Hydraulic control on the Fendt 716

It is very easy to install the valves that I use in this tractor. They work great. There is a nice place for them behind the main hydraulic block. easy to connect to the system, as you have ready hoses installation takes about 1 hour.


Hi @baraki,
could you please write something more about whole project? Maybe some scheme, costs, how to connect all this together? I also have F716 and I’m very interested in this kind of modification. Thanks in advance

Autoster based on official PCBV2, CFD1 tablet, RTY Honney turn sensor.
The cost of plumbing with hoses is around 500E.

You will also need an electric motor and its gears, or an electro-hydraulic valve to control the direction, i think all you need is around 1000E-1200E

with hydraulic valves you will have problems if there is some accident in the road.

This setup is not approved for road.

I’m thinking of electo-hydraulic control as it doesn’t take any space in cabin and has no sprockets (kind a dangerous without cover). My tractor is often driving on public roads with full speed, @Stabilo why it’s not approved for road? Is there some unacceptable delay or what? I’m not planning to use AgOpenGPS for driving on public roads, it’s rather task for software like comma.ai OpenPilot or similar.

I am a little annoyed to always lisen this same refrain on hydraulic valves why a self-built system with plastic pinion made yourself in 3 D printing attached to the steering wheel would it more comply with the road regulations.
if you want a “homologate” system pay you a full option tractor


Can you share more info on the steering angle sensor? I’m looking at putting a system on a Fendt 926 and this looks like a nice clean install.

I use for 926 RTY120LVEAX

Sadly because the motor can just be flipped out the way, and no longer has any potential to control the tractor, its also way to weak to overcome the operator even if it was accidentally engaged…

Once you have modified the hydraulic system, in there eyes anything could happen…I use hydro myself, and have 3 safety systems (6/2 valve, total Cytron power isolation, and manual isolation valves on L/R lines) but im sure it would still pose a major issue in the event of a road accident… Most likely resulting in no insurance…

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The 6/2 valve protects 100%. It is enough to ensure that it does not accidentally get power. Probably the higher the probability that something will suddenly fall between the gears on the steering wheel, e.g. some piece of clothing, you can imagine many unfortunate situations that something will block the steering wheel. Automatic actuation of the 6/2 valve is practically impossible! The spring holds the slider in the open position and there is no way for anything to move it other than 12v on the coil.

but you have modified a vehicle safety system, in a way not approved by the manufacturer, without any declaration of work performed following the rule of the art, and above all, without any testing by the bodies predisposed to the approvals

you do the exact same thing by modifying the steering wheel

The Danfoss integrated steering systems used by the OEMs are rated to ISO 13849 Performance Level d. Without doing a risk assessment, it is reasonable to assume that PLd is the minimum requirement for the functional safety of steering system of a tractor that travels on the road. This requires a Category 2 or higher architecture for the safety related parts of the control system (i.e redundancy and various levels of reliability and diagnostics depending upon the selected architecture).

Whilst this could be claimed with the use of the 6/2 valve as one channel, and the proportional valve as the other channel (dependant on the valve architecture - some proportional valves do not have strong enough return springs to be used as safety components), there would be many pre-requisites. For example; Has the return spring inside the valve been designed so that in the event of a breakage the coils cannot interleave, is the return force of the spring sized so that a pressure spike cannot cause the valve to open, is the leakage rate of the valve low enough that the steering is basically unaffected, is the hydraulic filtration adequate to protect the valve from debris that may cause it to stick (alternatively do you have a method of detecting if one of the valves has stuck? pressure sensor or valve with limit switch etc.).

It is an interesting situation, as I wonder if the companies that retrofit steering systems are performing the modifications to a performance level and documenting each vehicular modification with risk assessment etc? I would have thought they should be.

In my opinion the difference between the valve and the steering motor is that with the valve a failure of the control system could remove the operators ability to control the vehicle, whereas the motor should be disengaged for road transport (i.e. leaving it engaged is the fault of the operator - not the installer). The line becomes blured with motors that use gears that are always engaged but a relay is used to disconnect power or similar - now your motor power control needs to have a performance level…

but I take off the motor on the road

non vous le déconnecter et ne démonter pas la couronne vous avez don MOFIFIER un system de direction

in some countries even the knob on the steering wheel is illegal :wink:

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I think, there must be a different way possible, see manufactures like trimble, they don’t have a redudant valve block, I haven’t seen any SIL/PL mark. But in fact it is CE signed.

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The redundancy doesnt have to be achieved through a second valve, it could also be via removing power (e.g. valve failure detected → de-swash hydraulic pump) or some other means, as long as it fits the chosen safety arcitecture. They may also have done a risk assessment that comes out at a lower PL/SIL than the Danfoss system (e.g. PLc would be achievable with Category 1 - e.g. a single valve) - it is up to the system integrator (i.e. Trimble etc.) to decide and document this (and for the notified body to agree with the assessment and provide a CE mark for the system).

Generally you won’t see a PL/SIL mark on individual components as the whole control system (the parts related to safety) achieves the PL/SIL, not individual parts. One of the Danfoss systems does have a PL as the steering computer, WAS, valve and valve controller are in one integrated system controlled by the tractors ECU.

It would not be impossible to develop a system with a performance level from standard parts, but the hassle and documentation that would need to go with it probably goes a bit beyond what most of us are trying to achieve!

If I get around to changing my tractor from a motor to a valve I would fit manual isolation valves like darrenjlobb as a means of justifyng some level of due dilligence in the event that something ever happened.