Interpreting Hydro pressure readings

[pfrederi 17,887]

The charge relief valve is really a steel ball and coil spring. the only rubber in the area is the o ring on the cap you will be removing.

[tommyg 152]

I'm certainly going to take the time to clean and check what I can. But I still have to consider that this is the second pump I've had in with similar symptoms (removing the implement valve from the picture). While its possible that two pumps and said valves in the exact condition, it certainly lowers the chances.

[tommyg 152]

By the way, is there any way to measure the tension of the spring in the charge valve? I had a crazy idea to find a way to stretch the spring back out to its original tension. In theory, it could work. But I'm not sure what kind of tension to give it. If it's reasonably easy to get to, perhaps trial and error could get me to the pressure I need.

[wheeledhorseman 574]

I'm certainly going to take the time to clean and check what I can. But I still have to consider that this is the second pump I've had in with similar symptoms (removing the implement valve from the picture). While its possible that two pumps and said valves in the exact condition, it certainly lowers the chances.

I tend to agree but as I think Paul has pointed out in threads before, you can't assume anything with a used pump no matter what the vendor said about it. It's a matter of working through the possibilities in a logical order eliminating things one at a time.

I don't know what others think but I don't think attempting to stretch a strong spring is a good idea when it performs an exact task. I'd be looking to check that the spring hasn't broken, become distorted and that the valve seat is clean in the first instance.

As Britt said:

To check the charge relief valve, all you need to do is pull the left side panel under the PTO lever. The plug is an ORB so all you need is a socket. The hydro motor is a little more involved. I ended up pulling the entire rearend out to get to my motor since I was already setup to do that. Another quick check to make would be the "buffer" valves that are connected to the hydro motor. If they are leaking they will bypass high pressure fluid over the low pressure side. The accel valves in the motor are another quick check also. They have an extremely tiny bleed hole in them that can get clogged. The accle valves will have to be disassembled for a thorough check.

I performed all of those checks before I pulled the motor and restored the valve plate.

Good advice I believe, check the easy things first before pulling the motor.

Andy

[coldone 35]

I'm certainly going to take the time to clean and check what I can. But I still have to consider that this is the second pump I've had in with similar symptoms (removing the implement valve from the picture). While its possible that two pumps and said valves in the exact condition, it certainly lowers the chances.

Then start at the motor and buffer valve. IMO easier to get to at least. The buffer valve and accel valves can be pulled and checked in less than an hour.

[JamesBe1 82]

By the way, is there any way to measure the tension of the spring in the charge valve? I had a crazy idea to find a way to stretch the spring back out to its original tension. In theory, it could work. But I'm not sure what kind of tension to give it. If it's reasonably easy to get to, perhaps trial and error could get me to the pressure I need.

I doubt that anyone could get lucky enough to return a spring to it's original value by stretching it, out in the field. Maybe this could be done on the bench, but I doubt it. Besides, you would need to know what value it needs to be.

If you think the spring is bad, you best bet would be to replace it with a new one of one from a donor pump.

I'm sure the vendor (sunstrand?), has a specification for the spring. Too bad we can't get any to join the site.

[pfrederi 17,887]

Rather than stretching the spring i would put in a shim(s) between the spring and the cap. I would think the ones used on the implement relief valve should work.

[tommyg 152]

Just a quick update... I've been out of town for a couple weeks, so I'm just getting back to this. After checking all the valves, I've moved on to the motor. I picked up a used one off of eBay figuring I'll use this one as my "guinea pig" in case I screw it up. And if I don't, I'll have a spare. With some help from Coldone, (I found out he has a real name, now. ), I am down to the valve plate. It appears to have a thin ring of scoring near the holes. I'm assuming that this is the standard place to see this damage since the oil is exchanged here. Plan on starting the lapping process tomorrow. Once I get it in shape and back together, I'll switch this motor with the one on the tractor now and keep my fingers crossed. If anyone can give me an idea how to post pics, I would love to do that. I'm not sure how you guys do it, but there's gotta be an easy way.

[JamesBe1 82]

Thanx for the update Tommy. There are several ways to post pics. You can upload them to an external server and link to them from here, or you can upload them to your gallery here and add them to your post with the editor. That's the way I use.

[Trouty56 567]

You can also just attach them to your post. Click the "more reply options" at the bottom right of the reply box next to the "post" button. You will see the "attach files" option at the bottom. Upload them there. Once uploaded you can use them anytime using the "my media" option at the top of the reply box and selecting attachments.

[tommyg 152]

Some pics of my lapping process on the valve plate of the motor. This is what I started out with. Notice the scratches were between the oil holes.

In order to get a better hold on the valve plate, I found a scrap piece of wood and countersunk two finish nails below the plate, but sticking out enough that is gripped it. That way, I was able to put more pressure without doing in my fingers.

