JD 855 Hydraulic Isolation - loader and deck

[layada]

I've owned a JD 855 for over a decade but have no manual for it. I bought it used with a JD 60" mid mounted mowing deck and 70a loader. I've just had reason to mount the loader but cannot figure out how to isolate the mower deck 'lower & raise' from the 'bucket tip' function - both run through the 4 way spool. I'd like to have both the mower and loader mounted but don't need to use them simultaneously. Looking to switch from one to the other by way of an isolation valve or similar. Is there a way to do it?

 

[Rara Avis]

The midmount mower deck lowering and raising is related to the 3pt hitch...NOT the 70a loader...at least the American version is...

And the midmount mower can be raised along with the 3pt hitch and then the mechanical crank between your feet can be turned to lock the mower deck in the up position while you continue to use the 3pt hitch

 

[joecdeere]

Deere did offer a hydraulic mid-ship lift kit to raise the deck without the three point being involved, everyone I have seen you locked the deck up, undid the QC for the lift cylinder and hooked up the bucket curl, both were not connected at the same time

 

[layada]

On mine the deck is connected to the 4-way spool not the 3pt lift. It also came with a grass collector / high lift dump that sits on the 3-point and connects into the other two valves of the 4-way. Currently the collector is not mounted.

I raised the mid-deck all the the way then turned the crank to 'lock' it in the up position. That seems to make the bucket tip work ok on the 4-way spool - thanks. However I've just seen the above post and I did not disconnect any hydraulic couplings for the deck (don't even know where they are as the cylinder is obscured). Will it damage anything if I don't decouple the deck hydraulics?

PS there is a valve just to the upper left of the 3point - anyone know what that does before I fiddle with it and potentially break something.

 

[JLwoodworks]

Mine was operated with the 3pt lever. There was a mechanical linkage that went to the deck. An additional "rockshaft" cylinder could be added to separate the 3pt from the deck. I always wondered where that cylinder would get its control from. Perhaps that's what you have and you could disconnect it and reconnect the other link?

 

[TractorGuy]

PS there is a valve just to the upper left of the 3point - anyone know what that does before I fiddle with it and potentially break something.

Rockshaft stop valve. I think you can use it to lock the 3pt but not 100% on how it works. It's too late for me to drag out the operators manual to look it up. If the 3 pt works okay don't mess with it.

You need to get an operator manual and a service manual. I have both and a parts manual for mine. I found a PDF service manual online somewhere but don't remember where.

 

[Spanner]

I think the knob (#31A/B) controls the Rate of Drop of the Rockshaft and eventually stops it altogether. It works by screwing the rod in/out to force the stack of 7x ball-bearings (21) to transmit the force around the 90* bend and against the spring-loaded valve. 90* is more convenient than making a straight valve fit between the mudguard and the seat.

The 855's I've worked on have all had the Mid-mower lift ram controlled by the Draught Lever. With the Height-of-Cut wheel locking it up it's convenient to be able to still operate the 3PH and the FEL.

Operating the Mower lift off the double-acting spool isn't such a bad idea though. It's not often you're mowing and loading at the same time.