1/4" Quarter Inching Hydraulic 3-Point Control Valve

[InTheWoods]

The B7510 in my shed is new to me and before buying it, I had a B7100 (the early variant) for 30 years. That B7100 is definitely the type of 'tool' that has become just an extension of my body. I never looked into 'position control' as Kubota calls their more modern control. I spent a lot of time using a grader box and landscape rake, and didn't have issues getting the implement height correct.

So, when I first saw the B7510 had 'quarter-inching', I assumed it must have been some sort of improvement over the B7100-era up-down lever. My first use of the grader box was a disappointment, as I had a lot of trouble dialing in the height.

Here's my understanding about quarter inching now. Straighten me out if I'm incorrect. I'd be curious to see what the Kubota literature of the day actually said about it.

The quarter inching control is nothing more than the old up-down hydraulic lever with 'stops' added to make it easier to put the valve into a 'slow up' or 'slow down' position. The owner's manual doesn't spell it out, but the 'stops' are adjustable, and if they're not set correctly, the quarter inching feature doesn't work. Setting them is pretty easy - Put an implement on the 3PH, start the tractor and run the throttle up. Loosen the two 10mm locking bolts on the hydraulic lever faceplate (highlighted below). Slowly move the hydraulic lever to a position where the implement is slowly rising - slide the lock up to the lever and tighten the bolt. Repeat for the down direction.

From what I saw, these slow speed settings didn't depend that much on the engine RPM and 'lowering speed knob' as I thought, but it's worth seeing for yourself. I expect the hydraulic oil temperature will affect the speed too.

Would Kubota's 'position control' be better? I'm sure it is, but that's not the point of this thread.

 

[GreensvilleJay]

The 'stops' will limit the height range implement can be put relative to the tractor. Now how fast or slow it takes to get the implement up or down does indeed vary whether the oil is hot or cold.
'position control' has feedback to actively adjust the implements actual height. better ? depends on what you're trying to accomplish with the implement.

 

[InTheWoods]

The 'stops' will limit the height range implement can be put relative to the tractor...

On the B7510, the stops I show above (highlighted green) control only the speed. The implement lower height limit is controlled by the 'locker' on the rod under the seat:

 

[GreensvilleJay]

oh, that's different than the original Fords and Fergies had.....

 

[North Idaho Wolfman]

Sorry you've got it wrong.
The stops on the lever limit the lowering and raising height they have nothing to do with speed.
The drop speed is controlled under the seat.

Quarter inching valves move the implement 1/4" per segment of the valve, the feed back (you second pic) is a feedback for the valve, it's not a limit setting.

 

[InTheWoods]

...The stops on the lever limit the lowering and raising height they have nothing to do with speed...

On the B7510 parked in front of me now, I observe that the stops (that I highlighted green above) allow the user to easily put the hydraulic control lever in a position to reduce the UP and DOWN speed. They have no effect whatsoever on the height, just the amount of time it takes the implement to get there.

When the hydraulic control lever is pushed slightly outboard to go beyond the stops (as it is designed to do) the fastest UP and DOWN speeds are achieved.

If there are Kubota instructions on how to set these stops, I'd like to read it - if it's in my manuals, I haven't been able to find it...

 

[N3BP]

Those stops highlighted in green give your machine "position control". If you run attachments like a mid-mount mower, you learn quickly how important they are to prevent damage. Trust us when we say their function is to limiting the range (or height) of the three point arms, not speed. Here is a little blurb from my BXX10 product guide from 2008 that explains the quarter inching feature of the B7510.

 

[InTheWoods]

If these are 'position control', why would Kubota, in my owner's manual have labels for SLOW UP and SLOW DOWN that point to these stops?

Thanks for the snip from your brochure. Do you have anything from Kubota on how these stops are to be set?

Maybe mine are set incorrectly - that's why I'd like to see it in a manual from Kubota...

 

[N3BP]

The position control stops are set based upon the requirements of the attached implement. Sometimes they aren't even necessary, and other times critical. For example, with a mid mount mower, you need to adjust an upper limit so don't force the deck into the bottom of the tractor and break sometime. You then set a lower limit so you prevent the deck from dropping too low (like entering a ditch) which can cause the slip-joint drive shave to become uncoupled and cause extensive damage.

The "slow up" and "slow down" are the quarter-inching settings.

Like Wolfman said, the rotary knob under the operators seat is the mechanism that controls the drop speed of the three-point hitch.

 

[InTheWoods]

Let's say I have a 3PH implement (like a grader blade) attached and lowered to its full down position. Now I move the hydraulic lever back until it hits the stop (highlighted green above) and hold the lever there. What should the implement do? In my case, it raises SLOWLY to the max height. This makes it easier to make small adjustments, maybe to 1/4" precision. But there is no way I can adjust this stop to limit the extent of motion. Limiting the extent of motion to anything other than max height requires the human to release the lever at some time.

As long as I hold the lever against the stop, the implement moves slowly until it hits max (SLOW UP) drops to the ground (SLOW DOWN).

Yes - I know about the drop speed knob under the seat.

 

[Willie1]

This looks similar to the " 1/4" inching valve" on the bx series.
InTheWoods has it correct. It merely keeps the valve from opening to its full extent so you can more precisely move the three point. In effect it slows down the speed of raising or lowering by not letting the valve open all the way. It's a cheap way of making you think you have a feature that you don't really have.
I modified my BX so that it will hold the valve in the down position thereby creating a float position for the three point.

 

[InTheWoods]

...It's a cheap way of making you think you have a feature that you don't really have...

Exactly!