What kind is this power steering?

paramax55

Member
I want to reseal my power steering box, but I don't see anything like it on the net. Under the steering wheel, I have a box that's about as big as your fist and it has all of the power steering lines going in/out of it. That's it. No long shaft going to some box on the frame or anything else. So... what's it called?
 
So far, the tractor appears to be a 20C. It looks like there are 4 lines coming out of it, unless some more are hidden. I'll look up Orbitrol and see what I can find.
 
Seems that there are a number of descriptions for this steering device.
Two major parts suppliers in the UK describe it as an 'ORBITAL STEERING UNIT'.
The MF parts books describe it as an 'ORBITROL HYDROSTATIC STEERING HOUSING'.
As to the 'motor' description I would agree that this is not quite correct. The steering unit is not much more than a divertor valve which sends a proportional supply of oil to whichever side of the steering cylinder it is told to and at the same time opens a return line for oil returning from the cylinder.
We do need to know what tractor we are talking about and what type of steering is fitted to it.
DavidP, South Wales
 
I did some looking and, indeed, I have the orbitrol power steering. My issue is... when I was trying to remove the steering wheel to pull up the instrument panel, the whole shaft came out of the steering adapter. I separated it from the steering wheel and put it back in, but it now weeps a fair amount of power steering fluid. I want to pull the bearing and seal and replace them with new ones. Does someone offer those parts as a kit? Do I need to just measure and order by size? And, if I replace the seal, is that going to solve my leakage problem? I'm thinking the orbitrol unit is supposed to have its own seal, right?
 
It is called a "steering control unit". Yours should be part number 520348m93. Looks like you need a couple of O-rings 833460m1, and maybe
831907m1? Look in Agco parts books online under 20c. I believe everything you need is there.
You may need the two snap rings to keep the shaft from coming out again as well.
Wayne
 
Well, I don't have an Agco account, but I have a parts/repair manual coming from Canada - however long that's going to take. Looking at those O rings you listed, they may be the ones for the steering control unit. But I need the stuff in the adapter head (whatever that's called) first. It's going to be a bearing that's somewhere around 1 1/2" OD and 3/4" ID with a corresponding oil seal. After doing some research, it looks as if MF used spring retainer clips, that are common with hydraulic components, to hold the shaft in. I don't know why it's common with hydraulics because they just don't have that much holding power - that's why the shaft came out. Maybe they use them in hydraulics because they don't have any sharp edges.

Anyhow, hopefully I can get that bearing out today. Then I can measure it and order another one.
 
My question would be what method you used to get the wheel off, that the whole shaft came with it. The force exerted must have been between the shaft and the housing instead of the wheel and the shaft.
 
Well, I didn't use a puller and there was a reason. The plastic hub on the steering wheel is so big that I would have just been pulling on plastic and it would have ripped.I used the old lawnmower trick of putting a pry bar under the hub while hitting the mounting nut with a hammer. It didn't take much force and it all popped out. But that retaining spring doesn't exert much force. You could probably pull the steering wheel out if you used both hands and were REALLY determined.

By the way... once I could walk everything over to the little, 12 ton shop press, I got it apart. I had to use the long jack bar and push with both hands. It shot out like a bullet and spewed jack oil EVERYWHERE.
 
UGH!... Blueballed! I looked at the online books. I found the area I was looking for. I tried to verify by looking at the diagram. Wait... there's no diagram! DENIED! NO SATISFACTION FOR YOU! Why can't eBay allow this guy to email me the pdf manuals I'm waiting on???

I got the bearing out with the help of a Harbor Freight pilot bearing puller stressed to the max, then a little heat until it goes "pop." Then reset and do it about 5 more times. The rain over the years made the hole for the bearing about .005 smaller than what the rust on the bearing had grown to. There was no danger of it falling out while I was mowing. Why do people leave tractors out in the rain???

As it turns out, there is a normal snap ring in there. The weak, hydraulic one is on the top - above the bearing. I guess they figure there's no danger of you pushing the shaft down into the orbitrol on accident. The bearing and seal, as it turns out, are not a common size. The ID is about .869 and the OD is about 1.405. This could have been so easy if they had just used standard bearings...
 
Yes I know, been in that spot too. So now the wheel is missing the plastic around the middle. Maybe someday we'll splurge for a new one. Don't remember exactly how I hooked it but I sure remember how it jumped in the air
when it finally came loose. There was huge corrosion of the top of the valve housing, bolts and all, so I just took it to my machinist who got it apart and replaced the bearing and seal which I had from the dealer.
 
(quoted from post at 07:25:44 11/09/17) UGH!... Blueballed! I looked at the online books. I found the area I was looking for. I tried to verify by looking at the diagram. Wait... there's no diagram! DENIED! NO SATISFACTION FOR YOU! Why can't eBay allow this guy to email me the pdf manuals I'm waiting on???

I got the bearing out with the help of a Harbor Freight pilot bearing puller stressed to the max, then a little heat until it goes "pop." Then reset and do it about 5 more times. The rain over the years made the hole for the bearing about .005 smaller than what the rust on the bearing had grown to. There was no danger of it falling out while I was mowing. Why do people leave tractors out in the rain???

As it turns out, there is a normal snap ring in there. The weak, hydraulic one is on the top - above the bearing. I guess they figure there's no danger of you pushing the shaft down into the orbitrol on accident. The bearing and seal, as it turns out, are not a common size. The ID is about .869 and the OD is about 1.405. This could have been so easy if they had just used standard bearings...


You can usually get the manuals from http://www.agcopubs.com/ depending on the manual you can download it from them in pdf files.
 
Well I finally got the repair manual and - NO PART NUMBERS! In fact, there aren't good part names. The Oil seal is labeled as a "bushing" in the exploded view, and as a "seal" in the description of what to do. I went to AGCO to order the parts manual and they want an ASTRONOMICAL ammount of money for the pdf version - which isn't even a pdf. You have to download some proprietary viewer. I'm just going to get a real pdf off eBay.

Anyhoo... I came up with my temporary solution. I grabbed a piece of scrap plexyglass, chucked it up in the lathe, added some o-rings, and made a seal. I was making a SWAG at all the dimentions, so it's a little stiff, but it will work for now. Here are a couple pictures...

6076.jpg

Here's the seal...
mvphoto6077.jpg

Here it is, on the shaft, ready to go in the tractor
 

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