Main Components and Functions

Main Components and Functions

Part 2 of 3:

Part 3 of 3:

Automatic Transmission-Sectional View

Torque Converter
The torque converter transmits and multiplies torque. The torque converter is a device which includes four elements:
^ The impeller assembly
^ The turbine assembly
^ The reactor assembly
^ The clutch and damper assembly





The standard torque converter components operate as follows:
^ Rotation of the converter housing and impeller set the fluid in motion.
^ The turbine reacts to the fluid motion from the impeller, transferring rotation to the geartrain through the input shaft.
^ The reactor redirects fluid going back into the impeller, providing for torque multiplication.
^ The clutch and damper assembly dampens powertrain torsional vibration and provides a direct mechanical connection for improved efficiency.
^ Power is transmitted from the torque converter to the planetary gearsets and other components through the input shaft.

Geartrain

Power is transmitted from the torque converter to the geartrain components through the input shaft and forward clutch cylinder.
^ By holding or driving certain members of the gearset, five forward ratios and one reverse ratio are obtained and transmitted to the output shaft. The ratios are as follows:





a Special operating strategy is enabled when transmission temperature is less than -15°C (5°F)

Input Shaft
The input shaft is supported by two bushings in the stator support. End positioning of the input shaft is controlled by the splines in the converter turbine and the overdrive planet assembly.

Output Shaft
The output shaft is supported by a press fit radial bearing in the extension housing. It is positioned by a bushing in the forward clutch cylinder, which in turn is positioned by the case center support and the center shaft.

Overdrive and Coast Clutch System
The Overdrive (OD) and coast clutch system consists of the following:
^ OD friction clutch assembly
^ Coast clutch cylinder
^ Overdrive sun gear
^ Coast clutch input hub
^ Coast clutch friction clutch assembly
^ OD planetary
^ OD ring gear
^ Center shaft

The OD clutch piston has bonded lip seals. It is installed into the piston bore, cast into the pump, and held in place by the return spring. The return spring is attached to the pump with three bolts. The OD clutch separator plates and pressure plate are splined to the case. The three OD friction plates are splined to the coast clutch cylinder. The OD clutch assembly is positioned between the pump face and a snap ring, and installed into the case adjacent to the OD pressure plate. The OD sun gear is pressed into the coast clutch cylinder.

The coast clutch piston is also a bonded lip seal type. The coast clutch piston is installed into the coast clutch cylinder and held to the cylinder along with the clutch return spring by a snap ring. The separator plates are splined to the case.

The coast clutch pressure plate is a mechanical diode One-Way Clutch (OWC) assembly. The OWC is splined to the coast clutch cylinder and held in with a snap ring. The coast clutch friction plates are internally splined to the coast clutch hub, which is held to the OD carrier by four bolts. Absorbing the load between the OD carrier and the OD sun gear is the "captured" thrust bearing, part of the OD planet assembly.

On the opposite side of the OD planet is a thrust bearing positioned between the carrier and the shaft. Splined to the center shaft and retained by a snap ring is the OD ring gear. On the opposite side of the center shaft is a thrust bearing that separates it from the center support. The overdrive/coast clutch system is driven clockwise by the input shaft, one end of which is splined to the torque converter cover, and the other end is splined to the OD carrier.

Center Support and Intermediate Clutch
The center support is rigidly held to the case by a tapered snap ring. The flat side faces toward the center support and the gap at 6 o'clock. The center support is also retained to the case by two hollow feed bolts. Both the forward clutch feed bolt and the intermediate clutch feed bolt are installed through the solenoid body worm trail of the case. The forward feed bolt has an orifice spacer installed on top of the bolt head.

The center support acts as the intermediate clutch cylinder piston bore, and also provides the snap ring groove to retain the bonded seal type intermediate clutch piston and the return spring. A black phenolic thrust washer is positioned by its two tabs into two holes in the center support. A seal pack containing two Teflon seals is pressed onto the center support hub below a pressed-on steel sleeve. The sleeve acts as the journal for the direct clutch cylinder bushings.

The intermediate clutch separator plates and pressure plate are externally splined to the case and the friction is internally splined to the direct clutch cylinder. The case and the center support define and limit the stroke of the intermediate clutch.

