andyklein

Member
I have a 772 loader on it, If the rear Gannon is down all the way, the loader works fine. If I raise the Gannon, the loader will not drop most of the time without cycling it 2 times form up to down? I changed the seal in the control valve for the Gannon, that made it a bit better, but did not fix the problem, anyone know a solution?
Thanks
 
Sorry for the confusion, yes the rear scraper box is a "Gannon" brand, so we all called it a "Gannon". Basically the 3 point rear attachment is the issue. If it is all the way in the down position, the front loader system works perfect. If the rear is up, the loader has the problem I described. I did have to change the complete control valve years ago that controls the loader. I don't think I mixed up any hoses, but?? I'm going to try and find a hose routing diagram (or if anyone has one?) for the Ford 1900 with the 772 loader bucket attachment. Doesn't seem likely that I did mix up any hoses as it works as intended with the rear 3 point in the down position.
The control valve is located just below the seat (part #19 in the diagram link below) diagramhttps://www.mycnhistore.com/us/en/newhollandag/na/tractors/compact/naba17com0543cyl/3-cyl-compact-tractor/hydraulic-systems/lift-cover-arms-1700-1900/cn/FA54B1CD-B8BF-E111-9FCE-005056875BD6/B3EE724F-E6BE-E111-9FCE-005056875BD6
and per the manual, it controls the down speed of the rear 3 point. Prior to replacing the seal, it did nothing, so I assumed the seal was allowing hydraulic fluid to blow past the valve. After changing it, it now does allow me to change the speed of the 3 point travel going down, so it was a problem. But, as I described, the loader is better but not correct yet so there is still a problem
Thanks
 
This site is miserably slow today, I have lost what I typed twice now on my phone due to switching between the part diagrams and the forum. What may be your problem is how the loader valve is returning oil to the tractor reservoir. Take some photos of the loader valve if it has any markings where the hoses connect make sure to show those. The part you show as 19 is the piston seal for the 3 point lift cylinder not something that would be considered “controls” All the flow valve does that you took off the front to change the valve is restrict the flow out of the 3 point cylinder or close it off completely to lock the 3 point at a certain level. Which that will only work correctly if the seal you replaced is good and seals oil in the cylinder. I be back later if they get this site straightened out.
 
I'm not at home today, but tomorrow I will take pictures. The 4 hoses to the lift and tilt I'm sure are correct as they function. I'm wondering if because we had to sub a different control valve ( the old one was not available) that maybe I switched the pressure/ return lines? Would it even work? The control valve did come from a Ford Tractor dealer who sold me the replacement. I think it did work fine after I changed it ( was a few years ago) but I might be mistaken.
Thanks for taking interest in this. I'll try and include pics of where the 2 lines to the tractor hydraulics connect also.
 
I'm not at home today, but tomorrow I will take pictures. The 4 hoses to the lift and tilt I'm sure are correct as they function. I'm wondering if because we had to sub a different control valve ( the old one was not available) that maybe I switched the pressure/ return lines? Would it even work? The control valve did come from a Ford Tractor dealer who sold me the replacement. I think it did work fine after I changed it ( was a few years ago) but I might be mistaken.
Thanks for taking interest in this. I'll try and include pics of where the 2 lines to the tractor hydraulics connect also.
Does it only bother when the box blade is raised all the way up? If that is the case you may need to adjust the link that moves the 3 point control valve to neutral so that it doesn't go into bypass. One way to check to see if it is going into bypass is to put the loader in the float position and see if the loader raises when you lift the box blade.

Mark
 
Actually the loader valve SHOULD have three lines connecting it to the tractor. If said valve has been replaced just prior to the problem then there's a good chance it's simply not hooked up correctly. Did the new valve come with a power beyond sleeve? Did the old valve have three lines?
 
As soon as I raise the box up at all it affects the loader.
I'm not near the tractor right now, I was going by memory, it might have 3 lines back to the hydraulics, will need to verify that. I know the old and new valves had the same number of lines. I don't know about the power beyond sleeve, I'll look at it and see if I can tell for sure.
I do think this is a new problem that has gotten worse, I changed the loader control valve years ago. I don't recall this being a problem then. I only use the tractor to clear snow, so maybe 4-6 times a year. I'm fairly certain this problem has just been getting worse each season.
 
If the loader valve has three lines then it needs a power beyond sleeve in order for the loader and three point to both operate correctly. Some photos of the loader valve from different angles, and maybe some of where the pressure and return lines connect to the tractor might help identify if that's part of the problem or not.
 
So I looked at the old valve and the new, both had only 6 connections, from what I know the connection at the tractor and the valve set up are always aftermarket, Ford sold the 772 loader and then the dealers just used aftermarket parts to install. Here are some photos of how the 2 lines connect from the control valve to the tractor. I also have attached some better pictures but the connections are not marked
Thanks
 

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Well the lack of power beyond is part (if not all) of the problem. Without that in play the return oil coming back from the loader cylinders has no escape without going through the three point lift system. With a load on that and possible demand for pressure to hold it up it's simply stacking up pressure in what SHOULD be a return passage. On the outlet side of the valve is large hex plug. Take that plug out and look inside. You will no doubt see an inner bore machined into the casting. You need to find a power beyond sleeve that fits the valve. Maybe contact the seller you bought it from and see what they can do for you. Then you need to add a third line directly to sump and connect it to the port you're using for return right now. Study this a while and see if the concept starts to make sense to you.

 
Yes it totally makes sense, what I don't understand is how it worked since day 1, as it is a 1972 tractor. I'm wondering if the old control valve had a power beyond sleeve you are describing? Would that work with no 3rd line?, as there never has been one? I've attached a picture of the old valve. I was able to get ahold of the Ford dealer that the tractor was purchased from and sold me the new control valve, he is looking into it also.
Thanks
Again for your help, sounds like this might be the issue for sure.
 

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I think where I'm getting confused too, is what are the 2 lines from the control valve to the tractor body? I assumed (we know what that stands for) 1 was pressure, and 1 was return?
Thanks
 
I've attached a link to the valve that was sold to me, it is the B8473. I guessing I have it plumbed incorrectly. I've attached more pictures, the 4 hoses going out the top of the valve straight up go to the tilt and lift cylinders. Maybe the other 2 are are the wrong ports?
 

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These days the standard markings seems to be P for pressure (inlet) T for tank or sump return and N for power beyond port. T and N are connected internally until you install a power beyond sleeve.

Why did it work okay before? Who knows? All I can tell you is that when I find a system that should have power beyond configuration but doesn't I will inquire as to whether or not any such problems come up on occasion and see what I get for an answer. Then go from there.
 
I've attached a link to the valve that was sold to me, it is the B8473. I guessing I have it plumbed incorrectly. I've attached more pictures, the 4 hoses going out the top of the valve straight up go to the tilt and lift cylinders. Maybe the other 2 are are the wrong ports?
It was very common for the early compact tractors to have a loader plumbed in without a power beyond port. The block on the tractor that the two hoses connect to was added to the tractor to supply oil to the loader. It feeds oil to the loader first and the return line feeds oil to the three point hitch valve. This creates back pressure on the loader valve when you have a heavy load on the three point hitch. Problems such as you are having is why they went to the power beyond style loader valve. When the loader doesn't want to lower does the box blade bounce some as you try to work the loader? It could be that you have an internal leak in the three point hydraulics. Does everything work as it should if you remove the box blade?
 

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