Torgue amplifier

I'm bought an international 300 with what they say is a TA. Never had a tractor with this. I really have no idea what it does. is it like a low gear/creep drive. thanks for any info. Norm

The Torque Amplifier (TA) is a gear reducer device that allows shifting between normal direct speeds like in a Farmall H, and when pulled back, a 33% reduction in ground speed. This is accomplished with a small dry clutch on the TA internal carrier that locks the TA carrier and gears together when it is engaged, and when released it allows the gears inside the TA carrier to turn reducing the engine to transmission speed. The turning tries to make the TA gear carrier spin backwards. This is prevented by a one way clutch that prevents counter rotation.
Operation is best described as use it or loose it. The components are going to wear in direct, and in reduction, so using it as needed is best practice. The control lever should be used like a switch, on, or off. Move the lever very rapidly forward or back. Moving it slowly is like riding the clutch (because it is). It is useful to provide intermediate speeds between the 5 gear shift gears, and in 1st, with the handle back, a slower than first speed.
It is not intended to be used with the foot clutch in any way. Just pull or release the lever. The only time you should not have the lever back is if the tractor can coast down hill and go faster than the gear it is in. Doing this can spin the TA gear housing faster than engine speed possibly destroying parts, and also provides an opertunity to go 45 miles per hour when you do not intend to. Slowing down when at the end of a furrow to make a turn is just fine. Pulling it back under load when in tough clay as the engine begins to bog down is a main intended use. I have a 350U with the original TA and engine clutch still working strong (one engine in frame overhaul) and they can last for a long long time. Jim

Its not a creeper gear. As mentioned below it reduces ground speed by 33% when pulled back. Think of it as a primitive "power shift". When "shifting" down or up you do it as fast as you can - you do not "ease" it back for the "low side" or "ease" it forward when going back into "high side" - basically you snap it. It will free wheel when in "low side", meaning if you pulled the TA back to slow down while mowing or baling you could speed up as the tractor coasts down hill.

It is really meant to be used under load - such as plowing, so you can work you way through a tough spot before snapping it back to the high side. The TA wears out like any part of the tractor, how you use it, or how it has been used will determine how long it lasts - just like the clutch or brakes. When it fails you can just leave the tractor in "high side" and use it in the single "high" range. We put thousands of hours on a 656 with the TA out.

Like a clutch it is important that it be adjusted occasionally as it wears. I have a 350 that I believe has the original TA with only a couple thousand hours on the tractor.

the torque amplifier does what it says , amplifies your torque when you hit hard ground. then once through the tough spot you go back to direct drive. it was not designed to be used continuously, as you need to select the gear to match the implement you are pulling. it was to prevent shifting gears going through tough spots. also good for baling when you hit a heavy windrow spots and need less ground speed. i like mine on the 560 when cutting hay with haybine and come into heavy hay in spots handy for that too. actually had the 560 in red power magazine this summer cutting hay.

Sowed some wheat a few weeks ago. When come to the turn row would pull the TA back to reduce speed turn square around and kick her into direct again. Love it for that.

Just some more on the TA, its a planetary gearset at heart. There are 3 parts, the sun gear, planets & arm (that connects the planets) and the ring gear.

Depending on the specific gear teeth counts, when one element in the asm is braked to a stop & held, it results in another ratio.

The above concept is also the mechanical foundation of an automatic transmission. By using hydraulic clutches to brake different parts of the 3 elements (one at a time), there are (typically for a 4 speed auto) 2 parallel-connected planetary gearsets that give the 4 "speeds" plus Reverse. Gears are not actually ever shifted...they are constantly in mesh, its just about braking the elements.

So there isn't a hydraulic clutch pack in the Farmall SMTA, its a manual shifter, and also as I understand it (have never torn them down...yet) the braking action is done by a sprag or one-way clutch involving a wedging action between ramps and rollers set on a circle.

I'm attaching a link to the tractordata website for the 300 transmission. Scroll down a bit and you will see the speeds for a 300 row crop. No guarantee on accuracy but they look close. So you see that 3TA is slower than 2DD. We had a 656 which has the same basic gear setup. We used 3TA more than 2DD when pulling a 3-16 plow. It just handled it better in that gear that was a bit slower. Sure we had to do some work on the TA when the tractor had 4 or 5000 hours on it, but we felt the extra productivity on the plow made up for the repair costs. If we would have thought the tractor should only be used in direct drive low gear would have been the only option.

Link didn't post???
300 row crop gear speeds

There are several youtube videos out there that show the planetary action much better than I could ever describe it...search for "planetary gears" "epicyclic gears" "how an automatic transmission works" for nice visuals.

From the posts below, sounds exactly like the 'multi-power' system on some MF tractors - I had it on a MF 550. Grand if you farm on the flat, but if you farm on hilly ground like I did it's basically bloody dangerous! Turn downhill accidentally with the lever in 'low' and you're off - no engine braking! Make sure if anyone else jumps onto the tractor they know about it!

I kindly disagree, I have used the TA on the 350U continually for the last 60 years pulling in reduction, and switching back and forth as needed. sometimes staying in reduction all day. We have not touched the TA except adjustment of the linkage in all that time. It was primary tillage and go to tractor all its life on about 180 acres. Jim