Reverse Gear

Reverse is very similar to first gear, except that instead of the small sun gear being driven by the torque converter turbine, the bigger sun gear is driven, and the small one freewheels in the opposite direction. The planet carrier is held by the reverse band to the housing. So, according to our equations from the last page, we have:

Ratio = -R/S = 72/36 = 2.0:1

So the ratio in reverse is a little less than first gear in this transmission.

Gear Ratios
This transmission has four forward gears and one reverse gear. Let's summarize the gear ratios, inputs and outputs:

Gear
Input
Output
Fixed
Gear Ratio
1st
30-tooth sun
72-tooth ring
Planet carrier
2.4:1
2nd
30-tooth sun
Planet carrier
36-tooth ring
2.2:1
Planet carrier
72-tooth ring
36-tooth sun
0.67:1
Total 2nd
1.47:1
3rd
30- and 36-tooth suns
72-tooth ring
1.0:1
OD
Planet carrier
72-tooth ring
36-tooth sun
0.67:1
Reverse
36-tooth sun
72-tooth ring
Planet carrier
-2.0:1


After reading these sections, you are probably wondering how the different inputs get connected and disconnected. This is done by a series of clutches and bands inside the transmission. In the next section, we'll see how these work.