Power Beyond vs Series for loader valve?

[California]

I have a new loader control to install on my Yanmar YM240 (YM2000). The old control was in series ahead of the 3-point, as specified in the YM240 Owner's Manual.

This new Prince control says to plumb the 3-point (or any downstream application) from the Power Beyond port on the control, with the Tank (out) fitting on the control separately draining into the transmission sump. It also says maximum back pressure allowed at the control's Tank connection is limited to 500 psi. I have the plug available that would separate the Tank from PB outlets. (Tank then would flow only the fluid returned from the cylinders, not the full continual volume as it does now.)

Do I really need to run separate Tank and PB lines out of this control? Or would plumbing it in series like the old valve work ok? So far as I know there isn't a fitting on the transmission to serve as Tank In. And I really don't want to return it to the dipstick hole as I once saw.

Any advice?

 

[ghenges]

The only reason to plumb in the power beyond is if you need to use the three point hitch simultaneous with loader operation.

Most dealer installed loader valves are plumbed in series.
Remember though, a loader valve for a series installation must have its own relief valve.
And, the loader valve must be able to flow all the GPM's the pump is putting out.

I plumbed a 3 spool valve in series and have never experienced a need to use the three point hitch simultaneously with the valve ahead of it.
I am sure there are applications where simultaneous operation would be more convenient, but I can't think of one.

 

[California]

Ghenges thanks for the reply. Sounds like I don't have a problem here.

 

[Car Doc]

There are multiple mentions of this California here and there and between myself and Kenmac he has his with PB now and mine is still in the works. So I cant comment from personal experience on the PB setup but he can. Talk to one of the used tractor dealers and plumbed in series is the best thing since sliced bread (because its simple) but read between the lines and it maybe just smoke just saying.

Think of the pressure the loader valves are taking when operating the 3 point? Thats one way to look at it besides the fact using 2 controls at the same time may be few and far between. As far as a return to the sump....it could be anywhere may take some creativity is there enough room in the shifter housing or an ispection plate on top of the trany like ours has?

fwtw my loader doesn't work worth a crap right now very unsatisfied with it and I believe the PB will fix it.

 

[J_J]

All open center hyd valves are plumbed in series.

Prince developed and built the valve , and you would think they would know how it should be used.

There are people that still connect the valve wrong, hoping that nothing will happens, even though the manufacturer says not to exceed a back pressure of say 500 psi.

Well guess what, if the 3pt system can max out the relief at around 2500 psi, do you not think the pressure will backup through the hyd system and perhaps blows the seals or valve itself.

There will be people that will tell you they have been doing it that way all their life and no problems. Even if the valve failed, they would never acknowledge the facts that they did it wrong and just took a chance.

I would recommend to connect the valve correctly and find a way to route all the OUT/return ports to tank, and run the PB with PB sleeve to the next valve.

 

[California]

JJ you sound like my conscience - I know what you say is right. :thumbsup: But it would be so much simpler to just plumb it like the old one that lasted for decades. Well maybe decades - I've owned this 30 year old tractor for going on 10 years and the curl has always leaked down under load. Maybe back pressure is what did it in. Also this valve specifies 10 micron filtration while the Yanmar just has a fine wire screen, really Old School.

Ok, the real obstacle - Does anyone know if there is some place to plumb a line into the sump?

 

[California]

... return to the sump....it could be anywhere may take some creativity is there enough room in the shifter housing or an inspection plate on top of the trany like ours has?

No, no inspection plate, or extra space on the shifter. I think creating a return port would mean drilling the transmission casting. Doing that competently is beyond what I can do. I don't see an alternative to returning at the dipstick hole, and I have no idea how to provide a dipstick after that.

 

[ghenges]

Ghenges thanks for the reply. Sounds like I don't have a problem here.

