Main Components and Functions
Main Components and FunctionsTorque Converter
The torque converter couples the engine to the turbine shaft in the transmission. The torque converter transmits the driving force from the engine through the use of fluid. The torque converter assembly houses the turbine hub, turbine, stator, impeller, and the torque converter clutch piston.
Torque Converter -Clutch
The Torque Converter Clutch (TCC) couples the turbine hub and the turbine shaft spline. During lockup, the TCC slides on the turbine hub and is pressed against the converter cover. The engine force is transmitted to the transmission with no fluid slippage within the torque converter.
Geartrain
Turbine Shaft
The turbine shaft connects the torque converter to the transmission geartrain. The turbine shaft is hollow to allow the oil pump shaft to run through it. The turbine shaft splines to the turbine inside the torque converter and the reverse clutch drum and the direct clutch cylinder.
Differential
The differential uses an open-type design that provides operation in the following ways:
^ Both drive axles rotate with transmitted torque at the same speed when the vehicle is moving forward.
^ Each drive axle rotates with the transmitted torque at a different speed when the vehicle is cornering.
^ If one drive axle is stationary, the other axle rotates with transmitted torque.
Apply Components
Band - 2-4
The 2-4 band locks the rear sun gear and drum to the transmission case. The 2-4 band encircles 2-4 band drum and small sun gear and operates during different conditions depending on the engine application. One end of the 2-4 band is secured to the anchor strut, the other end to the 2-4 band servo retainer.
Band - 2-4, Servo
When hydraulic pressure is applied between the 2-4 band servo retainer and the servo band piston, the servo band piston overcomes the spring force and causes the 2-4 band to lock 2-4 band drum and small sun gear.
When hydraulic pressure is applied between the servo band and the transmission case, the servo band piston is pressed toward the servo retainer side. This allows the 2-4 band to expand by its own spring force and release the rear sun gear and drum.
When hydraulic pressure is applied simultaneously between the servo band piston and 2-4 band piston retainer and the servo band piston and ' the transmission case, the servo band piston is pressed toward the servo retainer side due to the difference in surface area. The 2-4 band drum and small sun gear is released and rotates freely.
Clutches - Forward
When hydraulic pressure acts upon the forward clutch piston, the forward clutch disc pack is pressed tightly together, and the rotation of the turbine shaft is transmitted through the reverse clutch drum and one-way clutch to the primary sun gear.
Clutches - Coast
When hydraulic pressure acts on the coasting clutch piston, the coasting clutch disc pack is pressed tightly together, and the rotation of the turbine shaft is transmitted through the reverse clutch drum, the coasting clutch drum, and one-way clutch inner race, to the primary sun gear. With the coasting clutch engaged, the forward clutch is engaged, resulting in the one-way clutch becoming locked. Without the coasting clutch engaged, the one-way clutch will overrun during deceleration.
The return spring is common for the forward clutch and the coasting clutch.
Clutches - 3-4
When hydraulic pressure acts on the 3-4 clutch piston, the 3-4 clutch disc pack is pressed tightly together, and the rotation of the turbine shaft is transmitted through the 3-4 clutch cylinder and carrier hub to the front planet. The 3-4 clutch operates during third and fourth gear operation.
Clutches - Reverse
When hydraulic pressure acts on the reverse clutch piston, the reverse clutch disc pack is pressed tightly together, and the rotation of the turbine shaft is transmitted through the reverse clutch drum to the 2-4 band and small sun gear. The reverse clutch operates during reverse movement of the vehicle.
Band - 2-4, Servo
When hydraulic pressure is applied between the servo retainer and the servo piston (2-4 band engagement side), the servo piston overcomes the spring force and acts on the 2-4 band, locking the 2-4 band drum and small sun gear. When hydraulic pressure is applied between the servo piston and transmission case (2-4 band disengagement side), the servo piston is pressed toward the servo retainer side. The 2-4 band expands by its own spring force, releasing the 2-4 band drum and small sun gear.
