BX2200 Hydro power? Slipping???

[Henro]

<font color="blue"> I think I started slow with the hydro pedal and when nothing happened I increased the pressure expecting the motor to lug until I could stall it out. This never happened. Instead it started lugging down, got to a point and stayed there. No matter how hard I pressed the pedal the engine rpm niether increased or decreased. </font>

Not trying to beat a dead horse, but this puzzles me.

I can tell you with certainty that my B2910 would stall if I did the same thing.

In my mind your bx should have stalled. Are you sure one of the rear wheels was not slipping?

If that happened with my B2910, I would be worried.

Can anyone clarify this? Am I missing something obvious? Bxbuster...maybe you did not push the hydro pedal down all the way, and there fore did not reach a stall condition?

That is probably it. I guess that is possible. I wish I was home with my tractors so I could do a test. For example, I think if I put my loader bucket against a large tree and slightly push the forward directional pedal, I will exert force on the tree but will not slip the wheels or stall the engine. More pedal, more force...to the point at which the wheels slip OR the engine stalls... Somewhere in between there is a point at which the wheels do not slip AND the engine does not stall, right???

Better stop now...I`m confusing myself... /forums/images/graemlins/blush.gif

 

[Bird]

</font><font color="blue" class="small">( I can tell you with certainty that my B2910 would stall if I did the same thing. )</font>

Maybe so, Bill, but I've encountered the same result as bxbuster with my B2710, but only under the rarest of conditions. If I charged into something too fast, yes, the engine would stall, and if I went into it properly and slowly, then came down too much on the hydro pedal, I'd spin the wheels. But in high range, I've been down in a couple of holes and tried to come up a steep bank out of the hole, slowly, and when the tractor wouldn't move forward or spin the wheels, gradually coming down on the pedal would cause the engine to strain, but not die.

Now there's a way to make it do the same thing in low range. Try lowering one or more ripper teeth, drive forward and catch them under a good strong root that you can't budge in any way (you may spin the wheels). Now try to raise the 3-point hitch. That will pull down on the back end of the tractor putting an extra heavy load on the rear tires to the point that they cannot spin. Then start easing down on the hydro pedal, very slowly, and I'm bettin' you can push it all the way down without killing the engine or spinning a wheel.

In other words, it's not something that's going to happen in most normal operating circumstances, but it can be done and the relief valve will function.

 

[Henro]

<font color="blue">I can tell you with certainty that my B2910 would stall if I did the same thing.
</font> is what I thought...

Guess I better start telling that story with uncertainty, eh Bird? /forums/images/graemlins/smile.gif

Probably will not get a chance to try that experiment until spring...still got to learn more about HST power transmission too...it is not intuitively obvious to me how a pressure relieve valve would operate under a gentle pressure increase and not under a shock like it would seem to experience when one lugs and stalls his engine.

In my mind I guess I equate the hst transmission to positive displacement pump and hydraulic motor with no leakage...

 

[jrlichina]

<font color="blue">In my mind I guess I equate the hst transmission to positive displacement pump and hydraulic motor with no leakage... </font>

Your HST is a variable displacement pump with a fixed displacement motor. The internal leakage is compensated by the charge pump. The check valves make sure the fluid is flowing in the correct directions and the relief valves keep the system from being damaged by excessive pressure. A faulty relief valve could cause the tractor to stall. If it doesn't release and since hydraulic fluid is not compressable the HST would be in a state of hydrostatic lock which would stall the engine.