Automatic vs manual transmissions. How do they work, what are the similarities and differences in the way they
operate and what are the benefits and drawbacks of each?
Both transmissions carry out the same function by using several gear ratios to use the somewhat limited speed
(between 750rpm to 8,000rpm) and one directional rotation of the crankshaft and allow the vehicle to idle, reverse and
facilitate various driving conditions.
Both are located between the engine and the driveshaft or axles and can be temporarily disconnected (internally)
from the engine to facilitate stopping, idling and changing of gears.
Both transmissions can be improved or adapted as continuously variable transmissions and
tiptronics are built on automatic technology whilst automated manuals and
dual clutch are basically manuals with
computer controlled clutches.
All of the transmissions mentioned above are sometimes considered as automatics as you'll see an automatic gear shifter
but I will be discussing automatics and manuals in their basic form.
The most known difference is that the automatic changes the drive or forward gears on its own and you need to
switch between gear ratios yourself with a manual.
The first difference between the operation of the two is a torque converter vs a clutch as the method of connecting
to the engine. Both are housed between the engine and transmission although they're mostly inside the transmission
The torque converter uses a method of viscous coupling to connect which is by using a thick liquid to transfer the
power and doesn't provide a direct connection so it doesn't need to be disconnected.
A clutch uses an adjustable plate to provide a direct connection to the engine and must be directly disconnected
by pressing the clutch pedal to facilitate idling and gear changes.
The automatic uses sensors and hydraulic pressure to select and change the gear whilst the manual provides a link
from the transmission to the shifter inside the car to allow you to select and change the gear.
Another difference in their operation is automatics use planetary gears and manuals use gears along multiple shafts
as the actual gear ratio system.
Planetary gears works by using a system of a sun gear, a planet gears and a ring gear. There may be multiple sets of
planetary gears in one transmission.
The sun gear is at the center with the planet gears revolving around the sun gear but inside of the ring gear. Each gear
can remain stationary, be the input or outward ratio and each combination provides a different overall gear ratio.
The shaft gears have multiple shafts with gear ratios including an input and output shaft and all the gears rotate along
both shafts. A internal clutch connects to the desired ratio as you change gears.
In the end an automatic transmission offers operational simplicity and ease of use while the manual transmission offers
increased driver involvement, better control of the engine's power and mechanical simplicity.
So that concludes my brief discussion on automatic vs manual transmissions. Most people already know which one they prefer
and it appears that the operational simplicity and ease of use appears to the preference for most passenger vehicles.