major -
In the case of the Brand Hydraulics LV Series valves the "4th position" refers to a lever position beyond the 'normal' DA spool positions of
1. port "x" pressurized
2. neutral (center)
3. port "y" pressurized
In the case of the LV22RFSTKAB configuration specifically:
1. The stick can be pushed past a detent at the end of the "boom Lower" position to enable "Boom Float" (maximum forward/up on the stick).
2. The stick can be pushed past a detent at the end of the "bucket tip" position to effect a "Rapid-Tip" aka "Rapid Regin" as might be used to knock sticky clays out of the bucket (maximum to the right on the stick).
3. The stick 'springs to center' when released from any position
"Boom Lower" and "Bucket Tip" being positions associated with port>hose>cylinder assignments used in the normally intended FEL control application of the valve. For the Rear Aux application my thought is to assign ports 'normally' used for the Boom to the Top Link cylinder and ports 'normally' used for the Bucket to the side/Tilt Link cylinder.
Obviously, all this requires appropriate spool and valve-body machining to accomplish, it's all done within the valve body with nothing external to the valve, fluid is routed to the appropriate working port(s), PBY port or relief port 'automatically'. You can't just swap spools in the body willy-nilly and have everything continue to 'work right'; the same hold for the joystick mechanism - particular mounting plates are required to match-up with particular spool/body configurations and have the joystick operational orientation be correct per normal conventions (forward/up for boom lower, right for bucket tip, etc)
The basic "4th position" nomenclature seems to be fairly common / uniform among ag control valve manufacturers, I've seen it used in literature by several manufacturers in reference to the operational options for both monoblock valves and individual working-sections of stack-valves. But hey, I'm on the learning curve, too, things like float and rapid-regin weren't encountered in my process-plant engineering past-life!
I'm pleased with the Brand LV valve so far. Available 'on paper' with many different control configurations I found that in actuality only the one configuration I got is widely available as an in-stock item. I'd have preferred a different configuration which would have allowed me to install it on my OEM valve mounting plate and have everything be properly oriented in terms of ports and lever-action but that would have required a special order at substantial extra cost with a very long estimated/no guarantees lead time. I suppose just a reflection of their factory batch-processing system for the many products they offer. In any case, with a bit of re-fabrication of my mounting plate this valve is working fine and may in fact be a bit better than OEM in terms of the final ergonomics (a bit less 'reach' to the lever).
I certainly like the 4th position functions that my OEM valve did not have (boom float is a new joy for me!). It's taken a bit of practice to learn exactly when to push to the 'boom float' position to avoid a sudden 'boom drop of a few inches' or 'lift-and-drop of the front of the tractor' but 'the touch' is quickly acquired. All is good, I'm finding the boom float is very nice for lots of situations both forward and back-dragging.
The Yanmar 336D, a now ~40 year-old design, offered none of the very nicely integrated implement control valves and lever-panels I see on most modern tractors of similar size. I suppose that cuts two ways .... while not as nicely integrated it does allow lots of flexibility in fabricating DIY solutions. At least Yanmar did a fine job anticipating external valves/hydraulic implements with the built-in divider block arrangement and the 3PH draft control is just superb for lots of dirt work (automatically adjusting 3PH implement depth to keep constant load on the tractor when draft control is engaged, a feature I think maybe still not too common on similar-size tractors though seen a lot on larger units).
I still enjoy doing a fair amount of dirt work both on my own property and helping neighbors. I'm in a neighborhood of relatively small parcel owner-occupants (10 - 100 acres) and many don't have anything larger than a garden tractor so aren't well-equipped for things like road or pond maintenance which I enjoy helping with. Even those with bigger tractors are mainly oriented toward hay-field and horse/cattle pasture management more than dirt work. I've had it for ~30 years and the 336D has been a bullet-proof workhorse for me (I've not tinkered with the hydraulics at all 'till very recently, thus my new and fun learning curve).
