Load sensing OC steering

I was trying to find my way through the old topics, but could find only OC and CCLS discussion. What about OC system with LS Orbitrol, i.e. a priority valve hooked to the LS line from Orbitrol (Valta 8000/older T-series/etc.)? I was thinking of two options that could make things easier than the fluid-system.fr schematic presented in the other thread.

  1. Utilize a 6/2 valve to switch between Orbitrol and 5/3 propo valve for P/T lines with a shuttle valve for the LS line
  2. Just tee everything else (R/L/P/T) and have the shuttle on the LS line, as per this schematic from Raven autosteer install instructions raven_OCLS

Any thoughts?

PS. Stressed out as always with the first post, in case it’s something stupid or obvious;)

Is the shuttle valve electrically operated ?

Yes, excellent post…

Now I do not know orbitol on Valtra, but did similar setup on an older Fendt 714 from 2004, but before I mounted a 6/2 valve the steering wheel would stand and rotate and it was difficult to calibrate the agopen / control valve

You can check the diagram of the Dual steer and replace the second orbitrol with you prop. valve. Did-it on 8050 serie and Txx3 serie. It works! the dual pilot valve was 250 euro from original parts. not tested with AGopengps but similar stuff.

Thanks guys for the input! The shuttle valve in the Raven schema is just a mechanical one.

@kris I checked the workshop manual for 8000 series, and as far as I can understand, it’s exactly the same as the Raven retrofit from the functionality point of view, i.e.8000ser_twintrac

So everything else tee’d together except for the shuttle valve on the LS line (and separate tank returns). As I see it, this definitely works, as there’s always pressure in the P line so both systems are energized all the time. Whichever gives the first steering input, gets the priority valve open. The downside is that both systems are always hydraulically on, in the Valtra system they have in later models on-off Valves from the R/L lines from the twin trac wheel.

As for turning off, a pressure switch on the LS line from the Orbitrol should work. Or am I thinking correctly that the LS line will be de-pressurized on an OSPC LS type Orbitrol when ever the steering is not touched?

@pniels Might the Fendt have a reactive Orbitrol?

With Ls there may be another problem with pressure discharge on the Ls line when neither the orbitrol nor the solenoid valve is controlling. If you use alternative valves (probably schutle valve in the diagram above) you have to take this into account.The diagram above will not work on every tractor

Why a separate return to the tank ?

I don’t get the figure 8.

I lied in the foirt place, for my 8150 i did it with a simple no-return and flow control at the same time.

On the T163 with a shuttle valve. so i don’t have hand steerin if the prop valve is busy or i have give a good impulse on the steering to get priority.

I guess the separate tank connection is just one less hose to run under the cab.

@baraki in this case the LS line is only for prio valve, no LS hydraulics as such. The priority valve should always put pressure to the P line and rest goes to external hydraulics. With LS pump, I guess depressirizing LS line could be a problem?

I am planning mounting a Hydraforce SP10-57C valve on a Valtra 8050 Hitech 2002. It will be mount exactly like the shemas on your first post with a pressure switch at the same spot. I think it will work.
So far i read the pressure on the orbitrol LS port in the original config, when the steering is not moving the pressure drop quickly below 75 psi (5bar i think), when moving above 200 psi up to 1000 psi, limited to 1800 psi because there is a built in relief valve on the LS port in the orbitrol(or between the cylinder hoses?)
I will also put a relief valve on le LS port on the Hydraforce valve set (maybe) at 1200 psi to avoid to much pressure raise. I will have to wait the end of may to receive my valve and test.

Here from valtra shop manual

I have similar idea on the functionality based on the shop manual, thus far I can only provide moral support that it should work :smile:

The Hydraforce valve seems to be really short on supply, I was charting around for choices.

A similar cartridge valve could be Bosch-Rexroth OD53-10, schema differs slightly as regards the LS line, which as I understand is venting to tank with valve in neutral, otherwise similar, cf. scheme below:

Another idea was using a 4/3 way propo valve and a shuttle valve between the A/B pressure lines to feed the LS signal into the priority valve. Bit dirty, but could work?

My Hydraforce valve was delayed, form mid-april to end of may.
When I talked to my hydraulic guy, before I ordered the hydraforce, about my need of a 5/3 PWM valve with LS he coted this:

Bosch-Rexroth ED4-P1 (the component numbers are in blue)
bosch ED4-P1
I didn’t like the fact that A and B are always connected to LS. If there are externals forces on the axle the pressure will raise even in neutral? Maybe there are almost never hi pressures in the cylinder but I have never checked.

Thanks for the OD53-10, I think I would work, maybe with a check valve on 3? To reduce LS presure in neutral? there is always some pressures on T lines. I will check for the availability here.
I am in Quebec, Canada. The hydraforce was hard to find here, the ED4-P1 is one week delivery.

I’ll price the ED4-P valve as well, I also requested price for a similar setup with a Cetop 03 plate based system with a 4/3 propo and a shuttle valve. Essentially the same setup as the Rexroth diagram above.

I was also quoted 16 week delivery time here, don’t know if it’s a manufacturer problem.

