Ill try to keep this as short as possible. Purchased a 2014 E85 at an auction. The machine ran fine and hydraulic worked but could tell there was some "rigging" done on the main boom. The boom lock valve had been stripped of all internal parts, two lines capped, and a sensor unplugged. I purchased a new lock valve, installed it, reconnected sensor and lines in there proper positioning. Now the boom only goes up and will not go back down and you can hear the pump take on a load when you try to operate in the down position.
What's your serial number ? I can email the books on it .
Good day From your thread it appears that the hose boom hose rupture (HRV) is not releasing, if you could post the hydraulic schematic we can adapt some information to resolve the issue. Kind regards Uffex
I think the sensor is just for the overload alarm, don't think it affects the lock valve functionality at all. My understanding is that it needs to see pilot pressure from one of those small lines for the valve to open, so make sure that the lines are connected correctly.
Hear is a copy of the Schematics let me know if you need anything else.
Good day Willh The quality when I magnify the valve is not good however according to that schematic the valve you refer is indeed a HRV. which is optional in the USA a necessity according to European safety requirements. There should be a small line "PB1" in the schematic the same line that shifts the boom spool this must have pilot pressure to allow the boom to lower. If you can post the schematic in PDF form it may help see details. If this line has air it is possible it may prevent the valve from opening, try venting that small line I cannot see it from your photo, if the valve is not opening you should see the engine load and the main line to the boom cylinder lower stiffen. Kind regards Uffex
Sorry Will Correction the small line appears to be hanging in the photo which must be connected to work
Photo mod KR Uffex
Whats your serial and email ? I can send you the books.
Yes, Those lines have been reconnected after purchasing the new valve. That image is from pre-installation of the new one, and is how we purchased the piece of equipment. I will try and get a better picture of the schematics, just dont know how to upload the single picture and not the entire service manual that I have. I tried another screen shot for you guys but if it isnt better let me know and i will figure it out. The serial number is B34S11952. Thanks Again
Uffex, I do hear and see the lines move when i try and lower with them connected. Is it Possible that another line off the Pilot valve is disconnected?
Good day Will Sorry if I misinterpreted your post give me a short time I will make some information for you I guess that valve does not come pre-adjusted. I have some information on that HRV on file . Kind regards Uffex
Good day Will Please see attched come back if you need more, just a word of thanks to Tool King who makes this information possible worth his weight in gold. kind regards Uffex
I want to say thanks for all the help. I got the valve adjusted and the excavator boom is operating. When I adjust that valve enough for the boom to lift the machine the boom leaks down, when i adjust it so that i have no leak down the excavator will not lift itself off the ground. Can you steer me in the direction of where to look. Thanks again for all the help. Will
Good day Will Please give me some time I will come back with some information. Keep smiling Uffex
Good day Will Explanation much of my information relates to an Oil Control valve of which this Doosan is a copy, so some small differences may occur in the illustrations. The valve has no effect when raising the boom only lowering, I have made better (I hope) information on how this valve works please see attached. From your post I have interpreted that while the boom will lower OK you have a problem to raise the undercarriage from the ground, if you can confirm I will try to walk you through a fix, the most probable cause would be the shock valve that lives on the MCV. Stay safe Uffex
Uffex, That is correct. The HRV Valve now that it has been adjusted is what i think working correctly, However I do notice that if i adjust it more I have more power lifting the undercarriage, however the boom leaks down.
Good day Will You may need a little more adjustment than I suggested it is important that the HRV valve opens when lowering the boom before the main valve as this will pressurise the boom down circuit and make control unpredictable. If I interpret your post "Boom leaks down" I am assuming that if you raise the boom into the air and leave it the boom will creep down. Please run the following test > rest the bucket onto the ground >with a high pressure plug stop the line coming from the boom cylinder > start the machine and send the arm out to pressurise the boom cylinder. If it sinks your cylinder is guilty if not we have another issue, I attach the instructions for a larger machine but the principle is the same. Kind regards Uffex
Tim it is all good .Just trying to make it easier on everybody in this ime in age with stuff going on .
Hoping to get some more information about this issue. I will be testing the cylinders tomorrow however I dont think i am getting any pilot pressure.
Good day Will To open the HRV you need about 18 bars (250 psi) with full levy movement it should be about 40 bars (570 psi), time permitting I will make some better information. In the USA as you know the HRV valve is not necessary you could simply remove and directly connect to the boom cylinder if you prefer remove the internals of the valve. Kind regards Uffex
Good day Will It may not be identical but almost the same see attached. Kind regards Uffex
I should have mentioned you can pack the spool open by introducing a 4mm flat washer to the underside that will force the spool open. You can use this to see if your issue is with the HRV or not, it easier than even by-passing the valve. Kind regards Uffex