N5-series Valtra PTO external emergency switch

[Northern farmer]

We got a new N5-series Valtra and figured out it does not have the emergency switch off plug that Valtras have had for fifty years. On older Valtras the PTO spool valve drive current flows through the plug at the rear of the tractor. I guess this feature has been discontinued because of CAN bus controlled spool valves.

The tractor powers a portable circular saw mill and the operator (and people working close to the saw mill) must be able to shut down the PTO drive in an emergency. On older Valtras the external PTO emergency plug can be directly swapped with the plug from the saw mill. Any emergency switch at the saw mill opens the PTO drive and shuts down PTO.

CAN gurus at the forum would build an interface that commands PTO off if any of the emergency switches is operated. I would insist on a more simple and fool proof approach. Would anyone know if it would be safe to switch power off from a CAN controlled spool valve to switch PTO off, pretty much like the emergency control works on older tractors that have a simple on/off electric spool valve? I mean safe in the sense that none of the other devices connected to the CAN bus in question would start misbehaving? I'm not concerned about odd fault codes. The emergency switch is needed a few times per season, quite acceptable if e.g. the tractor needs to be turned off and on to recover normal operation.

Any other possibility for a simple PTO emergency switch? I don't know how the existing PTO spool valve is plumbed but I assume it is not possible to add another on/off electric spool valve in series with the existing valve.

 

[KB6930]

Can you not just extend the fender button wires to your sawmill off switch?

 

[Northern farmer]

Can you not just extend the fender button wires to your sawmill off switch?

I actually didn't look at the fender buttons wiring. Aren't the buttons working like "push to turn on" and "push to turn off"? I assume it is NO switch and the switch connecting momentarily will either switch PTO on or off. It is a signal switch, not a switch in series with the PTO solenoid.

I did have a look at the PTO switch at the armrest. It has 6 wires and the wiring diagram does not show how they are wired (considered part of the arm rest circuit board even if the switch is external to the board). In any case, this fender switch is something I should look at. Need to detach the switch and measure how it works.

 

[KB6930]

Not got any experience of valtra but all others are one push is off .

To turn on you either have to enable it from the cab and /or press and hold .

I'd definitely be looking at the fender buttons first

 

[zero]

Is there anything listed on the Valtra options list? I know it would be off the scale price wise but it might give an idea for a farmer fix solution.

 

[Mouser]

Some fender switches are more complicated than just on/off. I know our Massey had a fault in fender switch and pto wouldn't work at all no matter how wires were connected.

 

[Blue.]

I doubt it’s because of can bus spools,more just cost cutting.

Ideally your going to need to check the fender switch to see if it breaks the current when pressed,if it does you could simply wire in an emergency stop button.

 

[deleted user 837354]

Something this safety critical I think should probably involve a discussion with a dealer on how to best do it.

 

[Northern farmer]

Something this safety critical I think should probably involve a discussion with a dealer on how to best do it.

Agreed, started that discussion already but in most cases thefarmingforum gives an equal or better solution and way faster.

 

[Northern farmer]

Is there anything listed on the Valtra options list? I know it would be off the scale price wise but it might give an idea for a farmer fix solution.

Nothing on the options list that looks relevant.

 

[Northern farmer]

I doubt it’s because of can bus spools,more just cost cutting.

Ideally your going to need to check the fender switch to see if it breaks the current when pressed,if it does you could simply wire in an emergency stop button.

The sawmill has several of these (series wired) and simply plugged to the socket at the rear of older Valtras. On older tractors these safety switches cut the PTO spool valve power, very simple circuit and safe.

I did not find the N/T5 series wiring but it probably is the same as on a T4 (excluding the external emergency socket). Actually quite confusing diagram compared to anything I've seen for Valtra or other AGCO tractors. Seems like a single pole double throw switch that would need a simple relay wiring for parallel operation.

Accessing the switch seems complicated, cannot access from the fender top side like on Fendts.

 

[Northern farmer]

Just an update on the topic. The fender switch can be used but is not ideal as it is "push to stop" and "push to start". It would be possible to stop and start the PTO again from the emergency switch without any need to reactivate the PTO from the tractor.

I found the PTO spool valve, it is a voltage controlled proportional valve for soft start control but old style two wire valve control anyway. The spool valve has an AMP junior power timer socket, I just built an "extension cable" to wire the sawmill emergency switch group in series with the PTO spool valve feed.

The tractor still has the same operating logic as the older Valtras: if the external emergency wire loop is disconnected, the PTO obviously stops but it also remains off even if the sawmill emergency switch is reactivated. The PTO needs to be switched off from the tractor first before it can be turned on again. Makes it quite safe.

Difficult to see why the feature had been discontinued. I first thought maybe because they have added the same style socket for external power feed. Someone might get confused which is which but then I noticed the older T4 series tractor has them both. 1 Euro socket part and a bit of wiring.