Originally Posted By: Alex_V
I regularly operate several pieces of Kubota equipment with hydrostatic transmissions. In a system such as this, which puts the fluid under more stress at the same ground speed: wide open pedal in low range, or, say, 1/3 pedal in high range?
That's an interesting question that I don't know the answer for. I think that as long as you have proper engine RPM for the HST system to run and cool correctly, it won't matter too much regarding fluid stress in either scenario (just my opinion). You get more torque in low range and more speed in high range. I was taught to run the engine rpm at a minimum of 1700rpm to ensure proper HST cooling and operation. I generally don't run mine lower than 2000 rpm when doing work. You adjust the engine RPM above 2K, select low vs. high range, and foot pedal to match your work conditions (Low speed high torque plowing vs. high speed low torque road driving.). You don't want to lug the engine AND you do not want cavitation and excess HST heat with too low of engine rpm (with resulting low HST pump circulation).
Hope I'm not preaching to the choir here, and you are just asking your question, already knowing about proper engine/HST operation. Maybe it will help someone else here new to HST operation. It looks like the newer Kubotas have an ECM that adjusts engine speed and HST pump operation somewhat automatically.