|
 The
Transmission's primary job is to allow the
engine to operate in its narrow range of speeds
while providing a wide range of output speeds.
You've
probably never tried driving a manual
transmission car using only third gear. If you
did, you'd quickly find out that you had almost
no acceleration when starting out, and at high
speeds, the engine would be screaming along near
the red-line. A car like this would wear out
very quickly and would be nearly undriveable.
So
the transmission uses gears to make more
effective use of the engine's torque, and to
keep the engine operating at an appropriate
speed.
The
key difference between a manual and an automatic
transmission is that the manual transmission
locks and unlocks different sets of gears to the
output shaft to achieve the various gear ratios,
while in an automatic transmission, the same set
of gears produces all of the different gear
ratios. The planetary gear set is the device
that makes this possible in an automatic
transmission.
|
