New Holland SenseTrack and SuperSteer--Can someone explain how it works?

[npalen]

I have a NH TC29DA 29 HP FWA and would like to understand exactly how the SenseTrack works. The 4WD (Front wheel assist) lever has two positions: Automatic FWA and full FWA.
I do know, from checking the parts list, that there is a "one way clutch" in the driveline going to the front wheels. My understanding is that, in the automatic mode, the front wheels will always maintain "equal" rotation with the rear wheels. In other words if the rear wheels start spinning the front wheel assist will engage.
Would sure like to know exactly how this all works particularly with respect to sharp turns with the SuperSteer option.

Edit: I checked the speed ratio between the front and rear wheels and found that the fronts are geared to run about 3-4% "faster". I do realize this is fairly typical for front wheel assist tractors but also wondering how this relates to the "automatic mode".

 

[AGRIMAN]

The sense track is designed to be use with the super steer front axle and its purpose is to engage/disengage the FWD while turning. When you have the lever in automatic and start to turn, it senses the resistance and automatically disengages the FWD to improve the turning radius. Once the turn is complete and the resistance is gone, it automatically engages the FWD.

When you have the lever in full, the sense track is locked out and you have full time FWD. It will not disengage when turning.

 

[npalen]

I would have thought the opposite on the turning issue because, when turning so short, the inside front wheel is nearly perpendicular to the tractor. I would think the wheel would slide sideways in this situation if it wasn't powered, instead it tracks perfectly even on loose gravel.
Automatic FWA (or FWD) to me would mean that it engages only when needed such as in a tight turn to pull the front end around.
I don't mean to be argumentative and I do appreciate your input. Just wanting to get this 70 year old brain wrapped around what is actually happening. Would like to hear some ideas on how to prove/disprove the theories.

Edit: I did a search on Sense Tract and Super Steer and one of the thread posts I found was this: (When saying "rear wheels travel at a faster speed, I'm assuming the author means faster RPM)

2003-09-17 00:00:00 64165 BountyHunter | 3 Pix
Not to beat a dead horse, but in regards to the sensitrack 4WD, does it hold up as well as conventional 4WD? It looks pretty simple, basically a one way clutch at the front end of the drive shaft. If the rear wheels travel at a faster speed than the front it locks the front axle in until the wheels are at relatively the same speed and then it disengages. I plan on signing the papers in the next day or two and want to be relatively sure that I'm buying something that will last. I've talked to 2 dealers in the area and 1 says that it (supersteer and sensitrack) is just bells and whistles but he hasn't had any problems with them and the other dealer says he wouldn't have a tractor without the sensitrack. I even called New Holland, but they referred me back to the local dealer and said that is where I'd get the best information...GO FIGURE. I enjoy reading the threads on this board and look foreward to any other information or opinions on this subject. --Thanks

When saying "rear wheels travel at a faster speed", I assume the above author means "faster" RPM as they would under draft load in a slippery condition. Can I assume that the front wheels slow down relative to the rear wheels in a turn? If so, that would cause the FWA to engage automatically in a turn situation.

 

[npalen]

On the other hand , the attached would tend to substantiate what AGRIMAN posted above.

 

[SJay]

We where on a job building a deck and had to have the home owners shed put back on the new concrete driveway. The manager of the park came over with his NH tractor that had SuperSteer - worked great because of the tight space we had to work in. He was able to push the shed onto the concrete driveway with very little maneuvering of the tractor. Sorry, didn't answer your question, but it seems like a nice option.

 

[Thorny]

On the other hand , the attached would tend to substantiate what AGRIMAN posted above.

Does this imply that the front axle is the primary drive axle on this tractor? the only downside I see to that would be front tire tread life, but otherwise it seems like a handy option.

 

[npalen]

Welcome to the forum!
That is an interesting concept but, no, I don't think the front is the primary drive.

 

[npalen]

The sense track is designed to be use with the super steer front axle and its purpose is to engage/disengage the FWD while turning. When you have the lever in automatic and start to turn, it senses the resistance and automatically disengages the FWD to improve the turning radius. Once the turn is complete and the resistance is gone, it automatically engages the FWD.

When you have the lever in full, the sense track is locked out and you have full time FWD. It will not disengage when turning.

I definitely believe you are correct in your assessment. I had to see it for myself by making a sharp turn in both auto and full FWD. It's quite obvious that the front and rear are fighting each other when in full FWD but very smooth when in auto mode.
It's amazing in that the rear inside tire remains stationary during a slow sharp turn. I realize that any tractor with wheel brakes can do this but not without sliding the front tires "sideways" and doubling the speed of the outside rear tire due to differential action. It's also very hard to do a wheel brake turn with a hydrostat when the wheel brake pedals are on the same side as the HST foot pedal.:confused2:
I'm still wondering, however, how the one way clutch driving the front wheels is able to sense the "driveline wrapup" when driving straight on a paved surface and thereby "declutch" the front drive. This is very useful for guys like myself who might forget to disengage FWD when roading.
Would sure appreciate anyone who can explain this automatic stuff for me.

 

[dynasim]

In automatic, the link is essentially a slip clutch, and only engages if the back wheels move faster than the front. This allows the sharp turning radius speed differential to work out. The negative part of this is that you don't get 4 wheel braking in automatic mode. When off road, I put the 4wd in full time.

Chris

 

[dynasim]

On my TC45d, there isn't a clutch, and the hst and brakes are on opposite sides. It frustrates me that they discontinued that model!

Chris