Colt Case Ingersoll Garden Tractors

thebuildist wrote: ↑Wed May 04, 2022 10:32 pm Whelp, I took the plunge. The first step is to test the priority flow divider valve to see if I can find a happy adjustment.

In a nutshell, there are two paths I can take from here: either remove the TCV and modify it such that it has a power beyond port, and then feed the new loader valve from that power beyond port.
Or install the "priority flow divider" valve that I've already bought.

The TCV/power beyond option is fairly foolproof, in that it follows what Case did with the 646. All the oil leaving the TCV next heads to the loader valve for use in loader functions. But it's the most work, since I have to remove the TCV, completely disassemble it, do all the machining, clean out all the grit, and put everything all back together. And it's the most risk, as I could conceivably destroy my TCV by way of design error or machining mistake. (Not that I personally have ever goofed anything up, but I hear that it can happen to other people... ) The other downside is that the loader valve only gets pressure equal to the TCV's relief setting, in my case about 2100 psi. I think that 2100 is enough for what my loader needs, but just barely. As best I can calculate, my bucket tilt cylinders will need all of 2100 psi to tilt the bucket back with 1000lbs on the cutting lip. So I THINK it would be ok? But I'd rather have a bit of margin.

Meanwhile the priority flow divider valve would be a little easier to install. I just need to re-configure my new hard lines, both of them shorter than they are now. Working with hard lines is a pain, and I'm not happy to do it, but it's not as bad as reworking the TCV itself. And since it creates a completely separate circuit from the TCV, it can have a higher pressure relief than the TCV. Something like 3000psi seems reasonable. But the priority divider valve does have a potentially big downside: I don't know if its variable control is going to be granular enough to actually work in this application. It's rated for 20gpm, and I'm given to understand that these priority valves work best when operated near their rated flow. My flow at the divider valve is only about 9 gm. So my fear is that I may struggle to find a consistent workable sweet spot on the adjuster knob where the TCV is getting enough flow for normal operation, but there's still enough diverted for adequate loader operation. The adjustment knob reads from 1 to 10, and I'm afraid it may be a situation where a setting of "5" gives ALL the flow to the TCV, but then dialling it up a tiny bit to "5.1" suddenly cuts "all the flow" over to the loader valve and starves the TCV.

But there's only one way to find out for sure. So this morning, true to my decision, I pulled out the existing loader valve and piped in the new priority flow divider valve upstream of it. I ran out of time for today, so I didn't get to test it, but that'll be tomorrow's task: I have a loopback hose in place that routes all the oil from loader valve's "out" work port directly back into its "in" work port, and I'll drive the tractor around and see if I can find a setting on the priority valve's adjustment knob where I have "enough" flow to the TCV for workable driving, while simultaneously diverting "enough" flow through the loader valve.

Of course I'll have to judge the flow of the oil through the loader valve by sound, since I don't have an actual cylinder hooked up to it. But I at least ought to get a good sense of how "touchy" the divider valve adjustment is, and satisfy myself that there is a "wide enough" range of transition between "the TCV has all the flow" and "the TCV has zero flow."

I'll post back tomorrow with results.

Bob