Help Untwist my HST Brain, please...

Henro · Feb 25, 2004

Henro,

You have way to much time to think !!!!!!!!!!!


KevinJ,

Now you give me something else to worry about!

How can a guy who ( according to the wife ) doesn't have a brain, think???

/forums/images/graemlins/smile.gif /forums/images/graemlins/smile.gif /forums/images/graemlins/smile.gif

Hope she's joking... /forums/images/graemlins/blush.gif

thcri · Feb 25, 2004

( Henro,

You have way to much time to think !!!!!!!!!!!


KevinJ,

Now you give me something else to worry about!

How can a guy who ( according to the wife ) doesn't have a brain, think???

/forums/images/graemlins/smile.gif /forums/images/graemlins/smile.gif /forums/images/graemlins/smile.gif

Hope she's joking... /forums/images/graemlins/blush.gif )

I guess I would have to ask also. Henro, you have had two thats two(2) elongated threads in as little as well 1 week. Did you think these both up and hold them for this week or what. Your starting to scare me!! /forums/images/graemlins/smile.gif /forums/images/graemlins/smile.gif

SacandagaBrad · Feb 25, 2004

Henro,

I'm kind of having the opposite problem, as discussed over at How much slip? in the NH forum. I would give anything to be able to stall out my TC24D in low range. A stall implies to me that I have delivered all the power available from the engine to the task. I know all about light foot pressure on the pedal to achieve a lower "gear", etc., it just doesn't stall. You'll see what I mean in the discussions rather than me re-typing everything here. It's not really a high vs. low range thing with my problem, but I thought you might find it relevant.

Brad

Henro · Feb 25, 2004

Henro...Your starting to scare me!! 

Scare you, Murf??? /forums/images/graemlins/cool.gif

I could not help but think I could even be more scary... /forums/images/graemlins/smile.gif

Let me try:

I think I might visit Minnesota SE one of these days /forums/images/graemlins/grin.gif

Murf's expression: /forums/images/graemlins/shocked.gif /forums/images/graemlins/shocked.gif /forums/images/graemlins/shocked.gif

/forums/images/graemlins/smile.gif /forums/images/graemlins/smile.gif /forums/images/graemlins/smile.gif

art · Feb 25, 2004

Your hydro is in front of the range transmision so by putting it in low range there is more torque able to be applied. The relief valve is affecting the high range hill climb.

Henro · Feb 25, 2004

A stall implies to me that I have delivered all the power available from the engine to the task. 

SacandagaBrad,

It sounds like in normal operation a HST tractor doesn't stall, but builds up enough pressure to activate a pressure relief valve and that the engine will not normally stall out, unless something else like hydraulic cylinders are also taking power from the engine.

If that is the case, and it seems reasonable, then the question would be whether the trip point of the HST pressure relief valve is high enough or not. If it were too low, then it would trip before optimum engine torque could reach the wheels.

From reading the other thread though, it sounds to me like you may have an intermittent problem in your case, rather than 100% normal operation at all times.

rockyridgefarm · Feb 25, 2004

WOW, Art, that explains a LOT!!!

Junkman · Feb 25, 2004

Henro...... I am not even going to read all 3 pages of this post, but I know what you are missing. Unfortunately, I don't know of anyone that can help you with your problems. I believe that you are suffering from a severe case of cabin fever. I would prescribe that you sit under a sun lamp until you are red in the face and need to empty those two beers in your hands to cool off. Hopefully summer will be here soon so you will have more time to spend outside and less time to spend on the computer asking question that there are no answers to. You might also consider a dog as a companion to help you through those lonely periods of the day...... /forums/images/graemlins/blush.gif /forums/images/graemlins/grin.gif /forums/images/graemlins/shocked.gif /forums/images/graemlins/wink.gif

thcri · Feb 25, 2004

( Henro...Your starting to scare me!! 

Scare you, Murf??? /forums/images/graemlins/cool.gif

I could not help but think I could even be more scary... /forums/images/graemlins/smile.gif

Let me try:

I think I might visit Minnesota SE one of these days /forums/images/graemlins/grin.gif

Murf's expression: /forums/images/graemlins/shocked.gif /forums/images/graemlins/shocked.gif /forums/images/graemlins/shocked.gif

/forums/images/graemlins/smile.gif /forums/images/graemlins/smile.gif /forums/images/graemlins/smile.gif )

Yeah visit, I can get you a good room at the Mayo Clinic, I got connections /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif

RogerH · Feb 25, 2004

Let me lend another explanation to the original question. Note that the torque (and horsepower) requirements of a hydraulic pump are proportional to both the pressure and the displacement (i.e. the flow from the pump). Therefore it is possible to generate the same horsepower with high pressure and low flow or low pressure and high flow.

Here is what may be happening. In low range, the tractor is slow, so you push the foot pedal down almost to the floor to get some decent speed. That makes the flow rate in the HST pump go way up. You hit the pile with the loader and the pressure goes up rapidly so that pressure X flow = more HP than your tractor has and it the engine dies.

Conversely, in high range you probably aren't pushing the pedal down all the way on a steep hill because real steep hills usually aren't paved and it would be way to bumpy a ride. As you go up the steep hill, the pressure rises to the relief setting, but since the HST pump flow is low, pressure X flow = less than available horsepower. Therefore the tractor stops moving but doesn't stall.

As you know, you can always prevent stalling if you can lift off the pedal fast enough. Lowering the flow rate when the HST pressure goes up keeps flow X pressure under the available power and keeps you running.

As some one else has pointed out, the John Deere 10 Series tractors does this for you automatically with Load Match.