HYDRAULIC - Yanmar Flow for Power Beyond, Power Steering and 3PT

[Jtullis13]

Scotty I'm glad you got your system fixed. It has been pretty cold here and I haven't attempted to redo my setup yet because of the cold weather. But this spring I may change it. As of now mine has been fine with no issues.

 

[Scotty Dive]

Jtullis - Did you make any modifications to yours?

 

[rScotty]

Initially Scotty and I were trying to find a solution for the slow loader response after adding PS to our tractors,...SNIP

That's always been a problem with the add-on power steering. You want the steering to always work, but to work without stealing every bit of flow from the rest of the systems. In a perfect world, the steering would always have exactly the same amount of flow so that the same steering effort would always give the same amount of wheel turn. A dedicated power steering pump like cars use is maybe the simplest way to do that.
Since tractors already have high pressure hydraulics, the way it is usually done in the tractor world is to feed all the hydraulic output into a part called an adjustable flow splitter - also called a "prioritized diverter valve". From there, one output is a priority leg for the power steering. Excess fluid goes to the loader and to the return circuit. Those valves are never perfect and tend to be RPM sensitive. PS priority is usually set so that steering priority gets full flow just above idle.

The fabulous YM336D used exactly that sort of valve for their power steering and loader combo. Theirs was a pretty sophisticated valve and made the steering almost completely insensitive to RPM.
rScotty

 

[California]

The Yanmar-brand power steering on my YM186D works down to low idle, but it drags down rpms when steering. Also because its gets priority for hydraulic volume, the rpm's need to be raised toward 1000 rpm for the loader or 3-point to come to life.

So slow maneuvering such as attaching an implement or getting forks under a pallet on rough ground, needs mentally balancing a lot of variables. Engine speed sufficient to steer and control loader height and tilt, slow enough ground speed to not arrive before the hydraulic systems have done their work. There doesn't seem to be a 'sweet spot' where all that works harmoniously.

For contrast the YM240's (no power steering) loader and 3-point responses are nearly the same down to low rpm so delicate operation is intuitive without thinking about it.

This US-designed add on steering simply isn't up to the quality of the rest of the tractor in terms of functioning as expected, in my opinion. Its supplier no longer exists so its unsupported. I've put off replacing its piston O-ring (the only oil leak on the tractor) because I don't want to risk damaging the aluminum body casting, I couldn't get it apart with the maximum force I felt was reasonable.

While this makes the tractor far better than no power steering, this power steering add-on is not as good as the rest of the tractor.

 

[rScotty]

The Yanmar-brand power steering on my YM186D works down to low idle, but it drags down rpms when steering. Also because its gets priority for hydraulic volume, the rpm's need to be raised toward 1000 rpm for the loader or 3-point to come to life.

So slow maneuvering such as attaching an implement or getting forks under a pallet on rough ground, needs mentally balancing a lot of variables. Engine speed sufficient to steer and control loader height and tilt, slow enough ground speed to not arrive before the hydraulic systems have done their work. There doesn't seem to be a 'sweet spot' where all that works harmoniously.

For contrast the YM240's (no power steering) loader and 3-point responses are nearly the same down to low rpm so delicate operation is intuitive without thinking about it.

This US-designed add on steering simply isn't up to the quality of the rest of the tractor in terms of functioning as expected, in my opinion. Its supplier no longer exists so its unsupported. I've put off replacing its piston O-ring (the only oil leak on the tractor) because I don't want to risk damaging the aluminum body casting, I couldn't get it apart with the maximum force I felt was reasonable.

While this makes the tractor far better than no power steering, this power steering add-on is not as good as the rest of the tractor.

Yes, I remember that power assist steering kit being an "iffy" proposition even back when it first came out. Forget who made it, but it wasn't Yanmar. It could be adapted to just about any small tractor. BTW, John Deere offered their version of exactly the same ps device when Yanmar began to make the JD compacts, but it worked better. I remember seeing it on their JD650, and thinking at the time that it looked like it would come very close to bolting up to a Yanmar.
Basically it's just a small hydraulic cylinder crudely coupled between the engine frame and the drag arm and otherwise hanging out there in the open along with its hoses and a two way force-sensing valve. If the early ones didn't leak right out of the box, most began to leak shortly thereafter. Endless hassle for the dealers, and the kit had a mind of it's own when it came to how much "help" it was going to provide for the steering effort. Still, it beats the heck out of no power steering. You're lucky to have one...

On most of the imported tractors we always felt that the manual steering gearbox was geared a bit too high - or the torque arm too short. Perhaps loaders weren't popular where the tractors were first developed.
Nice of Yanmar to put real power steering on the YM336/D. For some reason I thought the YM276 also had that power steering. Anyone know?
rScotty

 

[winston1]

I sure don't know for certain but I do have copies of both the repair manual and the parts manual for the 276 and no mention is made in either about power steering. I also have a Yanmar published parts and owner's manual for power steering on the 186 and 186D. I do think I have read of 276 owners having the assist.

