The automatic transmission is a combination of 3-element 2-phase 1-stage torque converter and double shaft electrocally-controlled unit which provides 4 speeds forward and 1 reverse. The entire unit is in line with the engine.
The torque converter consists of a impeller(pump), turbine and stator assembly in a single unit. The pump is connected to the engine crankshaft and turns as the engine turns. This drawing force is transmitted to the turbine through the oil which is recycled to the by the stator.
The transmission has two parallel shafts ; the input shaft, the output shaft. Both shafts are in line with the engine crankshaft. The input shaft includes the overdrive clutch, reverse clutch, underdrive clutch, way clutch, 2ND brake, low&reverse brake, overdrive planetary carrier, output planetary carrier and transfer drive gear. The output shaft includes the transfer driven gear.
The gear changing mechanism utilizes three multi-disc clutches. The retainers of these clutches are fabricated from high-precision sheet metal for lightness and ease of production. Also, more responsive gearshifts at high engine speeds are achieved by a pressure-balanced piston mechanism that cancels out centrifugal hydraulic pressure. This mechanism replaces the conventional ball check valve.
The underdrive clutch operates in 1st, 2nd, and 3rd gears and transmits driving force from the input shaft to the underdrive sun gear(A).
The components comprising the under clutch are as illustrated on the below.
Hydraulic pressure acts in the piston pressure chamber(B) (between the piston(c) and retainer) and thus pushes the piston(C). In turn, the piston depresses the clutch discs and thereby transmits driving force from the retainer(D) to the hub(E) side.
At high speed, fluid remaining in the piston pressure chamber is subjected to centrifugal force and attempts to push the piston.
However, fluid in the balance fluid chamber(A) (the space between the piston and return spring retainer(B)) is also subjected to centrifugal force.
Thus, the hydraulic pressure on one side of the piston cancels out the hydraulic pressure on the other side, and the piston does not move.
The reverse clutch(C) operates when the reverse gear is selected and transmits driving force from the input shaft to the reverse sun gear.
The overdrive clutch(D) operates in 3rd and 4th gears and transmits driving force from the input shaft to the overdrive planetary carrier and low-reverse annulus gear.
The gear changing mechanism utilizes two multi-disc brakes.
The low-reverse brake(A) operates in 1st and reverse gears, when the vehicle is parked, and during manual operation. It locks the low-reverse annulus gear and overdrive planetary carrier to the case.
The second(C) brake(B) operates in 2nd and 4th gears and locks the reverse sun gear(D) to the case.
The components comprising the low-reverse brake and second brake are as illustrated on the below.
As shown, the discs and plates of the two brakes are arranged on either side of the rear cushion plate(E), which is itself secured to the case(F) by a snap ring.
Hydraulic pressure is applied to the LR brake and the RED brake, so power is not transmitted from the input shaft to the UD clutch or OD clutch, and the output shaft is locked by the park brake pawl interlocking the park gear.
Hydraulic pressure is applied to the LR brake(A) and the RED brake, so power is not transmitted from the input shaft to the UD clutch or OD clutch.
Hydraulic pressure is applied to the UD clutch(B) the LR brake(A) and the one way clutch(OWC), then the UD clutch transmits driving force from the input shaft to the UD sun gear, and the LR brake locks the LR annulus gear to the case.The UD sun gear of the planetary gear drives the output pinion gear, and the LR brake locks the annulus gear, and the output pinion drives the output carriers, and the output carrier drives the transfer drive gear, and the transfer drive gear drives the transfer driven gear of the output shaft, and power is transmitted to the differential gear through the differential drive gear.
Hydraulic pressure is applied to the UD clutch(A) the 2nd brake(B) and the one way clutch(OWC), then the UD clutch transmits driving force from the input shaft to the UD sun gear, and the 2nd brake locks the reverse sun gear to the case.The UD sun gear of the planetary gear drives the output pinion gear and the LR annulus gear, and the LR annulus gear drives the OD planetary carriers, and OD planetary carriers drivers OD pinion gear, and the OD pinion gear drives the output carriers, and the output carrier drives the transfer drive gear, and the transfer drive gear drives the transfer driven gear of the output shaft, and power is transmitted to the differential gear through the differential drive gear.
