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'68 - Case 155, '73 - 646a
2,020 Posts
Discussion Starter · #1 ·
My '73 646 did not originally come with a PTO valve and now that I have a tiller I have more of a reason to add one. I also would like to have a second 'lift' circuit so I can run a grapple on the loader.. Since, I scrapped a 446 out, I have an extra TCV valve, Why not? While we're replumbing most of the tractor, we might as well add the PTO / TCV.

Being an old Farm kid, the tractor I always ran was a JI Case 400, the PTO control is 'supposed to be' a push - pull lever and the 3 point hitch - lift is a lever located by the seat not something on the dash. So I came up with this for Controls once I had the valve installed:

Tent Automotive tire Bumper Automotive exterior Tire

The PTO control is the long rod that runs under the seat to the knob on the operator's right just below the seat. The 'lift' circuit is plumbed to the 3 point and is operated by the handle sticking up beside the seat.

I mounted the TCV on the right rear fender close to where an OEM valve would be.. Figuring out how to make the controls work, and squeezing it all essentially under the seat was fun.. :mechanic:

Lets start with the PTO - Lift controls, Here is the 3 point control without the PTO rod in place..

Hand tool Metalworking hand tool Tool Wood Font

Both of the Spools on the TCV need to be pushed and pulled in and out to function. the 3 point - lift spool has centering springs and a detent on it, the detent is for 'float' and it comes into play when the spool is pushed all of the way in.. Which I plumbed up as DOWN on the 3 point..

Therefore when I pull back on the '3 point lever' the mechanism needs to push the spool IN, and when I move the level forward, it needs to pull the spool out.

I have a bunch of 3/4" thick by 3-4" wide scraps of Ultra High Molecular Weight (UHMW) plastic, which is a super dense plastic that I've used for jigs and similar.. It's Very slippery and makes great low speed bearings. I sandwiched the shaft of the control lever in between 2 layers by cutting a Dado groove in the UHMW on the table saw..

Then, I drilled a 3/4 hole as the pivot point of the lever. Because UHMW is so dense you can drill and tap it, there are 3 - 5/16 bolts running from inside the fender into the UHMW that holds this in place in addition to re-using the bolt that holds the fender to the seat supports. The 'sandwich' is held together with 2 - 1/4" flathead bolts that are threaded into the other layer.

I used a 5/16" Male Heim rod end in the spool and a Grade 8 - 5/16 bolt running to the pivot point to connect this.. Somehow I got on the idea that rod ends would make the build easier and a 5/16 bolt should be strong enough to handle the spool valve.. The pivot is tapped for the bolt and that makes assembling and removing this real easy. Once I thread the bolt out of the pivot, the entire mechanism is disconnected from the spool valve.

What's not shown there is the PTO control mechanism. I took pictures as the project progressed.

One thing I figured out was that since the 'travel' spool on this particular vintage of TCV does not have ANY springs or detent on it. It's SUPER easy to move.. Therefore I could add another 5/16 heim rod end to the other spool and slip a 5/16 rod into the rod end and move the spool in and out with ease. I created a pivot point part way between the spool and the front of the seat support, which means I can engage and reverse the PTO my moving the rod to the right and left under the seat.

Automotive tire Motor vehicle Wood Bumper Gas

Because the TCV is mounted on the rear of the fender, that makes it lay there at an angle, that puts the 'PTO' spool ABOVE the '3 point' spool. There is this nice gap at the front of the seat support between the 'toolbox' and the fender where I added a slotted bracket. The center is neutral, and each slot at the end turns the PTO on in the different directions.

The 'magic' that makes this work are Heim Rod ends again.. Since the previous photos, I've added an additional 5/16" rod end vertically in the UHMW block that is the pivot point for the rod. The Center rod end is a slip fit in the UHMW and it has a bolt and spring attached on the bottom side that pulls and holds the rod down into the notches.

More accurately the function of this is that you lift the rod / knob UP against the force of the spring under the center pivot, you move the knob left or right and the spring pulls the rod down into the slot and holds it there..

The back side of the UHMW block looks like this:

Wood Table Gas Guitar accessory Water

The large washer and bolt closest to the camera holds the pivot for the 3 point lever in place, And, the Bolt and spring that pulls the PTO pivot point down is near the top. There is a cut out in the block to work around the hydraulic line coming off the TCV.. You might also be able to make out 2 holes about parallel to the spring that are the tapped holes for the 2 flat head 1/4" bolts that hold the sandwich together..

One last photo allowed (5 total) in a post, so here is the top of that block:

Plumbing fixture Tap Wood Kitchen sink Floor

The Heim rod end actually sets in a pocket, I drilled a hole for the shank of the rod end, and then to get it to sit lower in the UHMW I carved a pocket out in the plastic with wood chisels.. That shot shows the sandwich and also how I added a notch in the plastic to serve as stops for the 3 point lever..

Once I get the rest of the tractor back together we can verify that this works as advertised..


1973 Case 444, 1974 Case 644, 1976 Case 446, 1977 Case 646
2,613 Posts
It looks like you have been busy! Great job in the engineering dept! :clap: The lift circuit for a grapple is a great idea, can't wait o see it in operation. :thumbup:

Keep the Peace :trink:
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