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Discussion Starter · #1 ·
1520 J D leaks hydraulic fluid from both ends of the load control shaft. There is an o-ring with a flat seal that goes inside it.The shaft I'm referring to is where the 3 point hitch lift arms pivot at the rear end of the arms. J D stupidly ran this shaft thru the hydraulic/rear end housing. (Real Genius) Does anyone know how to change these o-ring/seals.
Thank you,gregjo1948
 

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Howdy gregjo1948,

Your problem may be more than just seal failure. There are bushings in the housing where the shaft passes thru that may be worn out-of-round, and/or the shaft itself may be worn. If you want to try just a seal replacement, they are tough, but can be pulled out with an o-ring pick, cotter pin puller, etc. Heat the new seal in boiling water and push it into place and roll it into the groove with a blunt tool so you don't damage it.
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Below is a post on the YT forum written by a guy named Bob on this subject:

"I usually change out the shaft, bushings and seals all at once to cover all bases. The seals are tough but can be pulled out with an O ring pick or cotter pin puller. The fastest and easiest way I have found to remove the bushings is to clean the bush and shaft of any oil, install the shaft as it would normally sit then weld the bush to the shaft ON ONE END then drive shaft and bush fom the diff housing. Now cut the shaft right next to the bush,reinstall and repeat for opposite side. It sometimes helps to chill the bushing before installing. When doing this job in the winter I put the seals in an inside pocket before leaving the shop if its a road call." Bob
 

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Discussion Starter · #3 ·
Hey sixbales,
I don't think we're on the same page. I have a shaft around 3/4" diameter and 19" long. The lift arms slide onto the ends of the shaft on each side of the housing. Where the shaft goes into the housing, there is a round o-ring inserted into a grove inside the housing and then an o-ring with flat sides goes inside the round o-ring. Then the shaft slides thru the flat o-ring and thru the housing and out the other side. The shaft is about 3" out each side of the housing and that is where the lift arms are slid on and fastened with a collar with a hole to put a fastener pin thru. There is no sleeve inside the housing unless you're talking about where the o-ring groove is. I've never seen this kind of double o-ring method used before to seal around a shaft. I can't figure why JD stuck the shaft thru the housing. They just needed to have an anchor/pivot for the back end of the lift arms. There is no need for any lubricant so why stick the shaft thru the housing at all? I just don't know how to get the flat o-rings in.
gregjo1948
 

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gregjo1948,

I think we are on the same page. My communications fail at times, but it was clear to me!! Sorry about that.

Quote: "There is no sleeve inside the housing unless you're talking about where the o-ring groove is."

That's what I'm talking about. There's two bushings (with o-ring seals seated in internal groove) for the shaft to ride and seal, one on each side of the housing. Did you get the o-rings seated in the groove?
 

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Maybe this will help.
Parts diagram of the load control shaft, seals and bushings for a 1520.

The bushings that sixbales mentioned are item # 16 and should be replaced if you're replacing the load control shaft seals. The bushings wear and don't provide enough surface area for the O'ring and back-up ring to seal.

Also, do a Google search for "load control shaft seals" There are several companies that claim to make replacement parts for load control shaft seals that eliminate the seal some how.

Here's a link to one article, though I don't know if the 1520 is available.
https://www.farmshow.com/a_article.php?aid=7043

HTH,
Mark
 

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Discussion Starter · #6 ·
Sixbales,
I did get the o-rings seated in the groove. That was quite easy but installing the sealing washers was a challenge. I used a heat gun to warm them up, then I had to fold them to insert them inside the o-rings. The hard part was unfolding them once I got them inside the o-rings. I think that is where my problem happened. The shaft showed no wear or out-of-round where the sealing washers ride. There was a little wear where the lift arm pivots on the exterior part of the shaft which doesn't affect the sealing. Do I need to remove the "bushings" where the o-rings and sealing washers ride? If so--- how do I get them out?
TraderMark,
Thanks for the the image and the link. The numbers 16-17-18 are what I'm working with. 18 goes inside of 17 and both go inside the housing.(number 16) It's difficult to get 18 into 17 and I'm wondering if I were to remove 16 from the housing, if that would ease the installation of 18 into 17? Then my problem is getting 16 out of the housing.
Thank you guys for the help, gregjo1948
 

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gregjo1948, if you have the seals in place, I would re-assemble and go for it. If you want to remove the bushings, see the second part of my original post. One man's method, but I thought it was a good approach.

TraderMark, thanks for the parts diagram. Where do you get these JD parts diagrams?
 

