Rock crawling, wall climbing = no mud = clean Jeep
I used rock crawling as a demo because very low gear reduction is not much use in mud where you need more wheel speed to fling mud out of the treads and maintain forward momentum.
...on a mud/muskeg run you usually cant even tell what color the Jeep is under the slop.
I was a Jeep Jamboree TrailGuide for 10 years in Alberta/B.C. ... believe me I've seen it all.
Been upside down a few times and ran through rivers over my hood ....that washes some of the mud off
anyway, back on topic , Gear reduction "dumbed down"
It works very much like a mountain bike (with multiple front/rear sprockets )
the rear sprockets on the bikes rear wheel represent your transmission gears (1-5)
ALL stock 4x4 Rams (and Jeeps) have a Hi and Low range transfer case, Low is a "true" planetary gear reduction
represented by the two sprockets attached to the mountain bike pedals. (smaller sprocket is Low, larger one is Hi)
To climb the steepest hills you need the smallest gear up front (transfer case low range)
and the tallest cog on the rear sprocket (1st transmission gear)... and yes it is a true gear reduction...for the bike and the Truck/Jeep etc.
In Low range it takes several engine revolutions (or pedal strokes) just to get a single rear wheel/tire revolution.
This allows you to bring the engine revs up earlier, without stalling due to the increased work load, and brings the engine into its power band for climbing obstacles.
Doing it the opposite way does not get the engine into the power band because the revs are too low to reach peak torque and you stall out.
Hi range is the equivalent to using the Larger gear up front, smallest gear out back more suited for higher speed/downhill run.
A 4:1 reduction kit simply swaps your smallest front low range cog out for one with even fewer teeth than stock low. Giving you a 4:1 ratio instead of 2.72:1 gear reduction in low range, 4 Hi stays the same.
a Klune-V is an extra gear reduction step between the transfer case and the rear final drive that can drop ratio's to 11:1.
...that's a little harder to explain using the bike example but the end results would be like keeping the bikes two front pedal sprockets stock, but adding a third smaller sprocket with an even lower number of teeth.