test on the pump and where adjustments are to be made if required. Not sure as what you mean by that you replaced the solenoids on the valves, that machine the valve spools are operated by oil from the joysticks.
OK guys here it is. PC400LC-6 We replaced all the solenoid valves on the control valve that work the operation of the boom and the bucket. Also replaced the governor motor. We replaced the hydraulic fluid thinking it might be just bad have water or just not full enough. Some of the boom cylinders are leaking but I'm told that will not affect the operation or movement.
These machines have plenty of technology in them and just changing parts until something changes is going to get real expensive real fast. Your experience level is generally not enough to work through this on your own. You need someone with experience on this make and model of machine. What engine is in the machine? Does it travel in a straight line when traveling? How many hours? Have you checked out the fuel strainer and filters for the engine. What is the condition of the air filter? Have you checked for fault codes in the monitor panel? I've only scratched the surface of the possible problems you might have. A dealer mechanic for a couple of hours is probably cheaper and quicker than all of us here trying to guess what you problem is. Good Luck!
I would recommend checking your cylinders, if they are leaking inside the cylinder it will slow the operation down, and also show external leaks, as well as bog down, you can either strip them or do by pass testing.
The first thing you need to do is cycle times on the hydraulics. Swing machine around and raise track off the ground. Mark a track pad and let the track make one complete revolution. Then using a stop watch time 5 revolutions of the track. Do it 3 times and use an average of teh three. Do the same to the other side. Next do the boom up, arm in and out and bucket curl and dump. Time all those functions and report back.
How do you lift the boom on a PC 400 LC-6?
Are there check valves on the boom cylinders? Is the machine equipped with an aftermarket load limiter for hoisting operations? If either component is faulty, it could explain slow boom function.
Thanks guys for all the info and I will try to do what I can to answer all the questions. John C. Yes my skill level it at or less than an apprentice but like I said I do have automotive experience and id say Im good at electronic diagnosing. We have performed all the service or maintenance all filters have been replaced air, fuel etc. I ordered it all as we wasnt sure as to the previous care of the machine so I treated it like I treat any new or used car I buy it gets a full tuneup. The traveling yes it travels in a straight line. All the operations seems to work fine its just the speed isnt as fast according to the operator (its slow) and the machine seems to bog down when the bucket starts to dig. The panel did show some codes which I verified what they were and which is why we replaced all the solenoid valves as two were bad so we just replaced them all. Also where I live their are no Komatsu mechanics here. Just a bunch of guys who claim to be heavy equipment mechanics and tell us to do what we already have done and still charge us for their time which they do nothing. Bulldog777 The boom cylinders are leaking externally which we can see but the operator tell me most of the excavator he has used all leaked and they still worked at a good speed. Dressta1 The swing speed seems to be ok as the operator just said that the boom operation is whats slow. cowboy36 Joystick inside the machine why do you ask? joispoi if by check valves you mean the solenoid valves i replaced the are not on the boom but on a main block by the engine or (Merge/flow divider valve) Aftermarket parts im not sure if or what has been down to it previously I will have to find the load limit but then again how would i be able to tell the difference between oem or aftermarket but I will look it up on my manual and see what the test procedure for them should be. Thanks again guys
I couldnt find "Load Limiter" on the service manual to find its location but I did find something similar called TVC Valve and LS valve. Which according to the manual this machine has two pumps with two TVC valves and LS valves. See below if the load during the operation becomes larger and the pump discharge pressure rises, it reduces the discharge amount from the pump; and if the pump discharge pressure drops, it increases the discharge amount from the pump. The relationship between the average of the front and rear pump discharge pressures (PPI + P~2)/2 and pump discharge amount Q is shown on the right, with the current given to the TVC valve solenoid shown as a parameter.
A couple things. The reason I suggested swing speed are for some of the reason's you just mentioned. Bucket bogging down important information that was not mentioned before. Also the swing speed seems fine is not a good enough answer. The machine has two pumps. Each pump does a job. One pump runs one track plus maybe bucket and boom one runs the other track and maybe swing. It is a little more complicated than that but you get the idea. We will be able to decide if you have one pump causing your problem or both. One thing I would check is the waste gate on the turbo to make sure it is working correctly.
A couple things. The reason I suggested swing speed are for some of the reason's you just mentioned. Bucket bogging down important information that was not mentioned before. Also the swing speed seems fine is not a good enough answer. The machine has two pumps. Each pump does a job. One pump runs one track plus maybe bucket and boom one runs the other track and maybe swing. It is a little more complicated than that but you get the idea. We will be able to decide if you have one pump causing your problem or both. One thing I would check is the waste gate on the turbo to make sure it is working correctly.