Clutch schedule for an eightspeed transmission
Transmissions
The 8Speed block consists of four planetary gear sets and five clutches. The base shaft connects to the:
Planet gear carrier of the second planetary gear
Other gears through three forward clutches that determine the power flow path.
The follower shaft connects to the planet gear carrier of the first and fourth planetary gears. The other two forward clutches serve as brakes, grounding various gears of planetary sets two and three to the transmission housing.
This diagram shows a ninespeed transmission. The labels for the gear components are superimposed on the input and output gears. The table lists the gear and clutch components that are labeled in the diagram.
Label  Component 

P.G.1–P.G.4  Planetary gears, 1–4 
R  Ring gear 
C  Planet gear carrier 
S  Sun gear 
C–E  Forward clutches that control the power flow path 
A–B  Forward, braking clutches 
The drive ratio between the transmission input and output shafts follows from the elementary gear ratios specified for the gear blocks. The elementary gear ratios are
$${g}_{x}=\frac{{N}_{{R}_{x}}}{{N}_{{S}_{x}}},$$
N_{Rx} is the number of teeth in the planetary ring gear x, where x = 1, 2, and 3.
N_{Sx} is the number of teeth in the planetary sun gear x, where x = 1, 2, and 3.
The table shows the clutch schedule, driveratio expressions, driveratio default values, and the plowerflow diagrams for each gear of the 8Speed block. The schedule and gear ratios are based on the manufacturer data for the GM 8L90 eightspeed automatic transmission.
The letters in the clutch schedule columns denote the brakes
and clutches. A value of 1
denotes a locked state
and a value of 0
an unlocked state. The clutch
schedule generates these signals based on the Gear port input signal.
The signals are scaled through a Gain block
and used as actuation inputs in the clutch blocks.
The plowerflow diagrams show the power flow paths between input and output shafts for each gear setting. Power flow is shown in orange. Connections to the transmission housing (a mechanical ground) are shown in black.
Gear  Clutch Schedule  Drive Ratio Equation  Default Ratio  Power Flow  

A  B  C  D  E  
8  1  0  0  1  1  $$\frac{1+{g}_{2}}{{g}_{2}}$$  1.54:1 

7  1  0  1  1  0  $$\frac{1+{g}_{2}\left(1+{g}_{1}\right)}{{g}_{2}\left(1+{g}_{1}\right)}$$  1.18:1 

6  0  0  1  1  1  $$1$$  1:1 

5  0  1  1  1  0  $$\frac{\left(1+{g}_{3}\right)\left({g}_{2}{g}_{4}\right)\left(1+{g}_{1}\right)}{\left(1+{g}_{3}\right)\left(1+{g}_{4}\right)\left({g}_{2}{g}_{4}\right)\left(1+{g}_{1}\right)}$$  0.79:1 

4  0  1  0  1  1  $$\frac{\left(1+{g}_{2}\right)}{\left(1+{g}_{2}+{g}_{3}\right)}$$  0.59:1 

3  0  1  1  0  1  $$\frac{1+{g}_{3}+{g}_{4}}{\left(1+{g}_{3}\right)\left(1+{g}_{4}\right)}$$  0.48:1 

2  1  1  0  0  1  $$\frac{1}{\left(1+{g}_{1}\right)}$$  0.34:1 

1  1  1  1  0  0  $$\frac{1}{\left(1+{g}_{4}\right)}$$  0.22:1 

R  1  1  0  1  0  $$\frac{\left(1+{g}_{2}\right)}{{g}_{2}\left[\left(1+{g}_{1}\right){g}_{1}\left(1+g4\right)\right]}$$  0.26:1 

4Speed CRCR  4Speed Ravigneaux  6Speed Lepelletier  7Speed Lepelletier  9Speed