Hydraulic Problem With Pilot Controls

[willie59]

Pardon my ignorance, but are the check valves you guys are referring to contained inside the valve block? Meaning do I have to pull the all the individual block assemblies apart to get to them?

Also, in normal power mode, when I try to raise the boom or curl the bucket, I do get flow through the hose from P4 to Z which indicates the check valves are not working. I pulled a few hoses off today and did see some black residue that could be the left overs of an o-ring. I also spent some time spraying the stuck rollers with oil to hopefully free them up.

With the help from you guys I am slowly making progress.

First of all, there's no shame in asking questions when your seeking knowledge of something you don't know. Asking questions is one of the ways you learn.

Two of the check valves in question are within the manifold. When you look at your schematic, notice all of the control valves and assorted goodies look like they're inside a rectangular box. The box is the manifold. That means anything you see within the box is inside the manifold. But now it could still be a cartridge type valve (like a relief valve in apperance), which you can remove from "the outside", but the valve is still technically "inside" the manifold. There is another check valve, one that is shown outside the box/manifold, the one that goes from the Z ??? port to the P4 port. Now that one should be an external valve outside of the manifold, mabey in-line in a piece of piping.

Let me make sure I understand you. Are you saying that you could take the line loose from P4, leave the port open, lift the boom or curl bucket, and oil would come out of P4. If so, that definately indicates you have a problem with that check valve.

 

[bremery]

http://www.bremery.com/530/Control_Block.JPG

Item A is a plug. Item B looks like it could be a check valve as it does have o-rings at the end. It did not seem hung up, but I did not look like it moves at all.There is one of these on each side of the function block. My manual does not have any drawings for this part. I could not snap a picture at the time, but I can attempt to get one if that will help. Item C is a port relief / anti shock valve for the left track.

I am not 100% that I am getting flow from P4 to Z. I used a wooden dowel to listen to see if fluid was moving through the hose. Its not quite accurate. I will loosen the hose and see if it leaks. That seems like a more surefire way to check.

I tried to pull the main check valve near Z but it did not budge. I need to come up with a better way to get at it. Its the long brass tube in the middle of the picture. http://www.bremery.com/530/check_valve.JPG

 

[willie59]

In that last pic you sent, is that the Z port with the inline check? If so, where does that hose go?

 

[willie59]

If the schematic is true to your machine, the check valves we're looking for should be in the valve section for the aux circuit. The schematic is fairly good, but I noticed one flaw that might confuse you if you were not familiar with schematics and symbols. The relief valves don't show the internal pilot lines that open them under pressure to shift the spool and dump oil to tank. Here's what the reliefs should look like. The "dotted line" indicates an internal oil passage of the valve, or, internal pilot. Dotted lines on a schematic usually indicate either an internal pilot line or control pilot lines. It looks like your machine has British Metric Pipe Inverted Flare fittings. My local hose shops have the fittings to make hoses, but they don't have plugs/caps for the fittings or fittings that the hoses connect to, like the fittings that are installed in the valves, so be carefull working with these fittings so as to not damage them.

 

[bremery]

In that last pic you sent, is that the Z port with the inline check? If so, where does that hose go?

This hose goes from Z to P4.

As for the fittings my local hydraulic shop is well versed in BSP fittings. I always try to be careful with these things anyways.

I guess the next step is to pull off all the hoses and pull the valve block to see what is happening in there.

 

[willie59]

This hose goes from Z to P4.

Well, I guess I asked the question wrong, my bad.
Have you got a good pic of the valve section where that hose connects to? That should be, as you said, the P4 port, and the checks should be in that valve section. They should be serviceable externally without valve section disassembly. Notice I said "should be", it would surprise me if you had to bust everything down.

 

[bremery]

Here is another shot of the control block. (Ignore the pile of paper towels).
http://www.bremery.com/530/Control_Block2.JPG

There is another greyish plug on the back side of the block. I assume these are the check valves.

I also verified that I do get leakage at P4, when I crack the hose fitting open.

 

[willie59]

Here is another shot of the control block. (Ignore the pile of paper towels).
http://www.bremery.com/530/Control_Block2.JPG

There is another greyish plug on the back side of the block. I assume these are the check valves.

I also verified that I do get leakage at P4, when I crack the hose fitting open.

Looks like your in the right spot. I'd start pulling cartridges/plugs there and get a better look. Also, you could get leakage by cracking the hose at P4 because of flow from the Z port. You would have to take the hose loose and put a plug in it to prevent flow from the Z port.

 

[bremery]

I know the top one is a plug. The other one threads into the block and has o-ring seals on the end. It is the same on the opposite side of the block. I will try to snap a picture of it tomorrow. When I pulled it out a day ago, I did not get a good look at it.

 

[willie59]

I know the top one is a plug. The other one threads into the block and has o-ring seals on the end. It is the same on the opposite side of the block. I will try to snap a picture of it tomorrow. When I pulled it out a day ago, I did not get a good look at it.