When hydraulic pressure is applied simultaneously between the servo retainer and the servo piston and between the servo piston and transmission case, the servo piston is pressed to the servo retainer side as a result of the difference of the surface area between the two, releasing the 2-4 band drum and small sun gear. The 2-4 band operates during second gear and fourth gear.
Clutches - Low/Reverse
When hydraulic pressure acts on the low/reverse clutch piston, the low/reverse clutches are pressed tightly together, and the transmission case and the low/reverse clutch inner race are connected. The rotation of the front planet stops when the low/reverse clutch is applied. This brake operates during manual low (first gear) and reverse.
One-Way Clutches
The forward one-way clutch on the front planet is a roller-type clutch. The one-way clutch allows rotation in one direction only. If the clutch tries to rotate in the opposite direction, the rollers are forced into the smaller slots of the gauge and the outer race is secured to the inner race. The low one-way clutch on the primary sun gear is a sprag-type clutch. If the clutch tries to rotate in the opposite direction, the sprags become wedged between the inner and outer races and rotation is stopped.
Hydraulic System
Fluid Pump
The front pump support and gear provides the volume of fluid required to charge the torque converter, main control valve body, cooling system, lubrication system, and hydraulic apply devices. A variable-capacity, roto type pump is used for discharge efficiency and reduced fuel consumption. The front pump support and gear is shaft driven by the torque converter cover.
Filter
All fluid drawn from the transmission fluid pan by the front pump support and gear flows through the filter. If a transmission is to be repaired for a contamination-related failure, always use a new filter and grommet.
Main Control -Valve Body
The main control valve body houses the hydraulic valves and shift solenoid valves. These valves direct fluid flow, restrict fluid flow, and change fluid pressure. The main control valve body receives signals from the solenoid valve body and changes electrical signals into hydraulic actions. The actions control the operation of the hydraulic clutches and the 2-4 band, and supply lubrication to the transmission. The main control valve body consists of four sections: the upper control valve body, main control valve body, premain control valve body, and the lower control valve body. The main control valve body also contains the electronic pressure control solenoid.
Accumulators - 1-2
The 1-2 accumulator reduces shift shock when shifting from first to second gear. The accumulator piston is normally pressed to the right by line pressure. When there is a shift from first to second gear, the 2-4 band engagement pressure pushes the accumulator piston slowly to the left. As a result, the 2-4 band engagement pressure builds up slowly, reducing the shift shock when there is a shift from first to second gear.
Accumulators - 2-3
The 2-3 accumulator reduces shift shock when shifting from second to third gear. The accumulator piston is normally pressed to the left by line pressure. When there is a shift from second to third gear, 3-4 clutch engagement pressure pushes the accumulator piston slowly to the right. As a result, the 3-4 clutch engagement pressure builds up slowly, reducing the shift shock when there is a shift from second to third gear.
Accumulators - N-D
The NEUTRAL-DRIVE (N-D) accumulator moderates a rapid increase in hydraulic pressure during forward clutch engagement. This reduces shift shock when the D range is selected from NEUTRAL. In the NEUTRAL position, line pressure is constantly applied to the right side of the accumulator piston, pushing it, to the left. When the D range is selected from NEUTRAL, line pressure which engages the forward clutch is applied to the left side of the N-D accumulator by the manual valve. As a result, the combination of line pressure and spring force overcome the line pressure on the right, moving the accumulator piston gradually to the right. This movement of the piston moderates a rapid increase in line pressure.
Accumulators- N-R
The NEUTRAL-REVERSE (N-R) accumulator reduces shift shock when shifting from NEUTRAL to the REVERSE range (R). The accumulator piston is normally pressed to the left by spring force and line pressure. When there is a shift from NEUTRAL to REVERSE, the accumulator piston is pushed slowly to the right by the reverse clutch pressure. As a result, the reverse clutch pressure builds up slowly, reducing the shift shock when there is a shift to REVERSE.