The problem of seeking advice on these boards is that you'll receive so much information it tends to make your head explode.
If your Yanmar manual says to use a series connection, that should be confirmation that the series connection isn't the bugaboo some deem it to be.
Yes, there's a possibility of high back pressure if your three point hitch is carrying a relatively heavy load and you move the three point control while simultaneously moving a loader valve.
My sense is that you won't be moving your three point control lever simultaneous with the loader levers.
Kazillions of FEL's have been plumbed in series by major dealerships like Messicks in PA; have there been valve failures from back pressure, yes, but I think you are intelligent enough to assess the risk and operate your machine accordingly.

What model Prince valve are you using? The LV series is a very popular valve.

 

[oldnslo]

Do you have a model or schematic for the prince valve?

Most directional valves will not allow or withstand pressure in the tank port. Yes they may for a period of time depending on construction. My Prince LVT has O-rings installed in grooves in the casting so they will withstand some pressure for awhile. Some models just have a bolt-on cover that seals the ends of the spool. These will not take very much pressure before leaking or breaking.

Major concern would be that back pressuring the tank line will make the relief valve in your prince control valve inoperable. So if you do not have a relief before the Prince valve and the 3PH you could potentially build pressure until the weak link brakes. Could be the valve casting cracking, pump splitting, 3PH housing, etc..

 

[California]

The problem of seeking advice on these boards is... so much information it tends to make your head explode.
What model Prince valve are you using? The LV series is a very popular valve.

Do you have a model or schematic for the prince valve?

Most directional valves will not allow or withstand pressure in the tank port. Yes they may for a period of time depending on construction. My Prince LVT has O-rings installed in grooves in the casting so they will withstand some pressure for awhile. Some models just have a bolt-on cover that seals the ends of the spool. These will not take very much pressure before leaking or breaking.

Major concern would be that back pressuring the tank line will make the relief valve in your prince control valve inoperable. So if you do not have a relief before the Prince valve and the 3PH you could potentially build pressure until the weak link brakes. Could be the valve casting cracking, pump splitting, 3PH housing, etc..

This new valve is a Prince valve with Float (LVT1GB5AB1) replacing an AICO. The manual says 500 psi limit at the Tank port.

Photos below.

I added into another thread asking about general mounting before starting this PB inquiry, and first posted these photos there. I have worked out the mounting problems; I now plan to mount the new valve hoses-down. The handles will now be correct, and I bought the two In/Out -6 to -8 hose adapters for about $7 total instead of the $50 hose revisions I discussed there. (Plus using these adapters, I could re-install the old valve if my misuse destroys the new valve)

 

[Car Doc]

No, no inspection plate, or extra space on the shifter. I think creating a return port would mean drilling the transmission casting. Doing that competently is beyond what I can do. I don't see an alternative to returning at the dipstick hole, and I have no idea how to provide a dipstick after that.

If you decide to do it which may not be necessary if it worked before satisfactorily 10 years.

Nipple, a tee,plumbing in to the tee, a pipe plug on top of tee and that is what gets drilled and a dipstick added to that. The fluid level should be correct if its right before you do the new valve or compensate as necessary. Obviously the pipe plug would have to seal and a wrench used every time to check it not as handy as before but workable. my .002

 

[J_J]

Excerpt from Prince web site.


Q: I just put a Prince control valve on and it’s leaking out the back of the valve. What went wrong?

A: There is a very good chance that the outlet line (return to tank line) has been pressurized. Just one tank line spike, over 300 psi, can cause the valve to leak at either the handle or the spool end cap.

 

[California]

Wow. That would be my luck.

Is there another series of valve more tolerant of serial plumbing - as recommended in my Yanmar manual, and as used on my old valve?


In my research I found Chief valves on Baileynet.com that were only $148 for two-spool and $185 for 3-spool. (Both have float on first spool). I would have needed hose size adapters including two elbows, PSI reset down to 2,000, some kind of new mount to get the side inlet away from my throttle, and I couldn't find detailed specs (maybe cheap unsupported generic Chinese junk like HF???) so I moved up to this Prince LVT at $215 thinking it was the better buy. Now I wonder if those would work just as well. Has anyone used them?

