Mechanical System
MECHANICAL SYSTEMCOMPONENTS:
FUNCTION:
FRONT CLUTCH
Front clutch is engaged at 3rd gear of D range and R range. When it is engaged, reverse sun gear of the planetary gear rotates.
Power flow:
Input shaft-> Rear clutch retainer-> Front clutch-> Kick-down drum-> Reverse sun gear-> Long pinion-> Ring gear-> Transfer driven gear
REAR CLUTCH
Rear clutch is engaged at 1st-3rd gear of D/2/L range. When it is engaged, forward sun gear of the planetary gear rotates.
Power flow:
Input shaft-> Rear clutch retainer-> Rear clutch-> Rear clutch hub-> Forward sun gear-> Short pinion
END CLUTCH
End clutch is engaged at 4th gear (Actually, end clutch is being engaged from 3rd gear.
This is only for smooth shifting to 4th gear).
When it operates, planetary carrier rotates.
Power flow:
Input shaft-> End clutch retainer-> End clutch-> End clutch hub-> End clutch shaft-> Planetary carrier -> Ring gear-> Transfer driven gear
KICK DOWN BRAKE
End clutch is composed of a kick down brake band, drum, servo piston and servo switch. It is engaged at 2nd & 4th gear. When it operates, reverse sun gear of the planetary gear is held.
Power flow:
Kick down brake-> Kick down drum hold-> Reverse sun gear hold
The kickdown brake is a band type brake; it is composed of a kickdown band, drum, kickdown servo, switch and anchor. When the 2nd pressure is admitted to the apply side chamber of kickdown servo cylinder, the kickdown piston and rod moves toward the left, tightening the brake band to hold the kickdown drum. As a result, the reverse sun gear (interlocked with the kickdown drum) is held. This brake functions during 2nd gear and during overdrive. The kickdown servo switch detects the position of the kickdown piston just before the brake is applied, and sends the signal to the transaxle control module. Using this signal, the transaxle control module controls the 2nd pressure both before, and during application of the brake. In the initial control stage or until just before the kickdown brake is applied, a higher 2nd pressure is supplied to the kickdown servo so that the kickdown piston con move quickly for faster response to the kickdown condition that has been initiated. In the second control stage or while the brake is being applied, the 2nd pressure is regulated at an optimum level so that the band is tightened on the drum the proper amount for good kickdown "feeling".
LOW& REVERSE BRAKE
Low & Reverse brake is engaged at 1st gear of L range and R range. When it operates, the planetary carrier is held.
Power flow:
Low & Reverse brake-> Planetary carrier hold
Low & reverse brake is of the multiple disc type and is composed of a center support, disc plates and a piston. The brake operates when the shift is in 1st gear in the "L" range or back gear. It fastens the carrier in the planetary gearing set. That is, the shafts of the long and short pinions are fastened.
ONE WAY CLUTCH (O.W.C)
One-way clutch is of the sprag type and is incorporated between the pinion carrier and the center support.
In 1st gear (D or 2 range), the long pinion rotates clockwise. This reduces a force which has the tendency to cause the carrier is blocked from rotating in that direction by the one-way clutch. As a result, the long pinion transmits its force to the annulus gear. The carrier, which is coupled with the one-way clutch outer race, is free to turn in clockwise direction. In an engine braking condition under which the annulus gear is turned first, the carrier turns clockwise freely and, therefore, the engine braking effect is not obtained.
PLANETARY GEAR
The planetary gear set incorporated in this transaxle consists of a forward sun gear, a reverse sun gear, a short pinion, a carrier to support both pinions, and an annulus gear.
The reverse sun gear is connected to the front clutch retainer via the kickdown drum, while the forward sun gear is connected to the rear clutch hub.
The carrier is built in one unit with the low reverse brake's hub and the outer race of the one-way clutch. The carrier is connected to the end clutch via the end clutch shaft.
The annulus gear, to which the output flange is connected, conveys driving force to the transfer drive gear installed on the output flange. And the parking sprag is provided on the outer circumference of the annulus gear.
The Ravigneaux type planetary gear set consists of two sun gears, each meshing with one of two sets of planetary pinion gears in a single carrier, and a single annulus gear that meshes with one of the sets of pinions. The two sun gears are called the forward and the reverse sun gears, for the gear conditions they operate in. Power input is to either of these two sun gears. Power output is through the annulus gear, which has the parking sprag on the outer circumstance. Various holding elements are built into gear set components.Ravigneaux type planetary gear ratio.
PARKING MECHANISM
When the shaft is in the "P" range, the parking pawl engages with the parking sprag provided on outer circumference of the annulus gear to fasten the output shaft, to prevent the wheels from rotating. In other words, when the select lever is set to the "P" range, the detent plate and the parking sprag rod move in the direction of arrow, causing the cam on the parking sprag rod to push up the parking pawl to engage with the sprag.
In case the parking pawl collides against a crest of the sprag, only the rod moves because the parking pawl cannot be moved upward, and the cam, while pressing the spring, collides with the parking pawl and the support, and is with held in this condition. If the car is moved even slightly in this condition, the turning of wheels causes the annulus gear to turn as well. Since the cam is pressed in the direction of arrow, the parking pawl is pushed up as a bottom of the sprag aligns with the parking sprag to engage with the sprag.
In this way, the parking mechanism eliminates any chances of the vehicle from being.