As for safety, I was thinking of not putting a 6/2 valve anywhere, but rather put on-off valves on the R/L lines from the autosteer valve, solenoid for normal on/off and maybe mechanical stop for road use etc. Should prevent all unwanted autosteer action.

Yes putting on-off valves on R/L lines from autosteer valve is a great idea!
The ED4-P will then work perfectly I think, no back pressure when no autosteer and safety!
I think I will go this way for my first tractor, The hydrafore will be for the 2th

I have built mine using a Hydraforce valve, and then just used a 6/2 valve with 2 bungs inline between steering T’s and hydraforce valve as a “saftey” valve, with lockout switch in cab. I also have two mechanical lever valves on these lines as a second saftey.

Im yet to actually get my system up and running, but my setup is sort of similer, as its a deere (30 series standard), with the gear pump, so not a true LS system, but with a priority valve / standby pressure.

I am hoping it will function just the same using the LS port, but until I get it hooked up I wont know, but as far as I can see, it just demands pressure by applying pressure to LS line, which pushes the valve to make more system pressure, rather than stroking the pump to do the same thing…

Should know next week!

As for sourcing the hydraforce valve, I also had a long wait from mine, got it in the end though…Seem very hard to get hold of here in the UK thats for sure so alternatives would be a great thing…

@darrenjlobb I guess the system is pretty much identical to the Valtra setup. The other machine I have is a T4 series with loadsensing, something similar should work. Maybe needs bit more care in not messing up the pump control with something funny happening in the LS line.

If going Rexroth all the way, the shut-off valves could be implemented with a EDM-VEI block flanged directly into the ED4 valve body so should be pretty compact setup. Let’s see tomorrow what the quote is on that system.

Last option was Cetop 03 setup with the 4/3 way + shuttle, but the price gets out of hand. The Rexroth valve was the only one I could find with LS functionality built in and it’s in the Rexroth “readily available at stock” GoTo focused delivery program.

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For Valtras Mega/Hitech tractor (and others with gear pump):

Depressurized trough the orbitrol
I just checked again all the schemas in the shop manual and it seem that when the orbirol is in neutral the LS port is connected to T in the orbitrol.
So the hydraforce sp10-57c is probably not the best valve, the best will be the SP10-58C.
the Bosch-rexroth OD53-10 will also work.
The Bosch-rexroth ED4-P will maybe not.
The pressure will maybe not fall as fast as it should once the steering is still.

I didn’t like the fact that A and B are always connected to LS. If there are externals forces on the axle the pressure will raise even in neutral? Maybe there are almost never hi pressures in the cylinder but I have never checked.

If you are worried about this, use an additional controlled check valve (lock) between the Ls check valve entries and the piston. However, instead of 2 check valves, I recommend one alternative valve.

You are correct, there will be residual pressure in the LS line for the ED4-style valve.

When the steering is not used, I think there is 7 bar pressure in the CF and LS lines according to the description and diagrams, so as I understand the LS flows then towards the Orbitrol and is bled to the tank, hence the 7 bar pressure drop into the EF line.

After operating the autosteer with -57C/ED4 type valve, there is residual pressure in the LS line that has nowhere to escape as there’s no vent to tank from the autosteer valve. Hence, the shuttle valve in the LS line only operates after the LS pressure from Orbitrol has risen above this residual pressure after operating the steering wheel.

So as I see it, autosteer would work, but there could be significant delay in getting steering input from the Orbitrol unless the LS line is vented to tank.

Looks like I may run into this problem on my deere vane pump / pressure compensated LS system also as I have a 57C valve…yet to actually try it…

From what I can see, once the valve has stopped operating, the pressure on the LS port for the 57C has no where to go? so will remain high? Could we add a tin controlled leak to this line possibly?

What im not sure about though, I am connected to the tractor via the deere “power beyond slice” which is essentially just an extra block on the back of the tractor that give you P / T / LS ports, used for front loader installations, and implements that need power beyond behind the tractor as im sure you know!

How do these devices work, or are we saying most loader spools, and / or power beyond implements have a bleed to T on the LS lines when valve is in neutral?

Unless the deere system / power beyond slice has something built into it for this purpose?

The tractor I am fitting it to, has said power beyond slice, which is currently connected to front loader valve block, so I am just T’ing the P and T lines, and then T’ing the LS line, with a shuttle valve to direct LS feed from either loader spool, or autosteer 57C…was hoping this setup would work, but now concerned it may never unload / be slow to unload the LS line and cause constant pumping / high system pressure?

Any thoughts?

Doing a bit of reading, seems there is normally a small orifice / “bleed down” on the load sense system somewhere on alot of systems, often adjustable… Assuming the deere has this, it should work right?

And if it doesn’t, would imagine by T’ing in a super small leak valve / orifice on the LS line, to tank, it should accomplish the same thing? Just need a way of allowing LS line to drop in pressure once spool returns to neutral, assuming the tractor dosnt already have this in its hydraulic system either in the power beyond slice, or further / deeper in the valve block for the tractors hydro system?