Automatic TransmissionCh 39

• 3 spd, 4 spd OD, 5, & 6 spd automatic.

• 4L60E - 4T60E

Torque Converter• Operates by hydraulic force created by

transmission oil

• Between engine & trans. (filled w/ fluid)

• 3 Main parts

– Impeller

– stator

– turbine

• Converter multiplies twisting motion of crank shaft

T/C operation

• Impeller-input member, receives power from engine

• Turbine-output member, splined to transmission

• Stator-reaction member or torque multiplier– redirects fluid to enable torque multipication

• Pump drive hub-notches on converter shaft, ground 180deg. apart

TCC valve reversesfluid flow & causes thepiston to push against theturbine and cover

Planetary gear sets are the way different gears rations are achievedAutomatic transmission hold and input different combination of these gear sets to achieve ratiosRule to remember: external to external=direction change

external to internal =no direction change

T-39-1pg1001

Sli http://auto.howstuffworks.com/automatic-transmission3.htm de 1010

Types of planetary gear sets• Simpson gear set

– two gearsets share a common sun gear– most commonly used (simpson gear train)

• Ravigneaux set– two gear sets share a common ring gear– more compact– carries more load due to more tooth contact

Transmission Bands• Band-braking assembly around a drum

• takes up minimum space

• creates self energizing action

• paper (high speed) or metallic (low speed)

• Single wrap or double wrap

• Flexible (more self energized or Rigid (can hold more)

Trans Clutch Discs-Can hold or apply components-Clutch hub holds all components; cylinder, piston,piston return springs, seals, pressure plate, friction linings, steel plates, & return springs.

-Friction linings are cellular paper,graphite, & ceramic.

Bearings, Bushings, & thrust washers

Thrust washer - sliding bearing, made from copper, bronze, teflon, or nylon. Used with low speeds & low loads. Can be selectiveTorrington bearing - has small rollers, used at high speeds, & heavy loads. Can be selective

SealsStatic, dynamic, positive, non-positive

Lip Seals -seals around moving parts-spring & lip allow .0001 clearance-rubber seals used for non moving parts

Ring Seals-seal in excessive heat range-when positive seal is not needed-can be made from metal, teflon, or nylon

Hydraulics

• Pressure Regulating valves– Changes fluid pressure– changes shift feel & quality

• Flow directing valves– direct fluid to appropriate apply devices

• Trans Cooler– when fluid reaches 175 deg it varnishes– fluid will break down & oxidize (hard on seals)– cooler should be replaced or at least flushed

when rebuilding transmission

Hydraulics

Spool Valve