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  1. T

    Caterpillar 305CR - help needed for boom hydraulic problem

    So I pulled the two check valves on the bucket valve but they appeared clean. I couldn't quite figure out the difference between the two (2 and 3 below) so I made sure they were clean and moving freely and reassembled. I didn't have a lot of hope for it to be fixed and initially, it looked like...
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    Caterpillar 305CR - help needed for boom hydraulic problem

    So these check valves are the load check valves on the top of the main control valve? Is that correct? This page helped me understand my confusion on the check valve symbol. They seem to be illustrated on the opposite form to diodes. https://www.engineeringclicks.com/hydraulic-symbols/
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    Caterpillar 305CR - help needed for boom hydraulic problem

    I am clearly reading the schematic incorrectly; I thought that the check valves only allowed fluid through in the direction of the arrow. If that is correct, how is fluid getting past the check valve on the right hand side of the diagram and through the check valve at the bottom? I suspect the...
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    Caterpillar 305CR - help needed for boom hydraulic problem

    Looking at the schematic (first time looking at a hydraulic version but I'm used to electrical schematics) some observations come to mind but I'm acutely aware they may be flawed: 1) The pilot system running through the controls seems not to be a cause as the same problem occurs when the...
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    Caterpillar 305CR - help needed for boom hydraulic problem

    CAT 305CR Hydraulic schematic
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    Caterpillar 305CR - help needed for boom hydraulic problem

    It does. I can post it here if the rules allow?
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    Caterpillar 305CR - help needed for boom hydraulic problem

    Yes, initially we figured that was the most likely problem so we started there. The service manual procedure for checking main relief valve pressures is to close the bucket and hold it to test the main relief at P1 and the pressures are good. We only discovered by good fortune yesterday that...
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    Caterpillar 305CR - help needed for boom hydraulic problem

    I have a 2006 Cat 305CR, prefix DGT. 5300 hours. First noticed a problem with the boom not pushing deep on a pit excavation but it then spread to slow lift on boom raise before finally quitting raising the boom altogether. I did some basic troubleshooting, looking for leaks etc and...
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    Looking for some old knowledge

    It is probably also way too big for the CAT 305 that I'm trying to run it on but I chatted with a couple of guys that know way more than me and their view was that there is no reason it shouldn't work but it will run with less power and slower than it would on a 200 or 300 series. I only need it...
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    Looking for some old knowledge

    I believe so. I'm no expert but I have auxiliary lines with matching connectors and I made sure that the lines flow by bleeding the existing fluid from the unit before I connected the circuit loop on one side (I connected the flow side and then bled the fluid into a bucket until is was clear). I...
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    Looking for some old knowledge

    Yeah, I thought the same but NPK have confirmed that it isn't one of theirs. Thanks for the comment though, I still haven't found what it actually is.
  12. T

    Looking for some old knowledge

    Yeah, I wondered the same thing. I got the one guy in my local area that services all the logging equipment to take a look at it but the net result was him telling me I needed to get more info on the unit. I'm thinking it may be NPR. It is probably one of those items that someone looks at says...
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    Looking for some old knowledge

    I recently acquired an excavator hammer but have very little experience with them. It is unbadged and will charge (raise up) when activated but will not cycle (bounce the hammer). I figure I need to get some manufacturer info but to do that, I need to figure out the manufacturer. Any ideas?
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