3pt hitch Hydraulic top link and control

[joea99]

Did do another posting on this over in the Kubota forum. But my follow on questions are more hydraulic oriented.

I did pick up a Kubota B8032 Top and Tilt kit that came with the two cylinders, threaded fittings, 4 hoses and the male quick connects and dust covers. The other kits are not to be had.

The kit has instructions, which lead me to believe this was intended to plug into the BH quick connects when it was removed. Left me less than excited as the third (aux) spool valve is useless for non 3pt implements.

The simplest would be to do it their way but only use a two spool as I cannot envision any use for a third, for anything I expect to do. It would be nice to be able to angle a york rake or back blade, but, that would be a lot of fab work. Maybe two spools sane way to do it. After all, I gotta uncouple hoses anyway and plug em in somewhere.

But, being they procrastinator I am, I'd rather delay the actual purchasing and knuckle busting, so here's a thought to plumb for "always on". That way I could use the third spool (assuming I go for a three spool) for a hydraulic thumb. Someday I may convert the manual thumb.

I'll try to attach some rooster scratch drawings that might help explain. I have two questions with the "hard wired" scheme. The tank/return line would T into the tank return of the FEL at the FEL, which requires it to "pump uphill" but hits the T below the height of the 3 spool valve exit (I think, based on where I expect to mount it). Other question is because I don't have a lot of spool valve knowledge, Just enough to be dangerous as they say. Most of them have a Tank and a PB port. Some seem to combine them and somehow function properly. So what I wonder about is, how much flow is there through the Tank port when spools are centered? How much through the PB port when centered? I'd expect "full flow" (valve rating) in last case and much less in the first, but, I think that could be wrong.

The first shows the simple plug in (forgot to name the new local built hose from valve to QC), the second how I propose to T into two existing fittings. Open to helpful comments
Even the other kind if the have some redeeming value . . .

 

[K5lwq]

Did do another posting on this over in the Kubota forum. But my follow on questions are more hydraulic oriented.

I did pick up a Kubota B8032 Top and Tilt kit that came with the two cylinders, threaded fittings, 4 hoses and the male quick connects and dust covers. The other kits are not to be had.

The kit has instructions, which lead me to believe this was intended to plug into the BH quick connects when it was removed. Left me less than excited as the third (aux) spool valve is useless for non 3pt implements.

The simplest would be to do it their way but only use a two spool as I cannot envision any use for a third, for anything I expect to do. It would be nice to be able to angle a york rake or back blade, but, that would be a lot of fab work. Maybe two spools sane way to do it. After all, I gotta uncouple hoses anyway and plug em in somewhere.

But, being they procrastinator I am, I'd rather delay the actual purchasing and knuckle busting, so here's a thought to plumb for "always on". That way I could use the third spool (assuming I go for a three spool) for a hydraulic thumb. Someday I may convert the manual thumb.

I'll try to attach some rooster scratch drawings that might help explain. I have two questions with the "hard wired" scheme. The tank/return line would T into the tank return of the FEL at the FEL, which requires it to "pump uphill" but hits the T below the height of the 3 spool valve exit (I think, based on where I expect to mount it). Other question is because I don't have a lot of spool valve knowledge, Just enough to be dangerous as they say. Most of them have a Tank and a PB port. Some seem to combine them and somehow function properly. So what I wonder about is, how much flow is there through the Tank port when spools are centered? How much through the PB port when centered? I'd expect "full flow" (valve rating) in last case and much less in the first, but, I think that could be wrong.

The first shows the simple plug in (forgot to name the new local built hose from valve to QC), the second how I propose to T into two existing fittings. Open to helpful comments
Even the other kind if the have some redeeming value . . .
View attachment 716332View attachment 716333

The flow is the same on the tank side when PB is pugged. The problem is the tank port can not handle the back pressure when a valve down stream is used. The correct way is get a valve that has PB and use tank port tied in with tank line from the loader and PB to feed next valve down stream. This is the only way to do it properly.

 

[joea99]

The flow is the same on the tank side when PB is pugged. The problem is the tank port can not handle the back pressure when a valve down stream is used. The correct way is get a valve that has PB and use tank port tied in with tank line from the loader and PB to feed next valve down stream. This is the only way to do it properly.

Don't get it. The Tank port flow is full flow when PB is plugged? So in this scheme the BH or 3pt would be starved of oil? That was one of my concerns being relatively new at this stuff.

That would seem to leave me with doing it the Kubota way, or, plumbing so the BH / 3pt are supplied by the PB of the new spool valve. In that case would I still need a tank connection on the new spool? Some vendors seem to want Tank connected to tank no matter what, while some do not.

I reposted one picture. to show a new hose for what that's worth.

 

[K5lwq]

Don't get it. The Tank port flow is full flow when PB is plugged? So in this scheme the BH or 3pt would be starved of oil? That was one of my concerns being relatively new at this stuff.