Hydraulic pressure is applied to the UD clutch(A) and the OD clutch(B), then the UD clutch transmits driving force from the input shaft to the UD sun gear, and the OD clutch transmits driving force from the input shaft to the overdrive planetary carrier and low-reverse annulus gear.The UD sun gear of the planetary gear drives the output pinion gear and the LR annulus gear, and the LR annulus gear drives the OD pinion gear through the OD planetary carrier, and the OD pinion gear drives the reverse sun gear and the output carrier.The OD clutch drives the OD carrier, and the OD carrier drives the OD pinion gear, and the OD pinion gear drives the reverse sun gear and the output carrier, and the output carrier drives the transfer drive gear, and the transfer drive gear drives the transfer driven gear of the output shaft, and power is transmitted to the differential gear through the differential drive gear.
Hydraulic pressure is applied to the OD clutch(A) and the 2nd brake(B), then the OD clutch transmits driving force from the input shaft to the OD planetary carrier and LR annulus gear, and the 2nd brake locks the reverse sun gear to the case.The OD clutch drives the OD carrier, and the OD carrier drives the OD pinion gear and the LR annulus gear, and the OD pinion gear drives the output carrier, and the output carrier drives the transfer drive gear, and the transfer drive gear drives the transfer driven gear of the output shaft, and power is transmitted to the differential gear through the differential drive gear.
Hydraulic pressure is applied to the reverse clutch(A) and the LR brake(B), then the reverse clutch transmits driving force from the input shaft to the reverse sun gear, and the LR brake locks the LR annulus gear and OD planetary carrier to the case.The reverse clutch drives the reverse sun gear, and the reverse sun gear drives the output carrier through the OD pinion gear, and the output carrier drives the transfer drive gear, and the transfer drive gear drives the transfer driven gear of the output shaft, and power is transmitted to the differential gear through the differential drive gear.
The electronic control system consists if the transmission control module (TCM), sensors and solenoid valves. Shifting is electronically controlled for comfortable drivine under all conditions.
The TCM is located below the dashboard. However, in the ß-engine vegicles, there is not TCM but PCM.
As can be seen in the solenoid valve layout below,there are major differences between the previous A/T and New A/T.
In previous A/T, there were only two solenoid valves to enable shift andone solenoid valve to control hydraulic pressure which resulted ininaccurate shift and rough ride.
In the new A/T which is adopted for the EF and XG-Car, there aresolenoid valves for each clutch & brake which enable control of both thedisengaging and engaging clutch simultaneously for independentcontrol. This system provides a much smoother shift and comfortableride as well as preventing Engine run-up or clutch interlock. In additionto advanced shift feeling, the 1st gear is selected at the creep state foreliminating the shift shock during 2nd gear → 1st gear.
The turbine speed is monitored and controlled during shifting tosatisfy target turbine speed which is accomplished by feedbackcontrol of solenoid valve duty value. Therefore the compensation oftorque for the outworn engine or A/T is possible. This has resultedin the ability to control the change in torque during shifting andproduce smooth shift and better shift feeling. Feedback shift controlis also applicable in N→D and N→R.
To prevent damage to transaxlecomponents make sure that themanual control lever and the park /neutral switch have been removedbefore attempting to remove thevalve body.
Be careful not to lose two steelballs on the valve body whenremoving and installing the valvebody.
The valve body mounting bolts have different lengths. Note the locationsof the bolts to aid in assembly.
Torque converter pressure control valve : The function of this valve is to maintain a constant pressurewithin the torque converter.
Damper clutch control valve : Its function is to control the hydraulic pressure that acts on theDamper Clutch.
Manual valve :The position of the manual valve is determined by the selectorlever and applies or cuts line pressure to different valves.