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gregjo,
Getting item 16 out of the housing is what the quoted part of sixbales message was about. That gentleman simply welded the load control shaft (item 25 or 26) to one of the bushings (Item 16) then drove the bushing out using the existing load control shaft. He then cut the bushing off the shaft, reinserted the shaft and welded it to the other bushing and once again used it to drive the bushing from the housing. However, this means replacing the shaft as sell as both bushings. Seems like a pricey way to do it if the shaft isn't worn.

HTH,
Mark
 

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Discussion Starter · #9 ·
gregjo,
Getting item 16 out of the housing is what the quoted part of sixbales message was about. That gentleman simply welded the load control shaft (item 25 or 26) to one of the bushings (Item 16) then drove the bushing out using the existing load control shaft. He then cut the bushing off the shaft, reinserted the shaft and welded it to the other bushing and once again used it to drive the bushing from the housing. However, this means replacing the shaft as sell as both bushings. Seems like a pricey way to do it if the shaft isn't worn.

HTH,
Mark
I understand that method but, I don't want to waste my good shaft. The shaft does have tapers on each end so could I use the shaft, inserting it from one side to drive the bushing out the other side and then put it thru the from the other side to remove the remaining bushing? With the tapered ends it shouldn't mushroom the end of the shaft enough to create a problem. I could clean any burring on the shaft ends before installing. Does that sound like a good plan? Thanks, gregjo1948
 

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sixbales,
I have a link to the old John Deere parts website before they did the latest update to that site. From the old website I can save the images of the parts diagrams and then upload them here. It doesn't work that way with the new website unfortunately.

Mark
 

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If it were me gregjo, I'd find a piece of cold rolled shaft that's close to the same size as the load control shaft and use that to weld the bushings to. Keep in mind though that while I am familiar with these parts I've never actually done the job myself so all I can do is speculate.:dazed:
 

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Discussion Starter · #12 ·
TraderMark,
You mentioned that the bushings(#16) should be replaced because they wear. The shaft doesn't move and is inside the sealing washers plus the o-rings. The bushings(#20) may get some wear because they're at the pivot of the lift arm. How do the bushings(#16) get worn? What am I missing in your need to replace the bushings?
gregjo1948
 

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gregjo,

The shaft may not turn in the bushings, but there is a constant pull against the shaft any time you have a plow in the ground. The harder the ground, the more the pull against the shaft and bushing. There is also pressure against the other side of the bushing when you have the implement raised. The weight of the implement is pushing the shaft forward. This constant change of pressure from one side of the bushing to the other is what wears the bushings. The bending and bowing of the center of the load control shaft is also what makes the draft control work. Harder ground means more pull so the load control shaft bows in the center which in turn moves the arm (item 9) which is hooked to the lift control valve and lifts the plow enough to ease the load.

Think about sticking a screwdriver through a piece of cardboard and moving the screwdriver forward and backward. Even without rotating the screwdriver, you still elongate the original hole.
Same principal applies here. The load control shaft is the screwdriver, the bushings are the cardboard and the implement is the force that moves the screwdriver back and forth.

HTH,
Mark
 

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Discussion Starter · #14 ·
Mark,
Thanks for the good explanation. I've had a few 3 point hitch systems apart to repair and must say Harry Ferguson was very smart to fabricate/design/invent the system. When looking at it, it's logical and understandable but, to put it all together back in the late 1930s, is quite remarkable.
gregjo1948
 

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Hey guys. I realize that this is an old post but need to do this job on my 301a. Service manual states that I need to remove the axle. Is his true or can the load control shaft be moved at least enough to get to the seals (going to try that first). Are there any clips holding the shaft from moving left to right or do you just tap with a hammer? Thanks!
 

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Hello Yellow99, welcome to the tractor forum.
Answers to your questions: 1) You do not have to remove the axle, and 2) There are no clips holding the shaft internally.

Here's a couple of U-Tube videos that may help:


 

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If there’s any wear in the load shaft...the seals themselves won’t last. If you’re going to replace the bushing anyway...take a look at the Bolling or JD is also selling a similar upgraded bushing w/Oring, it has a replaceable Oring which adds an additional sealing point. Then use the JD seal out side. I have replaced the bushings in both my JD4020 &2510 with the Boling and haven’t had an issue since. B.
Go here for replacement bushings
http://bolingmachine.com/
 

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IMHO there's not much advantage to use Boling Mach shop bushings to replace JD L/D control bushings on JD utility tractor such as OP's 1520 because both designs are very similar But in JD rowcrop tractors such as 3010 through early 20 series rowcrop Bolings bushings has a distinct advantage over JD factory seals
 
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