First time I've actually posted a question in 9 years, so here goes. I've got a Komatsu D51-EX22 dozer. Operator was pushing wet dirt, said it felt like something popped (or broke) and the machine stopped pulling and went dead. Motor runs fine, but nothing else works. Screen now shows an E02 fault code and I've lost all hydraulics (no drive function or blade lift, and no fan turning). I'm fairly sure I'm looking at a drive coupler failure on the back of the motor. (If anyone has a different opinion, I'm open for comment). To repair the machine I need to haul it, which should mean pulling the axles out of the drives so it will free-wheel and raising the blade to pull it. My question is about raising and securing the blade. Instead of doing the normal " lift the blade and crack open the hydraulic lines to drain fluid and then close them back and hope it stays up" way of doing things, I'm wondering............ can I start the engine (so that all electronic functions are enabled) and activate the blade lift function while someone lifts the blade to it's highest point with an excavator, and the blade come up and hold itself? I know I have no hydraulic flow, but activating the valves should allow the oil to flow through the system, I'm thinking. Or will the relief valves in the system interfere with this? Has anyone tried this? My local Komatsu dealer had not thought of it and couldn't advise me one way or another. (they are however very interested to know if it works). Does anyone have thoughts on this? I plan on trying this in a day or two when it stops raining. Thank you.
The drive shafts are a bit of work to pull as its the outer cover job, so make sure its cleaned well off, to raise the blade is a simple job as all you have to do is pull the pins out of the rod ends, then place the pins back in the arm and place some lengths of timber under the cylinder then catch onto the top of the pin in the blade frame, ensure that when you pick up the blade the rods stay on the timber by using a bit of cord, when you go to shift it I would suggest you hook a chain/s from the top of the blade with the chains going underneath the blade from the back side so you can secure to your excavator or tow vehicle from the front of the blade, as you need to be able to pull it and stop it with control, to replace the bit of plastic that lasts around 8'000 hrs you need to lift off the cabin, the floor plate has loads of cable plug connectors below it, best of luck. p.s.don't bother messing about with the valve chest as its not worth the time waste, just pull the pins at the end of the shiny bit.
If I am not mistaken the charge pump that supplies pilot pressure to blade control lever is gear driven off rear gear train of engine. If this is indeed the case then your idea of starting the engine and operating the blade lever in raise position should shift the spool and allow blade to raise with whatever external force you are using to lift blade. If there is oil in the hydraulic tank the rod side suction valve (anti-cavitation) should open and allow oil in.
Thank you. That's what I was thinking, given the information that I've been told. I plan on attempting this so we can move the machine to the dealership for repairs. Our shop isn't set up for this task, plus I have two major truck repairs already in progress. Dealership says they can jump right on it when we get it there, so we're going that route. I'll post if it works or not.
The pins will tap out in moments, all that messing about is just time wasting chap.
Not really. Didn't waste any time. We just tried it and the blade lifted right up. No problems. Pins are all still in. Mechanics are pushing it up on the float right now. I'm on my way back to the machine right now. Thanks for the input everyone.
Give your self a Big Pat on the Back, credit to them they are a horrid bit of kit.
Nice work! Now I know if I find myself in that pickle that it will indeed work.
Well, it wasn't a total success that I hoped for. While the blade came up without all the extra work, it didn't hold itself up in the air like I hoped for. We still had to support the blade independently because it came right back down. I'm going to research that later to learn a little more about the system.
I have had to recover these little Tractors more than just the 1 time, so I might know a tad more about doing this task, the pin out and chain hooked from the back of the blade then passed under the blade to be hooked up from the front of the blade is the way, the setting the final drives free can be done with a pressure pump but pulling the shafts is the best method, quick drop valves or recycling valves need an oil feed to activate, there was no way that after moving the spool to lift the blade was it ever going to stay up, so with the pins still in place on the ram ends it needs 2 people to move that dead blade, the control could be put in to float position but stop the engine that will stop, so why try to be clever for nothing, Man up and knock out 2 pins then 1 person can recover it safely.