Cool, pics are good!
I'm thinking the plugs are where you would normally connect hoses for aux circuit and you don't have your aux plumbed. Like I said, "If" the schematic is true to your machine, those checks "should" be in that valve section. I'd pluck everything out of that section if I had to in order to find them. By the way, did that relief valve illustration I made make sense to ya?

 

[bremery]

I believe my machine is plumbed for one way operation for the aux circuit, meaning it will not run a double acting cylinder. I guess that is why its called the hammer circuit in the manual. The schematic does appear to be true to my machine so far.

I pulled the fitting that P4 threads onto and it has nothing in it. It is an extension fitting and it is a clear pass through into the block for oil flow. My guess is the grey plug is one of the check valves. I really need to get a better look at them.

Earlier someone mentioned the seals on the check might have failed. If the seals are the problem is it better to rebuild them or get a new check valve?

I will also look at the check valve at Z.

Thanks,

 

[willie59]

I believe my machine is plumbed for one way operation for the aux circuit, meaning it will not run a double acting cylinder. I guess that is why its called the hammer circuit in the manual. The schematic does appear to be true to my machine so far.

I pulled the fitting that P4 threads onto and it has nothing in it. It is an extension fitting and it is a clear pass through into the block for oil flow. My guess is the grey plug is one of the check valves. I really need to get a better look at them.

Earlier someone mentioned the seals on the check might have failed. If the seals are the problem is it better to rebuild them or get a new check valve?

I will also look at the check valve at Z.

Thanks,

I don't suspect an issue with the inline check at this point. I've looked at the schematic, and actually don't see a point in that check valve being there except a redundant check in case the ones in question fail, then it would prevent unwanted oil flow from P2 and P3 over to the P1 circuit. Pull the goodies out of that aux section and we'll go from there.

 

[bremery]

Here is a picture of what I think is the check valve. There are two of these in the function block. If this is not a check valve, what is it?

 

[willie59]

Here is a picture of what I think is the check valve. There are two of these in the function block. If this is not a check valve, what is it?

Need a little more than that. Are there holes in the side of the vavle? What's the bottom of the valve look like?

 

[bremery]

The bottom is flat with no holes and there are no holes in the side.

I expected it to look similar to this, but clearly it does not.
http://www.nbhhyy.com/en/p_detail.php?id=31

The only other fitting on the aux block is the supply line to the boom. I guess this means I have check valves built internally?

 

[willie59]

The bottom is flat with no holes and there are no holes in the side.

I expected it to look similar to this, but clearly it does not.
http://www.nbhhyy.com/en/p_detail.php?id=31

The only other fitting on the aux block is the supply line to the boom. I guess this means I have check valves built internally?

No holes, it's not a check valve, it's some sort of plug. But even a plug, if it has seals, has a purpose. I can't tell in the pic what the seals look like, they're kinda covered with oil. I'd go ahead and put a new o-rings on both of these plugs, you may be able to re-use the back up rings. You woldn't happen to have a parts book illustration that shows an exploded view of the valve sections would ya?

 

[bremery]

No luck on a diagram for this plug. It was tough to tell the condition of the rings, but they were not torn or nicked.

Are there any other places the checks could be other than in the block? If not, I guess its time to take the hoses off and pull the control block out. The checks must be pretty small because the aux block is not that wide.

 

[willie59]

No luck on a diagram for this plug. It was tough to tell the condition of the rings, but they were not torn or nicked.

Are there any other places the checks could be other than in the block? If not, I guess its time to take the hoses off and pull the control block out. The checks must be pretty small because the aux block is not that wide.

Bummer! :Banghead
They don't necessarily have to be torn, age and heat causes o-rings to get hard and square, they no longer have the roundness and pliability to make a good seal and oil can leak by them. This usually makes a hissing sound, but it also usually causes failure of the o-ring. It's worth a shot to put new o-rings on it just to give it a try.

Could they be somewhere else? Possible. It's just the schematic shows them located in the aux section. They could be inside the valve section body, but even then there would have to be a plug to access them. Cound even be underneath in the bottom of the valve section, I haven't seen that too many times though.

 

[bremery]

I will try replacing the o-rings. I bet there metric. It will take a few days to get them, unless my local hydraulic shop has something that will work. Some Buna-N / Nitrile 90 durometer rings will do the job.

If this was a circuit for a dual acting cylinder, like the boom swing, there would be a port relief valve instead. Maybe these rings keep the flow from getting to the discharge port, and if the rings are shot the oil passes by them creating a hiss.

This usually makes a hissing sound, but it also usually causes failure of the o-ring.

I do get a hiss / squeal sound when I try to move a function like the boom under normal power. Sounds like a good place to start.

Thanks.

 

[willie59]

Most cartridge o-rings are 70 duro, but 90 would work. The aux on this unit doesn't use port reliefs like other functions. If you look at the schematic, the aux uses the main reliefs. Your thinking what I was; these "plugs" are where port reliefs are normally located, and it's where the port reliefs are located on the other valve sections. Since it doesn't use port reliefs on the aux, they block the access to tank by installing the plugs instead of reliefs. And I would bet you can remove that plug on top of the valve section and connect your other aux line to it to have double acting, at least that's what the schematic is showing.