3-Point Hitch top link hydraulics

[jim442]

Will you need the loader when using the hyd 3pt cylinder? If not why not connect by quick coupler to the loader valve and use that to control the cylinder?

 

[CHDinCT]

For what it's worth, here's what the valve looks like after install. The existing hydraulic block is in the pic to the right. There is a pipe that wraps around the back of the HST that pipes into the block that get's removed and then fed into the new valve. The valve then pipes into the existing block in the same spot, so it would appear that you could put your valve in between these two points.

I believe the return to tank is fed into the HST where the bolt is just below the existing pipe that wraps around the hst connects to the hydraulic block. You can not see that in my pic as the bolt is removed and connected to the new valve and is behind the valve in the pic. You'll have to look at your tractor to see what I'm talking about. Follow the pipe that wraps around the back of the HST and connects to the side of the existing hydraulic block, then look down and a little to the back side to see the return to tank bolt that I'm speaking of.

I'm sure this is confusing, but the best I can explain from this one pic that I have and from looking at the Kubota directions.

 

[CHDinCT]

Here's another pic where I've crudely labeled the feed and return or PB lines. Again, from what I can tell from the install, the return to tank is behind the new valve and is accessed by removing a bolt in the side of the HST.

 

[teg]

I checked the manual and the ports that it shows are consumed by the FEL. Can I just "tee" those?

No and yes, the high pressure side has to be done in series... either before or after the FEL so it's one continuous flow. The low pressure return to the tank can "Tee" together. Tons of stuff to read... and re-read (for me) before I know what's going on (I think).

This wk/ed I'm hoping to add 3 spools (valves) to my tractor (1 for a grapple, 2 for TnT) So my plan (it's on a L2800) is to take the high pressure hose from the FEL controls, that goes back to the "block" and pipe that to the new valve... then the new valve's high pressure return line will return to where the FEL used to go. The low pressure line will Tee into the same low pressure FEL return line.

Sounds easy but there are a bunch of different type connections and tons of different types of spools depending on what you want to run off of them. Mine are "DA" Double Acting (I may have that term wrong) that's for push and pull hydraulic cylinders... Hope some of this is correct...

 

[terry2shot]

I'm going to basically do the same thing. I want to add a 3 spool stack valve config with power beyond and a relief. The valves will be closed centers. You are correct that that the high pressure has to be a series connection, my bad. You are also correct that the high pressure line for the fel should go to the rear valve stack then to the fel via the power beyond port in your rear stack. I do not know if the fel valve is power beyond (probably not) so this is the proper way to do this.

 

[CHDinCT]

terry2shot, you sound like you know what you're doing but I've never heard of putting closed center valves in an open center system, but, hey, I'm no expert.

Anyway, after re-reading my posts, I think I can sum it up much easier and that is, based on how the OEM Kubota valve is installed, you could remove the pipe that wraps around the back of the HST and connect your valve(s) in between the two end points for that pipe, then T or pipe the return to tank however you want. Hope any of this is helpful. Good luck.

 

[terry2shot]

Back ground -I design and manufacture auto transporters (the big ones). All a closed center valve vs an open center is when a closed center valve is in the neutral position the work ports are closed off, effectivly (but not safely) locking the cylinder in position, an open center is well..open. The work ports are not closed . I am not a hydraulic engineer (I'm a mechanical) but I've been doing this for thirty years. It seems to me we can accomplish our goals without spending $300 for $10.00 worth of fittings and $15.00 worth of hose and tubing.

 

[teg]

:thumbsup: I'm *trying* to learn... Don't know why this is so hard to sink in???


Now, that you mention it... the valve I bought says "Open Center Convertible to power beyond or closed center" (where is the icon of a guy hitting himself in the head with a mallet?? Insert it here )
Surplus Center - 3 SPOOL 8 GPM PRINCE MB31BBB5C1 DA VALVE

 

[Jay4200]

I'm going to basically do the same thing. I want to add a 3 spool stack valve config with power beyond and a relief. The valves will be closed centers. You are correct that that the high pressure has to be a series connection, my bad. You are also correct that the high pressure line for the fel should go to the rear valve stack then to the fel via the power beyond port in your rear stack. I do not know if the fel valve is power beyond (probably not) so this is the proper way to do this.

Assuming that your tractor is OC and plumbed like most, your FEL valve does have a PB port, and that is what is returning to the run the 3pt hitch. The 3pt is last in line - typically there is a hydraulic connector block with a bypass switch - the switch allows internal running of the 3pt in one position, and runs accessories in the other, where pressure runs out to the accessories, then back to run the 3pt. You will have to re-route the FEL PB line (currently running back to the 3pt block) and run it to your remotes, then run the PB line from your remotes back to the 3pt block. You will have to tee-connect the tank return line from your remotes with the FEL tank return line.

Hope that makes sense.

JayC

 

[Jay4200]

Back ground -I design and manufacture auto transporters (the big ones). All a closed center valve vs an open center is when a closed center valve is in the neutral position the work ports are closed off, effectivly (but not safely) locking the cylinder in position, an open center is well..open. The work ports are not closed . I am not a hydraulic engineer (I'm a mechanical) but I've been doing this for thirty years. It seems to me we can accomplish our goals without spending $300 for $10.00 worth of fittings and $15.00 worth of hose and tubing.

Work ports are typically still closed off in neutral in an OC valve, but the pressure line is open to the OUT/Tank (or PB) port. Valves are positioned in series, with work port returns to tank.

In a CC valve, the pressure port is closed when the spools are in neutral - CC valves are positioned in parallel between pressure and tank, so multiple valves can be used at once and at full pressure. In an open center system, if you run a valve wide open, the downstream valves lose pressure and don't work. I'm not totally on top of what you are referring to with your closed port description, but open vs. closed work ports are a spool option. If work ports were open during neutral position, they wouldn't hold their position. Work ports are held open during 'float' operation.

I just found this - fairly good description with pictures:

http://www.edgeroamer.com/sweethaven/mechanics/hydraulics01/default.asp?iNum=0201

JayC