In the case of the Brand Hydraulics LV Series valves the "4th position" refers to a lever position beyond the 'normal' DA spool positions of
1. port "x" pressurized
2. neutral (center)
3. port "y" pressurized
In the case of the LV22RFSTKAB configuration specifically:
1. The stick can be pushed past a detent at the end of the "boom Lower" position to enable "Boom Float" (maximum forward/up on the stick).
2. The stick can be pushed past a detent at the end of the "bucket tip" position to effect a "Rapid-Tip" aka "Rapid Regin" as might be used to knock sticky clays out of the bucket (maximum to the right on the stick).
3. The stick 'springs to center' when released from any position
"Boom Lower" and "Bucket Tip" being positions associated with port>hose>cylinder assignments used in the normally intended FEL control application of the valve. For the Rear Aux application my thought is to assign ports 'normally' used for the Boom to the Top Link cylinder and ports 'normally' used for the Bucket to the side/Tilt Link cylinder.
Obviously, all this requires appropriate spool and valve-body machining to accomplish, it's all done within the valve body with nothing external to the valve, fluid is routed to the appropriate working port(s), PBY port or relief port 'automatically'. You can't just swap spools in the body willy-nilly and have everything continue to 'work right'; the same hold for the joystick mechanism - particular mounting plates are required to match-up with particular spool/body configurations and have the joystick operational orientation be correct per normal conventions (forward/up for boom lower, right for bucket tip, etc)
The basic "4th position" nomenclature seems to be fairly common / uniform among ag control valve manufacturers, I've seen it used in literature by several manufacturers in reference to the operational options for both monoblock valves and individual working-sections of stack-valves. But hey, I'm on the learning curve, too, things like float and rapid-regin weren't encountered in my process-plant engineering past-life!
I'm pleased with the Brand LV valve so far. Available 'on paper' with many different control configurations I found that in actuality only the one configuration I got is widely available as an in-stock item. I'd have preferred a different configuration which would have allowed me to install it on my OEM valve mounting plate and have everything be properly oriented in terms of ports and lever-action but that would have required a special order at substantial extra cost with a very long estimated/no guarantees lead time. I suppose just a reflection of their factory batch-processing system for the many products they offer. In any case, with a bit of re-fabrication of my mounting plate this valve is working fine and may in fact be a bit better than OEM in terms of the final ergonomics (a bit less 'reach' to the lever).
I certainly like the 4th position functions that my OEM valve did not have (boom float is a new joy for me!). It's taken a bit of practice to learn exactly when to push to the 'boom float' position to avoid a sudden 'boom drop of a few inches' or 'lift-and-drop of the front of the tractor' but 'the touch' is quickly acquired. All is good, I'm finding the boom float is very nice for lots of situations both forward and back-dragging.
The Yanmar 336D, a now ~40 year-old design, offered none of the very nicely integrated implement control valves and lever-panels I see on most modern tractors of similar size. I suppose that cuts two ways .... while not as nicely integrated it does allow lots of flexibility in fabricating DIY solutions. At least Yanmar did a fine job anticipating external valves/hydraulic implements with the built-in divider block arrangement and the 3PH draft control is just superb for lots of dirt work (automatically adjusting 3PH implement depth to keep constant load on the tractor when draft control is engaged, a feature I think maybe still not too common on similar-size tractors though seen a lot on larger units).
I still enjoy doing a fair amount of dirt work both on my own property and helping neighbors. I'm in a neighborhood of relatively small parcel owner-occupants (10 - 100 acres) and many don't have anything larger than a garden tractor so aren't well-equipped for things like road or pond maintenance which I enjoy helping with. Even those with bigger tractors are mainly oriented toward hay-field and horse/cattle pasture management more than dirt work. I've had it for ~30 years and the 336D has been a bullet-proof workhorse for me (I've not tinkered with the hydraulics at all 'till very recently, thus my new and fun learning curve).