Chapter 14 Automatic Transmission Fundamentals
hypoid gears
Pinion type, instead of spiral bevel gears, allows lower contact point with ring gear, therefore lower car height. Also changes the axis of the input gear to the output gear 90 degrees.
sun gear
The central large gear in a planetary gear set
ring gear
The outer gear in a planetary gearset.
dual-clutch transmission
type of automatically shifting manual transmission in which two separate input shafts are connected to their own clutch. Shifting of the gears alternates between the two input shafts.
power-splitting transmission PST
type of hybrid transmission that splits the power flow going to the wheels from one or more sources.
fluid coupler
type of hydraulic coupling used on vintage vehicles to connect and transfer power from the engine to the transmission
coefficient of friction
value assigned to materials that describe the amount of friction when two objects slide against each other.
Thrust washer
A bronze or a hardened steel washer placed between two moving parts.
gasket
A compressible material placed between two surfaces to prevent leakage.
thrust bearing
Also called a torrington bearing, small flat roller bearing that almost resembles a flat washer.
gear ratio
The ratio of the speed of the driving member of a gear train to that of the driven member.
automatic transmission
Transmission that shifts automatically through the gears as the vehicle's speed increases
Continuously Variable Transmission
Transmission that uses a steel belt and sheaves to provide an endless amount of gear ratios.
Lock up converter
Type of torque converter that "becomes one" when the PCM energizes the TCC solenoid. During this state, there is no slipage between the engine rpm and the transmission input shaft.
Band
a metal device that wraps around a drum with friction material bonded to one side. This device squeezes the drum from rotating when the appropriate gear is selected.
extension housing
aluminum or cast iron enclosure for the transmission output shaft and bearings.
Overdrive
any gear ratio that results in torque reduction with increase in speed.
differential
component that allows power to flow to both wheels while allowing each wheel to go at different speeds such as during a cornering event.
planet carrier
device that holds planet gears in place keeping them equally spaced.
spur gear
gear that has straight cut gears
standard torque converter
hydraulic coupling device consisting of an impeller, turbine, stator, and housing. Connects the engine's power to the transmission
planetary gears
small gears that revolve around the sun gear.
Flex plate
steel plate that is thin and bolts to the crankshaft flywheel. Typically has a ring gear for the starter as part of its construction.
helical-cut gear
type of gear in which the teeth are cut in a spiral down the axis of the gear. This allows for one or more teeth to be in contact at all times and makes the gear stronger.
One-way Clutch (overrunning clutch)
type of holding device that stops the rotation of a component one way but allows for it to over run the other direction.
multi-disc clutch
type of holding device used by automatic transmissions to stop the movement of one component of a planetary gear set. It uses several thin friction discs and flat steel discs. When applied, all of these discs are squeezed into one solid unit.
series-parallel hybrid drive train
type of hybrid drive train that can function as both a series hybrid and a parallel hybrid
Parellel hybrid drive train
type of hybrid transmission in which power can flow from either a gasoline engine or an electric motor.
series hybrid drive train
type of hybrid transmission in which power flows from the engine through an electric motor. The electric motor supplements the power from the engine to the wheels.