Pressure control valve & Solenoid valve : The pressure control valve prevents a rapid decrease in hydraulicpressure when the clutch becomes disengaged. It also reducesthe sharp increase in input shaft speed during clutch to clutchcontrol.
Switch valve : When the OD clutch is applied, the hydraulic pressure is appliedto the regulator valve via the switch valve. Hence, the linepressure is reduced at 3rd and 4th gear.
Fail Safe Valve-A : During fail safe mode, this valve releases the pressure in the LRBrake.
Fail Safe Valve-B : During fail safe mode, this valve cuts the pressure from the 2ndpressure control valve to 2nd brake.
Fail Safe Valve-C : 5A/T-F5A51 onlyDuring fail safe mode, this valve cuts the pressure from switchvalve to direct clutch.
The Lock-up clutch is designed in a torque converter for the fuel economy.The lock-up clutch works in low speed range as minor slip.And it operates in high speed range as Full lock-up. Low fuel consumption andsilence can be obtained with combination of Partial lock-up and Full lock-up control.The damper clutch is operated in 3rd and 4th gear in 4-speed ATA, 4th and 5th gearin 5ATA.In addition, Lock-up control is adapted in order to improve the fuel economy, whenreducing vehicle speed too.
As all the conditions below are satisfied, it locked up. The cross point of throttleopening and turbine rpm is within shadowed area.
D range (more than 2’nd speed), but damper clutch operating in 2’nd speed, theATF temperature must be higher than 125 ℃.
The TCM does not control under N → D or N → R.
Oil temperature is above 50℃ under full lock-up.
Oil temperature is above 70℃ under minor slip.
The system is not under Fail - Safe (3’rd gear hold) condition.
Uphill (above 5%) longer than 1.5sec. : Reducing speed Lock-upDuring this control, the vehicle is running uphill (less than 2.5%) for 1sec., thepartial lock-up control is functioned again.
The TCM controls the solenoid valves. The conditions of the solenoid valve and positions of the solenoid valve are as follows :
The LR solenoid valve is turned off, and the LR pressure solenoid valve is moved to the left side.
The 2nd solenoid valve is turned on, and the 2nd pressure solenoid valve remains in the right side.
he UD solenoid valve is turned on, and the UD pressure solenoid valve remains in the right side.
The OD solenoid valve is turned on, and the OD pressure solenoid valve remains in the right side.
The line pressure is supplied to the regulator valve and the fail-safe valve A.
The line pressure is supplied to the each element (fail-safe valve B, switch valve, DCCV, LR solenoid valve, LR pressure control valve).
The fail-safe valve B moves to the left side by the line pressure through manual valve.
The switch valve moves to the left side by the line pressure.
The line pressure is supplied to the DCCV, and DCCV moves to the right side.
The line pressure is supplied to the LR pressure control valve and the LR solenoid valve, and TCM turns off the LR solenoid valve, so the line pressure is supplied to the LR brake through the switch valve and the fail-safe valve A.
The regulator valve moves to the left side by the line pressure through the manual valve, and the line pressure is supplied to the torque converter pressure control valve and the oil pump.
The TCM controls the solenoid valves. The conditions of the solenoid valve and positions of the solenoid valve are as follows :
The LR solenoid valve is turned off, and the LR pressure solenoid valve is moved to the left side.
The 2nd solenoid valve is turned on, and the 2nd pressure solenoid valve remains in the right side.
The UD solenoid valve is turned off, and the UD pressure solenoid valve is moved to the left side.
The OD solenoid valve is turned on, and the OD pressure solenoid valve remains in the right side.
The line pressure is supplied to the regulator valve and the fail-safe valve A.
The line pressure is supplied to the each element (fail-safe valve B, switch valve, damper clutch control valve, LR solenoid valve, LR pressure control valve).
he line pressure through the manual valve is supplied to the each element (DCCV, 2nd solenoid valve, 2nd pressure control valve, OD solenoid valve, OD pressure control valve, UD solenoid valve, UD pressure control valve).
