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post #1 of 13 Old 09-13-2019, 10:17 PM Thread Starter
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646 travel control valve linkage

I have recently replaced the travel control plate on my 646. Forward travel now seems to be very strong, with good response from the speed control pedal. However, I've clearly done something wrong, as reverse has almost no power at all, barely enough to move the machine. Looking at the linkage, it seems that when the direction control lever is in the reverse direction and the speed control pedal is pushed the linkage tries to push in the TCV spool, but the combination of the spool being able to turn and the ball joint movement, the linkage simply turns to the side and barely moves the spool. Clearly, I have something wrong here, but I'm not sure how it EVER worked like this. I'll try to upload some pictures tomorrow, but if anyone has any ideas I would greatly appreciate it!
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post #2 of 13 Old 09-14-2019, 09:28 AM
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Re: 646 travel control valve linkage

I have a post on here with setup tips.

Search banana plate setup or posts by myself.
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post #3 of 13 Old 09-16-2019, 10:55 AM
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Re: 646 travel control valve linkage

How Banana & TCV work and adjustment:
http://casecoltingersoll.com/showthr...l=1#post103076

1973 Case 646 (w/Custom Power Steering)
1968 Case 155
1958 JI Case 310 Terratrac Crawler Loader
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post #4 of 13 Old 09-16-2019, 09:23 PM Thread Starter
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Re: 646 travel control valve linkage

Thanks for the links to adjusting the linkage, that will be really helpful.

I've uploaded a video of the problem I'm having. Fortunately for me, the previous owner cut out a section of the floor making accessing the travel linkage much easier than crawling under the tractor. The forward direction seems to work easily, but as you can see when shifted into reverse, the linkage allows the valve spool to simply spin rather than push in. Has anyone seen anything like this before?

Here is a link to the video on YouTube.
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post #5 of 13 Old 09-16-2019, 09:34 PM
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I don't know how the PO got that to work. Thats the WRONG valve for that tractor. Both spools should have the ball joint that the lower, lift control has on it.

That joint at 90 degrees to the spool is from a old old 4xx tractor.

See if the end of the spool is drilled and tapped for 5/16 fine thread. If so you should be able to get a ball joint and put it in and get it working.

1973 Case 646 (w/Custom Power Steering)
1968 Case 155
1958 JI Case 310 Terratrac Crawler Loader
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post #6 of 13 Old 09-17-2019, 08:42 AM
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Re: 646 travel control valve linkage

The part manual for that tractor should be online here: https://casecoltingersoll.com/showth...ckhoe-Tractors Look for the section on Valve - control Linkage, around page 65 and it will show how that is supposed to be assembled.

The joint on your 'lift - 3 point' control looks correct, and you could swap the ball joint out of that side into the travel side and I think you'll then see how it supposed to work. New joints are readily available: https://salempwr.com/c19025/ Also good picture of what the part looks like..

1973 Case 646 (w/Custom Power Steering)
1968 Case 155
1958 JI Case 310 Terratrac Crawler Loader
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post #7 of 13 Old 09-17-2019, 09:27 AM
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Re: 646 travel control valve linkage

Quote:
Originally Posted by sddunt View Post
I don't know how the PO got that to work. Thats the WRONG valve for that tractor. Both spools should have the ball joint that the lower, lift control has on it.

That joint at 90 degrees to the spool is from a old old 4xx tractor.

See if the end of the spool is drilled and tapped for 5/16 fine thread. If so you should be able to get a ball joint and put it in and get it working.
That is not correct. The valve is the correct valve. But obviously the linkage parts are wrong by the way it is not working. I attached a link to the correct parts diagram.
Attached Files
File Type: pdf 646 Travel Control Linkage.pdf (39.1 KB, 8 views)
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post #8 of 13 Old 09-17-2019, 10:25 AM
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Re: 646 travel control valve linkage

Thanks for correcting that.. I should have said the linkage looks wrong..

I've gotten a hold of one of the TCV valves with the 90 degree linkage for parts, but I never realized that they put those in the 1st 646 that were made.. Hmmm. if the rod #19 C17557 is gone the only work around would be to drill and tap that spool to 5/16 fine thread like the other spool and use the inline ball joint like the later models.

Or, I guess MAKE a new #19 rod.. Which Steve you or I could do in our shops, Not so sure how shgreen can accomplish that..

1973 Case 646 (w/Custom Power Steering)
1968 Case 155
1958 JI Case 310 Terratrac Crawler Loader
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post #9 of 13 Old 09-17-2019, 01:35 PM
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The parts are not available?
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post #10 of 13 Old 09-17-2019, 06:21 PM Thread Starter
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Re: 646 travel control valve linkage

OK, looks like the linkage is wrong I guess. I've had this tractor for a few years now and I'm not sure how it has been working at all. Maybe the 90 degree ball joint piece was seized up or something, preventing it from just turning. Anyway, I removed it and yes, the end of the spool is tapped! I've got the new linkage bolted directly to it now and it seems to be working just fine. I'll have to adjust it's length to maximize the movement, but it is drive-able again!
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post #11 of 13 Old 09-18-2019, 08:44 AM
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Re: 646 travel control valve linkage

What engine are you using?

Girls with large lawns like a guy with a really big deck!
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post #12 of 13 Old 09-18-2019, 02:29 PM
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Re: 646 travel control valve linkage

Hydronerd, I'm not sure who your question is directed to, I have a '73 646 that is running the Original Onan CCKa engine.


Quote:
Originally Posted by Hydronerd View Post
What engine are you using?

1973 Case 646 (w/Custom Power Steering)
1968 Case 155
1958 JI Case 310 Terratrac Crawler Loader
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post #13 of 13 Old 09-18-2019, 09:04 PM
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Re: 646 travel control valve linkage

The OP.

Seeing his avatar, I remember he had trouble starting the clone, and I think some one said the clone wasn't big enough. Just wondered where he went with it?

Girls with large lawns like a guy with a really big deck!
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