You are fortunate to have a low hour Kubota
L3430 as your first tractor.
I have an
L3560 HST, your tractor's direct descendent, as my third tractor, my second Kubota HST tractor.
HST transmissions deliver max torque at low ground speed. Therefore your HST has three primary ranges so you can move over the ground at varying speeds.
[
In addition, your L3430 may have a HST+ feature offering two HST sub-ranges within each HST primary range via a two-position wand shift on the steering column.] ***
Your Operator's Manual will have a page showing speed over the ground in each of the three HST primary ranges and three sub-ranges, selected by the two-position wand shift on the steering column.
Max speed in each HST
+ range on my
L3560 are:
HST
+(1) LOW = 2.1 mph, MED = 4.3 mph, HIGH = 09.9 mph. ***
HST
+(2) LOW = 3.5 mph, MED = 7.1 mph, HIGH = 16.4 mph.
***
My guess is HST remained in HST+(1) sub-range while HST primary range was shifted between LOW and MEDIUM.
Did you have Four-Wheel-Drive engaged as you went up hill?
You do not have an 'early version' of the HST transmission.
Johnson City Kubota & Equipment, LLC
"Hydrostatic Drive". There is nothing new-fangled about this transmission. It has been around for a long time. Nevertheless, it is among the least understood of all transmission types. It is common for it to be compared with the automatic transmission in an automobile. They are different animals altogether. The only similarity is that they both use oil to transmit power. Tech types describe a hydrostatic transmission as being a variable-displacement hydraulic pump, driving a fixed-displacement hydraulic motor. Now, to the un-initiated, that's a bunch of gobblety-gook. So let's s t r e t c h that explanation out a little bit. Any hydraulic pump's sole purpose in life is to deliver some amount (volume) of fluid to some other device, which in turn moves whatever is attached to that device, causing work to be performed. This can be either through linear motion (as in a hydraulic cylinder), or rotary motion (as in a hydraulic motor). If we want to control how quickly our gizmo moves (or rotates), one way we can do that is to vary the amount of oil that the pump sends to it. If our pump is delivering four gallons a minute, things will happen four times faster than if we only pump one gallon a minute. Since we can control our pump's output, we can control the motor's speed. Now, unless we just want to go around in a circle all day long, we've got to figure out how to change directions. No problem. Most hydraulic motors don't care whether they are turned clock-wise or counter-clockwise. Since a hydrostatic transmission operates in what is called a "closed loop" system, consisting of the pump and motor units, we simply reverse the direction of flow from the pump, causing the motor to operate in the opposite direction. Oh, by the way, "closed loop" means that a fixed amount of system oil can be considered as trapped, or contained, within the pump/motor circuit. Assume that a certain hydro transmission is of a size that it contains 500 ml of oil within the closed loop. That volume remains constant, never changing regardless of tractor speed or direction. So, for any change that we make in the output volume and/or direction of flow of oil from the pump section, a reaction must occur in the motor section, inducing a corresponding change in motor speed and/or direction. In reality, there is a certain amount of oil that is constantly escaping from and being replenished back into the closed loop section of the transmission. This is because a small amount of oil is allowed to flow all around the various components for lubrication and cooling purposes. The greatest advantage of a hydrostatic transmission is the ability to infinitely vary the ground speed, and quickly change directions. It's like having a million speed transmission. If you need a travel speed of 1.200589 MPH, it is available. Another advantage is reliability. This transmission is, by way of design, pretty much self-protecting from operator abuse. Also, on foot pedal controlled transmissions, there is a built in safety factor in that you need only lift your foot from the pedal, to bring the tractor to a controlled stop. The only disadvantage of note is a slight loss of power at the PTO shaft. You must also remember to apply the parking brake should you park the tractor on a slope. Hydrostatic is, by far, the best choice for turf mowing applications or for any tasks that require constant speed and direction changes within a small area. Loader work is another area where hydrostatic is a great choice.
LINK:
http://www.tractorbynet.com/forums/...5995-hydrostatic-transmission-hilly-land.html
