kx71-3 looking to add flow control to travel circuits

[graves14]

Hello. I'm trying to maximize the usability of my KX71-3 mini ex, and one thing that bothers me is moving sucks the life out of my other motions and controls.

Can I add flow controls on the travel circuit (like those inline one direction flow controls for $30), and when i want to move slower simply dial those way back - giving more flow to everything else? There looks to be two lines off the manifold for each track drive. I'd even be ok if the restriction was in one direction - maybe just one flow control limiting forward on each side?

I basically want a super slow tracking mode when cutting or using the thumb.

 

[oceanobob]

Rather than installing a flow control which may impede the operation of series parallel (is low or high speed), could you install some form of adjustable mechanical stop (like a throttle stop on a drag racer running index class) on the control lever? Maybe such a plate with the stop 'flips into position' when you want creep, then flips out of the way when you want to relocate.

 

[lantraxco]

Without a hydraulic schematic it's hard to make suggestions. Flow dividers maybe rather than flow control but it depends on how the supply circuits are set up, sometimes the tracks are supposed to have priority flow by design and you would only end up pushing oil across relief valves.

 

[graves14]

i was working off this. thinking of putting the flow control on 190 or 180.

as soon as i touch the track control, the aux flow is reduced to next to nothing. so thanks for the idea on the mechanical stop on the controls - prob wont do what i need though.

the tracks definitely have priority.

 

[lantraxco]

Well, that is normal for an excavator, the thinking is that they travel, then they dig, but not both at the same time. They want the machine to track straight, and also not be moving wildly about while tracking. Different machines will have different behavior and some of the newer electronic excavators will have selectable work modes.

One thing I have done in the past with mini excavators is plumb in a parallel two spool valve connected to the blade pump which works but may have lower pressure and is kind of a pain as you have to find room for it and all the plumbing, plus a method to control it.

 

[graves14]

If I restrict flow on one line, would this introduce an imbalance that could damage the drive motor seals? I was thinking if I installed just one flow control that permitted full backwards flow, then I should be limiting flow in one direction and the return side would be wide open. Making sure I put it on the supply side would be critical.

What is the purpose of the spool valve labeled "confluence"?

 

[lantraxco]

Right, you want the free flow pointed away from the motor, controlled flow in.

Confluence? Sounds like a flow combiner for some purpose, won't swear to that.

 

[John C.]

Just heard this same issue with a larger Kubota. Fella wanted to run a mulcher. Basically put the mulcher in one place relative to the machine and then travel down the road cutting the ditches and sides. Because the land isn't flat the boom or stick would have to be picked up at times and there was not enough oil available to do that. I haven't looked at the valve schematics for these machines yet but I don't think there is any pressure compensation so all the pressures fall to the lowest operating function. If your travel circuits are running at 2100 PSI then that's all you get for the rest of the implements until you stop traveling. The other issue for this gentleman was that the engine and pump combination could not provide enough oil to run all those functions at once without slowing everything down. It comes down to the basic physics the machine is using to operate with.

The machine was a lot less expensive up front that all the competitors. Now you know why.