The fail-safe valve B moves to the left side by the line pressure.
The switch valve moves to the left side by the line pressure.
The line pressure is supplied to the DCCV, and TCM turns off the DCCSV, so the DCCV remains in the right side
The line pressure is supplied to the LR pressure control valve and the LR solenoid valve, and TCM turns off the LR solenoid valve, so the line pressure is supplied to the LR brake through the switch valve and the fail-safe valve A.
The line pressure is supplied to the UD pressure control valve and the UD solenoid valve, and TCM turns off the UD solenoid valve, so the line pressure is supplied to the UD clutch and the fail-safe valve B.
The regulator valve moves to the left side by the line pressure through the manual valve, and the line pressure is supplied to the torque converter pressure control valve and the oil pump.
The TCM controls the solenoid valves. The conditions of the solenoid valve and positions of the solenoid valve are as follows :
The LR solenoid valve is turned on, and the LR pressure solenoid valve remains in the right side.
The 2nd solenoid valve is turned off, and the 2nd pressure solenoid valve is moved to the left side.
The UD solenoid valve is turned off, and the UD pressure solenoid valve is moved to the left side.
The OD solenoid valve is turned on, and the OD pressure solenoid valve remains in the right side.
The line pressure is supplied to the regulator valve and the fail-safe valve A.
The line pressure is supplied to the each element (fail-safe valve B, switch valve, damper clutch control valve, LR solenoid valve, LR pressure control valve).
The line pressure through the manual valve is supplied to the each element (DCCV, 2nd solenoid valve, 2nd pressure control valve, OD solenoid valve, OD pressure control valve, UD solenoid valve, UD pressure control valve).
The fail-safe valve B moves to the right side by the line pressure through 2nd pressure control valve and the line pressure through the UD pressure control valve.
The pressure through the manual valve is supplied to the fail-safe valve A, and the fail-safe valve A moves to the left side
The switch valve moves to the left side by the line pressure.
The line pressure is supplied to the DCCV and the DCCSV, and TCM turns off the DCCSV, so the DCCV remains in the right side
The line pressure is supplied to the 2nd pressure control valve and the 2nd solenoid valve, and TCM turns off the 2nd solenoid valve, so the line pressure is supplied to the 2nd brake and the fail-safe valve A through the fail-safe valve B.
The line pressure is supplied to the UD pressure control valve and the UD solenoid valve, and TCM turns off the UD solenoid valve, so the line pressure is supplied to the UD clutch and the fail-safe valve B.
The regulator valve moves to the left side by the line pressure through the manual valve, and the line pressure is supplied to the torque converter pressure control valve and the oil pump.
The TCM controls the solenoid valves. The conditions of the solenoid valve and positions of the solenoid valve are as follows :
The LR solenoid valve is turned on, and the LR pressure solenoid valve remains in the right side.
he 2nd solenoid valve is turned on, and the 2nd pressure solenoid valve remains in the right side.
The UD solenoid valve is turned off, and the UD pressure solenoid valve is moved to the left side.
The OD solenoid valve is turned off, and the OD pressure solenoid valve is moved to the left side.
The line pressure is supplied to the regulator valve and the fail-safe valve A.
The line pressure is supplied to the each element (fail-safe valve B, switch valve, DCCV, LR solenoid valve, LR pressure control valve).
The line pressure through the manual valve is supplied to the each element (DCCSV, 2nd solenoid valve, 2nd pressure control valve, OD solenoid valve, OD pressure control valve, UD solenoid valve, UD pressure control valve).
The fail-safe valve B moves to the right side by the line pressure through the UD pressure control valve and the line pressure through the OD pressure control valve.
The pressure is supplied to the fail-safe valve A through the OD pressure control valve, but the fail-safe valve A does not move to the right side
The line pressure is supplied to the DCCV and the DCCSV, and TCM turns on the DCCSV, and the DCCV moves to the left side, and the damper clutch is operated.
