If the pump is checking out as good,it should build the same pressure 3100 psi ,assuming the relief valves are set the same,when hooked up to either the 6 spool section,or 3 spool section.Id hook it to the 6 spool,check psi,then swap reliefs again and check psi.If everything is pretty close on the psi,and its not going past 1500 psi on the 3 spool valve,there has to be some internal leakage in that section of valves.
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Komatsu PC50uu-1 hydraulic problem
- Thread starter apm
- Start date
apm
Well-Known Member
OK, so I put it all back together on Saturday and it all runs like a champ. Strong on all functions and full pressure from all stages of the pump. The only thing I did was remove and disassemble the pump, and when I put it back together, I changed the hydraulic suction strainer and filter. I guess it's possible that we "tweaked" something in the pump that was originally assembled incorrectly, but that's a stretch.
What I'm thinking was happening was that the suction strainer on the outflow of the hydraulic tank was clogged to the point of not allowing enough oil through for all 3 stages of the pump to see enough flow. The first two stages are larger, therefore higher suction, and the third stage in line (the weak one) must have been starved for oil.
All I know for sure is it's sure working well and I'm grateful. Thanks for all the advice and input.
Greg
What I'm thinking was happening was that the suction strainer on the outflow of the hydraulic tank was clogged to the point of not allowing enough oil through for all 3 stages of the pump to see enough flow. The first two stages are larger, therefore higher suction, and the third stage in line (the weak one) must have been starved for oil.
All I know for sure is it's sure working well and I'm grateful. Thanks for all the advice and input.
Greg
apm
Well-Known Member
Just to update and thank everyone again for the help, I've used this thing all summer on several good sized projects and everything continues to work great. Still plenty of power. I added a hydraulic thumb. That's the biggest improvement yet.
Thanks,
Greg
Thanks,
Greg
thebig450es
Well-Known Member
APM how did you add your hydraulic thumb? did you go off of the off set cylinder?
apm
Well-Known Member
I put a 12 volt diverter valve in the boom offset cylinder circuit. If I flip a toggle switch one way, it powers the boom offset, flip it the other way (default position) it powers the thumb. Works slick.
Greg
Greg
nihon_reform
Member
Hi Greg,
I tried to get my local Komatsu dealer to do the same thing for me but they weren't willing to, basically saying, "It wasn't designed for this kind of setup and we don't want to take responsiblity for ruining ". Could you post photos of your hose/pipe setup and give details on the diverter valve (manufacturer, part number, etc)? Do you know if you can run a breaker using your setup?
I tried to get my local Komatsu dealer to do the same thing for me but they weren't willing to, basically saying, "It wasn't designed for this kind of setup and we don't want to take responsiblity for ruining ". Could you post photos of your hose/pipe setup and give details on the diverter valve (manufacturer, part number, etc)? Do you know if you can run a breaker using your setup?
apm
Well-Known Member
I'll try to get some pictures in a day or two. I'm not sure about running a breaker, there may not be enough flow for it to run effectively. The Komatsu dealer is technically correct that it was not designed as an auxiliary circuit and won't contain the normal components of a typical auxiliary. But, the boom offset only gets used on my machine once in a blue moon, so why not take advantage of it for a thumb that gets used every time I get on the machine. I did plumb in a crossover relief valve while I was at it. All of the hydraulic components came from Surplus Center, including hoses and fittings.
Greg
Greg
nihon_reform
Member
Thanks. I look forward to seeing your pics.
Regarding the flow rate, there are two control valve blocks for the PC50-UU. The flow rate for the offset control valve block is higher than that of the control block that would contain the auxiliary circuit. The Komatsu mechanic said that rather than not being enough, there is a risk of it being too much. I checked into this before and the offset flow rate fit within the specs that my breaker listed. Unfortunately I can't find those specs any more...
Regarding the flow rate, there are two control valve blocks for the PC50-UU. The flow rate for the offset control valve block is higher than that of the control block that would contain the auxiliary circuit. The Komatsu mechanic said that rather than not being enough, there is a risk of it being too much. I checked into this before and the offset flow rate fit within the specs that my breaker listed. Unfortunately I can't find those specs any more...
apm
Well-Known Member
If this works, here are some pictures.
