Unloading Valve

[Gman]

Hello everyone. For JC, see my post "stuck control rod/rack" on how I was able to get her starting. I'm going back to the unloading valve to see if I still have a problem there. Not knowing the correct way it should be installed wanted to see if anyone could give advice. When I put the valve in without unloading valve seat the unloading valve bottoms out into tapperd bore which seems right to me but with valve seat and ball bearing in the unloading valve does not go all the way down into tapperd bore which indicates to me the valve is still open but then again like I said not sure how it should be. The lifts are working without weight, will raise with weight a few inches. New seal and o rings have been done, new oil and filter cleaned. All advice is greatly appreciated.
Thanks
Gerald

[Gman]

Hello everyone. For JC, see my post "stuck control rod/rack" on how I was able to get her starting. I'm going back to the unloading valve to see if I still have a problem there. Not knowing the correct way it should be installed wanted to see if anyone could give advice. When I put the valve in without unloading valve seat the unloading valve bottoms out into tapperd bore which seems right to me but with valve seat and ball bearing in the unloading valve does not go all the way down into tapperd bore which indicates to me the valve is still open but then again like I said not sure how it should be. The lifts are working without weight, will raise with weight a few inches. New seal and o rings have been done, new oil and filter cleaned. All advice is greatly appreciated.
Thanks
Gerald

Can anyone tell me the purpose of the ball bearing and the correct diameter. I plan to go into the valve chest today and see if I can figure something out. Thinking if I take ball bearing out the valve may close as it should or as I should say" the way I think it should". Can't find any info in the manuals on this.
Thanks

[Brian]

I think we are all at a loss. The unload valve is just a housing in a sleeve that just goes in and is held in place by a spring pressing on a plate.

The ball bearing should be part of the unload valve, not loose on the seat.

There are no holes to line up as these are between the lands of the valve and the oil will flow around the valve to find them.

If the valve is not going onto the seat something must be holding it off. The valve must be jamming in the sleeve.

If the spring is weak or there are not enough shims between the spring and the retainer, then you will get the problem you have.

If you go to the manuals on this site, there are pictures of the three types of valve in the hydraulics section.

[Gman]

I think we are all at a loss. The unload valve is just a housing in a sleeve that just goes in and is held in place by a spring pressing on a plate.

The ball bearing should be part of the unload valve, not loose on the seat.

There are no holes to line up as these are between the lands of the valve and the oil will flow around the valve to find them.

If the valve is not going onto the seat something must be holding it off. The valve must be jamming in the sleeve.

If the spring is weak or there are not enough shims between the spring and the retainer, then you will get the problem you have.

If you go to the manuals on this site, there are pictures of the three types of valve in the hydraulics section.

Thanks Brian, yea I'll see if I can explain better. The part I'm referring to is the bottom of the valve which has several holes in bottom of it and there are two holes in the side of it. When I had the valve chest on the bench and without seat and ball bearing in the part would go all the way down and bottom out in sleeve/bore, the two side holes in part would be in line with the hole in the back of valve chest. With seat and ball bearing in this part would stop with the two holes on the side of it only showing a portion of them through the back hole of valve chest. I added a couple of shims but it did not change, the ball bearing is loose, I have to put it in place before dropping valve in each time I pull it out. I understand the holes in the side does not have to line up for oil to flow but should these holes be level with back hole in valve chest for it to be closed? I guess that is what I'm trying to make sure off, is if the valve is closed all the way or partial open before I start thinking it is pump problem. I will be pulling it back out to study on it some more and see if I can figure anything out. Sorry for the confussion with my explanations. As always your help is greatly appreciated.
Thanks
Gerald

[Brian]

Gerald,
The ball bearing should not be loose. It is part of the valve not a separate item. If it is loose this is quite possibly the answer to your problem.

The change to the valve itself took place early on in the tractors. Originally the end of the valve was pointed where it fitted into the seat and the seat was tapered to match it.

This left possible leakage due to seat wear so the design was changed and the ball end fitted onto the valve to give a narrower seat and therefore less problem.

[Gman]

Thanks again Brian. The manual mentions the ball bearing may need to be held in place with some grease when putting valve back in, which I have done and also have just set ball bearing on top of seat in indention. I have pulled the valve out several times and the ball bearing is always laying to the side on top of seat. I will look closer at the valve and seat as to where the ball bearing should be and see if some cleaning is needed there in order for it to seat properly. As I understand it, the pressure pushes valve up against spring to open, is this correct? When valve opens under pressure does oil flow down through small holes in bottom of valve and out? Understanding the process helps me figure out what to do. With me not having the knowledge required I know the way I ask questions causes problems. Again thanks so much for all that you have helped me with. Without you she probably would already be back under the shed.
Gerald

[Brian]

Gerald,
That is your problem!

The ball should not be able to escape, there should be a stop to prevent the valve from rising enough for the ball to escape. The part number in the old book was E 121 GF 9 and it goes down over the spring from the top so that the spring is nearly enclosed with the valve at the bottom and the stop at the top.

If you have the square topped adjuster, the ball getting out of position was a problem, that is why they prevented the valve from moving too far. The valve can be replaced by the later type by dicarding the adjuster and replacing it with the stop and the shims which are used with it. The shims have to fit inside the the stop housing.

Alternativly you may not have enough shims on your spring to hold the valve down tight on the seat and restrict the rise of the valve. It only needs to move a fraction to allow oil to escape.

A picture of your valve would be a great help. Laid out on a sheet of paper, exactly how you are assembling it.

[Gman]

Thanks Brian. I will look again but I have the stop on top with shims, spring inside of it. I will try to get back into it once the rain goes away here and look some more at the ball bearing and the seat to see if I can determine what is going on with it.
Thanks as always.
Gerald

[Gman]

Hello to everyone. I took the unloading valve out again, have added shims with no change in lift. It will lift arms without any weight, will lift bushhog a few inches. I am off for a week after today so may have some daylight hours to look at her some more next week. I can hear pump when I engage lift, new o rings and seal is in. Any suggestions on anything else I can do to figure out this problem. Is it ok to take cover off behind ram cylinder while running and raise lifts, thinking I may be able to see or hear something.
Thanks for any help.
Gerald