The line pressure is supplied to the UD pressure control valve and the UD solenoid valve, and TCM turns off the UD solenoid valve, so the line pressure is supplied to the UD clutch and the fail-safe valve B.
The line pressure is supplied to the OD pressure control valve and the OD solenoid valve, and TCM turns off the OD solenoid valve, so the line pressure is supplied to the OD clutch and the fail-safe valve A/B and the switch valve.
The switch valve moves to the right side by the line pressure through the OD pressure control valve.
The regulator valve moves to the left side by the pressure through the manual valve and the pressure through the switch valve, and the line pressure is more supplied to the oil pump.
The TCM controls the solenoid valves. The conditions of the solenoid valve and positions of the solenoid valve are as follows :
The LR solenoid valve is turned on, and the LR pressure solenoid valve remains in the right side.
The 2nd solenoid valve is turned off, and the 2nd pressure solenoid valve is moved to the left side.
The UD solenoid valve is turned on, and the UD pressure solenoid valve remains in the right side.
The OD solenoid valve is turned off, and the OD pressure solenoid valve is moved to the left side.
The line pressure through the manual valve is supplied to the regulator valve and the fail-safe valve A.
The line pressure is supplied to the each element (fail-safe valve B, switch valve, DCCV, LR solenoid valve, LR pressure control valve).
The line pressure through the manual valve is supplied to the each element (DCCSV, 2nd solenoid valve, 2nd pressure control valve, OD solenoid valve, OD pressure control valve, UD solenoid valve, UD pressure control valve).
The fail-safe valve B moves to the right side by the line pressure through the 2nd pressure control valve and the line pressure through the OD pressure control valve.
The line pressure through the OD pressure control valve is supplied to the fail-safe valve A, and the fail-safe valve A moves to the right side by the line pressure through the fail-safe valve B and the line pressure through the OD pressure control valve.
The line pressure is supplied to the DCCV and the DCCSV, and TCM turns on the DCCSV, so DCCV moves to the right side, and the damper clutch is operated.
The line pressure is supplied to the OD pressure control valve and the OD solenoid valve, and TCM turns off the OD solenoid valve, so the line pressure is supplied to the OD clutch and the fail-safe valve A/B and the switch valve.
The line pressure is supplied to the 2nd pressure control valve and the 2nd solenoid valve, and TCM turns off the 2nd solenoid valve, so the line pressure through the 2nd pressure control valve is supplied to the 2nd brake through the fail-safe valve B.
The regulator valve moves to the left side by the line pressure through the manual valve and the line pressure through the switch valve, and the line pressure is more supplied to the oil pump.
The TCM controls the solenoid valves. The conditions of the solenoid valve and positions of the solenoid valve are as follows :
The LR solenoid valve is turned off, and the LR pressure solenoid valve is moved to the left side.
The 2nd solenoid valve is turned on, and the 2nd pressure solenoid valve remains in the right side.
The UD solenoid valve is turned on, and the UD pressure solenoid valve remains in the right side.
The OD solenoid valve is turned on, and the OD pressure solenoid valve remains in the right side.
The line pressure through the manual valve is supplied to the reverse clutch and the fail-safe valve B.
The line pressure is supplied to the each element (fail-safe valve B, switch valve, DCCV, LR solenoid valve, LR pressure control valve).
The fail-safe valve B moves to the left side by the line pressure.
The switch valve moves to left side by the line pressure, and the line pressure through the LR pressure control valve is supplied to the LR brake through the fail-safe valve A.
The line pressure is supplied to the DCCV, so the DCCV remains in the right side.
The fail-safe valve A moves to the right side by the line pressure through the switch valve.
The line pressure is supplied to the LR pressure control valve and the LR solenoid valve, and TCM turns off the LR solenoid valve, and the line pressure is supplied to the LR brake through the LR pressure control valve and the switch valve and the fail-safe valve A.
The regulator valve moves to the right side by the no line pressure through the manual valve, and the line pressure is higher than other range.