 

[winston1]

I am certainly no hydraulic guru so please take my comments as trying to learn and not teach. California, am I correct in thinking your loader was dealer installed? I know for a fact many and probably most of the vn tractors with loaders are plumbed just like yours (through the loader valve and then the 3 point). My vn is plumbed that way and believe me it has been tested with a load on the 3 point. My joystick does not have a power beyond outlet. Said all that to ask the question: Are there any loader valves made to work like California's is currently plumbed?

 

[brain55]

Here is my practical experience. I started working at a Kubota dealer in the mid-eighties. At that time we were selling a lot of L345's and L355SS's with 1720 loaders with the loader valves plumbed in series. These were big Cross valves with significantly more flow capacity that those tractors put out. They were having a problem with leaking seals on the spools, the factory reps came and had us convert them all to power beyond. The problems went away and I never plumbed a tractor in series again. They explained the problem as pressure stacking not a back-pressure issue. So whatever line pressure there was to the 3-pt increased the relief valve pressure in the loader valve by that much. I can't swear to the physics behind that, but I can swear to the results we saw.

Brian

 

[California]

Winston I'm pretty sure this Great Bend (now Bushhog) loader was dealer installed when the tractor was new. I was told the tractor was bought for mucking out a riding stable daily. It has the optional heavier 'loader-ready' front axle.

I too am curious if there is a different brand of loader valve designed for series plumbing.

Brian the stacking, doubling, of pressure makes sense. But I think it also means that the doubling can be avoided by never having the 3-point under pressure in its Lift position while using the loader valve. (3 point Hold position puts no load on the pump). And it certainly makes sense for a quality dealer to adopt 'best practices', and avoid warranty returns caused by shortcut procedures. If I had an external Tank Return port on the transmission I would definitely convert to separate PB / Return plumbing from the output side of the valve, but I don't.

 

[ghenges]

Here is my practical experience. I started working at a Kubota dealer in the mid-eighties. At that time we were selling a lot of L345's and L355SS's with 1720 loaders with the loader valves plumbed in series. These were big Cross valves with significantly more flow capacity that those tractors put out. They were having a problem with leaking seals on the spools, the factory reps came and had us convert them all to power beyond. The problems went away and I never plumbed a tractor in series again. They explained the problem as pressure stacking not a back-pressure issue. So whatever line pressure there was to the 3-pt increased the relief valve pressure in the loader valve by that much. I can't swear to the physics behind that, but I can swear to the results we saw.
Brian

Thanks Brian

Now, that is a head exploding explanation that must be stored in the ole data bank.

 

[Neat 1500]

My return to tank is an extension piece that screws into the trans fill plug hole in which the cap then screws on top of the extension then it has a threaded hole for the hydraulic hose to go in. i have even drilled another hole in the side if it, tapped it and added a filter for a breather which has reduced my oil blow out around the gear shifter.

 

[Scotty Dive]

California - I wish I could help you out since you provide so much great info. The only thing I can add is that I was having problems with power on my V2 loader - plumbed in series. I put a gauge right at the loader to see what was going on. It was a 3000 psi gauge. My three point was not adjusted correctly and when I had it all the way up and while using the loader I was seeing pressure spikes that buried the gauge well over 3000psi. So far I did not break anything, but I want to share that the pressure spikes can be significant and I am thinking even on a properly adjusted 3 point, its possible to have a branch or something snag the adjusting lever and receive a pressure spike.

Also - Hoye includes a part number HA-39 in their power steering kit that allows you to easily dump into the oil dipstick hole - See the Power steering instructioions here: http://www.hoyetractor.com/techhelp/PS-KIT-INSTRUCTIONS.pdf

 

[Car Doc]

Good job Scotty nice find! :thumbsup: I wonder what the flow rating would be as far as dumping the loader thru it? If a large enough fitting would fit the adapter say a straight instead of a 90 (looks like a 90 in the pic) that would increase flow alone? Just thinking out loud for the next instance this comes up.