It was initially released in 1939 for vehicles. It is made of the fluid coupling and 3 planetary gears. They collectively make a few ahead and one particular reverse velocity. There's no clutch for engagement and disengagement in the motor. Most transmissions in modern autos use synchromesh to synchronise https://gearbox04681.blogsidea.com/40195911/the-best-side-of-gearbox