 

[California]

... Still, it beats the heck out of no power steering.

Yes, I feel very fortunate to have found this one. Steering - especially when backing - can be palm of the hand on the center of the steering wheel and rotate my wrist. The tractor does the rest. It's lighter than automotive power steering.

And unlike the YM240, catching a wheel on something while backing can't rip the wheel out of my hand.

That kit was great in concept but then poorly designed. If there weren't a shoulder in the way of getting a wrench on the part that blocks access, it would be easy to get in and replace the little steering-piston O-ring, without taking off the hydraulics and taking the whole assembly off the tractor. The leak is real simple, there's a vent hole beyond that little piston (a small piston driven from the steering wheel, not the parallel, larger steering force piston) so the piston isn't bound up. As soon as the piston's o-ring wears and lets fluid past, steering moves the piston which squirts fluid out the vent hole. I put an inner tube 'diaper' on to divert the squirt down away from the sheet metal and some day if someone else posts how they repaired theirs, I'll tackle this one.

A note to anyone who attempts repairs without reading the manual: The manual says don't take apart the balancing valve that maintains equal pressure for left/right turns! I think its a part of the cover where the little piston comes through the cover. The balancing valve requires calibration on factory equipment - which no longer exists.

I have the manual if anyone wants a copy to repair theirs. Thanks Winston for sending a copy of the critical pages, and I have the paper manual that I found on Ebay.

 

[CalG]

I read through this thread with interest in hydraulic systems and assisted steering options.

If I may make some "general comments", please don't consider them either critique, nor suggestion to change what works.

The first thing that caught my attention was the election to NOT return the valve to tank. If I have it correctly, Directional Control Valves can be configured with different seal arrangements that offer differing acceptable values for "case pressure". What works for some may NOT work for others. The fact that the "Power Beyond" function is being accomplished by what should be case drain or "return to tank" ports says a lot about that particular valve seal arrangement. I do not endorse the plumbing this way however. 50-100 psi maybe, but not 2000 psi plus as when using the 3 pt. But, I don't know how those particular DCVs are sealed. This is much like the difference between a two way hydraulic motor and a hydraulic pump. It's all in the seals.

The mention of the difficulty of finding the correct adjustment for the priority flow valve caught my attention as well. It may be because of the reduced differential in system pressures resulting from the high pressure return to tank, but it would seem to me that finer adjustment of the priority valve might be obtained by selecting a compensator spring of a softer spring rate. Springs can be pretty well compared by wire gauge, coil count coil diameter and overall length. A softer spring with sufficient preload could equal just about any setting of the heavier spring and also make screw type length adjustments less sensitive.

It's a pounds per inch relationship. It's possible to modify the original spring, NOT by cutting coils! That only increases spring rate. Reducing the spring wire diameter by grinding the Outer Diameter is a better option. Better would be to see what options might be purchased, then you can always go back to original.

Possibly, an entirely different priority valve might be advised. Of course, not knowing just what type of valve is part of the PS kit, it's hard to make suggestions. But a proportional pressure sensing circuit might allow a balance between steering assist and loader operation under all engine/pump speed and output conditions. It could be that the present valve is sized for much higher flow rates, and so is operating in the margins of it's design specification.

Always remember, pumps do NOT produce pressure, They produce flow. Pressure comes from resistance to flow.

 

[Jtullis13]

Thanks for your input CaIG. Gives us something to think about. And no Scotty I haven't made any changes. My plans was to try the set up that you have. It was super cold this last winter and I put it off and never got back to switching it. It's worked flawless for me. The only problem I have had on a few occasions is hydraulic pump cavitation. First thought it was my filter. So I drained and cleaned the screen, it was pretty dirty. Filled with new fluid and all was good but it has happened twice since then too. So could be something in my plumbing.

 

[Gary Blecke]

Let me apologize for this long thread but hope it will help many of us Yanmar owners out there who have or are planning on installing Power Beyond or Power Steering or a combination of both. However we are looking for feedback from any members who understand this stuff better than we do.

A little Background, I have an YM2020D with a V-Tek loader. My original loader valve did not have power beyond and the loader valve out port fed to the 3pt. This set up is very common on all of our loaders but there have been threads stating it is incorrect. My loader was responsive both upwards and downwards. Also, it raised with strength at low idle. 3 PT worked as it should. No issues at all.
Last fall, I installed the Hoye/Fredrick's Power steering kit and at the same time, I replaced my loader valve on my V-Tek loader. I installed a Brand Loader valve with power beyond and float.
Here is the diagram of how the hydraulics are hooked up with the new power steering and loader valve.



