<VV> Powerglide ratios

[Padgett]

Are two elements to figuring the gear ratios in a PG, being the gears 
(1.82:1 Low and 1:1 high) and the multiplying effect of the torque 
converter (2.6:1 at stall) for an effective starting gear ratio of  4.73:1 
which is actually lower than first gear in a four speed. There is about a 
5% slip in high above 3000 rpm so at 60 mph with a 3.55 that is another 150 
rpm.

Reason for a two speed goes back over 100 years and the Model T Ford had 
one that was manually shifted. The epicyclic or planetary gearbox is very 
compact since all gears including reverse fit inside one another and gears 
are selected by stopping one element and allowing the rest to rotate but is 
limited to one geared ratio in forward and reverse plus "everything locked 
up" which gives a 1:1 top gear ratio.

You can stack planetary gearsets which is how you get more than two speeds 
- can get four forward "gears" (and two reverse gears) from two stacked 
planetaries.

But the simplest, shortest, and cheapest is a two speed plus reverse.

Padgett