Single acting cylinder control on Kubota

[JimFeet]

I have a Kubota L3010 with a front loader attachment. I am adding a 3 pt cement mixer with a single acting cylinder for dumping. I'm trying to figure out what I need to operate the dump cylinder.

I assume a 3-way valve with 3 ports total (two pump ports, one for pressure and one for tank, plus one cylinder port) and open center would be required. Yes?

It seems to me the pump pressure line should go from the existing "hydraulic block type outlet" (as it's named in the Kubota operator manual) to the pressure port of the 3-way valve, then from the 3-way valve tank return port to the pressure side of the front loader control valve and finally back to the hydraulic block type outlet tank port. In essence the 3-way valve would be in series (as opposed to Tee'd in parallel) with the front loader remote hydraulic control valve.

With both control valves (3-way and front loader) centered, this would result in circulation from the pump through the 3-way valve, through the front loader remote control valve and back to the pump. You could activate either the front loader or the cement mixer but not both at the same time.

Does this sound correct?

 

[Gravdigr]

Sounds right to me. On my tractor when I added the new holland backhoe it ran off the tractor hydraulics rather than a pto pump like the old 'hoe. It basically got plumbed in series with the loader.

 

[Farmerford]

Jim:

If the mixer dump valve is in series and upstream of the loader valve (or any other valve) both its inlet and outlet ports will be under full pump pressure when the loader valve is activated against a heavy load. That pressure is almost certainly much higher than the outlet circuit of the mixer valve is designed to handle.

You need a mixer valve with power beyond (also known as high pressure carryover) to avoid high pressure on the outlet. In a PB valve, the pump connects to the inlet, the outlet connects to the tank (tee into the outlet line from the loader valve back to the "hydraulic block type outlet"), and the PB port connects to the loader valve to carry high pressure fluid to the FEL and (usually) beyond the FEL to the TPH.

 

[kennyd]

Welcome to TBN Jim

You can plumb a regular 4-way valve into your system so you could operate DA cylinders as well. The SA cylinder would just plug into one of the ports.

If you search here for "remote" you will find hundreds of posts about it.

But you need to determine first if your FEL valve has a powerbeyond connection on it...look at the valve and see how many hoses are connected to it. If the answer is 6, then you do NOT have it-but it still may be added. If it has 7 on it, then you are good to go. Check this and get back to us and we can talk you through it more.

It would also help to know what the GPM rating of the pump is so we can suggest a valve.

 

[zzvyb6]

I suggest that you reconsider a double acting cylinder. I have a 1/3 yard mixer and that stuff is heavy. Because of the mass of the slurry, you tend to pour too far, then need to control it by tipping it back. I use one of the loader circuits to get it done. I also need to keep the loader on with gravel in the bucket because the mixer + cement + water is really heavy.

 

[Fiero guy]

Your loader should already have BP port on it, and you will use the tractor's hyd pressure relief valve, just like you loader presently does. In other words--unless it's an aftermarket loader, your loader does not have it's own relief valve in the loader valve. If you chose not to use the PB option, The loader valve being open center, you should be able to come out of the "out" (return) port of your loader valve, go to your new auxillary open center valve, and let it's "out" port become return for both loader and mixer.
I'm not real familar with the 3030, so you might want to check with your local dealer to confirm this.
I 2nd the suggestion about using a double acting cylinder and valve, versus a single setup. A little more initial cost, but much more funtionality, and make sure you use a cylinder with a large enough diameter to handle the weight of the slurry in your mixer.
Don

 

[JimFeet]

Wow! Great responses. Thanks for all the helpful information and suggestions.

The mixer is rated for 5 cu ft which I believe translates to about a 750 lb load. I haven't calculated what that translates to for the dump cylnder - it should be considerably less since most of the weight is on the hitch arms.

The single acting cylinder that came with the mixer uses power to pull the mixer back (retract the cylinder), allowing gravity to perform the dump.

In the spring-centered position, the 3-position valve spool simply passes hydraulic fluid from the valve pump port directly out the valve's tank port. The valve cylinder port is blocked, effectively holding the cylinder in position.

My understanding is that when a 3-position spring-center valve is moved to the dump position, the 3-way valve spool moves to the 'X' position, allowing the cylinder to bleed back to tank as it extends. Pump flow should also bypass to tank in this position. In the retract position, the valve spool moves to the '||' position, allowing pressure to retract the cylinder.

I'll need to investigate the BP port option on my FEL valve. I haven't been able to find decent Kubota hydraulic schematics (or ANY for that matter) and my Kubota dealer is 100 miles away and apparently not particularly computer literate since they don't respond to my email inquiries.

Thanks again for the great advice. Keep it coming - I'm loving this site!

 

[JimFeet]

OK, I've decided to go with a 4-way, 3-position mixer dump control valve to give me future flexibility. However, for now at least, I'm sticking with the single acting dump cylinder - mostly because I've got one that came with the mixer - the one I have in hand is cheaper than anything I have to buy. With a 4-way valve installed I can always change my mind later.

AND, my FEL control valve DOES have a PB port that connects into a likewise labeled port on the tractor's hydraulic block type outlet.

So now my question is, how do I hook the mixer control valve into the PB port? Do I Tee into the connection at the hydraulic block to the mixer control pressure port, or do I run in series from the PB port to the mixer valve pressure port? And I guess the control valve tank port runs back to the tank port on the hydraulic block, right?

 

[kennyd]

So now my question is, how do I hook the mixer control valve into the PB port? Do I Tee into the connection at the hydraulic block to the mixer control pressure port, or do I run in series from the PB port to the mixer valve pressure port? And I guess the control valve tank port runs back to the tank port on the hydraulic block, right?

Good choice on the 4-way valve!

You will need to add the new valve in series on the PB line. You CANNOT Tee any high pressure lines, only low pressure return-to-tank lines can be Tee'd.

 

[dfkrug]

OK, I've decided to go with a 4-way, 3-position mixer dump control valve to give me future flexibility. However, for now at least, I'm sticking with the single acting dump cylinder - mostly because I've got one that came with the mixer - the one I have in hand is cheaper than anything I have to buy. With a 4-way valve installed I can always change my mind later.

Do a search on 3pt concrete mixers. I have posted many times on this
subject. I found the SA cyl works poorly, so I converted it to DA. If you
operate the SA cyl with a normal run-of-the-mill open center 4-way spool
valve, you can simply block the unused work port as KENNYD suggests. This
will cause the tractor's relief valve to operate briefly as the mixer uses
gravity to dump. This is OK for brief periods, and I did it that way initially.
A better setup is to connect the unused work port to a T connection on the
OUT port that returns oil to the tank. This allows the hyd pump a path to the
tank without going thru the RV.

There are, of course, spool valves designed to operate SA cyls. These are
harder to find than the afore-mentioned valve, and there is a good chance
you will go to DA.