This topic has about the same degree of intensity/logic/emotions as a bunch of handgunners trying to decide which is better, wheelguns or autoloaders. I like 'em both. I use the autoloaders for target work and hunt with a wheelgun. (Incidentally, a 125 grain jhp out of a .357 Trooper MK III with a 6 inch barrel will take out a groundhog at 135 yards. /forums/images/graemlins/wink.gif) I know target shooters who use revolvers and hunters who use autoloaders. It's just a matter of what works for you in either case.
HST and/or gear have their proponents for different tasks, but anyone worthy of driving a tractor in the first place will be able to use either with good effect for whatever they want to do. I'm just trying to weigh a number of factors to let me decide where to spend my money when I finally get a replacement for my little Kubota. I don't know about the rest of you guys, but I have a lot of fun debating the merits of this or that feature and listening to what everyone thinks and what their reasons are. Of course, it helps a lot if the reasons given are based in logic rather than emotion for the learning process, but the emotional side adds to the fun, up to a point.
So far as I can tell, the following different types of transmissions are out there:
Non-synchro manuals like a pre WWII automotive crashbox. You can shift between forward gears on the move if you're good, but you need to stop between ranges and between forward and backward. Reverse is built into the main tranny and is part of the shift pattern.
Synchro manuals which are intended to be shifted from gear to gear while moving and take much less skill to avoid grinding. Reverse may be in the main tranny or as a choice among the ranges. You need to stop to change ranges or directions, but you'll have several speeds in reverse, often as many as you have forwards.
Shuttle shifts, which have the reverse and low or medium range selection positions aligned with each other to allow easy changes of direction. Some require clutching between direction changes and some don't, but you don't have to stop moving to shift the directional lever.
Power shuttles which are similar to the above, but you don't use a clutch, just move a lever usually located near the steering wheel. Shifting into reverse while moving forward is considered normal operating procedure and the tractor slows and reverses for you.
HSTs, which have what amounts to a hydraulic pump driving fluid to move the tractor. You control the speed and direction of the tractor through a valve usually controlled by foot operated levers. Many of these have a cruise control feature that locks in a given valve position by one means or another.
HSTs seem to be subdivided into several groups, I think. One group shifts the valves to neutral whenever a brake pedal is moved. A second group only does this when both brake pedals are moved. It seems some have the cruise control deactivated by a brake and some don't, but I think all will have the cruise deactivated by both brakes.
Lastly, and most complex on the development scale, are the electronically controlled hydros offered by Deere and maybe others. On these the controls for hydro are "drive by wire" to minimize the pedal pressure needed to keep the tractor moving under load. This, coupled with Kubota making reference to minimizing pedal pressure on their latest units, makes me believe that many hydros need a fairly heavy pressure on the pedals when the tractor is pulling hard.
I'd appreciate any corrections or additions to my little list. If you can put names with the different types, including brand, model, and tranny name, it might help the ignorant among us get a better grasp on this thing. For example, Kubota has an HST, a GST and an FST, while Deere has a collar shift and a sychroshift and maybe a shuttleshift and a powershuttle in addition to the hydro and the ehydro and on and on.
At least no one here has strongly favored a particular tranny type because of the color of the oil inside it -- yet!