That would seem to leave me with doing it the Kubota way, or, plumbing so the BH / 3pt are supplied by the PB of the new spool valve. In that case would I still need a tank connection on the new spool? Some vendors seem to want Tank connected to tank no matter what, while some do not.

I reposted one picture. to show a new hose for what that's worth.

Some people have tried to power another valve downstream with the tank port. This will result in a failure. The only exception is a electric over hydraulic valve like a third function valve. There tank port is rated for higher pressures.

Yes, you should feed the BH/3PT from the PB port of the new valve. Yes you still need the tank line on the new valve to be plumbed back to tank. This allows return to tank when you are using the spool valve. Hope that helps.

 

[joea99]

Some people have tried to power another valve downstream with the tank port. This will result in a failure. The only exception is a electric over hydraulic valve like a third function valve. There tank port is rated for higher pressures.

Yes, you should feed the BH/3PT from the PB port of the new valve. Yes you still need the tank line on the new valve to be plumbed back to tank. This allows return to tank when you are using the spool valve. Hope that helps.

I don't think the Kubota setup has a return to tank, as there is a tank return at the "hydraulic block" for the 3pt. That is also used by the BH when it is plugged in.

At this point, it may be best for me to doing the K way and scrounge up the fittings I need, get the hoses fabricated and make the mounting plates. Oh, and buy a valve. Probably decide on the valve first would be a good idea.

The kit supplied male quick disconnects that appear to be ISO ag style with lots of compatibles, but, from what I'm seeing getting known mated pairs is not much more than just the female alone. So that seems the way to go and just toss or shelf the provided ones. I can get the females from Kubota but at $45 bucks each, that would be foolish. As would getting their valve at over $1500. I see some that could work on Ebray and AmazinCon for $50-100. Even name brands are under $500.

 

[K5lwq]

I don't think the Kubota setup has a return to tank, as there is a tank return at the "hydraulic block" for the 3pt. That is also used by the BH when it is plugged in.

At this point, it may be best for me to doing the K way and scrounge up the fittings I need, get the hoses fabricated and make the mounting plates. Oh, and buy a valve. Probably decide on the valve first would be a good idea.

The kit supplied male quick disconnects that appear to be ISO ag style with lots of compatibles, but, from what I'm seeing getting known mated pairs is not much more than just the female alone. So that seems the way to go and just toss or shelf the provided ones. I can get the females from Kubota but at $45 bucks each, that would be foolish. As would getting their valve at over $1500. I see some that could work on Ebray and AmazinCon for $50-100. Even name brands are under $500.

You T into the tank line from the loader like you described in your first post. It is not gravity feed so going uphill does not matter.

 

[joea99]

Searching for a valve I can use to substitute for the one Kubota would have supplied.

Apparently, in the original kit, there was not separate tank port and the PB (outlet) relied on the tank port in the 3pt circuit, as the BH would as well.

Problem is, all the spool valves I can find seem to state they require the tank port hooked up even with PB plug installed and a tank connection provided down stream. Even one of the vendors I contacted says that.

So, are they correct? Are there valves that function as I surmised? Am I missing something?

Since the kit instructions provided, intended for dealer I guess, are for all the kits, brackets, valve and hoses, cylinders and fittings, I think I would have noticed a specific tank connection if it was needed.

I mean, I could T into a return if needed, but then I might as well consider hard fittings for supply and PB. I guess an 11GPM valve would not hinder the BH when it is connected. Or, would it?

I love it when I'm in over my head and need to learn a new swimming stroke . . .

 

[K5lwq]

Yes they are correct. Without the tank port there would not be a path for oil to return to tank from the cylinders. The back hoe will only have the flow of the overall tractor flow rate. Just match the valve to that and you will be fine.

 

[joea99]

Yes they are correct. Without the tank port there would not be a path for oil to return to tank from the cylinders. The back hoe will only have the flow of the overall tractor flow rate. Just match the valve to that and you will be fine.

Thanks for the reply. But I am still missing something, or not explaining well. Since you guys are a lot more savvy about this stuff that I am, the problem must be on my end.

There is an existing WR Long "3rd function valve" in the circuit from the FEL PB port to the BH supply. There is no return to tank on the WR Long. There is a T port, but it goes directly to the quick connect for the BH/3pt. The only other ports on WR Long are P (pressure) A and B (4 in 1 bucket).

The BH, also does not have a specific T connection, there are only the 2 lines with quick connect to supply and return (to 3pt). The 3pt "control block" (my term) does have a (return to) tank that appears to serve both the 3pt and BH as selected.

.

 

[K5lwq]

I think the 3rd function is confusing you. That type of valve is designed to handle the system pressure on the tank port. Because of that it does not need power beyond to feed the next valve.

Normal spool valves like remote valves need to have power beyond to feed the next valve and a tank port for return flow. The tank port can T into any tank line except the 3rd function valve. So the set up would be like this.

Tank line from 3rd function to Power in on new valve. Power Beyond from new valve to power in on back hoe. Tank from new valve connected with a T to the tank line from your loader.