Finished product

Ready to reassemble with a homemade gasket.

[JamesBe1 82]

Pretty impressive. What grits did you use?

[coldone 35]

That looks great! But i am calling you a cheater for using the board, it took me a week to grow my fingerprints back . Looks like you are a pro at lapping now. I am looking forward to you getting on your tractor and see how it does. I know it did wonders for mine but I still need to go into the pump. I am sure that my pump valve plate looks as bad as the motor valve plate.

[tommyg 152]

Pretty impressive. What grits did you use?

I started out with 400 to remove the scratches. After that, it was a pretty quick process to move through the others... 800, 1000, 1500, crocus.

[wheeledhorseman 574]

Nice job there Tommy, great photos, and a neat trick for holding the plate.

From the looks of it the scoring was just fair 'wear and tear' erosion of the brass through prolonged use.

I did read in one of the very many Sundstrand manuals / data sheets that I've come across that performance was expected to start tailing off after about 2000 hours heavy use. Didn't seem like exactly a huge life expectancy before servicing was required.

BTW I think now you've made over 50 posts you can change the status above your avatar and become a 'family member' if you wanted to.

Andy

[pfrederi 17,887]

That is a really cool idea about the backer board!!!

[tommyg 152]

Nice job there Tommy, great photos, and a neat trick for holding the plate.

From the looks of it the scoring was just fair 'wear and tear' erosion of the brass through prolonged use.

I did read in one of the very many Sundstrand manuals / data sheets that I've come across that performance was expected to start tailing off after about 2000 hours heavy use. Didn't seem like exactly a huge life expectancy before servicing was required.

BTW I think now you've made over 50 posts you can change the status above your avatar and become a 'family member' if you wanted to.

Andy

Andy, there was one scratch that I wasn't able to fully remove. If I kept with the lapping process, I was afraid of taking too much off, so I left it go. You think that will come back to haunt me? I am also wondering about the Sunstrand manual showing an O ring behind the aluminum pilot ring on the drive end of the motor. Do you know anything about this? There wasn't one there when I removed it, but there appears to be a groove to accept one about the size of the ring itself.

And wow, I did't know my acceptance into the "family" hinged soley on the number of posts! This calls for a celebration! :happy-partydance:

[tommyg 152]

By the way, for what it's worth, when I started the lapping process, I had a spare cast iron extension wing from my table saw that was milled to within thousanths of an inch, so it provided a good base for the process. I also started by lapping in a circular motion, but I found out that as I finished each stage, I wrapped it up with more of a twising motion. This seemed to give me a finer finish.

[JamesBe1 82]

Just wondering if a valve plate for the 15 series (?) would be interchangeable, and if so, how costly would it be.

Also, can anyone tell me what part(s) come into contact with the valve plate that causes the wear and scratches? Is that something that would need further inspection and remediation?

[wheeledhorseman 574]

Andy, there was one scratch that I wasn't able to fully remove. If I kept with the lapping process, I was afraid of taking too much off, so I left it go. You think that will come back to haunt me? I am also wondering about the Sunstrand manual showing an O ring behind the aluminum pilot ring on the drive end of the motor. Do you know anything about this? There wasn't one there when I removed it, but there appears to be a groove to accept one about the size of the ring itself.

I'm no expert Tommy but my reasoning goes like this. High pressure fluids, even oil, will erode the surfaces that it is being forced between. This would be more significant the softer the material i.e. brass. This type of wear is inevitable hence the Sundstrand reference I found to life expectancy before major overhaul being required. Modern hydro fluids contain additives that effectively reduce this wearing away, particularly of the softer materials and several members have made cases for using these in posts on the forum.

Getting back to the scoring I'm drawn to thinking that there are two types i.e that caused by general wear and tear (erosion) and the rather more dramatic damage that's been caused by either grit or more likely tiny fragments of metal that have resulted from other damage perhaps in the tranny which seems to trash the whole surface area. Looking at your photos I just kind of felt that as there was a main groove central to the pistons it looked more like general wear. Once a groove begins to form more oil will be forced along it and the wear rate will increase cutting the groove ever deeper. Just my theory - I'm sure others will chip in.

So leaving any scoring will inevetably lead to wear again but hey - it's a million times better than it was and will probably work for many years.

And wow, I did't know my acceptance into the "family" hinged soley on the number of posts! This calls for a celebration!

The fifty posts bit is a forum thing, it used to be 100 posts before you got access to being able to change what it says above your avatar but Lonny (Otrelwood) managed to get it reduced, as I recall, to fifty. I'm sure the other guys will chip in if I'm wrong but I believe it's an open invitation to fellow 'D' owners to join our little family group.

Just wondering if a valve plate for the 15 series (?) would be interchangeable, and if so, how costly would it be.

