HST Plus Follow-up
I now have over 100 hours on my GL3240 and the Auto-Throttle has been ON for the last 50+ hours. The trick to making Auto-throttle useful 100% of the time was adjusting the Auto-throttle linkage as suggested by a couple of very helpful TBNers in another thread.
The GL 40's engine throttle is controlled by two cables. They are "attached" so that either or both of them can be used to increase the engine speed. One cable is permanently connected to the hand throttle. The other is optionally connected to the HST pedal via the Auto-throttle lever. You can adjust the Auto-throttle cable so that the HST pedal does not begin to increase the engine speed until after the tractor begins moving (forward or reverse). The result is that with Auto-throttle ON a GL 40 starts moving as if you had the hand throttle set to idle but as you continued to press down on the HST pedal you simultaneously pulled back on the hand throttle.
So contrary to my previous post...
the GL 40s HST Plus CAN function much like the throttle on the L39's GST. The main difference being the number of "gears" you can select without stopping. The GST allows you to select any of 12 forward (8 reverse) without stopping. Although the GL40s HST Plus has 6 forward (6 reverse) settings, you can only select 2 forward (2 reverse) of them via the D-HS lever (rabbit-turttle) without stopping. But you also have a variable "overdrive" range in forward (AKA Cruise Control).
IOW the GL40's HST Plus Auto-throttle cable can be adjusted so that with the HST lever set to M, you can use the HST pedal, H-DS toggle and Cruise Control to approximate an L39's Throttle/GST ranges from 4-8. In L the HST Plus approximates a GST 1-4, etc.
FWIW if I need more power (e.g. a very heavily loaded FEL, pushing into a pile of heavy soil, etc ) I just pull back on the hand throttle before stepping on the HST. This has the effect of setting the minimum engine speed (AKA power) but still allows the HST pedal to act as a throttle above that minimum RPM.
Talon Dancer
ps Many thanks to the helpful TBNers that gave me the tip required to make my GL3240 work like I orginally expected