HST in larger tractors?

[GlueGuy]

<font color=blue>How wide is the top?</font color=blue>

It varies quite a bit from one spot to another. Out at the toe of the ridge, it's probably only 100' at the widest point. Further back, it's several hundred. I also have a trail that switch-backs down to the lower part of our property. The steepest it gets along that trail is 30 degrees or so.

 

[MossRoad]

Just thinking about that fall gives me a shrinky winky!/w3tcompact/icons/tongue.gif

Where I grew up, we had a 90 foot drop down to the lake. Somewhere around 60 degree angle. Lots of trees to stop your fall. One day, the neighbor lady came over crying and asked us to help her husband. She had a thick German accent and we could barely understand her. She pointed over the hill and said mowing machine. We looked down and there he was, about half way down the hill, still sitting on a little snapper riding mower, too scared to move. Apparently, he was mowing near the edge and had stopped to do something. When he went to leave, he selected reverse instead of forward and drove off the edge. /w3tcompact/icons/shocked.gif He managed to ride it all the way until it stopped against some trees. He was OK, but very upset. We got him calmed down and the three of us picked up the snapper and carried it over to a stairway and back up the hill. His wife made him sell it and get a walking mower. /w3tcompact/icons/laugh.gif

 

[JATO_RaT]

Richard, perhaps you could explain to me why HST couldn't keep a constant speed. That statement still puzzles me. I can keep as constant a speed with an HST as my geared (8 speeds) International. In fact, as the load on any tractor increases whether it be a hill or increased resistance to the tires from deeper soil to wetter conditions or increased drag because of tougher soil conditions when pulling a soil loosening implement, the speed must be adjusted for on any tractor. I can as easily adjust for that with an HST as I can by increasing the throttle on my geared tractor. I cannot comment on the use of hydrostatic on ag tractors because I know nothing about the agriculture history on tractors. I must agree with you about there just not being a real need for HST, GST etc on a seeder type ag tractor since the benefit of HST in a straight forward direction is really not utilized. Some folks may confuse a torque converter transmission found on older tractors with HST, but they have nothing in common. While agricultural tractors would see very little benefit from HST, homeowner, multi purpose tractors found here in predominant numbers receive all off the benefits with virtually no drawbacks. Sure the transmission of power from the engine to the drive wheels suffers a little, but that is more then compensated for with the excellent manuverability, safety and control they get from HST. While Kubotas shuttle shift and JD's power shift are great advances and something I still regularly use today, they are no match for the direction control and safety especially on slopes that HST offers. I know you know all this but am reiterating it for those folks considering a new tractor. Rat...

 

[MDNick]

Rat,

The reason a gear tractor can maintain a steady constant speed is because there is zero slippage in the drive train. While you say you can maintain the same speed with your HST as your gear, you don't KNOW this for certain. With a gear tractor, once you work out what rate of application for a specific groundspeed, with the same gear (shifted into it so there is no, yeah, I think the pedal is in the same place) and same RPM you have exactly always the same groundspeed.

Race car drivers do the same thing with the TACH. They use the pace car to set the pace (that is why it's a pace car), in a specific gear, at a known RPM they will always be at 45 for the pit lane.

You are right that you can very the groundspeed with the throttle and your HST pedal in the same way on the 2 different tractors. In truth, an AG tractor used in this application tends (not exclusively) to be big enough that any reasonable, tillable hill it comes to won't phase it a bit in RPM. And if it does, just a bit more throttle to maintain the RPM and you KNOW you have the same groundspeed. Some of the modern tractors with radar and GPS (as Cowboydoc said) will maintain that constant speed all by themselves. Also, for the most part, AG tractors tend to have enough traction that variations in the soil conditions have a marginal affect. The farmer tends not to go to areas that are going to provide really bad traction, he might get stuck, and that really screws with efficiency. Not to mention it gums up a planter.

In short, HST is great for harry homeowner applications as we all know, but if you want a constant groundspeed for the application of fertilizer, chemicals, or seed, and your tractor isn't a new fangled job with a computer, it is impossible to do with HST.

A modern Big AG tractor is truly an incredible machine. With the GPS they might have a map of their field identifying nutrient poor and rich areas. In those areas the computer will automatically adjust the flow rates of the fertilizer or chemical to deliver exactly the amount the soil engineer told him to. Heck some farmers ARE soil engineers. With dead constant groundspeed, the farmer can apply 1500 lbs/ac in one spot and 1700 lbs in another. Much more efficient than having to shoot for the average need of the whole farm.

Nick

 

[JATO_RaT]

Thanks Nick, I live in perhaps the richest farming areas in the entire country yet know very little about it. I see the farmers almost year around with various equipment in their fields working it, but not always aware of what they are doing. I see laser leveling done quite a bit, but am never aware of GPS. I gather from what your saying is that most of this equipment is well beyond the scope of tractors typically discussed on this forum. I have seen this constant speed thing discussed quite a bit and wondered if everyone was farming or simply relating their experiences about it. I should think few farmers would find the time to dabble on the internet as when the equipment isn't out in the field, its in the shop. I have often wanted to go to some of these farms and talk to the farmer to see just what their lives are like. I'm sure it would be most interesting and educational, Rat...

 

[JJT]

Buck, I was just giving you a hard time. I'd be strapping on a parachute if I had to regularly creep up to a 500' drop.... JJT

 

[fieldman12]

International Harvester tried the hydrostatic transmission along time ago in tractors around 100 hp. I think there are a few reasons why they and other companies don't offer them any more. The main reason is it takes allot of horsepower to run a hydraulic pump that will move a tractor, and also these tractor are designed for the big fields and pulling heavy loads. The transmissions they have these days (power shift) in big tractors have at least 13 gears and the gear ratios are very close to each other so you always have the right gear. Most of the tractor companies now are working on a variable transmission that they use over seas that is very similar to an automatic in a car and will be on the market in the US soon. Now, if you want to talk combines all of them made in the last ten years all come with a hydrostatic transmission because you are always speeding up or slowing down.

 

[rbargeron]

Hey Peter - looks like you've sparked another active thread !!

I thought I'd toss in another 2 cents on the constant-speed thing. Way below the GPS-scale operations, there is a lot of chemical application in farming that needs to be acurately callibrated. My experience is with tree fruit (apples) where a lot of money goes into the sprayer tank and shouldn't be either under or over-applied. Nozzle size, pressure, ground speed, all have to be accurately tied together. With a gear tractor and pto sprayer, keeping everything in step is straight forward. Operator instruction is kept simple and outcome is more predictable. One less thing to worry about. Of course HST would work - but not better.

 

[JATO_RaT]

Hey Dick, now your talking my subject. Here we apply fertilizer for the orchards via the drip watering system and eliminate much of the hassle of applying via tank spraying or with dry fertilizer. It is rarely applied with the tractor. Rat

 

[rbargeron]

Hey Mark - How's that L48TL ? Got it dirty yet? Remember that dirty is when you can't see where to get on. /w3tcompact/icons/smile.gif

In my orchard days it was always fungicide or insecticide or growth regulators that needed controlled dosage. My plants were far enough apart that I fertilized by hand ! That was a sight, especially if I was working alone. I'd put a ton of fertilizer in a small trailer behind my Kubota, put in 2nd low range, bungie the steering wheel so it went down the middle of the aisle, and I'd run back and forth from the trailer to the trees on each side spreading fertilizer with cans - once in a while making a course correction of the wheel ! /w3tcompact/icons/smile.gif The driverless Kubota was steady as a rock. Ah, the things we do when young and foolish - not to mention when old and still foolish /w3tcompact/icons/laugh.gif