Also, can anyone tell me what part(s) come into contact with the valve plate that causes the wear and scratches? Is that something that would need further inspection and remediation?

Coldone has confirmed the 15 Series connection and that not all parts are interchangeable. Basically the technology used when Sundstrand designed the tranny for WH was based on this but the casings and may other parts are different. Fortunately the key components i.e. cylinder block / piston assemblies and valve plates are standard '15' components but most of the other bits are specific to the WH transmission. Paul has also made a discovery re the one-way interchangeability of cylinder blocks.

I've looked at parts diagrams for standard 15 series motor but the O-ring mentioned deosn't appear to be standard so I'm guessing it was specific to the WH application as was the centering pilot ring. Another thing I noticed is that two different valve plates were used in 15 series motors, one being refered to as 'Thin'. In all I think if you need to go this route then following Coldone's suggestion is the best option to be sure you're getting something that will fit. No idea what the prices are though.

Andy

[tommyg 152]

Also, can anyone tell me what part(s) come into contact with the valve plate that causes the wear and scratches? Is that something that would need further inspection and remediation?

The scratches I encountered were located along a ring that connected the holes that the oil flows through. As the oil picks up "stuff", it's deposited between the valve plate and the cylinder. With nowhere to go, it just scratches it's way to it's next destination. With the pressure between the cylinder and the valve plate, it's inevitable that it would score it. The one thing I didn't count on was that there is potential for scoring on the base of the cylinder where it contacts that valve plate. I guess it only makes sense. But the cylinder is harder metal. Nevertheless, I did see a bit of scoring on the cylinder and thus had to lap that as well. The other parts I lapped were the brass piston tops. This rides against the fixed valve plate inside the cap. I did not need to remove this plate as it looked to be in great shape.

Tom

[coldone 35]

Tom,

Its my understanding that the valve plate for the motor will not interchange with the 15 series valve plate. From looking at pics of the 15 series valve plates I am guessing that the motor valve plate is different in that the motor is designed to work in two directions. If you look at the motor valve plate, it has indentions, kinda sloping cutts, in the 4 of the slots that would be in the 12 and 6 postions. In the regular 15 series valve plates, there are only 2 of these indentions and the seem to be directional. Now if you have a good machinist I am sure they could convert a standard plate into a bidirectional plate but by the time you buy a plate and pay to have it converted then you probably could have bought a new one.

As to the source of the scoring, the one thing I believe to cause the mafority of what we see is that the design of the system dosent really filter the resivour of oil before it is sucked up into the pump system. The fluid is filtered before it is dumped into the resivouir (rearend) so its clean fluid sitting in there, but if anything gets into the oil thats just sitting there then it gets sucked up into the pump. My differential was busted and metal shrapnel got sucked up into the system and circulated through the pump and motor before the stuff could be filtered out. There is a screen on the pickup opening but it is not a filter, it keeps big particles from being sucked up but not the small ones.

Britt

[wheeledhorseman 574]

I'm not giving up on this just yet when the link to 15 series has now been confirmed and we're getting so close!

Although we're dealing with a transmission put together to meet WH requirements there's quite a bit of evidence that wherever possible Sundstrand used standard parts e.g. the motor housing looks to me like its from their standard 'in-line' configuration.

I've been studying the exploded parts diagrams for the various 15 series pumps and motors.

There are two different designs of valve plates used in the pumps each type being available in LH and RH versions so from the tranny tags on ours I suspect ours would be the LH type. I'm guessing LH and RH has to do with rotational direction of the prime mover (engine) as only pumps (and not motors) have LH and RH versions of valve plates.

Re the 15 series motors there were in fact three different valve plates used in standard units so there's hope that one of these has the same number of 'sloping cuts' as in our units. I'm in the process of compiling a list of the original Sundstrand part numbers to follow up. It could lead nowhere but it's worth a try.

Andy

[coldone 35]

I'm not giving up on this just yet when the link to 15 series has now been confirmed and we're getting so close!

Although we're dealing with a transmission put together to meet WH requirements there's quite a bit of evidence that wherever possible Sundstrand used standard parts e.g. the motor housing looks to me like its from their standard 'in-line' configuration.

I agree, most companies do not want to retool just for a single low production component.

I was thinking that the valve plate in a 15 series used in teh massey ferguson 1855/1655 Gt should be bidirectional.

[tommyg 152]

OK, you guys, the plot thickens. Anxious to give the "new" motor a try, I set to work removing the old. What I found was kind of interesting. I'm not sure the strainer is supposed to look like this would you agree? I don't think this was my problem, but it may have certainly contributed to the system's demise if those strands of metal were floating around in there. Crazy stuff! Anyone know if these things are still available? What about the gasket? I thought I could make one, but this thing is pretty complex.