856 T/A question.

[Brandt856]

Just finished with the rebuild of the 856. Paint and everything.
T/A was professional shop in Indiana. Tractor runs and drives
fine but when we pull the T/A back...nothing. We had tractor
split in three parts, totally apart. Now it?s all done but T/A does
not work. Any help on where to start? I just don?t have the
background knowledge on this. As always thanks for your
time.

 

[Janicholson]

On a big frame tractor there are 2 components that allow TA to reduce. One is most important, it is the sprag clutch preventing reverse rotation of the TA reduction module/unit, the other is a hydraulic clutch that keeps the TA unit from spinning forward when in TA reduction. (the second one prevents free wheeling down hills). If there is no forward motion when the TA is pulled back, Both of those are in question. If the speed just stays the same, there is a MCV control issue and is serious, but not always "splitsville". Jim

 

[cornerpost]

When you pull TA lever back "nothing". If it quits moving bad sprag. If it stays in direct pressure is keeping high side clutch engaged.

 

[caterpillar guy]

T/A is like concrete either going out or is out. Cracked or going to crack. That is why we delete all of them on ours.

 

[Brandt856]

When we pull the T/A back the tractor just keeps driving along. No change, or drop in gear happens. Tractor does keep driving fine. Where would you experienced folks look first? What is the easy fix? You know the ?Air, fuel, Spark? kinda stuff. Is it possible the linkages need adjustment? Again thanks for your time.

 

[BarnyardEngineering]

Well, if you just slapped it back in there and didn't at least make sure everything was in adjustment... Very likely something is out of adjustment or connected improperly.

There's a procedure in the book, and plenty of descriptions how on this forum and others.

There are two scenarios here with a non-shift:
1. It is in direct and not shifting.
2. There is no hydraulic pressure to the TA at all, and it is driving on the sprag. Your tractor will freewheel down hills if this is the case.

I suspect you are experiencing the second scenario.

Couple of questions:

When you move the lever, does the plunger on the top of the MCV on the left side go up and down?

When you push the clutch, does the plunger on the BACK side of the MCV go in and out? That is the dump valve. I've seen them stick open before. This will cause scenario #2 above.

Also, TA's are not either out or going out. That's pure BS. They're no more or less complicated or reliable than any other early powershift system. They do wear out like any other thing, but once you replace them, it's a lifetime repair. These tractors just don't get the hours like they did back when they were new.

 

[Timmyih]

Does it have a hydraulic seat and are the hoses connected together now since it?s been to the paint shop most 856 is had a hydraulic seat

 

[Timmyih]

Make sure that the line going to the hydraulics he is plugged

 

[the tractor vet]

Well sounds to me that the PROFESSIONAL SHOP is not so professional and they MESSED up . And They should be the ones fixing there screw up. Now as to what they messed up ????????????? it could be something simple as a forgotten O/Ring or could be they forgot to install the constant mesh gear .

 

[the tractor vet]

That is because YOU just don't know how to do a proper instillation and use a top quality replacement. The LEAST amount of time i have gotten out of one of my T/A jobs is 24 years and one 1066 is now setting at 35 years on a rebuild and is the main heavy tillage tractor on a small dairy farm in hill country and that one is setting at 175 Hp . The one in my buddy's is just now startting to go south due to his kid usen the T/A as a Jake brake to hold back 35000lb plus silage wagons on the down hills and that one is in a 1066 setting at well above 200 Hp and is the heavy tillage tractor in hill country and gets used ALOT when deep ripping pulling five DMI tiger parabolic shanks 14 to 16 inches deep .