TEST RESULTS!
Probably no one is interested in this, but I did it so I'm going to post it. First, it was 18 degrees this morning (got down to 8 last night) and my tractor sits in an unheated shed with three sides and out of the sun. The glow plugs auto-cycle only. They ran for about 10 seconds and the tractor turned over three times and started. It hacked for about two seconds and then ran fine. Throttle was set to about 1100 rpms. I cleared the drive for about 30 minutes so it was warmed up, then I went to my steepest navigable hill.
The range shifter was in MED-Rabbit. For reference, top speed in this range and setting is 7.4 mph. Auto H-DS was set to OFF. In each instance I climbed the hill with the hydro pedal mashed to the floor and operated only dual functions of the loader.
1500 RPM: as soon as I took off, dropped to 1400, then dropped to about 1200 with loader operation added in.
1700 RPM: dropped to 1600 at GO, then to about 1300 with loader added in.
1800 RPM: dropped to 1700, then about 1450-1500.
2000 RPM: dropped to 1800, then 1600.
2400 RPM: dropped to 2200, then 1900.
So it dropped more the higher the revs were. Of course, my speed was a lot faster with higher revs, too. I then tried it in MED-Turtle. Top speed in this range is 4.4 mph.
1500 RPM: dropped to 1400, then 1300.
1800 RPM: dropped to 1700, then 1600.
2000 RPM: dropped to 1800 and stayed.
2400 RPM: dropped to 2200 and stayed.
Just for kicks, I put the range shifter in LOW-Rabbit. The top speed in this range is 3.6 mph.
1500 RPM: dropped to 1400 and stayed.
1800 RPM: dropped to 1700 and stayed.
2000 RPM: no drop, no drop.
2400 RPM: no drop, no drop.
I usually putt around the yard in MED-Rabbit with the revs anywhere from 1500-1800. I expect some change in engine note from idle (no load) to moving/working (under load).
I think something huge that is being overlooked here is that MED-Rabbit has a top speed that exceeds 10th gear on the GST model or 2nd-High on the manual shift model (both of those have a top speed of 6.9 mph). I don't think anyone would put their GST in 10th or 11th gear and try to crawl up a steep hill while working the loader at half throttle where the engine is only making a portion of its rated hp. Yes, the HST pump is variable but the main gear it is driving isn't.