Greg
apm
Well-Known Member
OK, in the post above, the first picture shows the SPST toggle switch installed next to the throttle. This actuates the diverter valve in the picture immediately below it to select either the thumb cylinder or the offset cylinder. In the off position it defaults to the thumb cylinder. The original lines to the offset cylinder go to the "in" ports on the diverter valve. From there, new lines run to the offset cylinder and the thumb. In this post you can see a picture of the crossover relief valve intended to keep the thumb from overpowering the bucket.
Greg
nihon_reform
Member
Could you provide more pics in the areas from the pipes on the boom to the connections on the offset cylinder (the general area shown in the attached pic)? I understand the connections but I'd like to see how you connected your hoses to prevent flow restriction and/or binding/catching during operation. Also, did you have to get any adapters from the original pipes to your hoses or the valves you added (i.e. are the threads different)? I tried posting this earlier but don't seem to have been successful with getting it to post so I'll repost...do you have a parts list of the parts you used for this (including hose lengths)?
apm
Well-Known Member
I'll try to get the pictures you're looking for. I did use adaptors that changed from Komatsu to "regular" fittings so that I could find hose replacements more easily when in a hurry.
Greg
Greg
apm
Well-Known Member
Here's a video of a PC50UU-1 running a breaker. You can clearly see the operator using the foot pedal for the offset boom to run the breaker.
http://www.youtube.com/watch?v=MvyJoHKUOe0
Greg
http://www.youtube.com/watch?v=MvyJoHKUOe0
Greg
apm
Well-Known Member
See if these help. I'm not sure what views you're looking for.
Greg
Greg
smttt
New Member
Hi!! new member here and new to excavator, I also have a Komatsu pc50uu-1 Blade control lever won't move and blade won't go up or down
komatsugreg
Member
Glad I found this thread, I have the same machine and exact same problem, I'm not a mechanic by trade but can generally get stuff to work. I would appreciate it if you could send me some help/pictures/diagrams of how to remove and clean the pump so I can check the suction section on my pump. My symptoms came on slowly and my machine does sit for long periods of time.
Many thanks !
Greg
Many thanks !
Greg
apm
Well-Known Member
komatsugreg
Member
Very much appreciated, hope your machine is still running great !
apm
Well-Known Member
The machine is running great, Thanks. There are two filters for the hydraulic system. The first picture is the primary filter on the return oil side of the system. It's located up top of the hydraulic oil tank under the large cover with 4 bolts, right next to the fuel filler neck. On my machine that filter is P/N 07063-01054.
the second and third pictures are from underneath the machine, looking up at the bottom of the fuel/hydraulic tank. If you swing the machine so that the bucket is off to the right side, you can lay between the tracks and look right at it. The large pipe connected to the 4 bolt flange is the suction oil line going to the pump. Underneath the flange there is another filter that I was totally unaware of initially. Mine was P/N 21E-60-11130. Changing that one cured all of my symptoms. Unfortunately, to change that one requires you drain the tank. You can see in the picture there is a drain plug next to the flange. The ball valve is the fuel drain.
Good luck, and let me know if you need any other shots.
Greg
the second and third pictures are from underneath the machine, looking up at the bottom of the fuel/hydraulic tank. If you swing the machine so that the bucket is off to the right side, you can lay between the tracks and look right at it. The large pipe connected to the 4 bolt flange is the suction oil line going to the pump. Underneath the flange there is another filter that I was totally unaware of initially. Mine was P/N 21E-60-11130. Changing that one cured all of my symptoms. Unfortunately, to change that one requires you drain the tank. You can see in the picture there is a drain plug next to the flange. The ball valve is the fuel drain.
Good luck, and let me know if you need any other shots.
Greg
komatsugreg
Member
Thanks so much, I'll do the filter change first, I too was unaware of the second filter - these are very reliable machines I've found, I expect to do the hydraulic thumb next.
Greg
Greg