Forward Drive System
The forward drive system consists of the following:
^ Direct clutch assembly
^ Forward clutch assembly
^ Forward ring gear
^ Forward planetary assembly
^ Forward/reverse input shell assembly

The direct clutch "robbed cylinder contains the following:
^ A bonded lip seal piston
^ A direct clutch return spring
^ A direct clutch bonded lip seal balance piston

These components are held in by a snap ring to the direct clutch cylinder.
The direct clutch separator plates and pressure plate are splined to the direct clutch cylinder and held by a snap ring. The direct clutch friction internally splined plates mate with the "robbed splines on the forward clutch cylinder. The forward clutch has a bonded lip seal piston, a beveled design return spring, and a bonded lip seal balance piston which are held to the cylinder with a snap ring.

The forward clutch cushion wave spring is splined to the cylinder, as are the separator plates and pressure plate and are held together with a selective snap ring. The forward clutch friction is splined to the forward ring gear.

Positioned on the center support hub is a thrust bearing to locate the forward clutch cylinder. There is a thrust bearing positioned between the direct clutch cylinder and the forward clutch cylinder. There is also a thrust bearing positioned between the forward clutch cylinder and the forward ring gear; and between the forward planet and the forward clutch cylinder. There is a thrust washer separating the forward carrier from the forward ring gear hub. The six gear forward planet has a black, phenolic lube dam which snaps onto the rear of the carrier body. Into the center of the input shell is the forward/reverse sun gear positioned by a spacer and held in by a retaining ring.

Low and Reverse Drive System
The low and reverse drive system consists of the following:
^ Reverse side of the forward/reverse sun gear
^ Reverse planet assembly
^ Reverse ring gear and hub assembly

The reverse ring gear and output shaft hub assemblies are splined to the output shaft. The reverse bonded lip seal piston installs into the case. The return spring is held to the case by a snap ring.

The reverse separator plates are splined to the case, and the friction plates are splined to the reverse carrier. The pressure plate is combined with a mechanical diode one-way clutch, which is splined to the case and held in with a snap ring. There is a thrust bearing located between the case and the output shaft hub; and between the output shaft hub and the reverse sun gear. Located on both sides of the reverse carrier are white, phenolic thrust washers (four-tabbed).

Apply Components
The following information describes the operation of the two one-way clutches.

Overdrive One Way Clutch (OWC) Mechanical Diode
The overdrive OWC mechanical diode is a one-way clutch which also acts as the coast clutch pressure plate. It provides direct drive through the overdrive gearset when in power on mode. It overruns in power off mode or when the overdrive clutch is applied.

Engine torque is transmitted in first, third, and fifth gears while the range selector lever is in the (D) position. The input shaft drives the overdrive carrier clockwise. The overdrive carrier has the coast clutch hub bolted to it which also turns clockwise. The overdrive sun gear would turn counterclockwise, but is held from turning by the coast clutch mechanical diode. The input shaft turns the same speed as the center shaft and transmits torque through it.

In second, fourth and sixth gears the overdrive clutch is applied, the mechanical diode overruns and holds the overdrive sun gear fixed to the case. This causes the overdrive planet to walk around the sun gear and over-drive the overdrive ring gear.





Overdrive One-Way Clutch Mechanical Diode

Low/Reverse Mechanical Diode
The low/reverse clutch mechanical diode is a one-way clutch which also functions as the low/reverse clutch pressure plate. The low/reverse mechanical diode has fewer external splines than the coast clutch mechanical diode. The low/reverse mechanical diode external splines mate with the case and the internal splines mate with the reverse ring gear/reverse planet assembly.

In first and second, the center shaft drives the forward cylinder clockwise. The forward clutch is applied and holds the forward ring gear, driving it clockwise. The forward planet provides a counterclockwise resisting torque and the forward/reverse sun gear is driven counterclockwise. The low reverse clutch is off. The low/reverse mechanical diode holds the reverse planet carrier body and allows the forward/reverse sun gear to drive the reverse planet gears which in turn drive the output shaft ring gear and hub assembly. The forward planet and output shaft hub are both splined to the output shaft.





Low/Reverse Mechanical Diode-One-Way Clutch