what is the TA

what is the TA and exactly does it do? i am a deere fan and am goint to buy a IH since about $10000 cheaper for the same amount of HP and the parts are cheaper also i am looking at a 966 986 1066 or 1086 do all of these have the TA and how do i tell if bad and if they say they are bad can they be used that way i see some that say they are stuck in hi i dont know alot about IH at this point but i will soon be owner thanks

The best way to tell if the T/A is good is to drive the tractor around a bit get it warmed up then get it out where ya can get it in high range in third or forth gear open her up and start riding the brakes BOTH BRAKES and start dragging her downto about 1400-1600 RPM and pull the T/A lever back or down depending on what tractor you are on and have your left foot on the clutch pedal because if she just up and stops when ya pull her into low ya had best be pushen the clutch i as they can just up and stop then all of a sudden grab this is not a good thing to have happen IF it grabs hold and holds thn the T/A is good BUT for how long have no idea i guess till it goes out then ya know she is bad . Myself i just love to by them with bad T/A's and put a new one in then i know that it will be there for a long time to come. But that is just me.

In addition to what vet says about testing the TA, a quick description:

TA, or torque amplifier, is a two-speed powershift. It gives you two speeds in every gear. Normally you run with the TA in "high" until the tractor runs out of power or needs to slow down for a rough spot.

thanks guys for the information just so i understand on the tested if i pull back to low and it is good it is going to basically slow down a few rpms to a lower gear basically if bad it may lock up the wheels thanks again

Not quite on both counts.
If it is good, it is the same as using a powershift and getting in a hard pull. As the engine RPM begins to drop lower than maxtorque/HP ballance, (lugging) the TA is shifted to Low range with a single purpose lever. The lever is moved swiftly from one to the other position like a light switch.
The tractor engine should increase in RPM and the speed might stay the same on the ground, or actually increase if the engine picks up enough.
The TA is like down shifting an 8 speed Powershift one gear. No clutch pedal action is needed.

If it is bad, or mis adjusted, pulling it back into Low range under load will possibly cause it to slip as though it was in neutral (which in a sense it is) then (as the Tractor Vet indicates) it can grab from that neutral and jerk forward suprizing the operator quite a lot. So keeping your foot over the clutch pedal is prudent if it goes into a false neutral. The TA is not as convienient as a full powershift trans, but provides a long and usually trouble free life in High HP tractors on down to 30 HP range. It also has the efficiency of a mechanical system rather than fluid couplings found in --some-- other systems. I hope this helps. Best of luck. JimN