Just because I felt like geeking out a bit:
Rocklobster gearset. It's not accurate for a number of reasons, but high ratio should be right. I *think* low is also right, but aaaanyhew it gives you an idea of what the gears *look* like in motion.
If you want to know how to work out how to work out the final drive ratio of a t-case, it's this:
We assume that the gears are in order, top to bottom, in columns
(a)
(b)(d)
(c)(e)
So (a) is the input shaft, (c) is the high ratio output, (e) is the low ratio output gear, and (b) and (d) are the intermediary gears in the middle.
In high ratio, (d) and (e) are not connected to output, and power goes from (a) to (b) to (c). In low ratio (c) is not connected, and power goes from (a) to (b) which turns (d) 1:1, then to (e).
So the math goes like this: (c) divided by (a) gives high ratio (you can ignore (b)) That is to say, c/a=high ratio. To get low, you do this: b/a/(d/e)=low ratio. So altering high ratio gears also alters low ratio gears, but altering low ratio gears does not alter high ratio gears.
Also, because the spacing between the centre line of the input shaft and the centre line of the second gearset (b and d) is smaller than the spacing between the second gearset and the output shaft, your high ratios are limited not just by gear strength vs tooth count (as with the low ratio specific gears) but also physical dimensions - as (a) gets smaller, (b) has to get bigger, and so (c) also has to get smaller - and vice versa. Because of this, you can never get a 1:1 high ratio without altering the way the gears mount in the case - i.e. cutting and welding the transfer case shell, or (more likely) making a whole new case on a CNC machine with new spacing.
Sorry if that's over-simplified for those of you who are engineers (or, it might be wrong somehow - but I'm working this out as I go along) but I'm just, as I said, geeking out.