This was done according to the Hoye instructions except for the fact that instead of my loader out port going to 3pt (as it was originally) it now goes to the sump and the loader valve power beyond fed the 3pt. In the Hoye/Fredrick's Power Steering system is a FCR-51. The FCR is a Flow Control block allowing adjustment of flow to the power steering cylinder and the loader valve.
It is clear that since the Power steering is first in the flow that it takes priority and works well, however the adjustment in the FCR is very sensitive and you need to strike a balance between power steering and loader functionality. An adjustment a little one way or the other stops one of the systems from working correctly. I adjusted the FCR to a point where the power steering just barely works as it should. This setting is a 2.5 on a scale of 1-10. I believe this means, 25% of the flow goes to the PS and the 75% remaining goes to the Loader Valve in this set up. For example, adjusting the FCR to a setting of 3 and higher and you lose all loader functionality regardless of rpm and anything below 2.5 you lose all PS and the loader works at all rpms. At the 2.5 setting and at full rpm, I have both power steering and loader valve functionality. However, the loader response is slower and I lost all loader functionality at low idle where I had it before. I then upgraded to a 9cc pump (per the recommendation of Hoye) over the stock 7cc pump. With the new larger cc pump the loader hydraulics were quicker in response but still nonexistent at low idle. Another serious issue experienced was the loader dropped very quickly and violently when a heavy load was in the bucket. It makes finessing a load downward a delicate operation and risks damaging what is in or attached to the bucket and the platform you are dropping it onto. Before Power Steering and the new loader valve this was not an issue.
Now on to my partner in crime; Jtullis13, who has a Yanmar 2210D with a Koyker 120 loader and I have collaborated via PM and on the phone. This all started because he was installing the Hoye PS kit and I offered to lend my experience from installing the PS kit. Based on my shared experiences and what he experienced with his install, he began making a series of configuration changes to the hydraulic routing with varying results. After multiple changes, what he ended up doing is interesting and created a solution that is about 95% perfect. As he made port and flow adjustments certain results were experienced, like the 3pt not working when the loader was being used and the Power steering stopping when raising the boom arms and so on.
What he ended up with is this (his flow diagram is below). Instead of having the flow go to the FCR first per the Hoye Instruction, it flows to the loader Valve IN port. The loader valve power beyond AND the out port connect to a 1/2" Y valve (Purchased off EBay and rated for 10K psi) and the out port of the Y valve feeds the IN Port on the FCR. Let's discuss this logic here. We believe the flow to the loader valve (when the Joy Stick is in neutral (and not being use to tilt or raise/lower) flows through to the Power Beyond. When the Loader valve is being used the excess flow from the cylinders travels out the valve OUT port. By connecting these two independent streams they flow into one stream and provide fluid and pressure to the FCR at almost 100% flow. He set his FCR flow control valve at 7.5. The EX (Excess) port on the Flow Control valve returns to the Tank. The CF port feeds the IN port of the Power Steering. So 75% of flow goes to Power Steering and the 25% excess flow to the tank. Power Steering Out Port feeds the 3 PT. 3PT flows to the Tank.



Now, back to my YM2020D with Power beyond feeding the 3pt, we believe there is no back pressure (like there was when it flowed out through the Loader Valve OUT port to the 3PT) and is why I see the violent dropping of the loader when carry a heavy load. Jtullis13 also experienced this when using Power Beyond supplying the 3PT, but he has eliminated that because his system has some back pressure (we are guessing here) and therefore has much better loader control when lowering heavy loads.
Jtullis13's results are these: He has full use of the loader at all times and rpms. Lowering the boom or bucket with a load is controlled. Power steering works perfectly except he loses partial power steering when lifting the loader (makes sense to me because flow needed to fill cylinders) AND using power Steering. His 3 Pt works and has lifted upwards of 1000 lbs. with it. No whining at the pump. He plans on adding a gauge to his system which I am sure he will share his results if there is anything odd going on. I have one in my system and that's how I found out I was having spikes upwards of 5000 psi when the loader and 3pt were used at the same time. An adjustment of the 3pt fixed that.
So, Jtullis13's results are terrific and I am seriously considering making these changes but a bit hesitant because of my limited experience with hydraulics and not wanting to blow a pump out or worse. We both realize that not having Power Steering first in the hydraulic flow is a No No when it comes to cars, but we are not concerned about losing power steering in the case of a hydraulic power loss. At that moment we have more pressing issues to consider. Plus the steering will still work manually. The question is - is there something glaring that comes to mind that may cause issues with a set up like this?

I have just bought a 1500d and have installed a Hoye ps following your diagram (I hope). 3 pt won’t work if diverter is open any amount. only if closed. ps has stopped severe jolts and improved slightly the ease of steering at any setting of diverter. I can live w/this but should I be satisfied?