Bleeding Air From a 440ic Hydraulic System

[Roger440IC]

Hi,

Is there a way to bleed the hydraulic system on a 440ic? I just put on a new hydraulic controller along with two new cylinders, lines, etc. for the rippers on my crawler. I filled up the reservoir and started it up but the cylinders on the front dozer blade and the rippers only move about 1/4 of an inch either way when I push and pull the control levers. I ran the engine for about 10 minutes and held the levers at the extremes but they still only barely move. I also topped off the reservoir after running it for a while.

Thanks

[dtoots1]

Roger440ic,
i dont recall having to bleed air out of either of my cylinders, both of which were rebuilt, so obviously empty.
if i recall correctly you simply need to operate thru the cycles and make sure to lee the reservoir checked.....what fluid are you using?
also does you fluid appear to be milky?

[Roger440IC]

dtoots1,

Thanks for the reply. Upon further investigation I found out that my problem isn't air in the lines. When I reconnect the fittings to only one controller at a time and isolate the circuits then both the front blade works, as before, and the ripper works as well. But when the circuits share the same supply and return lines each circuit barely moves.

I installed the new controller by putting a T-fitting on the supply side, so that the pump supplies both controller inlets. I also put a T-fitting on the return path to the hyd oil tank so that both controller outlets use the same return line to the tank. I've done this on my 420 and my 2040 wheel tractors and it works fine.

I think that I might have a compatibility issue with the controller that I put in which is a Prince RD-2575-T4 ESA1 open center valve.

Any idea on how to resolve this with the controllers that I have?

Thanks

[Jim B]

Good morning,

First; closed center pumps, valves and/or plumbing are different components, not interchangeable with open center components without modification. Your 440IC and 420 are open center systems, unless someone made some major changes, which I would doubt. A 2040 can be either open or closed center depending on when it was produced. It appears serial number 349999, and prior, 2040s were open center systems. 350000 and after they were closed center systems. If you just tee’d another valve into your others as you have here, and they work, I have to believe something is different than what you have done here.

To work using your current valves they need to be plumbed in series, not parallel as you have it now. The oil will take the path of least resistance. Open center means the when in neutral position the center of the valve is open, allowing the pressurized oil from the pump to pass through the valve and return to the tank. When a second common open center valve is connected into the supply (pressure) line with a Tee, the oil just returns to the tank, through the first valve, when you operate the second valve, while the first is in neutral. The same will happen if you operate the first valve with the second in neutral, the second valve will allow oil to dump back to the tank. In series the pressure oil will have to go through the first valve, then its return oil will be the pressure supply oil for the second valve. The second valve's return allows the oil to return to the tank. This the way oil would flow internally, if you had a multi-spool stack valve, like a 2 spool valve used on a loader. A drawback here is each valve has a relief valve, you will need to be sure the main relief valves are set properly In this series arrangement. The relief valve in the first valve (the one receiving the pressurized oil from the pump) will be the controlling relief valve for both spools and must be set at the specified system pressure. The relief in the second valve should be set the same or higher.

Some other options, which will add cost and parts, are: You could get one, two spool open center valve (with a main relief in it) and replace both of your current valves. Another option is to install a diverter valve to shift oil from one valve to the other, so only one valve will be operational at a time. Diverter valves were often used on machines equipped with backhoes to shift oil supply from the loader/blade control valve to the backhoe control valve. Another common arrangement, such as a loader with a backhoe, would be that one valve (the first one in line, feeding the second valve) would have a “power beyond” feature in the valve.
Just my thoughts,
Jim

[Roger440IC]

Jim B,

Thanks for pointing that out, I did use the power beyond port for the supply on my 2040 and a T-fitting for the return.

I'm looking at the cut-away view of the 440 control valve on page180-15-4 of my service manual (SM-2023), and it shows a power beyond outlet. When I look at my controller there are two plugs on the opposite side of the inlet port. There's a large flat plug in the center, which is marked outlet, and another plug with a recessed hex key next to it. It's not clear from the diagram in the manual but is this other port for the power beyond? BTW the return path on my dozer is plumbed using another outlet port on the top corner of the controller.

Roger

[Jim B]

Sorry, I would only be guessing if I were to say that is the power beyond port of your controller (valve), at this point. I don't have a 440IC manual to look at and I can't see your valve to compare the two. I looked at some of the online parts books, but I don't know what model blade you have. It appears there are different plumbing setups for different blades and the breakdown of the valves I looked at didn't call out anything as power beyond. What I was looking at might not even be what you have. Someone who has a 440IC plumbed with an extra valve or knowledge of the valve will have to answer the porting for you.

[Roger440IC]

Lavoy mentioned that I would need to add a power beyond adapter to my two-spool Gresen valve in order to have this feature. Does anyone happen to have one of these?

I'm also looking for a dual hydraulic lever set-up (handles, shafts, rods, etc.) for my 440 to upgrade from the single lever set-up that I have

Thanks,
Roger

[original possum]

If your second valve has its own relief then simply install them in series. The relief in the first valve is out of play unless it has a separate line to tank. If the second valve has no relief then you need to use power beyond stuff.

[Jim B]

original possum, I can see I misstated the relief valves' actions somewhat, after reading your post. Actually I believe they will both be in play.
When the first spool valve in line is operated the relief valve in it will control maximum system pressure as it is between the pump and any spool in that first valve body. That first relief valve sees the path through the second valve body (as long as the second valve spool is in neutral) as the return to the tank with an open center second valve body, the second valve body's main relief will not function as the pressure is blocked at the first valve. When a spool in the second valve body is operated, the first relief valve's oil path to tank return is blocked by the second valve body's spool, so it has no path to dump oil to the tank if it does reach its set opening pressure. At that point the second valve's main relief will control the system pressure as it has a return path to the tank. So both relief valves should be set to the required system pressure, although the second one could be lower and not affect the first. This is all based on operating only one function in one valve body at a time. If one feathered a spool in both the second relief would control both. High pressure hose will be required between both bodies with this setup. Does this sound right? A power beyond set up as Lavoy told him, or get one three spool valve and not use the two valve bodies, would be cleaner.
Jim

[original possum]

Sounds right to me. I left the dealership just when closed center hydraulics came out, so have no expertise in those.

[Roger440IC]

Thanks for your help guys.

Putting the two controllers/valves in series and adjusting the relief valves as Jim mentioned looks like a good solution if I can't locate the parts that will allow me to use my existing Gresen valve.

Roger